Question regarding machining of an Air Pistol Barrel

[Vic Thompson]

Maybe not in the right section, but I'll carry on anyway. I fancied converting my Feinwerkbau P44 to full length with Carbine Cylinder but couldn't source a second hand barrel and a new one was £234 (which made the conversion non viable). How easy is it to machine ports into a Barrel (at the Breech end for air inlet and along the Barrel length for "braking Muzzle Flip") ? I've got a Milling Machine and Lathe and various tooling for both, but am wary of leaving Burrs inside the Bore and seek advice as to "drilling" a hole with a perfect "break through" to the bore. I've thought about tight fitting Brass or Lead Slugs, but is there any other way to do it that I should consider.

Thanks in advance for all helpful suggestions.

Vic Thompson.

[master_shriller]

Hi Vic

When I drill a transfer port hole, I always use a new quality HSS drill bit and run it at high speed.

HTH

Atb

Ben

PS Do you still have a VX111 silver Leupold you would like to sell to me, a long shot, but if you don't ask.

[vbull]

For precise perfect holes I use a smaller drill bit then go through with a reamer of the exact size needed.

[RichardH]

You can’t avoid burrs in the bore.

Look at getting it spark eroded.

[andrew375]

What I do to get a clean hole in tube is to drill a millimetre under size and open the hole with a slot mill, you need a milling machine for this. This will still leave a burr but very small. Also try pushing a tight fitting piece of dowel down the barrel to the point where the hole will be, that way the edge of the hole will be better supported so resisting the cutting forces.

[nige346]

There are very few things I won't do myself on a lathe or mill but porting a barrel, especially as precision as a match target pistol is one of em,

Any machining method is likely to leave a burr that will effect pellet stability, also you need to ensure the holes are in the rifle grooves and not the lands, This would taken some very careful maths (something i'm sure your capable of) and also some VERY precise machining, the space in the grooves is very tight to the size of holes needed to make the porting effective, EDM would I think be the best method if you were to go ahead.

Machining an alternative and already ported barrel from another supplier to fit would be an easier option. (lp10, lp50 etc)