I made a BAR gas regulator

[Clark]

The 300 Win Mag BAR was 25 years old, came with a beat up shock buffer and the reason why: it had a 7mm Mag gas regulator instead of a 300 Win mag gas regulator.

If I load wimpy ammo it works, but put in 12% more powder and the rifle ejects the empty case into the next county.

So the regulator is just a 9/16-24 ultra fine thread bolt with a hole in it. If FALs have adjustable by pass gas, BARs have fixed jets.

7mm Mag is .066" hole
300 Mag is .077" hole

I am going to make the hole bigger until the rifle just ejects hot load nicely.

The one on the left in the picture is a 7mm Mag regulator, the one on the right is the one I just made.

 

[Dans40X]

Clark,
Instead of drilling/enlarging the gas hole-
Drill & tap the vent hole & install different sized orifice set screws so you can just change the orifice size by changing the set screw.
Example-
M1A/M14 gas plug
I/D bored to 3/8" for higher volumne
Hex wrenching area end drilled & tapped #4-40tpi w/ 1/64" thru hole
Different material set screws drilled thru the centers with varying orifice size to tame cycling/battering of the bolt/action.

 

[Clark]

Good idea.
It takes me a couple hours to make a bolt, but I could drill out a set screw much faster, and it would be reverse able.

 

[Dans40X]

Clark,
A #6 or #8 JET/set screw would be the ticket for your .066/.077 gas holes.
With an unmodified JET/set screw you can run basically a stock appearance plug as in the first pic.
Remove the JET/set screw-inset drilled orifice JET/set screws & calm the battering as you posted with alot less work.

 

[nfhjr62]

Are you saying auto/carb jets for different sizes

 

[Dans40X]

No,JETs was just a figure of speech.
I drilled s/s set screws,.0145,.0125 etc)to vary gas venting/breeding.

I don't know how long Mikuni main jets would last with high pressure hot gasses passing through it.