I have BARs from 1969 to 1990 in 300WM and 338WM.

The gas system is not adjustable..... or is it?

If FALs have adjustable by pass gas, BARs have fixed jets.

With an FAL one can tune the gas bypass with a turn of a knob. This adjusts the rifle to the ammo. Enough gas to operate without jamming[small enough bypass hole], not so much gas the bolt hammers the frame [big enough bypass hole]. The recoil buffer helps a little with frame hammering. Check out the condition of that part.

But a BAR regulator is fixed. I like to load really hot [11 gr more H4350 for 140gr than Hodgdon says is max], and tune the rifle to the ammo.

The regulator in a BAR 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.

It is easier to modify a different cartridge regulator than to fabricate a regulator from a piece of steel. I have done both. [Look for a lack of bluing to spot the one I fabricated from scratch]

a) 7mm Mag is .066" hole
b) 300 Mag is .077" hole [p/n B3176146]
c) 338 Mag is .059" hole
d) My home made is .078" hole
e) recoil buffer [p/n B3176065]


[Linked Image]
https://www.midwestgunworks.com/browning-bar/parts.html

There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. -Ernest Hemingway
The man who makes no mistakes does not usually make anything.-- Edward John Phelps