Holey Gas Checks -- brilliance or noobish stupidity

[Dannix]

For some reason while reading some of Pats posts and chatting with him, I realized you can't shoot a boat-tailed bootlit if you gas check...but then I thought about rebated boat-tails.

Wouldn't it be possible to design a gas check with a hole in the middle so it could be used on a rebated boat-tail boolit? This way you could have a proper edge seal, but also the high BC the rebated boat-tail offers.

Thoughts? Dumb, brilliant, not worth the extra effort? I wonder by how much the BC of the wide metaplat boolits we love would improve if a respectable rebated boat-tail was introduced, with the same flat nose profile held constant.

:Fire:

[dragonrider]

My first thoughts about it would be how to seat this check. In a Lyman or RCBS it would take a custom made push rod in the size die. In a Star it would mean a custom punch. I don't see it as being impossible but more work.

[Ben]

Of the available choices........Dumb, brilliant, not worth the extra effort?

I'll go with the last one........

[jhrosier]

It would probably work just dandy, until the first one came off in the bore and the next shot ringed the barrel.:cry:
Other than that, I don't see any problem.

Jack

[Maven]

Actually this was promoted in Handloader mag. in the late '80's or early '90's. One GC had a hole punched in it and was used as you normally would. It worked and showed that a partially exposed alloy base did not result in bore leading or deiminished accuracy. The other type was actually a gilding metal ring, one or more of which was carefully placed in the hot mold (with a tweezer) prior to casting. The resulting CB essentially had gilding metal driving bands and could be accurately driven at high velocity. I believe it was known as the Wilk gas check. Needless to say, as the inconvenience outweighed the advantages, it essentially disappeared.

[mroliver77]

I am thinking along the lines that Maven followed. Cast the gas check that has a hole threw the center right in the mold and it would be fixed in place above the boat tail. I have no idea how the BT works at cast speeds. Maybe somebody with a BT swaging setup could somehow work up some prototypes to try?
Jay

[Maven]

If you google Wilk gas checks, you'll get a link to the July- August, 1988 "Handloader" containing an article on them. I think it begins on p. 34.

[

[Pirate69]

You caught my attention on something. Has there ever been a documented case of a gas check staying in a barrel and the next shot ringing the barrel??

[Dannix]

If you google Wilk gas checks, you'll get a link to the July- August, 1988 "Handloader" containing an article on them. I think it begins on p. 34.

Link to article (http://www.riflemagazine.com/magazine/PDF/hl134partial.pdf) Can't upload it due to forum size parameters.

[GeneT]

CH used to make a deal with a zinc washer for a gas check. I have details somewhere, but IIRC it showed promise for reduced leading, but the death of the founder (C.H.) brought a change to the company and that concept was dropped.

GsT

[Outdoors]

Ch is again making dies for the zinc base bullets. At least, the dies listed on theri website.

Pat

[drinks]

A friend in Canada sent me a few bullets that had a gas check in the middle, it had a hole through it and sat in the mold about midway, the alloy went through and filled the bottom of the mold.
Funny looking, I never fired any so I have no idea how well they worked.

[Dannix]

Zinc-based. That's an interesting idea since I imagine most of us have zinc laying around in the rejected ww pile. Going to look into that.

[30calcaster]

It is a good idea but not practical until a way is found out to easily incorporate a Wilks gas check. There would definately be benefits, but mostly when the bullet is subsonic. I found this at the Corbin web site.

Subsonic (below about 1090 fps depending on air density) bullets have their BC more affected by the shape of the base than the nose. A very blunt bullet can have its BC improved by nearly 40% by changing from a flat base to a rebated boattail shape, whereas a supersonic bullet will only improve by 10-15% by changing the base, because the shock wave generated at the nose is so much greater an effect than base drag. Without the shock wave, most of the drag is at the base. Therefore, subsonic airgun, shotgun, and blackpowder bullets do not really need a longer ogive to get higher BC in comparison to using a boattail shaped base. The problem is that a boattail base is incompatible with a hollow base for sealing the bore. Therefore, a special under-cut form of rebated boattail may be used to create a seal at the boattail shoulder.


To read the entire article this is the link http://www.corbins.com/minwt.htm