Bullet setback in .45ACP

Not open for further replies.


Dec 22, 2002
I'm really tired, so bear with me.

I've been loading West Coast 230 gr RN in mixed brass, OAL 1.254, crimped to .471, using an RCBS carbide die set, seat/crimp simultaneously. No significant setback when repeatedly chambered from slide lock in my Kimber. Loaded and shot about 1500 rounds.

Tried a 185 gr FP tonight (230 RN were out of stock), started with the listed OAL of 1.275, and almost 0.030 setback from one chambering. I seated deeper and crimped tighter, but more setback.

I went back to my trusty 230 gr RN loads, and they were setting back, too. After much fiddling around (seating depth, crimp, different bullets, brass, etc...) it seems that rounds chambered from a full magazine would set way back, but rounds chambered from an empty magazine would only shorten by a couple thousandths. No adjustments I made would prevent it.


The gun is a customized Compact, but the barrel/throat/ramp areas are stock, as is the recoil spring. Mags are Wilson 7 round.

I pulled the Dillon powder funnel, and it measures 0.448 across the expander section.

I'm going to bed now, but any comments would be welcome.

Call LEE and order their "U" sizing die; undersized slightly as to increase case neck tension, the mechanics which prevent bullet setback.

About $20, life-saver (NS).
I agree 1010% on the U-die.

Most people don't understand that crimp keeps the bullet from coming OUT of the case but does NOTHING for bullet setback. In fact a crimp that is too tight will make setback WORSE!!!!!!

Case neck tension is the ONLY way to prevent setback.
Thanks. I was afeared I'd have to have my expander turned down or something. I'd read here that extra crimp is bad (lead squishes in, but brass springs back out), but then some people have posted about going to .469 or .468. I'll get into a Lee die post haste.

Can I expect a short bullet like a 185 to seat securely at the listed OAL of 1.275?

Too long; get more data sources.

Suggest Lyman's #2 Handgun thingie, Sierra's new one, or every data pamphlet you can e-order.

I'm thinking my 252g LRN-FP 45 ACP load is perfect at OAL of under 1.2XX".........

Alliant lists 185's at 1.190", 1.190", and one longer.
See? Confusing.
I suspect bullet setback in .45 is more common than realized.
A set back bullet in a .40 can run pressures up enough to separate the casehead and kaBoom the gun.
If a telescoped .45 bounces into the chamber of a well-throated barrel, it may shoot without visible difference. But it can also increase the pressure just enough to seize the case in the chamber and cause a failure to extract in a well set up gun. (Ask me how I know.)

I am fixing to phase .45 ACP back into regular use after a season of shooting 9mm for IDPA ESP. The standard sizing, expanding, and Lee CFC die are fine for cast SWCs, but I will take extra precautions to keep jacketed bullets from setting back.

1. I have a "U" die that I will use for jacketed.

2. I will turn my expander down if necessary. Elmer Keith recommended a .423" expander for .44 Mag and .430" bullets. That indicates a .445" expander for .45ACP.

3. I will cannelure the brass at the base of the bullet for short bearing surface 185 gr JHPs like some Remington and Federal ammo. I designed and my FLG made a tool that will do that in one step in a single stage press, much faster than the usual roll device, but still an extra step. I hope not to have to make the extra step with 230 hardball. If it is not required I will load ball or heavy hollowpoint for my jacketed stuff after the 185s on hand are shot away.

4. I will use jacketed, not plated bullets. Plated bullets are soft and slippery relative to conventional drawn jacket bullets and I think that may contribute to setback. Sometimes inexpensive is inexpensive, sometimes it is cheap.
I've loaded about 7000 rounds of .45 this year. 155 gr Sinterfire to 230 LRN. Crimp should be standard at about .469-.471. For setback the trick is to use as little belling as possible. I also recommend a "U" die or just seat and crimp at different stations.
On the Lee "U" die, if it undersizes the case, the expander plug is just going to push it back out to the diameter that's currently causing me problems, right...? The plug goes about a quarter inch into the case, even with minimal belling, so if the bullet isn't seated at least that far, I'd think the undersizing wouldn't have any/much effect on keeping the bullet put. (note to self: yer missing something, boing)

Also, I gave my last batch of brass a light coat of One Shot (cases in a box, spritz, jiggle the box around). Could lube inside the case neck be the cause of the setback I'm seeing?

Thanks for the input, folks.
I have had simillar problems, in my foolishness I waited for someone else to ask.:banghead: I will also look into the U-die asap. Thanks fellow reloaders.
That is why you have to be sure the expander plug (Dillon powder funnel) is well under bullet diameter except at the flare. If you are loading single stage, a Lyman M die is the best expander going. I think I will ask FLG to lathe turn a Dillon funnel to that shape. Don't know if it will cycle the powder measure like that, but it is a cheap experiment.
I'm loading on a 550B.

Is a .448 expander typical for use with .451 bullets? If I'm using "standard" stuff that tons of other folks use, I would think the problem would lie with another variable.

Any thoughts on my use of lube? I'm hoping for an easy solution with this one, which I'll test when I get some more 230s. And when that doesn't work, I'll come back here. :)
Try new IMI or Starline cases; setback?

IME 45 ACP, 357 Mag, and 38 Super cases get used over enough to lose their ability to size sufficiently for correct case neck tension. The spring is sprung.

So, I size tight, use fat bullets, or simply retire old cases and start fresh.
Not open for further replies.