Boolit Base Deformation

[wv109323]

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I hope I have attached a picture. I have a new Mi-hec mold that I can not get to group in my S&W Model 14. The mold is a 360-158 SWC. I am sizing the bullet to .3577 from an as cast size of .3603.
I am getting what I think is unusual deformation of the base of the boolit caused by the rifling. The deformation of one rifling extends about 1/3 of the diameter of the boolit The base is anything but flat.
Have you seen this and would this drastically affect accuracy?
I can not get this bullet to print 10 rounds on a 24 X 24" paper at 50 yards. Rounds from different molds I can get around 2" with everything else constant.

[HeavyMetal]

Can we see an unfired base? That might help.

What sizer are you using?

[popper]

Sizing down too much, losing space in the lube groove so all the lead goes to form the tail. Weak alloy maybe concaving, making it worse.
edit: land marks are straight so alloy appears OK, but if you look close, the front band lead is broken off in the groove and pushed to the base. I had the same problem with 40SW. Slower powder may help.

[wv109323]

Sizer is a Star. Boolits were sized nose first with a flat punch. Sizer is marked .358 but actual is .3577. I will get a pic of unfired Boolit.

[303Guy]

Do know the alloy hardness number? I made an effort to eliminate trailing edge feathering and base cupping but that was without hardening the alloy.

[HeavyMetal]

Going to suggest you size these in two steps .360 to .359 then .359 to 357.

Also we need to se pic's of both unsized and sized boolits if you can base area of course.

You may need to bump your alloy hardness up do you have an idea of alloy content or hardness?

[44man]

Very common, soft lead has to go somewhere, it flows back. If it is even and exits the muzzle straight, it is OK. I see nothing to get excited about but you can harden the boolit to reduce the tails. If it shoots good, forget it.
What you need to look at are the rifling grooves to see if they have not exceeded the dimensions of the rifling. No skid so to say.

[beagle]

You might see if one of these guys will ship you a few of Pat Marlin's .35PB gas checks to try.

I had a similar situation with a Marlin .30/30....extruded bases after firing. The bullets plinked well but would not shoot groups. While all plain base bullets do this to some extent, yours seems to be more than normal./beagle

[wv109323]

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Here is a couple of pics. One is an un-sized,as-cast boolit and the other is the sized fired boolit. I put a thread in the Handgun/Pistol Section titled "This problem is for the experts" which details my journey with this bullet and mold.
The short story is that I could get satisfactory results from a RCBS 158 gn. RN and a NEI 158 GN. SWC but bullets from this mold will not group. I could get the RCBS and NEI boolits around 2" at 50 yards but this boolit I can not get to stay on a 2 foot by 2 foot cardboard backer.
The alloy content is range scrap( from a Bullseye pistol range) mixed with COWW.
I ordered this mold as a .360 diameter mold thinking that when sized from .360 to .358 I would get boolits that would be fully sized and perfectly round. It would also give me the flexibility to go to .359 or .360 if needed.
Apparently the rifling is "shearing" the lead body of the boolit causing the Fins. The fins/uneven base are destroying accuracy. The rifling of the this barrel is engraving deep enough to go through the crimping grooves in to the body of the boolit. What is the ideal depth of crimp grooves and grease grooves in relationship to the rifling?

[wv109323]

I will try to attach the picture.107045

[wv109323]

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