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Mostly curious here as blow-by is normal in my Marlin. However, yesterday it got worse as the day went on! Maybe always has, and I just noticed! The rifle had about 150 rounds since last cleaning and the temp was around high 50's to low 60's.

The one on the left is from early in yesterdays match progressing to the third at the end of the match-6 stages. The fourth I shot this morning after keeping it in my pocket for about 1/2 an hour. I always get dirty brass pretty much, but noticed the blow-by hitting my cheek by the last stage and the rifle getting stiffer. I chronoed the shot this morning and was surprised to see it at 900 FPS, I've never chronoed them B4!  They are loaded with 5.4 grains of Clays under a 200 grain RNFP Hy-Tek coated bullet. What's the fire think? Thanks, EH

 

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I've asked to have this moved to the wire as I must have mis-clicked.

 

EH

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Well, since you ask, you have two conditions.  Condition # 1).  Your rifle has a chamber cut at maximum allowable for .45 Colt cartridges.  Condition # 2).  45 Colt brass will NOT expand to seal the chamber.  As the fouling builds up the gun gas is heating the fouling and carrying it back to cartridge and back thru the straight line Bolt/Action.  As a result you also have a bunch of carbon spooge back in the action and the raceways for the Bolt making things stiffer.  Condition #3).  (I added one) it appears your load doesn't provide real good ignition and burn as temperatures get lower.

 

I haven't personally had enough experience to comment on the effect Hy-Tec coated bullet may or may not have had.  No Clue.  I do know Hy-Tec coated bullets don't play well with Black Powder without proper lubes. 

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Agree with CC.

And I will add #4.

If any of your brass is slightly shorter than other brass, your crimp on that shorter brass will not 

be as sufficient as with longer brass.  And I'm talking about a few .000's

 

Therefore, weak crimp on shorter brass allows for incomplete combustion of your powder.

More residue will be obvious due to unburnt (or insufficient burning) of the powder, which you

will experience by less sealing of the brass to the chamber walls..... thereby allowing 

the blowback you are experiencing.

 

..........Widder

 

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Posted (edited)

This is from the SNS Casting Web site, regarding coated bullets:

"Over the years, we have noticed one common theme when it comes to dirty/leaded barrels...Powders with fast and or hot burn rates.  Here is a link to a powder burn rate chart.  https://imrpowder.com/wp-content/uploads/2019/12/2020-burn-rate-chart.pdf. We recommend powders with burn rates slower than the top 15 on this list, with the exceptions being Ramshot Competition, Red Dot, and N310. 

 

We HIGHLY recommend checking out "Alliant Sport Pistol."  It's an excellent, cheap, and readily available powder that is made specifically for coated bullets.  There are plenty of other options out there, so please stay away from very fast/hot burning powders with our coated bullets.  Thank you!"

 

Hope this helps, 45 LC is notorious for blowback, as others stated a the pressures we shoot it does not seal the camber, hence Winchester never made  '73 in 45LC

TB

Edited by Turquoise Bill, SASS #39118
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22 minutes ago, Colorado Coffinmaker said:

 

Well, since you ask, you have two conditions.  Condition # 1).  Your rifle has a chamber cut at maximum allowable for .45 Colt cartridges.  Condition # 2).  45 Colt brass will NOT expand to seal the chamber.  As the fouling builds up the gun gas is heating the fouling and carrying it back to cartridge and back thru the straight line Bolt/Action.  As a result you also have a bunch of carbon spooge back in the action and the raceways for the Bolt making things stiffer.  Condition #3).  (I added one) it appears your load doesn't provide real good ignition and burn as temperatures get lower.

 

I haven't personally had enough experience to comment on the effect Hy-Tec coated bullet may or may not have had.  No Clue.  I do know Hy-Tec coated bullets don't play well with Black Powder without proper lubes. 

 

3 minutes ago, Widder, SASS #59054 said:

Agree with CC.

And I will add #4.

If any of your brass is slightly shorter than other brass, your crimp on that shorter brass will not 

be as sufficient as with longer brass.  And I'm talking about a few .000's

 

Therefore, weak crimp on shorter brass allows for incomplete combustion of your powder.

More residue will be obvious due to unburnt (or insufficient burning) of the powder, which you

will experience by less sealing of the brass to the chamber walls..... thereby allowing 

the blowback you are experiencing.

 

..........Widder

 

Thanks Gentlemen---

I was aware of these things and my Marlin has always had blow-by. I asked this because I've never had it get worse during a match before. As far as it coming back past the bolt, that usually clears up in a clean gun after a couple stages. I haven't measured the brass, but they are all Starline and have been reloaded about 1/2 doz. times. Checking the couple hundred I have left all the crimps look the same. At 900Fps, I think I'm getting as best a seal as I can expect from non-annealed brass and a 200 gr. bullet. I've been using this recipe for several years, just never bothered to chrono. I started at 5 grs. and went up to eliminate unburned powder. It all seemed odd, so thought I'd ask. I will clean the rifle and  see if all goes back to normal! Maybe just a first match of the season fluke!!

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6 minutes ago, Turquoise Bill, SASS #39118 said:

This is from the SNS Casting Web site, regarding coated bullets:

"Over the years, we have noticed one common theme when it comes to dirty/leaded barrels...Powders with fast and or hot burn rates.  Here is a link to a powder burn rate chart.  https://imrpowder.com/wp-content/uploads/2019/12/2020-burn-rate-chart.pdf. We recommend powders with burn rates slower than the top 15 on this list, with the exceptions being Ramshot Competition, Red Dot, and N310. 

 

We HIGHLY recommend checking out "Alliant Sport Pistol."  It's an excellent, cheap, and readily available powder that is made specifically for coated bullets.  There are plenty of other options out there, so please stay away from very fast/hot burning powders with our coated bullets.  Thank you!"

 

Hope this helps, 45 LC is notorious for blowback, as others stated a the pressures we shoot it does not seal the camber, hence Winchester never made  '73 in 45LC

TB

TB,  That's some interesting info on the speed of the powder. Of course ya can't get much of anything nowadays! That may also explain why since I went to coated I've been getting fouling in my Rugers that solvent doesn't really touch. It comes right out with a brush however. When it's available again, what do you think about Shooters World "Cleanshot"? Might be easier just to go back to uncoated boolits. !!

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Eyesa  I have had very good results with Cleanshot in .38/357, .44 and .45c. I use 4.4 gr in the .45c behind a 200 gr bullet, both coated and not. I have had no blowback in a 66 in .45c.

 

Imis

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OLG,

 

Will you please give us a quick rundown as to how you anneal your straight-sided brass?  I believe you’ve stated in the past, that you and swmbo shoot .38special.  Is that correct?  


I was going to post here suggesting he anneal,his brass, but thought better of it, since I have limited annealing experience and didn’t want submit possibly-flawed advice/information.  (My method would anneal the entire shell casing, including the case head, which may not be advisable.). 
 

I sure  would appreciate hearing your method if it’s not too much trouble.

Thanks,

 

Cat Brules

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16 hours ago, Cheyenne Ranger, 48747L said:

do you anneal your brass?

 

I found that when I anneal my 45 Colt brass the blow back is much less.  Good for a number of reloads.  Then just anneal again.

No I don't anneal, yet anyway! I just thought it odd the blowby would get worse as the match went on. Never has happened before.

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