Airgun .308 bullet shape

Pinzgauer
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Re: Airgun .308 bullet shape

Post by Pinzgauer » Tue Oct 13, 2009 6:21 pm

OK...no pointy bullets. :(

Now just to push it a little :D can you make a bullet mold with a hemispherical nose? Our thinking is that the flat meplat is bad for accuracy at the velocity we are shooting them at (850 - 950 fps).

If I have struck out on both counts and your CNC set up cannot do the pointy or hemispherical noses, could you suggest a competitor that can cut molds with a cherry to such a shape? It is fine to reply by private mail - mbarna at chartermi dot net

Kindest regards,

Mike Barna

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mtngun
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Re: Airgun .308 bullet shape

Post by mtngun » Wed Oct 14, 2009 8:01 am

Everything that I can cut is available in the online design program.

I don't plan to cut any more molds for airguns, however.

Any custom mold maker should be able to make a pointy or round nose mold. Paul Jones, Brooks, Old West, Lee, NEI, and probably a few more that I can't remember off the top of my head. There is a glut of custom mold makers.

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mtngun
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Re: Airgun .308 bullet shape

Post by mtngun » Sat Nov 28, 2009 2:36 pm

Well, I wasn't paying close attention and let someone slip in an order for what appears to be a 30 caliber airgun bullet, cast of 30:1 alloy.

As has been discussed on other posts, the force of cutting the sprue distorts the bullet base. My sprue plates are not designed for the combination of 30 caliber and black powder alloy (on the other hand, 30 caliber and wheelweight is no problem, since wheelweight sprues cut easily).

Here are the measurements of the base with 30:1 alloy. The spec is supposed to be 0.306" - 0.308":

0.3031"
0.3038"
0.3042"
0.3043"
0.3047"
0.3053"
0.3056"
0.3060"
0.3061"
0.3068"
0.3072"

We have a 0.0041" spread. Lotsa luck shooting that bullet.

The cavity is machined correctly, it's just that the sprue cutting force is pushing the base to one side, resulting in a pronounced egg shaped base. The only solution would be to make a custom sprue plate with itsy bitsy sprue holes, and that's not gonna happen. :evil: If you think making custom sprue plates is quick and easy, THEN YOU DO IT ! ! !

This mold will be shipped out this way. I don't feel responsible because my job is to machine the mold correctly, and I did that. I have no sympathy with the problem. This subject has been discussed over and over......... it may be that the only solution is to eliminate all alloy choices except wheelweight. :cry:

turbo1889
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Re: Airgun .308 bullet shape

Post by turbo1889 » Mon Nov 30, 2009 7:31 pm

mtngun wrote:. . . . it may be that the only solution is to eliminate all alloy choices except wheelweight. :cry:
Please, please, I know it's your business but if you do eliminate alloy choices to keep people from creating this problem. Please, please, make it caliber category dependent and not a blanket situation so we can still do large caliber soft alloy bullets.

Yah, I know, if push comes to shove we can always order a bullet mold and mark it as for WW alloy and then specify a slightly larger or smaller diameter trying to anticipate how much larger or smaller the result will be if we cast of a different alloy, but there is a lot more chance I'll guess wrong on how much to compensate then you will. :cry:

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