Do you compensate for bullet setback in your reloads?

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Do you compensate for bullet setback in your reloads?

Postby linksep on Mon Jul 31, 2017 8:50 pm

If so, how? Load long? Ultra tight crimp? Pick a powder/load that is compressed charge? Other?

I loaded up a few 9x19 this weekend and with a light crimp I measured one round that had .016" setback upon the first chambering :shock:

Even with a heavy crimp with a Lee FCD I measured .006" setback on one round with one chambering. The heavy crimp was enough to squeeze the bullet like a pimple and lengthened the COL by .002" on average (measured before and after crimping).
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Re: Do you compensate for bullet setback in your reloads?

Postby usnret on Mon Jul 31, 2017 10:11 pm

I don't even worry about it.
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Do you compensate for bullet setback in your reloads?

Postby gun_fan111v2 on Tue Aug 01, 2017 6:43 am

I'be read up on this a couple of years ago and ended up buying the EGW Undersized resizing die.

http://www.egwguns.com/undersize-reloading-dies/

Crimping only holds the bullet with the mouth of the case while these are supposed to help create extra tension all the way down
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Re: Do you compensate for bullet setback in your reloads?

Postby Seismic Sam on Tue Aug 01, 2017 7:33 am

The ONE thing you do NOT want to do is go down the road of trying to keep your bullets from moving by somehow "cooking up" a compressed load!!! It's not that compressed loads are inherently any more dangerous than non-compressed loads, but you NEVER, EVER, EVER, want to try to use the powder in a load to keep the bullet from setting back!!! There are ways to prevent setback with bullet choices, resizing dies choices, and crimp depth (i.e., a light .002" case mouth reduction for a 9mm vs. a heavy .005" case mouth reduction for a 500 S&W hot load.

In addition, it sounds like you are talking about crimp in a semi-auto pistol where the nose of the bullet is slamming into the feed ramp and causing the bullet to set back into the case. That could mean that you have a magazine and/or gun problem, and no amount of handloading tricks will fix something that is wrong with the gun and mag. For rxample, the feed ramps on some EAA pistols tend to be a bit on the short side, and a little dremel work on the bottom of the ramp can help a lot. Similarly, there is a hell of difference between high capacity mags with a plain oxide coating on the inside of the mag body, and a "more slippery" coating on the inner mag surface. The plain oxide coating may hold the bullet back until the full force of the recoil spring is brought to bear on the round, which then slams onto the ramp and into the chamber with as much force as possible. Sometimes putting 16 9mm rounds into a 17 round mag may solve the problem.

TO REPEAT: NEVER, EVER, TRY TO COOK UP A COMPRESSED LOAD JUST FOR THE SAKE OF KEEPING THE BULLET FROM SETTING BACK!!!
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Re: Do you compensate for bullet setback in your reloads?

Postby aprilian on Tue Aug 01, 2017 7:50 am

Did you make a dummy cartridge and try to move the bullet in the case?

Recently I was playing with different diameter .45 ACP expanders and I tested 4 different bullets and 3 different expanders. My conclusion was that the smaller expander (.451) worked best with the swaged lead bullets for resisting set back (and minimizing bullet diameter reduction) and the hard cast lead liked the .453 expander. I push the dummy load against the wooden 2x4 upright on my shelving, if it budges, I consider it not acceptable and try a different combo of expander diameter, dept and bullet.

For anyone not into reloading who wonders why you might use an expander that measures larger than the bullet, the brass case springs back and you are left with a smaller diameter for seating the bullet.

Sample data - chart formatting got messed up inserting it here

Magnus 814 swaged SWCHP (.452) measured as 0.4530
Winchester multiple fired cases
Redding dual ring sizer
Redding seating die - setting 20
Lyman crimping die
RCBS dial calipers (tested with guage blocks)
Crimp 0.4695
Noe bullets expander 0.4510 0.4520 0.4530
OD below flair 0.4695 0.4710 0.4720
OD at mouth flair 0.4735 0.4755 0.4770
bullet location to lube band by hand placement below middle above
COAL 1.2240 1.2210 1.2190
case OD over bullet 0.4715 0.4725 0.4730
case OD at flair (widest point) 0.4720 0.4730 0.4735
push test resisted fail fail
Bullet after 0.4510 0.4515 0.4520
# of hits to dislodge bullet (not an accurate test) 2.25 3 2
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Do you compensate for bullet setback in your reloads?

Postby gun_fan111v2 on Tue Aug 01, 2017 9:07 am

aprilian, very interesting - thanks for sharing

I could also see how over-expanding could lead to more setback
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Re: Do you compensate for bullet setback in your reloads?

Postby aprilian on Tue Aug 01, 2017 9:40 am

111v2 - You're welcome. Over expanding OR expanding too deeply so that the bullet is no longer grabbed by a section which was not expanded (a portion of the bullet should reside in the case which is the same size as the sizing die left it).

What surprised me the most was the direct correlation between expander diameter and COAL. Using my Redding micrometer seating die (which uses a spring inside), it appears that lowering the resistance in the expanded section allowed the force of the seating spring to be applied to the unsized section, allowing the bullet to seat deeper. That is the only working theory I could come up with as nothing else was a variable in this experiment.

Everything I experimented with was specific to a straight walled pistol case and was done to replicate a national competitor and pistolsmith's recommendations specific to expander dies.

Your mileage will vary.
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Re: Do you compensate for bullet setback in your reloads?

Postby Sigfan220 on Wed Aug 02, 2017 10:01 am

You do not want a heavy crimp on a rimless cartridge. I check chimp by pushing on a loaded round. If I can lean on it and it does not set back I call it good. I have found lead vs plated vs copper jacketed vs brass jacketed all require slightly different crimp settings. You may also be seated too long?? I'd make sure you are not getting into the rifling.
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Re: Do you compensate for bullet setback in your reloads?

Postby noylj on Fri Aug 04, 2017 3:59 pm

Set back is bad.
Using a COL that is too long or too short for your gun can contribute to set-back. If too long, the bullet slams into the feed ramp and can be pushed in. Too short, and the bullet slams into the top of the barrel and can be pushed in. You want the Goldilocks of COL. You should be able to relatively slowly close the slide and have the round chamber "effortlessly."
For 9x19 (and all cartridges, but particularly 9x19), ALWAYS try to push the bullet into the case with finger or thumb pressure immediately after seating. Any movement is a reject. I have found many 9x19 cases with case walls so thin that sizing did not reduce the case ID enough to hold the bullet.
Check the case ID before seating. It should ideally be 0.001-0.002" below the actual bullet diameter. Any less, and you don't have enough tension. Any more, and you could swage the bullet diameter down during seating. If you pull a bullet, you'll generally find the case ID is 0.001" less than the seated bullet diameter, so that is all you need going into seating.
Never think of a taper crimp as something to hold the bullet. All you want is enough "crimp" to remove the case mouth flare and allow the round to feed and chamber.
If you are shooting jacketed bullets and your case mouths have been lightly chamfered inside and out, you might be able to seat without flare or "crimp."
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Re: Do you compensate for bullet setback in your reloads?

Postby Seismic Sam on Wed Aug 09, 2017 11:20 am

Just for the sake of posting something funny and waking everybody up, YES, I do compensate for bullet setback! I move my gun 20 - 30 mils closer to the target to compensate for the bullet being that much farther away from the target!! :( :o :shock: :? :P :D ;)
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Re: Do you compensate for bullet setback in your reloads?

Postby hammAR on Wed Aug 09, 2017 4:17 pm

:rotf: ............you have to be on some great drugs!
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Re: Do you compensate for bullet setback in your reloads?

Postby Rodentman on Thu Aug 10, 2017 5:16 pm

Wasn't there some talk about using a compressed load of AA9 (maybe it was AA7) in .357 sig to prevent bullet setback? I've never used that load but I think I read it somewhere, maybe here...

I don't have setback issue ever since I started using boattail bullets and stopped flaring the case mouth. Light crimp though.
...nevertheless he persisted...
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Re: Do you compensate for bullet setback in your reloads?

Postby cobb on Fri Aug 11, 2017 9:08 pm

Do you compensate for bullet setback in your reloads?

Nope, go by the specs' in reloading manuals.
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