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Old 10-26-2012, 07:58   #1
offsidewing
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Bullet Creep reloading once fired brass - HELP

Hello All,

I've been reloading ammo for a couple years now. I lucked into thousands of new 10mm nickle/brass Starline cases a couple years back. While I was learning in the in's and out's of reloading the 10mm, I loaded new brass. Now I'm about halfway through my brass and and have started to load my once fired brass. In my first batch yesterday I noticed something yesterday - bullet creep.

I loaded some Nosler 200gr bullets into once fired Starline brass. I measure for length and headspace gauge about every 20 rounds. I measured the 60th round right at 1.250 inches. Then I kind of accidentally 'slammed' the bullet into the headspace gauge, and upon inspection, noticed the bullet was popping out of the top. I measured it and the OAL was now 1.270. I went back and tested the other 60 rounds I had made so far, kind of slamming them into the gauge. About half expirenced some bullet creep of approx 0.02 inches. I couldn't pull the bullets out with my hand, but there was some creep. I checked every station on my Hornady progressive press. Everything was in spec. I tighted down my taper crimp another .002 just to get it more snug. I put those 60 rounds back through the press just to crimp them, put them in the headspace gauge and still had creep. I tried two additional bullet types (Hornady and Speer) and got about the same amount of creep. Then I tried those three bullet types with new brass, and guess what? No Creep.

My press has five stations and is set up in this order: 1. Size/deprime/prime 2: Flaring and powder drop 3. RCBS Power check/lock out die. 4: Bullet seater 5. Taper crimp die. All dies except lock-out die are Hornady.

The resized brass is falling right into spec at .421 inches external diameter after sizing. My taper crimp is at .420. The only remaining variable that could be causing the creep is maybe I'm not cleaning the brass enough. Could residue on the inside of the brass prevent the bullet from ceasing properly inside. The outside of the cases are nice and shiny, the inside of the cases are a little "Cloudy" still. Some have just the teeniest bits of carbon left in the web area. I used Lyman treated corncob media with bits of paper towel and dryer sheets. Do you think this combination of media could be making the inside walls of the case 'greasy' preventing the bullet for making good contact against the case?

This only seems to be happening with my 10mm loads in used brass - the other calibers I load haven't experienced this.

HELP!
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Last edited by offsidewing; 10-26-2012 at 10:07.. Reason: grammar - typo
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Old 10-26-2012, 09:11   #2
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.424" is fat, and outside the SAAMI spec for a finished/loaded cartridge, let alone a "sized" case. SAAMI shows a max of 4.231". The SAAMI maximum chamber diameter is .424". The new brass I have (Starline, and others) is .4195"-.420", and once/multiple fired brass is sized to .420"-.4204" (Lee carbide, RCBS carbide). If you are sizing at or greater than "finish" diameter, neck tension will too little, or non-existent. This would leave the crimp as the only retention, and creep is to be expected. Sounds like your sizing die is oversized. Technically, you are sizing right at the ragged edge of the maximum (plus the maximum allowed diameter variation). Unless you use a larger bullet, you'll need to size smaller to increase neck tension. I crimp to [bullet dia. + 0.020"], but a max would be +0.022". This means, a .402" bullet should crimp to 0.422", with a maximum of 0.424", which happens to be the SAAMI maximum chamber dia. Some chambers (aftermarket barrels) don't allow for this extreme, or are right at it, meaning a tight fit. Starting at maximum could cause issues with feeding, in all but the generous OEM Glock chamber.
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Old 10-26-2012, 10:06   #3
offsidewing
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Oops, Typo. I meant to type "brass is measuring .421" NOT .424 - MY BAD! The four is right above the one on the key pad.

Quote:
Originally Posted by dm1906 View Post
.424" is fat, and outside the SAAMI spec for a finished/loaded cartridge, let alone a "sized" case. SAAMI shows a max of 4.231". The SAAMI maximum chamber diameter is .424". The new brass I have (Starline, and others) is .4195"-.420", and once/multiple fired brass is sized to .420"-.4204" (Lee carbide, RCBS carbide). If you are sizing at or greater than "finish" diameter, neck tension will too little, or non-existent. This would leave the crimp as the only retention, and creep is to be expected. Sounds like your sizing die is oversized. Technically, you are sizing right at the ragged edge of the maximum (plus the maximum allowed diameter variation). Unless you use a larger bullet, you'll need to size smaller to increase neck tension. I crimp to [bullet dia. + 0.020"], but a max would be +0.022". This means, a .402" bullet should crimp to 0.422", with a maximum of 0.424", which happens to be the SAAMI maximum chamber dia. Some chambers (aftermarket barrels) don't allow for this extreme, or are right at it, meaning a tight fit. Starting at maximum could cause issues with feeding, in all but the generous OEM Glock chamber.
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Old 10-26-2012, 10:33   #4
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Quote:
Originally Posted by offsidewing View Post
Oops, Typo. I meant to type "brass is measuring .421" NOT .424 - MY BAD! The four is right above the one on the key pad.
0.421" should be OK. What is the I.D. and O.D. of the cases, after sizing/deburring (should be 0.022-0.024" differential)? What is the dia. of the bullets you are using? What is the dia. of the case with bullet seated, between the case mouth and bullet base, and between the bullet base and case head?
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Old 10-26-2012, 11:36   #5
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Soo... I did some measuring of the bullet diameters. Every single Nosler 200 gr bullet, either pulled from this last batch or from the box had a diameter of either.399 or .398. With the same set of calipers, I measured new 180gr Gold Dots, all new, all dead nuts at .400. I measured new Hornday 200 gr XTp, again .400. I have a box of Nosler 180 grain, measured those, and every one was .400. The XTPs and Gold Dots I tested with yesterday were previously pulled from past mistakes and measured in the .398-.399 range around the crimp area - that may have explained why they creeped a bit too. 95% of the brass was fired in a LWD 10mm Barrel for the G20.

Interior brass dimentions were .396-.399 at the case mouth from the pulled cases. .400-.401 futher back in the case.

I'm hypothosizing that the .399/.398 dia Noslers may be the culprit with the fired brass for the exessive creep. I will load up some new New GD and XTP's in fired brass in a bit to see if that theory holds up.



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0.421" should be OK. What is the I.D. and O.D. of the cases, after sizing/deburring (should be 0.022-0.024" differential)? What is the dia. of the bullets you are using? What is the dia. of the case with bullet seated, between the case mouth and bullet base, and between the bullet base and case head?
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Old 10-26-2012, 12:57   #6
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Sounds like a working theory. At the extremes, a case I.D. of 0.396-.0.399", and bullet diameters of 0.398-0.399", the odds are favorable you'll have some loose fits. It's amazing what a difference of 0.001" can make.

How many of those undersize Noslers do you have? I may be able to take those off your hands. I can use them in the .38-40, without all this guff.
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Old 10-26-2012, 19:01   #7
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You do not have sufficient neck tension. If you do not have enough neck tension, then crimping is not going to help -- as you have already observed.

Nickel plated brass does lose neck tension pretty quickly in my experience. It is harder, and it is slicker. I have reloaded plenty of nickel plated brass, but it does not have a good shelf life before neck tension suffers.

Secondly, it sounds like the resizer is on the larger side (as dm1906 has explained). My 40/10mm RCBS die resizes to an OD of .418-.419. I get nice tight seating forces that lets me know that I am getting some good neck tension. I crimp regular Starline Brass to an OD at the case mouth of 0.421" - 0.422". Tighter than that and the case mouth begins to engrave the bullet.

Combine nickel cases, a larger resizer diameter, and a slightly undersized bullet, and voila! I would certainly not continue with that combination.

The Noslers can still work, but you'll need a slightly smaller resizing diameter in my opinion. I would probably look to that anyway. A lot of the slower-burning powders that work well in 10mm perform best with a high level of bullet pull.

If I were in your situation, I'd look to a different resizing die.
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Old 10-26-2012, 20:54   #8
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It sort of sounds like he is expanding the casing a little too much, I'd start with less case mouth expansion for true copper jacketed bullets, and then I would back off on the taper crimp as well to see if this improves case neck tension. Over crimping can squeeze the bullet dia. down too much and make them looser fit.

I push my finish rounds against a soft wooden edge of my table, then pull outward, then try to spin them with my fingers to inspect for bullet movement in/out or twisting around...
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Old 12-13-2012, 13:07   #9
BMiracletx
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Did you ever get this sorted out? I had a similar problem to this using the Hornady sizing die. My sizing die did not size down far enough. Even with a tight crimp, the neck tension was insufficient. I could place the bullet nose against my loading bench and with light pressure push the bullet deeper into the case.

My cure? A redding sizer die. It sized smaller and increased neck tension. My problems with setback/creep went away.
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