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"Crinkled" brass


Merlin Orr

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I have been reloading .357 for my PC Silhouette rifle using 125 Hornady XTPs and mixed (mainly Starline) brass with great results.  Just got a trial batch of 125 Precision Black Bullets and every load I am turning out on my 550b is as shown below.  The XTPs and Black Bullets come out exactly the same OAL but bent and crinkled.  I have turned the stem on the seat die all the way out of the die and it makes no difference. The cartridges are leaving the seating station in good shape - the damage is being done by the CRIMP die.... WTH am I doing wrong...?20170323_190644.thumb.jpg.28277355ed95de04c05a0509c6656547.jpg

Edited by Merlin Orr
CRIMP DIE - not seat die....sorry
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Merlin, I am using a seat/crimp die in station 3 of my 550. I was having the same issue. I backed the crimp off to a very light roll crimp, and it totally went away. My crinkled rounds look identical to yours. What made me say that about the crimp groove is, I was frustrated,  so instead of a lead round, I tried to load some MG 147's I had...and with the lead rounds with the crimp groove, it bulged the brass a tiny bit at the case mouth...enough so they wouldn't slide in the chamber smooth...but with the MG's, it crinkled the case exactly as yours. Backed the crimp off, and everything was good.

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CRIMP DIE - not seat die.  Sorry...:unsure:

 

Actually the cases are the exact same length - as far as I can determine - prior to being crushed all to hell...B)

 

RCBS dies. Three die set in conjunction with the standard Dillon powder drop setup. I reset the powder drop brass expander thingie to where it just puts a very small amount of bell to the brass.  Just enough to allow the bullet to start and remain "straight up". It expands the brass about 5/16 deep at the current setting.  If I set it to go any deeper the bell is huge and works the brass so far out it will not go into the crimp die at all... The seating die inside is about .7 across and, as far as I can determine, never comes close to the belled out brass. The only contact made with the bullet in the seating die station is from the center stem which actually contacts the bullet and sets the depth into the brass. I backed the crimp die out until there is no contact then started moving/screwing the crimp die downward. Everything looked great and the loaded ammo came out appearing to be perfect with a slight visible roll in at the top of the brass..but.. I could press (albeit very hard) with my thumb - my other hand on top of the thumb - and push the bullet into the case.  I adjusted downward about an 1/8 turn at a time and JUST when the crimp got to the point it held the bullet the brass started crinkling again. At the point the crinkling started the brass less than 1/2 the wall thickness crimped inward.  

As to the bullet "slipping" into the case under thump pressure. I am not a gorilla but I did put a lot of pressure on the bullet with basically a lot/most of my upper body weight into it.  Is my test faulty with unreasonable expectations....?

Edited by Merlin Orr
CRIMP DIE - not seat die....sorry
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It looks like the jacketed bullets have a cannelure that the brass is being roll crimped into, but the Black bullets do not. So when you are trying to put that much of a roll crimp on, and there is no cannelure for the case shoulder to go into, so something has to give, which is the case wall. Try backing off the roll crimp on the Black bullets. 

 

Side note, arent the Black bullets you're using coated?  If you roll crimp them you will be cutting through the coating, and probably result in a lot of leading in your barrel. 

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Merlin, check out these pics. These were MG 147's, no cannelure...I can load a lead round nose to the same length,  roll crimp the crap out of it (it has a crimp groove), and all it does is buldge the case mouth slightly. Drop the MG's in the case, and voila! Wrinkled/ crinkled case...same OAL, same seat depth, bullet heads are exactly the same OAL,  and the MG's are .355, where as the LRN are .358...all due to putting too much roll crimp on them.

20170324_090237.jpg

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Thanks to all..... I will go back through every step and make sure I am proceeding according to Hoyle... I just checked the case length again and on the undamaged brass they are really really close to the same ..... It depends how much pressure I use on the thumb roll on the digital indicator which comes out longer or shorter... A thousandth maybe with no particular brass being the longer.

I have loaded quite a few of the Precision Black Bullets over the years and really never had a problem with the crimping function. I have measured and my total crimp - even on the crumpled brass - is less than the thickness of the brass at the case mouth opening...

 

I am starting to think that my problem is that I am simply trying to crimp the bullets to an unreasonable amount.

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