New 5" Trojan

[harald]

My friend just got a brand new 5" STI Trojan in 9mm, this is a std Trojan from STI with a reciol master.

When he tried my reloaded ammo in his gun, the fired primers looked strange.

I use Rem. sp primers, 120 gr TC lead bullets sized .356 and 3.2gr vv 310, this is a light target load. Fired in my 6" STI the power factor is 131.

I think the recil spring was very light, can this cause the strange primers?

My gun have a #7 recoilspring, and I do not get this kind of strange primers after firing.

Any tips? new recoil spring? different firingpin?

[G-ManBart]

Man, those don't like like a spring issue caused them. They look cratered, melted and flowed. The case on it's side is bulged pretty good as well. You SURE about that load? R,

[harald]

Hi, G-ManBart

I have used the same ammo for 4 years and never had any problems of any kind.

That made me confused; same ammo in different gun and a strange result.

My 6" STI have a bullbarrel and this new 5" have a bushingbarrel, but I do not think the fired primers should look any different.

I am confused....

[lugnut]

They don't look flat at all so I don't think there are pressure issues. However- are you sure the primers didn't have mark on them before??? Were they sized well before firing? That bulged case doesn't look good at all though.

[pjb45]

Awhile ago, I did a primer flow search on the internet. There were some very good pictures of primer flow. They seemed very similar to the ones you posted. That bulged is strange. Is that a non-supported barrel?

Actually, looking at everything again, that looks bad to me. I would remeasure everything again. As a fairly new person to reloading 9mm, mine never look like that.

I use VV320.

[SA Friday]

VV N310 is the only powder I've ever seen bulge a case like that. You have HIGH pressure. The pressure is flowing the primer cup into the firing channel, sheering of pieces, and then continuing to flatten to where you can't see the sheering. That's probably where you are getting the funny primer marking from. The next round's primer is getting marked up from the sheered part of the previous primer. Just because the primer didn't completely flatten and the sides of the primer is still rounded doesn't mean you are OK. N310 is very fast burning, and probably isn't staying in the high pressure zone long enough to totally flatten out the primer.

The different barrels may have different throat lengths, and in your buddies gun the bullets might be getting chambered into the rifling. This would cause the pressure spike. Second, if the chamber is throated differently and is more loose, you could be seeing the brass bulge when fired from his gun and the tighter chamber in yours controls the brass more.

N310 is very touchy stuff, and pretty unforgiving.

[harald]

Primer flow was the first thing i thought of when I saw the primers, but this should be the same problem in my gun?

[G-ManBart]

As SA Friday mentioned, two different barrels will have different throats, chamber diamters, bore diameters etc. N310 is so fast that it can be a fine line from okay to bad.

I know I certainly wouldn't shoot any more of them! I don't have my loading guide in front of me, but I'd check that and then double check your powder throws. R,

Edit to add: Truncated cone bullets can be a bit more likely to run into the rifling than other bullet shapes.

Edited May 19, 2010 by G-ManBart

[JimmyZip]

Different guns, different barrels, setback maybe?

[harald]

My barrel is a gunsmith fitted Bar-sto, I guess there is a big diffrence between this barrel and a stock STI barrel.

Tomorrow I will try reloading with vv 340 powder, about 4 grains maybe....

[lugnut]

Just because the primer didn't completely flatten and the sides of the primer is still rounded doesn't mean you are OK. N310 is very fast burning, and probably isn't staying in the high pressure zone long enough to totally flatten out the primer.

I'm sure you are correct- I'm just very surprised there is NO primer flattening. I use Fed's with 231 and my loads flatten the primers a good amount.

[JimmyZip]

Is there any way the gun could be unlocking early? I just saw that bulged case looks almost like there was still pressure as the gun was unlocking. Another thing too is not only are the primers not flat, they look like hot brass or whatever alloy they're made of got hot enough to go molten. Is this gun running an XL firing pin? Could this be a punctured primer? Are these rifle primers?

[SA Friday]

Is there any way the gun could be unlocking early? I just saw that bulged case looks almost like there was still pressure as the gun was unlocking. Another thing too is not only are the primers not flat, they look like hot brass or whatever alloy they're made of got hot enough to go molten. Is this gun running an XL firing pin? Could this be a punctured primer? Are these rifle primers?

I saw that on the one primer too. I think based on the pics there could be enough shaving to allow some gas to escape before the divit is flattening. This would account for the molten shaving and probably some of the reason the primer didn't completely flatten out.

I thought about the gun unlocking too early too, but the OP stated he was using a heavier recoil spring in the gun in question. One way to check if this is the problem is to try the heavier spring in the working gun and see if the results occur again. Either way, I wouldn't be shooting that ammo out of that barrel.

[Bob DuBois]

One of the guys in our club bought a new Trojan 9mm and the firing pin channel was full of trash, might pull the firing pin and make sure every thing is clean.

While It's apart pull the spring then check the pin fit from the breach side to see if it's tight. If it's tight you can turn it in a drill, put the pin in from the hammer side and polish it with fine sandpaper.

Don't remove to much metal it should just fit with little clearance.

Looks like the firing pin is dragging across the case as it's extracted to me.

[harald]

Here is a pic of my friends STI barrel to the left, and my Schuemann gunsmith fittet barrel to the right.

The STI barrel chamber is wide and my barrel is not.

The ramp goes in the chamber on the STI barrel, but on my barrel it is not inside the chamber.

Edited May 20, 2010 by harald

[Bastian]

Hi there. This happens to be my gun, also the first one i have, so I'm a bit bummed out about the bad machining on the barrel and bushing (gun otherwise has worked great and has no slack). After trying some different ammo today we had a rather interesting experience. The back side of the casing blew up and alot of the pressure exited out the mag well and the port resulting in black hands and powder residue all over my face! (Safety glasses worked great luckaly!)

Here's an image of the casing

[atbarr]

Bastian, I'm glad that your safe.

Oh yeah, WELCOME!

A.T.

[Bob DuBois]

What are you loading? Think I would buy some factory stuff and see how it runs. Maybe loading issue.

[Croomrider]

I would return that gun to STI or whoever fitted it with that barrel, along with some of the fired cases in question. I'm was going to say to try some factory loads in it, but I'm not sure that would be safe. The machining on the back of that barrel looks terrible. To me that would be enough excuse to return it anyway!

Mike

[Bastian]

The ammo doesn't seem to be the problem, the casing that burst was apparently loaded with a pretty low factor (Harald knows more about that), anyway I've been in contact with the dealer, and it looks like he want's to send it to a gun smith for further inspection... As long as I can send only the barrel or top I'm fine with it since I might be able to borrow another top. In my mind there is no doubt about the barrel beeing a bad case of slip in quality control, the front end bushing doesn't fit completely either (you can woble it when it's slipped on the front of the barrel and the inside looks like it's been drilled with a chipped drill bit).