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A question about bolt caming, the force required to set rifling, and bullet design.

Jwestie15

Plastic
Joined
Nov 21, 2017
First post,

So I like airguns, I want to build one but I'm a massochist who wants to reinvent wheels, I want it to shoot Remington AccuTip-V Bullets 17 Cal (172 Diameter) 2 - MPN: 2416 so you kinda have to push really hard to do that into the rifling past the transfer port. Military bolt actions from the late 19th and 20th century are cammed for high primary extraction force; how does one do the opposite?
 
Last edited:
First post,

So I like airguns, I want to build one but I'm a massochist who wants to reinvent wheels, I want it to shoot Remington AccuTip-V Bullets 17 Cal (172 Diameter) 2 - MPN: 2416 so you kinda have to push really hard to do that into the rifling past the transfer port. Military bolt actions from the late 19th and 20th century are cammed for high primary extraction force; how does one do the opposite?

In a rifle, you have an angled lead-in on the locking lugs, but you'd need much longer throw to fully seat that bullet into the lands - probably a closing lever on the bolt. However, there's an easier way, and it's how the other high-power air guns do it - you create a chamber by opening the breech end of the barrel so the bullet may be inserted full length with your fingers. Let the air push it into the lands.

Good luck!

GsT
 
First post,

So I like airguns, I want to build one but I'm a massochist who wants to reinvent wheels, I want it to shoot Remington AccuTip-V Bullets 17 Cal (172 Diameter) 2 - MPN: 2416 so you kinda have to push really hard to do that into the rifling past the transfer port. Military bolt actions from the late 19th and 20th century are cammed for high primary extraction force; how does one do the opposite?

I am not sure it will be possible to use a jacketed bullet in an air rifle. This requires much higher pressures than the about 1000psi that you have in a typical air-gun. All airgun bullets and pallets relay on a thin, lead section of the bullet circumference to be forced into the rifling and to create the seal.
 
Or paper patch a smaller bullet (if you can find one.) Or swage the bullet down to bore diameter for all its length except 5 or 10 thou at the base so you don't have to engrave the whole length and don't have to cut a chamber.

And note that .17 cal bullets are .172" dia versus the .177" of air guns. So you likely would have to swage the base larger instead of the body smaller. Paper patching a bullet that small would be a real challenge.
 
I am not sure it will be possible to use a jacketed bullet in an air rifle. This requires much higher pressures than the about 1000psi that you have in a typical air-gun. All airgun bullets and pallets relay on a thin, lead section of the bullet circumference to be forced into the rifling and to create the seal.

Jacketed bullets are commonly used in the large bore high-power airguns. This is strictly the domain of PCP (Pre-Charged Pneumatics) where pressures start at 3000psi and many go to 4500psi.

GsT
 
Powder coating appears to be the wave of the present.
Call it a very thin skinned sabot, or a plastic wrap. It should be good for lubricity. Quite the rage with cast boolits ....

I would believe PC would be ideal for sizing up powder burner bullets to fit airgun bores. The "smooth twist" airgun barrel as produced by FX airguns may be a significant advantage for minimizing friction drag as the bullet accelerates down the bore.

But if you are making your own airgun, choose a barrel to fit your choice of projectiles. ;-)
 








 
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