Air Gun Home :: View topic

Jaxom · Senior Member

In same vein as my hypothetical situation threads, there's another issue I've been pondering.

After extensive googling, I have yet to find on any website plans for a diy barrel boring/rifling machine. I have asked on here about where ag barrels could be purchased, but most are for standard calibers. Usually the smaller bore ones in the .177-.25 caliber range. But what if I wanted to build an ag rifle that was say 7mm? Would I have to buy a barrel for a powder rifle and some how adapt that to the ag reicever?

Once I have this built, I would then need pellets for it. I've googled this as well. Read a bit on moulding pellets and swagging pellets. But really not enough information on the whole process of swagging. Is there a good website or perhaps book that goes into more detail of this process?

Thanks,

Jax

scroller99 · Veteran Member

I have an extra 12 ga. shotgun barrel I could send you Twisted Evil

Jaxom · Senior Member

LOL!!! I'll keep that in mind for future refernce.

dummyracer36 · Senior Member

Jax.... this site has a ton of info on pellet molding and swagging

http://www.corbins.com/pellets.htm

Jaxom · Senior Member

Wow DR, that IS alot of info. From what I've briefly read on that site it's basically possible to swag any caliber pellet. Although that site is a link nightmare! Think I'll keep an eye out for that book by Corbin on swagging, then go back again. I do have one question though...

On that site it says, once you find a particular pellet your gun likes, to send them a few and they can make a custom sized die for you. Now I've thought about this before.

We all know that it takes trying hundreds if not thousands of rounds to determine which particular pellet your gun likes over the rest. Now think about this for a moment, you're siting in a new gun not knowing which pellet it will like over the rest. Could we possibly be siting in our guns by not using the right pellets? When we're just compensating by adjusting the scope for a mediocer one?

Or how about this scenario. I wanna build a custom rifle. I wanna be different then everybody else, so I choose a different caliber, like say 7mm (.2756) or 8mm (.315). Nobody sells those locally for ag's! And I don't even have to try it to know that I can't just go to local gun shop and buy bullets and stick them in an ag and expect them to work right.

fritz · Silver Status Member

You could always use an old burner barrel and use standard burner bullets in it.

It would have a distinct advantage being that you can have bullets with excellent ballistics. A problem being you might need a wornout bore so you get less friction, so the air can give it more velocity. Air may also not be able to propel the round fast enough for the rifling rate which will give you a poorly stabilized bullet. You likely won't break 250fpe in calibers up to 7mm, but a 12g slug could break 500 easily.

I say if you found a slow rifling rate in like .223 (for cheap ammo), with a slightly worn bore, you could easily build a receiver for it. Making sure the bolt probe and the breach crown are perfect so the bullet is seated nicely, and not damaged by the loading.

Slavia · Moderator

Griff1950 · Member

Air rifles can't be compared to black powder rifles or contemporary powder burners. Black powder is an explosive, and that sudden jump in pressure is what flares the skirt of a Minie ball to engage the rifling. Most modern powder burners operate with pressures in the range of 30-50,000 CPU, which takes them far outside the range of any modern airgun. An airgun barrel should have shallow rifling with a very smooth finish. Projectiles should be pure lead for easy seating in the chambers. Just MHO.

Jaxom · Senior Member

So'kay...now I'm back to where to get odd sized barrels for an ag again. Anyone got any idea's on how to build a boring/rifling machine?

Also, what's the typical twist rate on a ag rifle? Anyone know?

fritz · Silver Status Member

IIRC most smallbore airguns are 1:16.

I think a LOT of .22lr barrels are in that area, too. Since .22lr's usually use solid lead bullets then it should be capable of firing standard airgun pellets. Not that I think you would want to anyway if you are building a high power gun- you would likely want to cast your own or buy like .22 bullets.

dummyracer36 · Senior Member

Jax have you thought about goin the sabot route? if memory serves, you can find sabot rounds as small as 9mm

fritz · Silver Status Member

If he used sabots then it would be possible to skip a real "barrel" and just use back iron pipe or what not. Assuming the pipe was straight... it might shoot good.

Jaxom · Senior Member

This all bein speculative, in as much as I don't have the $ to even by a tap n die set right now... Even to make a sabot barrel (smooth bore?), how would one go about boring a 24" long hole?

fritz · Silver Status Member

With a lathe I guess.

Jaxom · Senior Member

Fritz,

I've thought about that. HB carries a 9x20" lathe for $699. Occationally they'll have it on sale for $599. The center bore is 3/4" wide. This should be ample enough room to hold bar stock to make a barrel out of.

The issue then becomes, where do you find say a 26"-30" long boring/chamfering bit...and an end stock that was hollow so you could feed the bit through it?