.45 acp crimp question

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We're trying to debug a JR carbine issue with the stupid rifle mashing bullets into cases when feeding...

Anyway, I made a few reload rounds today and "tested" them at the range in a 1911. The results were jams and a couple of blown out primers (not good!). I'm sitting here dissecting the batch and the powder charges are right, however to combat the mashing I did give them what I would in hindsight say is a somewhat aggressive taper crimp. I guess my question is, would that have led to excess pressures enough to blow out primers?

Luckily I only did a few, and figure I know the answer to the question, but I count this as a learning experience, and figured I'd ask. I honestly thought I had somehow got my powder measure wrong, but it's perfect in each.
 
i can't say for sure, but i'm going to suggest that a heavy crimp isn't going to cause the primers to blow out.

what load were you using?
 
4.5 gr of titegroup on a 230 gr jacketed. I've shot probably ~2000 rounds of the same bullet/powder combo. I knew right away these weren't right, the recoil was way out of whack. I shot through 2 1911's just to be sure and both had identical results. I was 1000% sure my load was off.

4.5 is inching towards the high side of a powder charge, but definitely within spec. I just measured out 20 of them, and all are 4.5gr
 
Holy #### good call. The scale was a bit over 2 gr out of whack.

No idea what was wrong, Its an RCBS 505, I just took it apart and reassembled and re-leveled it and now it's reading okay. Damn, now I need a second scale to check the first scale to check the powder measure :(

Thanks guys, I honestly don't think I would have thought to check the scale, I really thought it was the crimp!! Appreciated!!!! :) Cheers.
 
.45 acp headspace's on the chamber at the case mouth. If you crimp so that the sharp edge of the case mouth is small/tapered enough it will enter the throat. You probably have enough of a crimp that just holds the case in position when chambering (extractor can do this as well) so that there is enough pressure required to fire the primer but the chamber pressure at the flash hole is enough to force the case into the throat far enough for the primer to back out at peak pressure. Your chamber pressure may be very very high if the bullet is still in the case mouth while the case is being jammed into the throat.
 
fingers284 said:
.45 acp headspace's on the chamber at the case mouth. If you crimp so that the sharp edge of the case mouth is small/tapered enough it will enter the throat. You probably have enough of a crimp that just holds the case in position when chambering (extractor can do this as well) so that there is enough pressure required to fire the primer but the chamber pressure at the flash hole is enough to force the case into the throat far enough for the primer to back out at peak pressure. Your chamber pressure may be very very high if the bullet is still in the case mouth while the case is being jammed into the throat.
Click to expand...

What he said!
Your bullet should be held in by neck tension only! Your crimp should just remove the flare created by your expander die. Make a dummy round and do the drop test into your chamber. you should hear a plonk when it falls in and it should slide out when you hold the barrel up. If it's stuck in there then something is up. Either OAL too long too much or too little crimp.

cheers
 
Good info, I don't think I was crimping it smooth, but close.

The problem seems to have been 2-3 grains too much powder in the rounds (!!).
 
Please don't think I'm dismissing the powder overcharge as a 50% increase is very significant in a pistol round and would definitely have symptoms of what you describe.

However a little more discussion on your crimping of the cases with a taper crimp may be of benefit. You say you started having problems after a crimp was introduced to the loading mix, is it possible your powder measure may have been out of whack before this.

Roll crimps are very easy to regulate with a very quick visual inspection, however, I've found taper crimps are very hard to judge just from a visual inspection. I need to actually measure the case mouth with calipers to accurately tell how much crimp I am imparting to the round. I start by measuring a new bullet and the thickness of the brass at the mouth of the round... then seat the bullet and crimp as you did with the problem rounds, now measure the o.d. at the case mouth, it should be the same as the total of the bullet plus twice the thickness of the brass. If the measurement at the crimp is less than the bullet dia and 1.5 the thickness of the brass I would re-adjust to get at least that reading
 
WRT proper crimp, Ken Waters of "Pet Loads" fame did a lot of research with taper crimp and the .45 ACP. Most taper crimp dies will deform the bullet slightly but not overcrimp to the point where the round will overchamber. If you have a set of calipers ( micrometer will work too) measure the case mouth area of a loaded round; light taper crimp should be about .471" give or take some thou of an inch. Using a Lee FCD on 230 gr CAMPRO FCP TCs I run about .467 - .469" depending on the copper plating thickness. Mind you, I run these in 1911 clones and crimp them so I don't get bullet walk issues while running a 1911 stupid fast so YMMV.
 
I will see about measuring some tonight, although to be honest I must have dismantled ~200 rounds just to be sure I got the ones that were "overloaded", and any ones that seemed to have an overly aggressive crimp. It does seem that only one batch of 50 was 2-3 grains over (!!). It has added an extra step to my reloading which I suppose is good.

I'll see if I can find one of my crimped rounds and hit it with the calipers. As stated this could be useful for other reloaders. Again, this was to try and keep the JR carbine from crushing rounds on the feed ramp (which I really suspect is an issue with the rifle, not the rounds).
 
I found 3.8 grains of Titegroup was more than enough. I usually don't go above 4 grains. I got the data from the on-line Hodgdon relaoding site and find the max loads push it a little.

I did a ladder load on my .308 using the Hodgdon site with IMR 3031 and in the middle of the range of recommended powder the bolt was getting hard to open.

Check multiple data sources to double check the loads.
 
i think its the rifle not your rounds. i am having the same problem using american eagle ammo. i cant get through one mag without a ftf. crushes the cartridge hard. sometime pushes the bullet right into the case.

have you had any luck figuring this out?
 
Sixgunjohnny said:
i think its the rifle not your rounds. i am having the same problem using american eagle ammo. i cant get through one mag without a ftf. crushes the cartridge hard. sometime pushes the bullet right into the case.

have you had any luck figuring this out?
Click to expand...

Well the blown primers was my scale being off (I simply must not have calibrated it right), but the feeding issues... well there is a thread we're discussing it here:
http://www.canadiangunnutz.com/forum/showthread.php/1132282-JR-Carbines-feeding-issues
 
I have a little piece of double sided tape stuck to my electronic scale. sitting on it is a 45 gr bullet. I chose that weight because it is a common powder charge I throw (for rifle). Before each session, I weight the bullet. For pistol, something lighter would be more appropriate. A dime?
 
Ganderite said:
I have a little piece of double sided tape stuck to my electronic scale. sitting on it is a 45 gr bullet. I chose that weight because it is a common powder charge I throw (for rifle). Before each session, I weight the bullet. For pistol, something lighter would be more appropriate. A dime?
Click to expand...

It's worse than that...I was using an RCBS 505. At some point the "0" level went way way out of whack, not sure if I dropped it or it just went out over time, but it was easily 2+ grains off which is amazing (in a bad way).
 
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