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Marlin 45 colt blow by Should this happen ?


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I have a Marlin 45 Cowboy limited and it seems to have excessive blow by. I've ever loaded some heavy loads (200 gr bullets with hot powder charge) and tired them and still get a face full of burnt powder. I am wondering if it could have an oversized chamber. Anyone have this problem with their marlin ?? I have a couple of 38's and don't have this problem even with light loads.

 

UPDATE

Measured some of the cases I fired yesterday after cleaning and found some surprises These were NOT resized

Of 20 cases checked

 

11 were less than .475 in Dia

2 were .475-.478

7 were actually over .480

 

Winchester and Starline brass

 

I guess I now know why I'm experiencing blow by.

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I have a Marlin 1894 Cowboy in 45 Colt that has a lot of blow by and soots the cases and makes the action pretty dirty. I always believed the 45 Colt blow by was why there were not any rifles chambered in 45 Colt early on. It has a thick walled case compared to the 44-40 which seals up the chamber better.

 

Colorado Lightning

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Blow by happens all the time with the .45 Colt. 200 grains isn't very heavy and a "hot powder charge" is meaningless without knowing the type of powder. You don't want slow burning powders typically associated with "hot loads." For example, H-110 would suck as a Cowboy powder.

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Nope !!!!

 

Ain't normal ,,,,,, use 250 gr. bullets and a strong crimp and enough powder to clock at least 750 Fps. out of your pistols and 900 out of your rifles ....

 

NO Blow-by ...

 

 

Jabez Cowboy

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You could also try a .454 diameter bullet, (If you can find them) I have heard that it helps.

I'm not getting much blow by with Trail Boss; charged from the middle of the data table, 200 grain .452 RNFP.

Low charge of Clays was the worst for me.

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You're load is too light. Try a heavier bullet or up the charge, maybe try a different powder. I have a midrange load with 250gr and bullseye, abt 1000fps. No blow-by. My trailboss load with 200gr has a little bit, not really an issue. 250gr is less blow-by. Both of those loads are poofy compared to the bullseye load above. Shooting left-handed + Marlin = sucks. Either by a 73 oe shoot rightie! :lol:

 

I don't have blow-by issues with my 38 Marlins.....just sayin

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It got so bad at one point my R eye would swell shut after a shoot. I now shoot 2 weights 250gr for rifle and 200gr for pistol. This has helped alot. I mark the 250gr with a Sharpie marker.

 

CPK

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.45 Colt chambers in almost every firearm produced in this day and age are generously sized. Take a look at the .45 Colt SAAMI Specs and then do a chamber cast on your rifle... I do believe you'll find it overly generous to chamber a rather small .452 boolit. After you do that chamber cast, hone out your sizing die to keep your brass within .002 of your chamber, use .454 bullets and you'll very likely see that problem disappear.

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Oh yea, you could anneal your case mouths in an attempt to help them expand and seal or use a cleaner burning powder. There ARE MUCH better powders than that which seems to be most popular based solely only its ability to use more case volume.

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Once upon a time, chambers were generous in most any rifle. Why? BP fouling and field conditions made it a necessary evil. Sometime around the 1950s they re-worked the barrel size of .45 Colt down to a nice .451, but the original chamber specs were left generous. If ya ever worked the unload table, you've surely seen pistols in .45 Colt that allow empties to fall right out. Ever notice how .44 mag/special guns will NOT do that? Shooters have to pick em out. The modern .44 mag specs are tight compared to .45 Colt. Ever notice the .44 mag/special Marlins are the most finicky? They have to be timed dead nuts perfect to run at all, let alone fast. Tight chambers...... Now yer .45 Marlin can be half out of time and still run. Loose chambers will do that. Could ya have a bad chamber? Sure. Could it be well within specs and still be loose enough to allow anything less than a service load (250 service loads run around 800-850 in pistols, and 1000 fps or better in a rifle) will not seal and will blow back some. If yer getting it in the face, yer running LIGHT loads. I get it all the time, running 160s at 700 fps or so..... WEAR BIG GLASSES!

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About eight or nine years ago, the family was shooting a match up in the gold country. I was lazy and made all the .45s in 200 grain. My little bond haired 13 year old girl ended up with some soot on her cheek and it was looking like I was gonna get strung up. I went down the hill and loaded some 250 grain rounds for her and there was no blow by and I lived through the match. Lesson learned.

 

Post script. My little girl informed me if she wanted wimp loads, she would shoot the 32s. But since she was shooting the 7.5 inch Vaqueors in .45, she wanted the real loads. I buy 250 grain bullets for her ammo.

 

 

Very Best Regards,

BJT

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I always believed the 45 Colt blow by was why there were not any rifles chambered in 45 Colt early on. It has a thick walled case compared to the 44-40 which seals up the chamber better.

 

Howdy

 

This has been discussed here many times. The reason 45 Colt was not chambered in rifles in the 19th Century is because the rim was much smaller than on modern 45 Colt cases. Take a look at this photo of old 45 Colt cartridges. Compare the rim size of the old cartridges to the rim of the modern cartridge on the left. None of these rims is large enough to reliably allow a rifle extractor claw to get a purchase on the rim. The 45 Colt cartridge was designed as a revolver cartridge. Extraction was unnecessary. They were poked out from the inside by an ejector rod. The round on the far right is an exception, it was designed to be extracted from the rim, but all the other cartridges have typical 19th Century rims.

 

45 Colt Cartridges

 

44-40 on the other hand was designed specifically as a rifle cartridge, and always had a larger rim, to aid in extraction from a rifle.

 

I agree, 200 grains is not a heavy bullet for 45 Colt. With the light powder charges typical with most cowboy loads, a 200 grain bullet often will not cause the powder to develop enough pressure to expand the case well enough to seal the chamber. Moving to a heavier 250 grain bullet will go a long way towards eliminating soot on the cases.

 

But is the soot really a problem? Are you getting gas in the face? Soot cleans off easily enough in a tumbler.

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This discussion comes up almost monthly either on the SASS WIRE or over on the LEVERGUNS.COM forum . Usually it is about the 45lc rifles and the severe blowback with the down loaded CAS ammo.

The reason the problem is more common with the 45lc rifle is because the makers all use the maximum SAMMI (Sporting Arms and Ammunition. Manufacturers’ Institute) specs when they ream the chambers for the gun.

This diagram shows both cartridge and chamber dimensions. Please note that unless noted all diameters are +.004 and there .200' inside the chamber the nominal is .4862. if you add .004 to that the chamber can be as large as .4902 and still be in spec. I believe this all came about when the industry changed from the non rebated old balloon style cases like the one shown to the modern rebated rim swaged brass. Notice the max bullet dia. .456. Modern 45lc bullets run to only about .454 max with the majority at .452. The current ammo specs don't fill the chambers like the old balloon case ammo. So hard brass and down loaded CAS ammo will exhibit these problems.

 

45LC CHAMBER AND CARTRIDGE DEMENSIONS

 

I think they did this so the modern smokeless ammo would not as likely harm the older black powder era guns. The smaller bullets loose in the bore keeps the pressure down. They also do this so the leverguns will more likely cycle with a broad spectrum of ammo's. The reverse of that is why semi-auto pistols with match grade barrels are finicky about the ammo they will run. The match grade chambers are tight.

 

I do warranty work for EMF. They import the Rossi M92 as well. Over the years the EMF folks have had me do chamber cast on various rifles because the customer insisted the chambers were bad. One feller bought an EMF 92 and before he ever shot it sent it to Doug Turnbull for color-case work. Once he shot it with his CAS loads he found that the cases would swell but only on one side. This to him indicated a bulged chamber. He sent the rifle to me along with some of his bulged fired brass to verify this. I did a chamber cast and found the chamber to be within SAMMI spec. and the cases were truly bulged but not beyond SAMMI. Think about this. If the chamber was bulged and the brass was bulged to match extraction would be difficult. Not the case here. The fired bulged brass would easily chamber and fall right out if the open rifle was held vertical. The brass was bulged because that was the softest or the thinnest area of the case, not because the chamber was bad. He insisted, they gave him his money back and I bought a Doug Turnbull CC-ed rifle on the cheap from them.

More recently, they had a feller send me a 92 and a 73 for the same reason. He insisted the chambers were too big on both. I cast both guns and both guns were within SAMMI. He still insist that they are bad, that SAMMI spec are not correct and the industry should do something about it.

 

 

This 45lc blowby in the rifle problem has been going on for so long now I believe the IMR folks came out with their Trailboss powder just to combat this. A good book charge of Trailboss and a 250 grain bullet crimped well in a Win or Starline case seems to be the solution for some folks. Win or Starline cases are somewhat softer brass than most of the others. Some folks only neck size their once fired rifle brass. For BP, there are some folks using 44-40 brass blown out to 45 and claim it works well. 44-40 brass is really thin.

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Dee Mack-

 

250gr bullet and a heavy crimp will work wonders for you. The Marlins seem to be worse when it happens. I think it's because of the side port that puts the blowby into your right cheek. Try not sitting on the gun when you ... oh... wait ... not that cheek

 

CR

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Yep this has been discussed here many a time. There is always a laundry list of things to do to help the problem. Bigger bullet, more powder, different powder, tighter crimp, anneal the case mouth, 250gr bullet.....etc......The problem is even worse when you use BP, I know there's a bunch of folks that say they can shoot BP with no problem, but there's many many more that fight it. There is a permanant fix to this problem :huh: , sell the 45 and buy a 44/40 :) or use your 38sp, problem solved. ;) So easy a caveman could do it. :D

 

Jefro :ph34r: Relax-Enjoy

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A. Jack- Would have never thought of that trick about leaving the chamber a bit fouled to reduce blow back/blow by.

I still use heavier bullets in the '73, it being so heavy the recoil is no consequence anyway. Cases are a little dirty, but bullets strike with authority ( easier to spot misses, too!)

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The .45 LC ctg. wasn't originally designed to be fired in a lever gun. That's a recent innovation, IMHO, brought on by CAS shooters wanting straight walled cases for easier reloading. This blow back problem is an ever repeating theme, like an old 8 track tape just that won't quit. One can either use the ctgs. designed for these lever guns, i.e. the 44-40, 38-40, 32-20, etc. or shoot the LC with enough power and bullet wt., generating enough pressure to expand the stiff walled case and seal the chamber. Otherwise, this recurring theme will go on and on like the Energizer Bunny... .38's don't seem to be much of a problem and are another option. For big bore, the former option, IMHO, is the way to solve this problem and stay with low powered loads.

 

I got tired of my Marlin Cowboy .45 LC spitting at me and I wanted to stay with light loads, so I retired it from CAS, put blanks in the sight slots, mounted a Bushnell Holosight and a Brownell's stick-on stock comb. I loaded 300 gr. bullets, cast and jacketed, to the max with 4227, pushing them out of the 26" bbl at around 1,600 fps. Now, those loads will definitely seal a .45 LC case in the chamber! This gun already had a super slick action job when I got it and I had added a Wild West trigger. It's made a wonderful 'diller gun. At low light, when they come out to play, just put the Holosight grid on their skinny little ___'s and pull the trigger. Amazing stuff happens. 300 gr. at around 1,600 fps is getting pretty close to a .45-70, plenty enough firepower for the average 'diller. (Probably for big ones, too).

 

And for CAS, I shoot tricked out '73's with .38 spec brass and long Moulton Lead bullets. No blow back and much faster.

 

Only losers in this deal are the 'dillers... And they not exactly complaining...!

 

DF

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