Need Help With Bullet Set Back With Masterblasters

[mscott]

I decided to buy some Masterblasters to get away from regular lead bullets, but found a problem. I ran 5 over the chrony to check my load and 2 were about 100 fps faster. I've loaded several thousand lead bullets on this press and never had an issue. I loaded a few more and just hand-cycled them through the gun and found bullets were moving back from 1.135 to 1.15. After a little re-adjusting I'm still getting a little movement (about .005-.008). I'm using LEE dies on a Hornady LNL and my sizing die is already set as low as I dare go as the press cams over pretty good right now. I moved my bullet seating die down to put a decent crimp (more than ever before) on the case before going to the factory crimp die. I considered the undersize die from EGW, but thought I'd check here for other ideas first. The gun I was testing them in is a SA 1911, but this ammo will also be used in a couple of Glocks so I can't go much longer. Is the black poly coating just too slipery? The bullets measure .4005-.4015

Edited February 25, 2007 by mscott

[wide45]

The bullets measure .4005-.40015

I think that is undersize. Do you have other .40 cal bullets to compare?

Your expander/flare may be over expanding. The U die wont help if it is.

[mscott]

The bullets measure .4005-.40015

I think that is undersize. Do you have other .40 cal bullets to compare?

Your expander/flare may be over expanding. The U die wont help if it is.

Sorry, too many zeros. The lead bullets I've used for a couple of years are sized the same or just a hair.

[SteveZ]

Try loading some up WITHOUT using the factory crimp die. When I was loading MBs in 45ACP, I had a similar problem. It seemed that using the FCD would actually result in loosing crimp...for reasons I didn't fully understand.

One theory is that the FCD would actually resize the bullet smaller and then the brass would spring back and you'd loose crimp that way....another theory is that on the upstroke the brass would "flare" at the mouth and loose tension that way. Again, I don't know what the exact cause was...but I quit using the FCD with 45ACP and the problem went away.

I'm loading MB's now in 40S&W (using the 180gr bullet) and Dillon dies and no FCD...I've never had a problem with bullet setback or losing crimp.

[mscott]

Try loading some up WITHOUT using the factory crimp die. When I was loading MBs in 45ACP, I had a similar problem. It seemed that using the FCD would actually result in loosing crimp...for reasons I didn't fully understand.

One theory is that the FCD would actually resize the bullet smaller and then the brass would spring back and you'd loose crimp that way....another theory is that on the upstroke the brass would "flare" at the mouth and loose tension that way. Again, I don't know what the exact cause was...but I quit using the FCD with 45ACP and the problem went away.

I'm loading MB's now in 40S&W (using the 180gr bullet) and Dillon dies and no FCD...I've never had a problem with bullet setback or losing crimp.

That seemed to be the problem. All I can figure is that is was squeezing the brass below the bullet and opening the top. I loaded a couple without the FC die and cycled them 6 or 8 times with no set-back. It was just that easy. Thanks, Mike

[HSMITH]

Yes, it is the factory crimp die, it is swaging the bullet down in the case. They work OK on jacketed bullets but they suck incredibly bad with lead or coated bullets.

Also put your crimp back where it should be, JUST laying the case mouth back on the bullet. Any more than that will be counterproductive.