Conversion, Semi to Straight-pull

ArcticNemo · July 31, 2009, 01:11 PM

I now live in a state where semis are barred from hunting use. My KelTec SU-16 has been a fantastic coyote gun so far, so I want to convert it to manual cycling. Anybody done it with this gun yet? I intend to simply plug the gas port, but any other knowledge is appreciated.
Could pressures increase to unsafe levels anywhere in the system? It is a gas piston design, same bolt head as an AR. I imagine the rifle would handle the same, maybe a bit sharper recoil...no biggie for a .223.

James K · July 31, 2009, 05:55 PM

I am not familiar with that rifle, but it seems to me that you want to do a conversion that is easily reversible. M1 rifles have been converted to straight pull by knocking out the piston in a spare gas cylinder lock screw. AR-15 type gas blocks are sometimes drilled out from the front end, allowing gas to escape without operating the bolt carrier, then the hole threaded for a plug screw to convert the rifle back to semi-auto.

Just turning off a gas valve, as in the M1A or FAL, probably would not be good enough to satisfy the state law, since you could convert back almost instantly.

Jim

ArcticNemo · August 4, 2009, 09:03 PM

Drilling the gas head sounds like a pretty good answer. Looking at the gasblock, it seems to be sweated onto the barrel pretty well; and I think there may be some solder in the joint as well.
The piston head may also get milled out some to reduce the chance of it rebounding, but I'm going to try the gas head modification alone first.
Here's a parts illustration to clarify.

July 31, 2009, 01:11 PM	#1
ArcticNemo Member Join Date: May 12, 2009 Location: Central WA Posts: 21	Conversion, Semi to Straight-pull I now live in a state where semis are barred from hunting use. My KelTec SU-16 has been a fantastic coyote gun so far, so I want to convert it to manual cycling. Anybody done it with this gun yet? I intend to simply plug the gas port, but any other knowledge is appreciated. Could pressures increase to unsafe levels anywhere in the system? It is a gas piston design, same bolt head as an AR. I imagine the rifle would handle the same, maybe a bit sharper recoil...no biggie for a .223. __________________ Liberals aren't Once you've been to Alaska, everything else looks like Texas.

August 4, 2009, 09:03 PM	#3
ArcticNemo Member Join Date: May 12, 2009 Location: Central WA Posts: 21	Drilling the gas head sounds like a pretty good answer. Looking at the gasblock, it seems to be sweated onto the barrel pretty well; and I think there may be some solder in the joint as well. The piston head may also get milled out some to reduce the chance of it rebounding, but I'm going to try the gas head modification alone first. Here's a parts illustration to clarify. __________________ Liberals aren't Once you've been to Alaska, everything else looks like Texas.

July 31, 2009, 05:55 PM	#2
James K Member In Memoriam Join Date: March 17, 1999 Posts: 24,383	I am not familiar with that rifle, but it seems to me that you want to do a conversion that is easily reversible. M1 rifles have been converted to straight pull by knocking out the piston in a spare gas cylinder lock screw. AR-15 type gas blocks are sometimes drilled out from the front end, allowing gas to escape without operating the bolt carrier, then the hole threaded for a plug screw to convert the rifle back to semi-auto. Just turning off a gas valve, as in the M1A or FAL, probably would not be good enough to satisfy the state law, since you could convert back almost instantly. Jim