Yet Another Coating ShootOut

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mtngun
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Yet Another Coating ShootOut

Postby mtngun » Sat Apr 09, 2016 4:20 pm

I used the 6BR to do another coating shootout, posted at the CBA forum.

The 6BR has forced me to go back to the drawing board on coatings. I was happy with oil-based polyurethane (OBPU) in the 6x45, but OBPU crapped out at 2300 - 2400 fps with plain base bullets in the 6BR.

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Re: Yet Another Coating ShootOut

Postby mtngun » Sun Jun 19, 2016 6:46 pm

Today we did a cure time shootout for powder coat.

The usual 75 gr. bevel base, 26.3 gr. WC844, Rotometals reclaimed shot. I didn't verify the BHN of each and every batch of cured bullets because there were so many batches, but I did measure one Durable Black bullet (12.3 BHN) and one Almond Hybrid bullet (13.1 BHN).

Only one 10-shot group was shot for each cure time, and as always "one good group does not prove that a load is good, but one bad group may prove that a load is bad."
Image

*If* we take the results at face value, then Durable Black doesn't like to be overcured, while Almond Hybrid doesn't like to be undercured.

But it's hard to take the results at face value when there was only one 10-shot group for each cure time. Before I draw any conclusions I want to repeat at least parts of the test to see if the trends are repeatable.

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Re: Yet Another Coating ShootOut

Postby mtngun » Sat Feb 25, 2017 11:50 am

It's been a while since I played with coated bullets, but I hope to hit it hard again when the weather improves (still a couple months away). When I left off my favorite coating was Columbia Hybrid Fire Red, applied in a tumbler. The tumble method is not as perfect as ESC spraying, but ESC spraying has its own issues. The hard part about tumbling is getting the bullets to stand up on their base -- easy perhaps for short handgun bullets, but a challenge with tall rifle bullets.
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I favor hybrid coatings because they are not as fussy about cure time, compared to the more popular polyester coatings. 25 minutes usually works OK.
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