what causes powder blow back on case

bossman · May 18, 2011, 01:59 PM

I loaded some 45 acp with a new powder and had powder blow back on the spent case. I was at min start so shouldn't be to much pressure. Is it to much crimp or not enought crimp?

I was trying for a light load with 4.2 Bullseye and 200 gr plated. any ideals?

AlaskaMike · May 18, 2011, 02:39 PM

Do you mean that the cases were sooty on the outside? If so, that's usually an indicator of low pressure, and if you bump up the powder charge a bit (within published data limits) it should go away. What's happening is that there isn't enough pressure to seal the brass case against the chamber.

bossman · May 18, 2011, 02:54 PM

OK that's what I was trying for maybe just too light a charge. They were nice loads though and cycled all my autos. I'll step up the loads just a tad.

brickeyee · May 18, 2011, 03:49 PM

Quote:

what causes powder blow back on case

Not enough pressure to seal the case to the chamber walls.

Sport45 · May 18, 2011, 04:50 PM

Quote:

Originally Posted by bossman

They were nice loads though and cycled all my autos. I'll step up the loads just a tad.

Soot on the outside of the case doesn't hurt anything. If you like the load leave it the way it is. You may have to clean a little more often, but if you're one that cleans after every range trip you'll never see a difference.

bossman · May 18, 2011, 06:51 PM

After i cleaned the soot off some of the cases were discolored . Will they still be good for reloading?

k4swb · May 18, 2011, 07:04 PM

After many many years of shooting and testing, I have come to the conclusion that the trigger is the cause of dirty ammo.

As long as I never pull the trigger when the ammo is in the gun, it stays perfectly clean. Ammo in a box on the shelf stays pristine and I can even chamber it in any gun I own and it will remain clean. Pulling the trigger messes things up every time.

Therefore I will no longer put any ammo that I wish to remain spotless in the gun and pull the trigger.

Uncle Buck · May 19, 2011, 07:53 AM

Bossman, they are still good for reloading. My wife likes lite powered .38 Special rounds and the discoloration is a result. (For really good discoloration, shoot some black powder in your .38 or .45 Colt! Looks pretty!)

Just tumble them and re-load. Some of her loads have been re-loaded several times and no sign of case failure. Like a lot of guys say about semi-auto ammo, you'll probably lose the cases before they wear out.

Just inspect the brass before each reloading session and if there are cracks, toss it.

overkill0084 · May 19, 2011, 08:53 AM

If the load is accurate & reliable, I wouldn't worry about a bit of soot. Pick up some once fired factory brass off the floor. You will find similar sootiness with a lot of it. Just leave it in the tumbler a bit longer.

May 18, 2011, 01:59 PM	#1
bossman Senior Member Join Date: November 16, 2010 Location: Arkansas Posts: 996	what causes powder blow back on case I loaded some 45 acp with a new powder and had powder blow back on the spent case. I was at min start so shouldn't be to much pressure. Is it to much crimp or not enought crimp? I was trying for a light load with 4.2 Bullseye and 200 gr plated. any ideals? __________________ NRA life member When the going gets tough, I just open another beer.

May 18, 2011, 02:54 PM	#3
bossman Senior Member Join Date: November 16, 2010 Location: Arkansas Posts: 996	OK that's what I was trying for maybe just too light a charge. They were nice loads though and cycled all my autos. I'll step up the loads just a tad. __________________ NRA life member When the going gets tough, I just open another beer.

May 18, 2011, 06:51 PM	#6
bossman Senior Member Join Date: November 16, 2010 Location: Arkansas Posts: 996	After i cleaned the soot off some of the cases were discolored . Will they still be good for reloading? __________________ NRA life member When the going gets tough, I just open another beer.

May 18, 2011, 07:04 PM	#7
k4swb Senior Member Join Date: July 11, 2009 Posts: 389	After many many years of shooting and testing, I have come to the conclusion that the trigger is the cause of dirty ammo. As long as I never pull the trigger when the ammo is in the gun, it stays perfectly clean. Ammo in a box on the shelf stays pristine and I can even chamber it in any gun I own and it will remain clean. Pulling the trigger messes things up every time. Therefore I will no longer put any ammo that I wish to remain spotless in the gun and pull the trigger. __________________ My posts are things I have tried or experienced. You may or may not wish to emulate them so read them with this in mind. Compromise means that both sides give something, but they never give, they just take. I'm The NRA!

May 19, 2011, 07:53 AM	#8
Uncle Buck Senior Member Join Date: June 21, 2009 Location: West Central Missouri Posts: 2,592	Bossman, they are still good for reloading. My wife likes lite powered .38 Special rounds and the discoloration is a result. (For really good discoloration, shoot some black powder in your .38 or .45 Colt! Looks pretty!) Just tumble them and re-load. Some of her loads have been re-loaded several times and no sign of case failure. Like a lot of guys say about semi-auto ammo, you'll probably lose the cases before they wear out. Just inspect the brass before each reloading session and if there are cracks, toss it. __________________ Inside Every Bright Idea Is The 50% Probability Of A Disaster Waiting To Happen.

May 18, 2011, 02:39 PM	#2
AlaskaMike Senior Member Join Date: September 26, 2005 Posts: 941	Do you mean that the cases were sooty on the outside? If so, that's usually an indicator of low pressure, and if you bump up the powder charge a bit (within published data limits) it should go away. What's happening is that there isn't enough pressure to seal the brass case against the chamber.

May 19, 2011, 08:53 AM	#9
overkill0084 Senior Member Join Date: August 7, 2010 Location: Northern, UT Posts: 1,162	If the load is accurate & reliable, I wouldn't worry about a bit of soot. Pick up some once fired factory brass off the floor. You will find similar sootiness with a lot of it. Just leave it in the tumbler a bit longer. __________________ Cheers, Greg “At the core of liberalism is the spoiled child – miserable, as all spoiled children are, unsatisfied, demanding, ill-disciplined, despotic and useless. Liberalism is a philosophy of sniveling brats.” — P.J. O’Rourke