Accurate 40-160b

[BulletFactory]

I was wondering if any of you have any experience with the mold. See avatar for pic.

Tom helped me with the design, but one thing that always concerned me, was the small size of the lube groove in the back. I wanted it small, to move the CG to the rear a bit, in an effort to increase the bullets stability. Judging by the marks on steel targets and bullets I have recovered, it seems to have worked, they all seem to hit square.

I have a bad barrel, so no matter what I've tried, its going to lead. Therefore, I have an unproven design. In hindsight, I would have made the groove a smidge bigger, and gone with a flat base instead of a beveled base, but it is what it is.

As for the mold quality? Wow, just, wow.

Someone on here is going to sell me a Lee mold, so when I develop the load for the M&P, I'll be working with a proven design.

[longbow]

I have to ask what you mean when you say you have a bad barrel?

Leading is probably more often than not due to poor boolit fit. Have you slugged the bore? If so then how much over groove diameter is the boolit?

I have a similar boolit design from Tom ( http://accuratemolds.com/bullet_detail.php?bullet=43-165B-D.png ) also with small lube groove but have no leading problems in my 1894 Marlin in .44 mag.

I lapped the barrel as it had some tight spots at dovetails which resulted in leading before with other boolit designs but no leading now with any cast boolits.

I also size boolits to at least 0.001" over groove diameter and often 0.002" to 0.003" over groove when shooting as cast (unsized).

And I agree on the mould quality ~ yes, WOW!

Longbow

[BulletFactory]

I have slugged the bore. It slugs at .4007. I size them at the same size, because if I get any fatter, they start shearing off as they leave the chamber and enter the throat. If I size them to .4017, enough lead will accumulate in the barrel where the casemouth rests to prevent the gun from going into battery.

http://castboolits.gunloads.com/showthread.php?t=108693

[longbow]

Well, I guess I am not going to be too much help here because I don't shoot semi auto.

Where do you crimp?

How do you crimp? Is it a taper crimp?

If taper crimp, then if you set seating depth so the case mouth is flush with the front edge of the front driving band how can the round not chamber with a reduced nose diameter?

If lead is shearing off it sounds to me like the throat needs to be opened up a bit or that there is a sharp edge that needs to be removed.

Possibly fire lapping would help but best to check with someone more familiar with .40 S&W.

I have a friend that had trouble with .45 ACP in a 1911 that just wouldn't chamber some rounds. It turns out that his Lee mould was casting slightly oval boolits that when sized had too much throat diameter lead past the case mouth to chamber reliably. If seated so that the nose ogive met the case mouth they chamber fine. The solution is a boolit reduced nose diameter and seated with the front edge of the front driving band at the case mouth.

The Accurate mould #45-230B works.

Sorry, that's all I've got.

Longbow