Inverted Gas Checks ?

[Al Bear]

Q: Is it proper to answer a question with a question?
A: Why not?

In my world there are 2 situations where I see a benefit of stuffing a sized (homemade) gas check - concave side towards the powder - into the neck of the casing before seating the bullet. And, when fired, the GC flies off like a shotgun wad.

I use sized 00 buckshot to make “game getter” loads for my 30 cal rifles. Using the inverted GC makes it possible to add a dab of Crisco ( my favourite lube) before seating the projectile.

I also have a mould that drops a 98 grain plain based .312 dia. bullet that benefits from a GC if I want to shoot it at around 1500 fps.

Both projectiles, as well as the GC, are sized to .309 (Lee sizer). Naturally, it makes sense to eyeball the bullet to ensure the GC doesn’t get pushed into the shoulder. A 30/30 shell has a longer neck than a 30-06 so the 30/30 is a better candidate for the 98 grain bullet whereas both have ample room for the 00 buckshot w GC combo.

This process is fiddly as heck so why bother? I’m a gun nut … so why not?

 

[legi0n]

the thing is, when the gas check separates, it may destabilize the bullet
I have had a few normally seated gas checks that (visibly) separated and the bullets became fliers

 

[Al Bear]

Legi0n, what you’re describing is a technical failure. What I’m describing is a design feature. My limited testing ( with the buckshot) shows that - like shotgun or muzzle loading sabots - they work as intended. Game-getter loads are (to me, at least) for head shots on rabbits or grouse within 25 yards. In order to see an appreciable difference, I tested 4 shots with inverted gas checks and 4 without - at 40 yards. The IGC shots grouped at 2.5” whereas the other 4 grouped at 3.5”. Interestingly, I found 1 fired GC (at maybe 15-20 yards) and it showed rifling engraved where expected.

On a different (but related) note, how could you determine whether a flier was caused by a GC separating in flight or some other reason? Sometimes the GC separates after the bullet hits the target. (I have proof of that from GC bullets recovered from deer.) There are many factors that can affect the accuracy of a cast bullet.