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Posted: 1/8/2007 1:19:21 AM EDT
| I'm sure this has been thought of before, but I've been kicking the idea over in my head a bit. How about a FSB with a short cylinder attached to the back and a piston, kinda like an SKS piston, that follows the same path as the gas tube? It would have to be some pretty tough steel and hardened to keep it from bending, but I can't think of a reason why it wouldn't work. Any thoughts? When the money tree out back blooms I'll have to pick up some parts and give it a go. I'll have to cut the piston in a few setups since my lathe is pretty small, but I should be able to handle everything else without a problem. |
| I had the same exact thought about a month ago. I made a rough design but I need to take into account factors such as the distance of bolt travel required and the volume of gas that typically is used to operate and AR. Once i get those details down I think I can start construction. Think 4150 steel will be heat resistant enough? |
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I'm thinking some kind of heat treatable stainless for the piston, at least the part that'll be sitting in the heat. 4130 should be good for the rest of it. I think it'll need a float tube to clear all the parts, possibly with a notch milled out to clear the cylinder. What really worries me is that this is a really simple idea. If it'll work, why hasn't it been done? If mass produced it could be had for under $150, possibly under $100, since it's just a gas block and piston. |
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You guys are confusing me. First off, I thought the gb was in a specific place on the barrel based on the length of the barrel. (gas port position based on barrel length) To me that means the action is not pushed open until after the bullet has gone past the gas port. I just don't see how some type of cylinder/piston arrangement is going to operate the action any better than the present setup. And how long does the stroke of the piston have to be? Maybe I just don't understand how things operate. If not, I'm all ears - clue me in. Don't consider this a criticism, only a search for more knowledge. cb |
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The biggest problem seems to be the junction of the gas key to the carrier. Ares has solved it the best way, by making a new carrier that includes the bump on it that the piston engages. Every other system has done major surgery to keep the gas key in place. The screws are not enough. Welds break LW dovetails their key into a keyway. |
Well I guess that shows it'll work  I was thinking more along the lines of a spring pushing back against the piston holding it in contact with the bolt carrier. My brain figures it would push the carrier back instead of hitting it, possibly reducing stress. Does the dovetailed lug work? If so, and if the bolt carrier isn't hardened, I could cut it pretty easy. Hog out the bulk of the slot with a small end mill, then cut the corners with a dovetail cutter. |
I don't think it matters much where the gas port is (well, as long as it's not so close to the muzzle that there's no pressure built in the gas system) since the bullet is moving at ludicrous speed and there's enough inertia in the the BCG that the bolt isn't opening before the bullet is in the next county. And, like it was said above, it's for cleanliness. The AK and SKS stay pretty clean since there isn't much crap getting blown into the receiver. The AK doesn't care about the crap, but still
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They make a new carrier with the dovetail slot cut in it. The piston is in full contact with the carrier when the bolt is in battery. No need for a spring as it would quickly get collapsed from being over-worked. When the gas pressure hits the piston head, that's where the force is that rips the key off the carrier. There is no slap or hitting of the key other than the force of the gas. The rhino system used polymer buffers to lessen the blow and still had this problem. That was 30 years ago... Best of luck in your venture. Please keep us posted. |
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