Crimping and copper fouling

[blackd24]

Can too much crimp cause copper fouling? I am running hoppes no 9 bore cleaner and it’s coming out green. Red copper streaks in the barrel so there isn’t a question of if, it’s why.

I’m loading starline 357 brass with 7 grains of BE-86. Using both hornady xtp and precision delta 158 FMJ. I noticed it mostly with the XTP bullets. Chronograph says an average of 930 FPS out of a model 19 classic 4 inch barrel.

I cannot put a bullet into the fired brass, when it should drop in freely. I can still see a noticeable crimp in the brass after it was fired which leads me to think I am crimping too much for this load (stripping the copper and leaving deposits in the barrel). A few pictures attached above. Another consideration is the potential of shooting some undersized coated bullets previously and not removing leading so copper is sticking to the leading in the barrel?

Any ideas?

 

[Palladan44]

I think the answer is no, the crimp shouldn't be the issue.
I personally only crimp heavier loads in 357 Mag using powders like H-110. WW-296 to prevent recoil bullet creep forward.
In a lighter end magnum load using BE-86 I personally would stick with a taper crimp.

I think if you are getting fouling, it is probably not because of your crimp.

I've heard of getting leading in barrels from pushing hard cast too slowly, and pushing soft swaged lead too quickly....no idea on jacketed going too slow, because you'll never push jacketed "too quickly" in this caliber, that's for sure.

The fouling is likely just bullet/gun combo. Period.
And what youre describing is actually quite common anyways, doesn't sound much more than copper traces in the bore that oxidized. No biggie.

 

[Archie]

That looks strange to me. I'm sure I have crimped bullets that tightly at some point. But the crimp usually gets blown out when the powder ignites to propel the projectile.

Looks to me like the pressure in the chamber wasn't sufficient or the cases were not annealed and the case was too hardened to expand. No firm guarantee on either suggestion.

 

[Palladan44]

That looks strange to me. I'm sure I have crimped bullets that tightly at some point. But the crimp usually gets blown out when the powder ignites to propel the projectile.

Looks to me like the pressure in the chamber wasn't sufficient or the cases were not annealed and the case was too hardened to expand. No firm guarantee on either suggestion.

Yes, I believe the case will obturate from pressure build up to fire-form to the shape of the Cylinder walls before the bullet even moves. Difficult to prove, but I think I know my physics well enough...I think.

 

[Archie]

Palladan44, my understanding is essentially the same.

 

[blackd24]

This load was based on Alliants data of 7.8 grains max. This is the low end (10%) starting charge. Was looking for a moderate 357 as an in between for 38 special and a 2400 357 load.

 

[Bearded Phil]

Over crimping won't be the cause of your copper fouling. A rough barrel is most likely the cause of that.

As to the crimp its self and the brass still having a "crimp" shape at the case mouth.... well, it does look like that crimp is very heavy on the picture of your loaded round.

Brass does expand upon firing but it has an elastic quality to it, meaning it will spring back to it's former position to a certain degree. With a modest crimp I often observe my case mouths having a slight inward roll after firing depending on the load. Running through a sizer and then a case expander will prepare it for another round just fine.

Personally I would back off of that crimp at least a little bit. And I'd anneal the case mouths of rounds that have been crimped that hard in the past.

 

[tightgroup tiger]

Your over crimping your cases. The crimped mouth shouldn't be cut to match the cannular of the bullet. Step your load up to 7.3 gr with the BE-86 with a 158gr bullet. It's a good load and very accurate.
As far as fouling your barrel with copper when it's already fouled with lead, copper will usually clean out the lead from a barrel. But if your barrel is already copper fouled you have to get that all out before shooting it again or it will just come back.

This isn't a new revolver your shooting is it. When I first got my S&W model 57 it had EDM cut riflings and everything I shot in it fouled the barrel. As the riflings broke in and polished up it quit fouling and now it doesn't foul at all.

If you need to, get some Copper Killer, it has a bear or coyote or something on the can, and use some big q-tips to put it in the barrel, let it sit for 1/2 hour at a time and keep going on and cleaning the barrel out, then put more in, until it's completely clean.
And don't use a copper barrel brush to try to get copper out of a barrel when using a copper remover. It will ruin your brush.
Just keep your nose turned away from the can when using it. It's 10% ammonia and will rip your nose off it you get a whiff of it.

edit to add: https://www.midwayusa.com/product/2161515117

 

[Walkalong]

No, the crimp is not causing copper fouling, yes, it’s not unusual with a heavy crimp for the case to keep some of it after firing. The case expands to release the bullet and not all of the crimp will be removed, especially in generous chambers.

I agree with @TT about that.

His load recommendation is also spot on. I tried it and it’s a winner. It’s my midrange.357 Mag load now, beating out all others.

 

[blackd24]

Thanks for all the replies. It is maybe 2 years old and has less than 500 rounds through it, mostly 38 special. Seems like the general consensus is clean really good and separately and unrelated, I need to crimp less and up the charge of BE-86.

any advice on the 300 I have loaded? Pull and redo? Or okay to shoot. I only have the precision light deltas loaded and I really started to notice this bad fouling with the XTPs.

 

[Heir Kommt Die Sonne]

any advice on the 300 I have loaded? Pull and redo? Or okay to shoot.

No i'd keep them, just shoot them after you clean the barrel and look for the signs of fouling to return.

 

[AJC1]

I use a nickle coated jag for cleaning with a copper remover like eliminator. Get your barrel squeaky clean and try an abrasive to lap the barrel a little.

 

[edwardware]

Can too much crimp cause copper fouling?

No. Also, nice moderate crimp, you'll rarely need more. That's perfectly appropriate.

Copper fouling, in revolvers, is a function of jacket material, bore finish, and bullet/throat/bore fit.

A bit of fire lapping might smooth things up. You could be also slug the throats and bore to measure.

 

[Riomouse911]

Looks a lot like a Lee Factory Crimp Die-crimp. As the guys said, no need for a mega-crimp unless the loads are recoil-generating stompers or you are loading for a lever gun or other tubular magazine rifle.

This is a hearty load with a 165 gr RN and AA #9. This is as heavy a roll crimp as I will use in any revolver round I load.



As for the fouling, also as the guys said clean with a copper-specific cleaner. Once its clean, shoot it until the bore smooths out .

Stay safe.