B_RAD

Tried some once fired brass I got from a friend. Same results. Removed sizing die, confirmed for the 4th time it is for 9mm. Set it again. I'm convinced it's a combination of things. 1. .355" bullets 2. 9 Major OAL 3. Dillon sizing die Other possibilities 1. Somehow I got a lot of bad, worn out brass? Not likely. 2. I'm an idiot and I'm doing somtheing wrong. Maybe? I'm gonna roll on and go with 124 gr JHP @ 1.155". Going to use Lee U die.

So, here's where I'm at...... I'm still having set back when pushing on bullets. It's mostly around the .005” - .007" but some are moving .010" and a few have moved as much as .050". It's not on all, but on some. All kinds of brass. 3 different kinds of bullets(all .355"). It's happening on 2 different presses with 4 different sizing dies. (1 U and 3 Dillon). I'm also getting some rounds that have .003" - .005" of set back when chambering. Though, this could be from bullet deformation. I've been marking the bullets so that there's a gap between case and the on bullet. This Gap is getting smaller when the movement is .010"+. So, there is movement. In some cases I can see the bullet move on the ones with .020 or more. Saying all that, it happens less with the U die and seems less with the 124 gr. Both of those make sense. Also, in the cases with significant movement, I'm pretty sure it's not happening when sized with the U die. I pulled several bullets to see if the .375" - .377" crimp was leaving any marks on the bullet. I couldn't see anything. So, I'm ruling out too little or too much crimp. My theory is, it's a brass issue. The brass is range pick up that I bought. I don't know where in the life of this group of brass something could have caused this? Sitting in the sun? During the cleaning prep process? My other theory is, this is more common than I thought. The ones that moved a lot I'm chalking up to bad brass and not using the u die. The U die should help but I still cant see how even with a standard sizing die, there could be this issue unless it's a brass weakness issue. Could it be from not belling/expanding the case mouth enough? I'm doing just enough that the bullet will sit on the case without falling off. It's not much. I had someone tell me after sizing and belling/expanding there should be .015" difference from case mouth to the area about 1/8” down. I can't see how this could cause an issue? I'm not getting what I'd call the bottle neck or coke bottle look either. I'm open to any thoughts or suggestions.

Yes, go with a reputable builder. I just got my gun from Don. I've had some issues. First thing Don said was send it to me. Problems turned out to be my fault but Don didn't even skip a beat. He said send it to me. Can't say enough about the guy! The gun is awesome and Don is a stand up guy! I went 9 major btw.

I should say that even though, I marked the bullets, the small amount that I'm getting now, could be from the bullet deforming. .003" is probably almost impossible to see with the naked eye.

I marked the case/bullets to make sure changes in OAL weren't actually due to deforming the bullet.

That's why you got red hair. You're a commie!

^^^^

Thank you for the info. I'll look into this. I'm starting to think open isn't for me.

I was pushing on them pretty hard but I wouldn't say I'm any stronger than anyone else....just put a lot of weight behind it. Not all of the ones I pushed on moved. I'd bet if you tired a few you'd get one to move a little. I'd think chambering a round would be a more realistic test since that's what happens. Anyways, I'm fairly confident I solved the problem I was having with significant set back.

Yeah. I'm thinking it's something that's gonna happen. Especially if you really push hard. I took some factory ammo and messured it, then chambered it and measured again. I got about what I'm getting on my reloads. About .003" Before I was getting a lot more and I'm thinking it was causing my feeding issues. I ran about 30 last night after solving the extreme set back and the gun ran 100% I'm gonna run a hundred more tomorrow.

I just pulled out some reloads in had from a buddy and pulled out some factory Winchester fmj. Got set back from both when I pushed on them against my bench.

I've double checked these numbers and the inside expansion might be closer to .354" but other than that, I've done all I know how to do. I've classed Dillon 3 days in a row. I've reset the sizing die on two different presses with 3 different dies. Only other thing is somehow this batch of mixed brass has undergone some type of change on a molecular level and the brass is weaker. Doesn't seem to matter which brand I choose out of the bunch, I'm getting set back.

I'm banging my head against the wall! I've had people tell me you're gonna get set back if and some tell me you shouldn't have any. I'm having the same issue on two different presses with different dies, brass, bullets.

Thank you for the pic.

Everglades 115 JHP. Precision Delta 124 JHP. both 355"

That's what I've heard.

It's my understanding that crimp does not hold the bullet. I'm removing any flaring of the case and when I measure, I'm at .377".

I'm using mixed brass. I'm using .355 bullets. 115gr and 124 gr. Powder does not matter. You shouldn't rely on powder to prevent set back. However, I'm using WAC and AA7.

Yes. I've never loaded .38. Never had does for it. Only 9. From memory, I don't believe I've had this issue before. But I'm fairly new to 9 major. I'm using bought, once fired brass. I'm using Hornady one shot for lube. Spray it in a bag and roll cases around. The only thing I can think of is the longer OAL isn't providing enough bullet depth to create enough surface area for friction agasint the case wall?

I'm lost. I'm using a U die. It's adjusted all the way down to touch the shell plate when the handle is down. St 3 is expanding to about .351". Flaring case mouth very little. Removing flare/crimmping to .377" Bullets are .355" Am I missing anything?

I'm using a u die now and I'm still getting some set back. It's a lot less but I'm getting about .003"

This did happen on ammo loaded with a Dillion sizing die. Though, I did load up some dummy rounds with my Lee u die and I chbered them in my open gun and they set back a little. Like 0.003". From what I understand, that's normal?

How much if any is acceptable? I had a dummy round that I pushed against my bench and it moved a lot. Like 0.070". I tried loaded rounds and they were moving 0.008" - 0.010". I'm thinking this could be causing my failures to chamber issues. Thoughts?