Cylinder Reaming - .45 Colt UPDATED MEASUREMENTS- Now I am confused…

[ShadowCatcher]

15 hours ago, The Original Lumpy Gritz said:

Give Blue Dot a go. 

Trust me on this....

OLG 

In 9mm?  I've been using Titegroup mostly, for 145 gr plated and even for some 100 gr loads (for steel),

lately was going to try some 135 plated using Bullseye. 

 

Is there any available load data for Blue Dot and 9mm lead or plated ammo? 

 

SC

[The Original Lumpy Gritz]

8 hours ago, ShadowCatcher said:

In 9mm?  I've been using Titegroup mostly, for 145 gr plated and even for some 100 gr loads (for steel),

lately was going to try some 135 plated using Bullseye. 

 

Is there any available load data for Blue Dot and 9mm lead or plated ammo? 

 

SC

Never loaded anything but FMJ 124gn in 9mm.

I use 7.5gn of BD. Duplicates the NATO load.

OLG 

[Buckshot Bob]

BD is great for 115 and 124 but takes up allot of case capacity so is not ideal for 147 

[Pat Riot]

I recently tried some test loads with 147 grain TMJ bullets using W244 powder in my Glock 34’s. So far the loads with 3.3 and 3.4 grains of W244 appear to be about the same in accuracy, but I only loaded and fired 5 rounds in each G34 just to see if W244 might be a promising powder for 147 grain 9mm. 
 

My normal 9mm loads are 115 grain TMJ over 5.0 grains of Universal going about 1150 fps. 

[The Rainmaker, SASS #11631]

Umm, what's a Glock?    

[Pat Riot]

2 hours ago, The Rainmaker, SASS #11631 said:

Umm, what's a Glock?    

Perfection!  

[The Rainmaker, SASS #11631]

3 minutes ago, Pat Riot, SASS #13748 said:

Perfection!  

Ugly, drab, Austrian tupperware pistol... that just plain works.

It ain't no Hi Power, but it sure does keep goin!

[ShadowCatcher]

3 hours ago, The Rainmaker, SASS #11631 said:

Ugly, drab, Austrian tupperware pistol... that just plain works.

It ain't no Hi Power, but it sure does keep goin!

The funny brown one is a Glock, the pretty blue steel and wood grips one is my Colt 1911, both in 9mm.

BTW - the 1911 with it's slow twist barrel is really happier with light weight bullets, such as the 100 gr FMJ at

1100 f/s.  Second picture.  It won't shoot 147 gr bullets worth a damn though.

[Pat Riot]

UPDATE:

 

I meant to do this much sooner, but I couldn’t find the doggone thread. 
 

Anyway, I bought a Lee bullet sizing die for .45 caliber bullets. The die resizes bullets to .451”. 
This thing has made a big difference in the accuracy of my hand loads from all 3 of my .45 Colt revolvers. I am very happy with the results. 
 

Thank you all for your input and suggestions. 

 

I bought this one:

Lee Precision - 90061 SIZING DIE KIT .451 https://smile.amazon.com/dp/B00162PX6C/ref=cm_sw_r_cp_api_glt_i_D7KQDX2XX0SCB2M5NSVA?_encoding=UTF8&psc=1
 

 

[Garrison Joe, SASS #60708]

On 11/12/2021 at 10:54 AM, Pat Riot, SASS #13748 said:

So, as you can see these measurements appear to be different from what I have assumed and read for years that lands are usually .451” and grooves are usually .001”-.002” larger. 

 

 

No, you have NOT read that for years, unless you were reading trash written by dummies.

 

Groove diameter is the important dimension for how a barrel works.   A bullet needs to snugly fit the groove diameter.  Only if you count on the bullet "slugging up" (obdurating) when fired do you get excellent accuracy with a bullet smaller than the groove diameter.   And a cast bullet of Brinnell 10 or so hardness can easily work without raising pressures even if it is 0.002" larger than the groove diameter.   But often best accuracy is at 0.001" over groove diameter.   Groove diameter was 0.454" up to 0.456"  on original Colt SAAs.     0.452" or slightly smaller is now the standard groove diameter for a .45 caliber barrel, standardizing .45 auto, .45 Colt, even .454 Casull.

 

The land diameter counts for very little.   The rifling lands simply spin the slug to stabilize it.  So, manufacturers vary the land diameter depending upon their historical practices and perhaps recent advances/trends.   Marlin for example cut their micro-groove barrel with very short lands, and the Ballard rifling with much taller lands.  They can't go to extremes on the lands, since bad heights will either not stabilize a slug (slippage) or cut the bullet body badly (distortion) or even increase pressures.  Since the lands are the metal that was left of the bore surface after the barrel was rifled, the diameter of the lands is also called the "bore diameter" or "caliber".   Most 30 caliber rifle barrels have a land diameter of 0.300 and a groove diameter of 0.308.  So 0.008" inch larger groove diameter than lands.  Or 0.004" high lands.  Pistol barrels usually have slightly shorter land heights, but still usually greater than 0.001" high.

 

SAAMI standards call for a .45 Colt barrel to be made today with a median groove diameter of 0.452" and land (bore) diameter of 0.444".  So the lands ought to be about 0.004" high.   .45 auto barrels - the same.

 

Revolver barrel forcing cones feed smoothly into the groove diameter (no leade).  So the "effective tip" of the forcing cone REAMER needs to ream right at the groove diameter. 

 

And throats of chambers in the cylinder are best cut just slightly larger than the groove diameter so the bullet swages the final 0.001" or so down to fill the groove diameter. 

 

The other dimension that is important is to get the chambers lined up with the barrel bore as closely as possible.  Alignment.  Something that the factory and the novice gunsmith often pay little attention to.   Yes, the forcing cone will push a slug a little bit in the right direction, but that usually distorts the bullet too.  And misalignment can lead to lead spitting from the gap.   It may never count for much in Cowboy matches, but it is important to top target accuracy.

 

good luck, GJ

 

 

 

[Pat Riot]

21 hours ago, Garrison Joe, SASS #60708 said:

No, you have NOT read that for years, unless you were reading trash written by dummies.

DELETED

[Garrison Joe, SASS #60708]

You didn't write that misinformation.  My post wasn't meant to be a personal attack.  It's about the facts.  Sorry if you took it that way.

 

good luck, GJ

[Pat Riot]

20 hours ago, Garrison Joe, SASS #60708 said:

You didn't write that misinformation.  My post wasn't meant to be a personal attack.  It's about the facts.  Sorry if you took it that way.

 

good luck, GJ

Thanks Garrison Joe. 

["Big Boston"]

For generations revolvers have been manufactured all over the world, it does seem odd that they even require anything but a bit of blueprinting, they should not require a complete rework.

 

I, and many other shooters, have chased this squirrel from tree to tree. My nemeses is a Colt New Frontier, 2nd gen, in 357. Throats are all equal at 0.360 and the groove is around 0.354. It's not a cheap gun, but it sure shoots like one. 

 

If you can measure the throats and groove diameters before you buy, you can avoid a lot of grief. After the Colt fiasco I bought a Ruger Blackhawk, and the store let me measure it. It was good, and I bought it. It's been a sweetheart. Both of those were purchased before I began shooting cowboy, I used them for a while, then "upgraded" to guns with fixed sights, a bit of a step backwards, but I like the look and I also changed to shooting duelist. 

 

BB

 

 

[Garrison Joe, SASS #60708]

23 hours ago, "Big Boston" said:

Throats are all equal at 0.360 and the groove is around 0.354.

 

Yeah, that's a lot of bullet obduration and then compression going on when the round fires.

 

It might be possible to have a gunsmith who cuts rifling to re-rifle the barrel to get close to 0.357" groove diameter.   That would make the throats quite a bit closer to the right size.   But he would have to have (or make) a rifling cutter to closely match the Colt land width and twist rate.

 

Second would be to have the barrel drilled and lined, rather easy to do.  And there's enough meat in the existing barrel to do that.  Probably would be my choice for a "shooter" gun.

 

Third - new barrel, of course.

 

And fourth would be to have a new cylinder set up for the gun.  Lots of money required for that.  But probably the best FIX for throats which are too large.

 

Decisions depend of course on whether the gun has collector premium value that you can't afford to give up.

 

good luck, GJ

 

["Big Boston"]

4 hours ago, Garrison Joe, SASS #60708 said:

 

Yeah, that's a lot of bullet obduration and then compression going on when the round fires.

 

It might be possible to have a gunsmith who cuts rifling to re-rifle the barrel to get close to 0.357" groove diameter.   That would make the throats quite a bit closer to the right size.   But he would have to have (or make) a rifling cutter to closely match the Colt land width and twist rate.

 

Second would be to have the barrel drilled and lined, rather easy to do.  And there's enough meat in the existing barrel to do that.  Probably would be my choice for a "shooter" gun.

 

Third - new barrel, of course.

 

And fourth would be to have a new cylinder set up for the gun.  Lots of money required for that.

 

Decisions depend of course on whether the gun has collector premium value that you can't afford to give up.

 

good luck, GJ

 

 

No collector value to me, and being a New Frontier in 357, not the most desirable to a collector. There are only a couple of gunsmiths in Canada that I would trust anyway. I mostly listed it as an example of what is out there. 

 

Thanks for the "fix" options. 

 

BB