Buddy with RFB, going shooting tomorrow for first time....gas setting questions

Going shooting his RFB, he hasn't shot it yet, and we are looking at the instructions for the gas setting. It doesn't make a ton of sense to us.

I am suire it isn't rocket science, but we don't want to waste 30 rounds of .308 to get it correct either.

Any advice to get us up and running with little effort?

We will be shooting some Port.

Thanks in advance.

Open up the gas knob all the way (unscrew it). Load mag with 1 round. Tighten 1 click at a time until the bolt will lock back on an empty mag.

I have a newer second gen gas system and a lot of them appear to be overgassed. Mine will work with maybe 5 clicks in from fully open.

If you have too much gas the rifle will jam the spent case on the ejection ramp. You'll start to see the dented or in the worst case completely squared case mouths.

Good luck!

Thank you.......

We ended up doing pretty much exactly what you mentioned. It did take him a fair number of rounds to get it set, but it seemed to be running pretty well once he did.

Fun little gun.

If this it the first out of box shooting, DO NOT touch the gas setting. It is set from the factory.

Only set the gas if it is not working when you go out there.

I've never heard that...I'm only following the instruction manual. From a practical standpoint, it would be impossible for the factory to pre-adjust the system for the wide variety of ammo that the end user might select.

There are a couple of different methods for setting the gas port, depending upon which revision of the gas system you have: old or new. I have an old version gas system, so the details of what I should do to find the right setting for a given lot of ammo are going to be different than what you will do. But with either system, the principle is the same. The RFB gas plug functions as a pressure release valve. Opening it vents more gas out and away from the piston. Less pressure on the piston means less push on the bolt carrier. So the MORE you open the gas valve, the LESS gas is available to operate the bolt carrier/bolt.

To minimize wear and tear on the RFB and keep it running smoothly, you want the gas plug adjusted so that there is enough gas diverted to the piston to reliably lock the bolt back on an empty magazine, but no more. Not venting enough gas will cause the bolt carrier to slam into the rear of the receiver/stock, increasing felt recoil and possibly causing it to rebound hard back into battery. This can lead to malfunctions and jamming.

I keep notes on what my gas settings are for various loads (I roll my own). I've not had any problems yet. The RFB is a lot of fun to shoot, though I find it a challenge to master. It's so short! As compared to, say, my M1A or AR-10.

Good Luck!

Well, all the guns are test-fired at the factory, so it must be set at least close to the correct spot (at least for the ammo used in test firing) before it is boxed up.
It is possible that the ammo you have is different. But I still suggest you shoot it first before messing with anything.


Would you re-do the alignment and rotate the tires on a brand new car right after you drove it off the lot? (not the best analogy, but you get the point)

One would think so. However, mine was not set correctly out of the box for the ammo I was using.

Ya pays yer money, and ya takes yer chance. Like everything else in life.

No, but I might adjust the mirrors and the seat before I drove it. And I only rotate the tires on my guns every 10,000 miles.

If it is brand new out of the box, at least check it and be sure the gas setting is correct.
If you purchased a brand new car, drove it over to the tire store and had different tires put on, you would more than likely have to rebalance them.
When I got my new RFB, I had to change the gas setting a little for the load I was using.

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