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Savvy Jack

Stretched Frames and Damaged Toggle Links

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This topic is not about shooting other than normal smokeless powder loads replicating original 1,350 fps chamber pressures.

By all means folks, don't shoot "high pressure" loads in a 73'...work with me here...

 

Howdy fellas,

I'd like to see some detailed updates on those damage issues with the 60', 66' and 73' firearms.

1. What firearm

2. What caliber

3. Toggles - original or kit parts 

4. What Loads

5. I would prefer first hand knowledge with photos and actual measurement's 

 

 

73boom.jpg

Edited by Savvy Jack

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Mike Venturino covered this in a couple of chapters of "Shooting Lever Guns of the Old West. Most of the problems for the "Brass" frame guns can be avoided by using "Cowboy" level loads. I just ordered 250 rounds from Choice ammo for my .44-40 '66 for this very reason.

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13 minutes ago, DeaconKC said:

Mike Venturino covered this in a couple of chapters of "Shooting Lever Guns of the Old West. Most of the problems for the "Brass" frame guns can be avoided by using "Cowboy" level loads. I just ordered 250 rounds from Choice ammo for my .44-40 '66 for this very reason.

 

True, but my question is for examples, Thanks!

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4 hours ago, Savvy Jack said:

Howdy fellas,

I'd like to see some detailed updates on those damage issues with the 60', 66' and 73' firearms.

1. What firearm

2. What caliber

3. Toggles - original or kit parts 

4. What Loads

5. I would prefer first hand knowledge with photos and actual measurement's 

 

 

73boom.jpg

 

Nothing a little duct tape and bailing wire wouldn't fix!! 

 

:D:D:D

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This probably won't help either, but I know there has been a Henry on the shelf at Cimarron for around 20 years that a customer sent in because for repair, but the frame was stretched.  When he found out how much it was going to cost (new frame plus labor) he declined to even get his gun back.  I doubt if anyone will want to take measurements for you, though.  I've always wondered if that gun could be brought back to life with a set of longer links.

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32 minutes ago, Abilene, SASS # 27489 said:

This probably won't help either, but I know there has been a Henry on the shelf at Cimarron for around 20 years that a customer sent in because for repair, but the frame was stretched.  When he found out how much it was going to cost (new frame plus labor) he declined to even get his gun back.  I doubt if anyone will want to take measurements for you, though.  I've always wondered if that gun could be brought back to life with a set of longer links.

 

Any idea of the caliber or how it was being used, hunting, CAS etc?

Edited by Savvy Jack

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46 minutes ago, Savvy Jack said:

 

Any idea of the caliber or how it was being used, hunting, CAS etc?

I think it is 44-40 but that's all I know, sorry.  It was on the shelf when I first started working there part time around 2003 or so.  

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I made a pretty good living as a CAS gun smith for 20 plus years.  I specialized in toggle link rifles.  Henry's, '66s and '73.  There was occasional rumor of a Henry or '66 with a stretched frame.  I never saw one.  I never met anyone whom claimed to have one.  I seriously doubt you're going to find an actual example.  That isn't to say it absolutely can't happen.  However, the load or diet of loads that would do that would venture on STUPID.  The rifle would have to be pushed at and beyond 44 Magnum pressure levels.

I have always preferred Brass Rifles.  After several Hundreds of thousands of rounds, I have never hurt one.  Good luck on your quest.

 

The pictures your included are of 1873 rifles (originals) that suffered Bore Obstructions.  You will note, the barrel ruptured before any damage to the links.  The toggle link system is far stronger than most folks imagine.  Most whom claim weakness are simple PARROTING someone else whom also has no real knowledge.

 

YMMV 

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Although I haven't shot it for a while (due to the balance putting a strain on my back), I shot a Navy Arms (Uberti) M1860 Henry, chambered in .44-40, for over 3,000  rounds with a load consisting of a 213.5 gr. bullet ahead of 8.0 gr. Hodgdon's Universal, periodically measuring the headspace.  I found NO CHANGE in the headspace.  Muzzle velocity measured around 1230 ft/sec.  As CC stated, the toggle link system is fairly tough, if you don't abuse it.  Repeated shooting of WHV ammo or similar might stretch a brass frame receiver, but I would have to subject the metal to some metallurgical tests to determine if there might have been the wrong choice in the bronze or gunmetal alloy, compared with Uberti-made guns.

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13 hours ago, Colorado Coffinmaker said:

 

I made a pretty good living as a CAS gun smith for 20 plus years.  I specialized in toggle link rifles.  Henry's, '66s and '73.  There was occasional rumor of a Henry or '66 with a stretched frame.  I never saw one.  I never met anyone whom claimed to have one.  I seriously doubt you're going to find an actual example.  That isn't to say it absolutely can't happen.  However, the load or diet of loads that would do that would venture on STUPID.  The rifle would have to be pushed at and beyond 44 Magnum pressure levels.

I have always preferred Brass Rifles.  After several Hundreds of thousands of rounds, I have never hurt one.  Good luck on your quest.

 

The pictures your included are of 1873 rifles (originals) that suffered Bore Obstructions.  You will note, the barrel ruptured before any damage to the links.  The toggle link system is far stronger than most folks imagine.  Most whom claim weakness are simple PARROTING someone else whom also has no real knowledge.

 

YMMV 


Thanks Colorado, I am glad you noticed it. That is exactly why I posted it. I also agree that I think what we hear is hogwash for the most part and just parroting hearsay. Doesn't mean there may be a few here or there for one reason or another. How do the strength of the toggle kits hold up?

As most here may know, my armature pressure testing with the Pressuretrace system yielded most factory cas loads barely hit 6,000psi while Winchester Super-X hunting loads came in at a whopping 6,600psi. Most Lyman 49th Group I (Winchester 73' types) max loads came in at 9,300psi while most Lyman Group II (Winchester 92/Marlin 94 types) came in 15,000psi to 18,000psi...18,000psi being close to 22,000 cup. ...and we all know the 73' came out in 44 magnum as well proving the toggles are not as weak as most think in the replica 73's. On a side note, notwithstanding pressure curves, my testing of swiss FFg black powder loads (.17" compression) in original semi-balloonhead pre-1884 cases yielded 14,000psi. Those same loads in starline brass (.21" compression) yielded 8,953psi. Goes FFFg loads in early headstamp cases yielded 12,500psi while WRA headstamped cases yielded 11,001 psi. Velocities were 1,373, 1,226, 1,350 and 1,272 respectively, paralleling advertised velocities during those years. CCI 300 primers were used. Small pistol primers used in some small primer pocket cases (1,276fps).

Early smokeless powder (Dupont #2 rifle powder) reported to produce even less pressures than black, to include flatter pressure curves. It seems that the higher pressures and sharper pressure curves came about with the transition into the faster burning 16gr of Sharpshooter which, if I was a betting man, would bet would be 12,000 psi to 13,500 psi (13,500 cup to 14,000 cup) loads.  

Sharpe - Complete Guide to Handloading, 1937 Load Data

Hercules Sharpshooter Powder

  • Revolver - 200gr Lead, 16.8gr, 905fps @ 15,000cup

  • Rifle - 200gr JSP, 14gr, 1,260fps

  • (Winchester factory loads had 16gr @ 1,325 fps, 1944)

  • Rifle - 200gr JSP, 17.3gr, 1,505fps @ 14,000cup

  • Rifle - 200gr JSP, 19.6gr, 1,680fps @ 20,000cup (maybe 18,000 psi)

The 1930's seems to be were guys were pushing these 92' type rifles to their limits with up to 30,000 cup loads. That's nuts! I pushed some with 12gr of Unique (simulated double charge of 6gr) in the 1 1/4" diameter test barrel and yielded 21,786 psi ( well in excess of 22,000 cup). A double charge or even a triple charge of Bullseye could go undetected and create a bomb!

Back to the toggles, I certainly don't think they are as weak as most claim. They can probably wear out but that is a different story.

 

 

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Absolutely, this topic is not about shooting other than normal smokeless powder loads replicating original 1,350 fps chamber pressures.

By all means folks, don't shoot "high pressure" loads in a 73'

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You think stretched frames and damaged toggle link myths and hearsay might of began when people used black powder guns, and the new smokeless powders during the early 20th century?  Years back I met a Winchester collector who told me he came across guns that were damaged/blown up due to people not paying attention to detail and loading ammo with smokeless, and filling it up like you do with black.  Then gun went boom.  Don't know if he was fibbing, but I can picture that happening.

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Here are two examples.  Both factory stock. The 73' with damaged links, sheared the pin in the links creating excess heads pace.  357

The 66' in 44-40 is and old uberti.  The frame is stretched and tweaked badly.  The side plates and top parallel are the indicators.  The bolt would not cycle.  This rifle is a wall hanger

20151008_083521.jpg

20140829_100055.jpg

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Both of those rifles appear to have been subjected to Gross Overloads of the WRONG powder.

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3 minutes ago, Colorado Coffinmaker said:

 

Both of those rifles appear to have been subjected to Gross Overloads of the WRONG powder.

 

YES  That is my assumption as well.

Contrary to what the owners said.....

 

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I am just grateful to the OP for starting this thread and the folks who have given so much good info!

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1 hour ago, Cemetery said:

You think stretched frames and damaged toggle link myths and hearsay might of began when people used black powder guns, and the new smokeless powders during the early 20th century?  Years back I met a Winchester collector who told me he came across guns that were damaged/blown up due to people not paying attention to detail and loading ammo with smokeless, and filling it up like you do with black.  Then gun went boom.  Don't know if he was fibbing, but I can picture that happening.


I agree...read this,

 

As a reminder, SAAMI's roots trace all the way back to 1913. However, it was not until the 1970's when SAAMI started "...the three decades of transformation and modernization of the firearms and ammunition industry". This is when SAAMI started the transition from the Copper Units of Pressure (CUP) to the more modern piezoelectric transducer chamber pressure measurement system (PSI). It is also during 1976 that the 44-40 factory loads were cut down to a safety percentage below factory Max.

 

One of the things I wanted to do was try and test original vintage factory loads and compare the pressures. At the time I was testing with the Pressuretrace strain gauge, I did not have any "reliable" amounts of vintage ammunition to test...now I do. The other problem is that the program stopped working with my laptop and I am now to understand it was probably a computer update issue. Most guys have a dedicated laptop that they never hook up to the internet.

 

With that, I feel very confident that pre-1976 (and definitely pre-1950's) factory loads probably maxed or exceeded the 11,000psi SAAMI max loads limit. While the quality of the arms and ammunitions excelled, the "red tape" caused performance to plummet.

 

In 1925, the major objective SAAMI was faced with was "...a major reduction of obsolete and nearly obsolete black powder and semi‐smokeless powder loads for both shotshells and metallic cartridges. When that undertaking was complete, the number of shotshell loads had been reduced by 95 percent and metallic cartridge loads by 70 percent"...according to their website. Although I have no idea when that "project" was complete, it was during the mid to late 1930's that the loads for the 44-40 were loaded so hot (Sharp even claims up to 30,000 [cup] with handloads, most even too hot for my liking! The 1930's was also the time when their High Velocity loads jumped up from a "low pressure" to 22,000 cup.

 

By the 1940's, SAAMI claimed that "...Since that time (referring to the 1940's publishing of "The Ten Commandments of Safety"), fatal firearm accidents have decreased dramatically and are currently at historic low levels".

 

All of this completely falls in line with what I have experienced in my testings. When SAAMI came up with 13,000 cup at some point, the 44-40 rifle performance plummeted.

 

The 1940's is when Winchester stopped manufacturing the 44-40 High Velocity loads, and the 1970's is when Winchester neutered normal factory loads. So called High Velocity loads were still manufactured by Remington but they were nowhere near what they used to be and were basically what normal loads used to be prior to the 60's. Remington's High Velocity loads by that time were noted safe for all firearms....not true for original HV loads. Top it all off by more modern High Power rifles...it all makes sense on why the 44-40 lost popularity and was phased out. It is certainly understandable because in the mid 1970's when I was ten and started hunting, I favored the Remington 742 30-06' and has always been a favorite of mine. Although I did hunt at that time with the 44-40, it was not until later that I started to have a desire to return to the older girl and not till the advent of the internet where I was able to really dig into the history.

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1 hour ago, El Mulo Vaquero, SASS #55942 said:

Here are two examples.  Both factory stock. The 73' with damaged links, sheared the pin in the links creating excess heads pace.  357

The 66' in 44-40 is and old uberti.  The frame is stretched and tweaked badly.  The side plates and top parallel are the indicators.  The bolt would not cycle.  This rifle is a wall hanger

20151008_083521.jpg

20140829_100055.jpg



Can I use these photos and explanation on the 44-40 website? If so can I credit you name or remain anonymous? I would like to add it here:
 

 

Untitled.jpg

and would look something like this
https://sites.google.com/view/44winchester/handloading/stretched-brass-frames-and-damaged-toggles

Edited by Savvy Jack

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1 hour ago, Savvy Jack said:



Can I use these photos and explanation on the 44-40 website? If so can I credit you name or remain anonymous? I would like to add it here:
 

 

Untitled.jpg

and would look something like this
https://sites.google.com/view/44winchester/handloading/stretched-brass-frames-and-damaged-toggles

 

Sure, you can use it

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58 minutes ago, El Mulo Vaquero, SASS #55942 said:

 

Sure, you can use it

 

Thanks, I'll see what else I can find to go along with them!

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7 hours ago, Savvy Jack said:


Thanks Colorado, I am glad you noticed it. That is exactly why I posted it. I also agree that I think what we hear is hogwash for the most part and just parroting hearsay. Doesn't mean there may be a few here or there for one reason or another. How do the strength of the toggle kits hold up?

As most here may know, my armature pressure testing with the Pressuretrace system yielded most factory cas loads barely hit 6,000psi while Winchester Super-X hunting loads came in at a whopping 6,600psi. Most Lyman 49th Group I (Winchester 73' types) max loads came in at 9,300psi while most Lyman Group II (Winchester 92/Marlin 94 types) came in 15,000psi to 18,000psi...18,000psi being close to 22,000 cup. ...and we all know the 73' came out in 44 magnum as well proving the toggles are not as weak as most think in the replica 73's. On a side note, notwithstanding pressure curves, my testing of swiss FFg black powder loads (.17" compression) in original semi-balloonhead pre-1884 cases yielded 14,000psi. Those same loads in starline brass (.21" compression) yielded 8,953psi. Goes FFFg loads in early headstamp cases yielded 12,500psi while WRA headstamped cases yielded 11,001 psi. Velocities were 1,373, 1,226, 1,350 and 1,272 respectively, paralleling advertised velocities during those years. CCI 300 primers were used. Small pistol primers used in some small primer pocket cases (1,276fps).

Early smokeless powder (Dupont #2 rifle powder) reported to produce even less pressures than black, to include flatter pressure curves. It seems that the higher pressures and sharper pressure curves came about with the transition into the faster burning 16gr of Sharpshooter which, if I was a betting man, would bet would be 12,000 psi to 13,500 psi (13,500 cup to 14,000 cup) loads.  

Sharpe - Complete Guide to Handloading, 1937 Load Data

Hercules Sharpshooter Powder

  • Revolver - 200gr Lead, 16.8gr, 905fps @ 15,000cup

  • Rifle - 200gr JSP, 14gr, 1,260fps

  • (Winchester factory loads had 16gr @ 1,325 fps, 1944)

  • Rifle - 200gr JSP, 17.3gr, 1,505fps @ 14,000cup

  • Rifle - 200gr JSP, 19.6gr, 1,680fps @ 20,000cup (maybe 18,000 psi)

The 1930's seems to be were guys were pushing these 92' type rifles to their limits with up to 30,000 cup loads. That's nuts! I pushed some with 12gr of Unique (simulated double charge of 6gr) in the 1 1/4" diameter test barrel and yielded 21,786 psi ( well in excess of 22,000 cup). A double charge or even a triple charge of Bullseye could go undetected and create a bomb!

Back to the toggles, I certainly don't think they are as weak as most claim. They can probably wear out but that is a different story.

 

 

What system does the Pressuretrace use to detect pressure?  I have used the Oehler M43PBL system, but haven't had a range to use it recently.  Besides which, I hate having to cement the strain gages to the barrels of my guns, as, first of all, the chemicals have to be ordered fresh, and it messes up the bluing.   Have you done any tests with Hodgdon's Universal in .44-40?

Thanks for the above data. 

Stay well and safe!

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21 minutes ago, Trailrider #896 said:

What system does the Pressuretrace use to detect pressure?  I have used the Oehler M43PBL system, but haven't had a range to use it recently.  Besides which, I hate having to cement the strain gages to the barrels of my guns, as, first of all, the chemicals have to be ordered fresh, and it messes up the bluing.   Have you done any tests with Hodgdon's Universal in .44-40?

Thanks for the above data. 

Stay well and safe!

 

I used the Pressuretrace II with the strain guage glued to a 1 1/4" diameter MGM barrel set in a custom stand. 
https://sites.google.com/view/44winchester/handloading/pressure-testing

I did not test Universal or Bullseye, two I wish I had tested! I have since shipped the Pressuretrace II module to Larry Gibson who also uses an Oehler to compare results on 44 Magnum loads. https://sites.google.com/view/44winchester/contributors/larry-gibson
 

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Here are some photos of my Uberti 73' that have had countless Max pressure 44-40 loads shot through it with Reloder 7. Notice the unburnt skeletons. I tested 26.5gr of Reloder 7 in the 20"x 1 1/4" MGM "test" barrel with a 217gr 43-215C lead bullet. This was test #72 of 83 (ten shot groups) I performed with various loads of different powders, bullets primers cases etc. This particular load recorded 1,469 fps @ 12,971 psi ( round it up to 13,000 psi) and loose 4" groups at 100 yards.

 

For the Winchester 73', I backed it down to 25.8gr and eventually settled for the 43-214A  cast .428" (.429" bore), 220gr. Velocities are stable at 1,350fps with pressures estimated to be 11,500 psi to 12,500 psi. SAAMI max is 11,000 (MAP) psi, 11,300 psi (MPLM) and  11,700 psi (MSLM) with CCI 300 primers and Starline brass.

So far, no ill results and I am grouping 4" 10 shot groups @ 100 yards. My best group was 3.30" and 3.15 MOA. Having lots of fun at 250 yards as well. I'd go further but that's the furthest range I have had available. Toggles are as tight as they were when I got the rifle and it had already been shot in CAS matches when I got it.

 

120132659_1722246917950938_2084497380675982215_n.jpg

120182213_806714383435873_5866043257315114098_n.jpg

120194440_340201357187061_4880154634008393043_n.jpg

120194885_335566747774239_4942838898909485358_n.jpg

120493741_2744436495830095_2071152090318668485_n.jpg

 

I will continue to shoot these loads and periodically perform "100 hr" & "annual inspections" and keep you updated.!!! If I am incorrect and pressures are actually lower or higher, awesome...great news either way..

.

.

.

.

.

.

Edited by Savvy Jack

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Jack,

What's with "100 hr. & annual inspections"?  That '73 has a scope on it. Does it also have wings and a powerplant? ;)  Sent you a PM.

Stay well and safe!

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5 minutes ago, Trailrider #896 said:

Jack,

What's with "100 hr. & annual inspections"?  That '73 has a scope on it. Does it also have wings and a powerplant? ;)  Sent you a PM.

Stay well and safe!

 

 

hehehehehehehe, yes...it fly's so it must be treated like an airplane!!!  Information replied!!!

72639241_1334123863434860_7280193579329257472_n.jpg

Edited by Savvy Jack

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Posted (edited)

Probably won’t help but aI have an original Winchester ‘73 in 32-20 that had excessive headspace when I got it.  I found that the pins In the frame that hold the links were bent.  I replaced them with drill rod and that solved the problem.   
 

As I’m sure you know, original Winchester’s links were not supposed to have the pressure bear on the pins.  The links were supposed to be machined to bear on the mating machined surfaces on the frame and bolt respectively.  After I replaced the pin in the frame, the links appeared to bear on the frame (rather than the pins) like they were supposed too.  I don’t know how replacing the bent pin resulted in a perfectly fitting link, but that’s what happened.  (I bought a lottery ticket the same day and didn’t win.  So it wasn’t luck.)

Edited by Cypress Sam, SASS #10915
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1 hour ago, Cypress Sam, SASS #10915 said:

Probably won’t help but aI have an original Winchester ‘73 in 32-20 that had excessive headspace when I got it.  I found that the pins In the frame that hold the links were bent.  I replaced them with drill rod and that solved the problem.   
 

As I’m sure you know, original Winchester’s links were not supposed to have the pressure bear on the pins.  The links were supposed to be machined to bear on the mating machined surfaces on the frame and bolt respectively.  After I replaced the pin in the frame, the links appeared to bear on the frame (rather than the pins) like they were supposed too.  I don’t know how replacing the bent pin resulted in a perfectly fitting link, but that’s what happened.  (I bought a lottery ticket the same day and didn’t win.  So it wasn’t luck.)

 

Absolutely, I like reading these experiences. Too bad you couldn't get the history, I bet it could tell some tells. I have a Marlin 1888 made in 91', wish it could talk!

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Posted (edited)

https://sites.google.com/view/44winchester/contributors/john-kort/bolt-thrust-pressure

John Kort writes,

 

Quote

by w30wcf » Wed Nov 06, 2013 10:14 pm

Ok, finally had a chance to test the .44-40 ....... a few days later than anticipated. Life gets in the way sometimes .......

Anyway, the test indicates that the case head did not make contact with the bolt.

I used 2 cases with thinned rims (front) allowing for .015" headspace.

I seated the primers to stand .012" proud of the base of the case then applied 2 small clay pads on either side of the primer to the same .012" thickness.

Cases were loaded with 6.5 / Trail Boss / 215 gr cast bullet. Pressure 13,000 CUP or thereabouts.

Result:

Primer protruding .010" . Clay pads the same. No evidence that the case head touched the bolt since the small clay pads were not distorted as they would have been if the case head touched the bolt face.

I will say that the cases used were not full length sized. Just neck sized as I do all my .44-40's with a special die.

I'll post a pic in the next day or so.

 
 

 

by w30wcf » Mon Nov 11, 2013 11:59 am

I had added a piece of scotch tape over the case head to keep the clay from possible sticking to the bolt face.

I would expect that as pressures would increase, the case head would eventually overcome the primer thrust and reseat the primer but this is specifically a test of low / standard SAMMI pressure for the .44-40......

 

 

 

 

Untitled.jpg

 

With my testing, I recorded 7,224 psi with 6.4gr and 15,182 psi with 9.3gr

Edited by Savvy Jack

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If you think your 73' has been exposed to covid...err...I mean Over Pressures, there is a simple way to check for stretched toggles....or even worn out toggles from wear.

 

There is a quick test you can perform to check your 73's bolt if you suspect the toggles are getting worn or stretched due to wear or over pressures. The obvious is to check the toggles themselves for excessive play. The other is to check the Case head Clearance. (see photos and video)

1. measure the case length of an empty resized case.

2. Finger start a spent primer

3. Insert case into rifle chamber and close bolt. This will push (seat) the primer into the primer pocket. The primer should not seat fully into the primer pocket.

4. Remove and remeasure case length with the primer seated by the bolt

5. Do the math

The goal is have a difference of only .006", my Ubert 73' is .007" and my Marlin is .006"...no change since I got both over ten years ago.

For photos and a video: https://sites.google.com/view/44winchester/contributors/john-kort/bolt-thrust-pressure

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Posted (edited)

Today I tested 6.4gr of trailboss. Scroll to the bottom of the page at the following link: https://sites.google.com/view/44winchester/handloading/bolt-thrust-pressure

 

This test was performed using 6.4gr of Trailboss. I chose this load because it gave me the lowest pressure recordings of my handloads which were higher than Winchester Super-X hunting loads and Magtech Cowboy loads.

 

6.4gr, 220gr

43-214A lead bullet

7,224 psi @ only 925 fps...but we are focused on pressures, not velocities. (Winchester Supoer-X factory loads are 1,025 fps @ only 6,600 psi), I may test some of those loads as well.

Target 16 feet

Penetrated - EDITED: Went through a 1" plywood board...but it traveled between the "surfaces" where two 4x4s were touching each other.

Hit a 1" thick steel plate and came to rest on the concrete floor directly below the steel plate.

 

 

It is obvious here that the pressure was enough at 7,224 psi to thrust the case aft. There is no way that even 12,000 psi is too much for the 60, 66 or 73's bolt, frame or the toggles. 

 

 

 

 

 

 

121107758_1616845455162698_3869472588308205647_o.jpg

I set the steel plate upwards at an angle so the bullet would deflect upwards into  a "shelf" then drop to the floor, which it did!

 

 

121143091_1616845488496028_231024833438933176_o.jpg

I am using a punch rather than the firing pin because I want the pressure to move the punch after, which it did....1 1/2" aft.

 

 

 

121161754_1616845461829364_123440900642859060_o.jpg

121182915_1616845395162704_6037957311264079162_n.jpg

Normal re-seating of the primer as it thrust aft into the blast plate. 

Edited by Savvy Jack

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Being a devil's advocate and asking out of true ignorance on this investigation, because I might learn something from any responses.

 

As I understand how a cartridge operates in a chamber, at low pressures (say 7,000 psi), the case does not swell and stick to the chamber by friction. So it seems to me low pressure rounds might damage a gun.

 

As a rough calculation, if my math is right, a .44" diameter casing subjected to 7,000 psi would exert about a half ton of force on the breech if the case is not held in the chamber by friction from swelling.

 

If this same case contains sufficient pressure to swell the case and stick to the chamber (10,000 psi?), the force on the breech would be negligible.

 

Of course, serious over-pressure can blow the gun apart. Also serious under pressure is a squib.

 

But for low pressure rounds where the case does not seal to the chamber, wouldn't the force on the breech be greater than a higher pressure round that sticks to the chamber?

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Posted (edited)
3 hours ago, John Kloehr said:

Being a devil's advocate and asking out of true ignorance on this investigation, because I might learn something from any responses.

 

As I understand how a cartridge operates in a chamber, at low pressures (say 7,000 psi), the case does not swell and stick to the chamber by friction. So it seems to me low pressure rounds might damage a gun.

 

As a rough calculation, if my math is right, a .44" diameter casing subjected to 7,000 psi would exert about a half ton of force on the breech if the case is not held in the chamber by friction from swelling.

 

If this same case contains sufficient pressure to swell the case and stick to the chamber (10,000 psi?), the force on the breech would be negligible.

 

Of course, serious over-pressure can blow the gun apart. Also serious under pressure is a squib.

 

But for low pressure rounds where the case does not seal to the chamber, wouldn't the force on the breech be greater than a higher pressure round that sticks to the chamber?

 

Excellent!!! I have no idea but I like it. 

However, go back up to my first video. The under pressure never contacted the blast plate. The plate bounced into the case head a little but no force was applied. Another issue would be the primer failed to seal and some pressure could have been released aft, out the the primer pocket.

I also tried a Magtech cartridge with the head space set closer. It did a but better, a little more aft thrust than the Unique load. Higher pressure loads would show any added data since I have no way to check the pressures themselves as they hit the blast plate. Only thing I can really check for is flattened primers but that is not much, even at 18,500 psi for the 44-40.

I think all I did was confirm John's findings, but added it happens at probably a lower pressure then he thought. I think 6k to 7k psi is where it all happens rather than 11k. Like you, 10k may be where the case starts to expand into the chamber walls. I do know with my revolver, I can see imprints of the chamber reamer marks on the case after shooter high pressure loads. But then again, the cylinder wall will expand much sooner than the thicker rifle chamber walls......I TIHNK!

Edited by Savvy Jack

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Posted (edited)
1 hour ago, Savvy Jack said:

 

Excellent!!! I have no idea but I like it. 

Well, I watched your videos and you have some serious (awesome) test equipment.

 

But I got the sense you were moving up in power... And I like using clay on the base of the cartridge (check out Plastiguage, a calibrated deformation plastic for measuring clearances); Platiguage may be for too small a clearance but the idea of any clay makes sense.

 

And I do plan to reload my scavenged modern powder cases and reload with BP (APP) for this sport. I have not yet read "the book" yet which councils some degree of recoil is needed for speed so the absolute minimum to avoid squibs might not be the optimum floor...

 

And your investigation combined with the intended function of sealing the breach by expanding the case in the breach to hold it in place..

 

A little bell went off in my head thinking about these things, I wondered what you might find if you went down in power rather than up...

 

Since that bell went off, I have also considered that polishing a cylinder might increase the minimum required pressure to seal the breach, some degree of "tooth" might be important in firearm longevity to promote friction just like a knife needs some "tooth" to cut a tomato well.

 

Anyway, I am an engineer and know I am getting into areas beyond my expertise. I want to go fast but not at the cost of safety or even damage to my firearms. I eagerly await your findings.

 

On edit: The above quote was all there was before you edited the post. I will read it tomorrow when the tequila wears off (had the tequila after I wrote the above). Just adding this to keep the conversation in sync. I am seriously impressed by your test rig!

Edited by John Kloehr

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13 hours ago, John Kloehr said:

Anyway, I am an engineer and know I am getting into areas beyond my expertise. I want to go fast but not at the cost of safety or even damage to my firearms. I eagerly await your findings.

 

On edit: The above quote was all there was before you edited the post. I will read it tomorrow when the tequila wears off (had the tequila after I wrote the above). Just adding this to keep the conversation in sync. I am seriously impressed by your test rig!

 

I am not an engineer and EVERYTHING is over my head!!!!!

 

Folks by now know when I post something, there is no need to read it until 24 hours after I post it. That gives me plenty of time to edit my errors!!!

 

See I just edited already!!! I forgot to say I have room for the clay so I will read up on it and see what I can do. I guess clay has a certain density and with a certain amount, when compressed, can be measured before and after to get some sort of pressure result. PLEASE DON'T MAKE ME DO MATH!

Edited by Savvy Jack

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