With the USPSA Nationals coming up next week, I figured I had better build a new gun that weighed about half of my old boat anchor. I'm old and feeble

Short gas, lots of Tromix parts, Doctor, choke tubes, and a mid-barrel compensator. Since (if I read the stages correctly) there will be only one reload (sigh), the lack of a mag well won't kill me too much.







Should be interesting!



Alex

I would love to no more about the mid-barrel compensator. What is it's purpose? Where can I get one? Do you mill out the sides of the barrel to install? I want it!!!!

You drill some holes in your barrel, clamp the comp over the holes, and gas is redirected to cut perceived recoil. A well-tuned gas system helps a lot, and that gizmo makes it even better

Looks good Alex. Good luck.

Wakal,

Do you guys have the CNC finalized on this? I know we discussed it before. Please PM me some details, I'd like to purchase one.

Also, after competition, could you send me pics of the barrel sans compensator so I can see what kinda holes you drilled? Thanks for everything.

~SN

thats the mutt's nut's.
what brand/where from - is the extended mag release ??
how do you find the Docter sight ?
good luck at the comp.

Bought the Doctor years ago. I got a bunch at the same time, and had The Man over at Grams Engineering do his "bulletproofing", added the Arrondodo double battery base, and set up the custom mounts. My wife's S20 has the only other one I have left, though.

Yeah, I have enough of these comps to outfit all my Saigas and then some, although it may rattle around on the .410 a bit

The extended mag release is a Tromix design; Tony welds 1/16" by 1/2" neatly bent and beveled bar stock to the tab. I liked how the one on my Tromix SBS worked, so I welded up a few more for my other guns. I will have to grind it to fit the mag well once we get those going, but steel can always be modified later




Alex

See you have them on the USPSA site also. I've ported my barrel... How far back does your comp go from the end of the barrel?mike A 17262

About four inches forward of the gas ports seems to work out well. Fred's has a double line of top ports on the top/right forward of the comp; I like his enough to duplicate the same porting the next time I fire up the mill




Alex

I have been meaning to ask, What advantage does shorting the gas system have?

IPSC_GUY
SIERRA II ALPHA

Very Interesting competition gun! Thanks!

It taps the gas earlier in the barrel, allowing ported barrels to still cycle effectively. I think the rule of thumb is that you treat it like the barrel has been cut off at the point where porting starts. If the gun would cycle without shortening the gas system (as with a 16.5" barrel) you are good to go. But if the barrel is "shorter," you need to shorten the gas system. A similar effect can be created by simply opening up the gas vent holes, but there is a limit to how much can be gained.

The downside of a shortened gas system on any weapon is increased bolt velocity and strain. Hence, a 14.5" barreled M4 will wear more rapidly on its bolt carrier than a 20" AR. There are a lot of variables, like spring weight, buffers and the type of ammo used, and pros like Tromix and E-Tac do it very effectively.

^Correct. Also, a long gun with short gas system will run lighter-power shells. It has a long dwell time from the gas port to the muzzle and produces a ton of gas. As stilletto mentioned, it's a must for a mid-barrel compensator since the comp releases a lot of gas.

Lots of gas..."blasty" is a word used to describe another comp design by the same bunch of west Texas idiots, on page 194 of AR15 Volume II

While the shooter doesn't notice anything except the dot staying on target through the recoil pulse, nearby shooters (and the poor RO's) are not amused by either of these two similarly configured guns (mine and Fred's)




Alex

LOL I know that's right. It always cracks me up to stand at the sidelines at see at the offended looks on people's faces.

Tony's M1919 with the 12" Barrel gets the same thing.

Damn, that is cool

I was bored (and had a camera)...here is the whole pile of crap that I have to haul to three-gun matches these days. Holsters and mag pouches by Blade-tech.



And in response to the question about porting the barrel, here is Fred's prototype short gas gun with comp off the barrel. Note the angled porting and the vintage Savage Acu-choke system







Alex