opening up gas port

[rapidrpr 3]

I have a mka1919 xn. I have cut the barrel and silver solder a tromix muzzle brake on it for a total overall length of 18 1/4 inches.it will shoot 1325 fps shell 100%, it will not shoot 1200fps. the gas booster rings (2) did not helped and where removed. I don't want to install a low power spring. I know I have shorten the dwell time. should I open the gas ports and if so how much? thanks

[Flatland Shooter 22]

Is the gun broken in yet?   Did it function correctly with lower velocity shells before the barrel was cut?

 

I did not realize cutting an inch or so off the barrel would create such problems.

 

Bill

[rapidrpr 3]

the gun was well broken  in and fired both low and high velocity shells with no problem with a standard recoil spring. richard

[Atomic Punk 25]

I would like to do this as well. Salem 6 has photos of an SBS'd MKA 1919 and when I asked them about it the owner told me the design is not very amenable to short barreling. I got the impression that their sample was not reliable and they were still trying to work it out. That was probably a year ago and their site doesn't indicate much in the way of progress.

 

Not much help but that's what I discovered.

[james lambert 3,059]

Thats why I designed the high energy op system for the gun....several years ago

[rapidrpr 3]

atonic punk    181/4 inches is not considered an sbs. the muzzle brake has a long slots so if gasses off around 17.' correct term?. I have a non xn with the firebird short hand guard from centerfire that has the early   heo system that shoots low velocity only. love it

[toothandnail 275]

mods Deleted my post ? ?

No wonder this forum has died.

see how long this one stays

[Atomic Punk 25]

atonic punk    181/4 inches is not considered an sbs. the muzzle brake has a long slots so if gasses off around 17.' correct term?. I have a non xn with the firebird short hand guard from centerfire that has the early   heo system that shoots low velocity only. love it

I understand that you aren't shortening to SBS length, my point was just that its a finicky gas system.

 

Hopefully, someone here can offer some advice as I'd like to shorten and perm attach the phantom-style FH to 18.25" myself.

[rapidrpr 3]

I think we lost toothandnail on the subject. sorry t&n.

[Atomic Punk 25]

Jim, are you saying the HEOS system (composed of a new Operating Rod, piston, o-ring and seal sleeve) that you sell for $105 will fix the OP's issue?

 

edit: never mind, I see now that he already has the HEOS system in his gun.

Edited December 31, 2014 by Atomic Punk

[james lambert 3,059]

he doesnt have our op system

 

check that the carrier runs free in the upper  no bolt, spring or drive block, just carrier

check that the bolt lock is not locking up to tightly

check for bent trigger or hammer pin\s they can induce drag

check piston ring for excessive drag, should slide into gas block with very little resistance

check piston to guide rod drag some are too tight

 

these are a few of the things to look at first