Last summer I took some time to set up a SAFN 49, 7mm Mauser, with the following load: Lyman 140 grain, round nose gas check bullets, wheel-weight metal, bullet # (not noted on the label I marked my rifle with), my own 50/50 lube, 43 grains of IMR 4350, CCI #34 primers, sized to .284", Winchester 7x57 casings, OAL: 2.755", to fit magazine of the rifle.
As unbelievable as it may sound, the rifle was brand new, unfired and the gas adjust was wide open, not set to function. I've wanted to do this for quite some time and finally took the time! The gas system on this rifle is readily adjustable by removing the front fore end wood (mine is a two piece wood top fore end) allowing access to the gas setting which is rotated over, and gradually, closes the actual gas port hole itself. Pressure is increased in the rifle as the gas port hole is closed gradually, building enough pressure to operate the action.I can set the gas system so that the rifle gets EXACTLY WHAT IT NEEDS TO OPERATE. I bought a gas setting wrench from Numrich Gun Parts. You will need one these so you don't mar things up with a pliers... It took ten cartridges to set up the gas system for this load. (This rifle is piston operated). My goal here was to get the rifle to perform all of the semi-auto functions that it normally does: Load from the magazine, fire the cartridge, bolt opens gradually until it ejects the fired casing (just dribbles it clear of the action, one neat pile on the ground, and then locks open. As this was going on, I would close the gas port a tiny amount, then fire the next round and repeat. The action was manually operated until all the semi-auto functions were achieved. I then loaded the magazine with ten rounds and fired the rifle until the magazine was emptied and the bolt locked open!. Was that NEAT!!
No pressure signs on the fired primer, no backing out of the primer. I chose to use IMR 4350 propellant as I have 8# of it! With this rifle's gas system, I tried to duplicate what I do in my two M1-A's and one Garand that I have Schuster Adjustable Gas Plugs installed in. Feed the rifle only what it needs to function.
When I completed firing the SAFN Venezuelan 49 rifle, I pulled the gas system apart and checked for fouling. Normal smoke fouling in the gas tube, piston head had normal smoke fouling on it. None on the rod itself. Checked the barrel next and saw no evidence of unburned powder granuals or leading. Cleaning turned up a light gray patch using Birchwood Bore Scrubber. The fired casings were still clean overall.
I did not check for accuracy as I ran out of summer. I did reload another 20 rounds and shooting the rifle is again on my list and ready to go.
Remember, this rifle is set up for this load only.
If you decide to use another load in this rifle, you must open the gas tube up and start with the gas port wide open, then gradually close as you shoot the next round.
Yeah, I know, I have too much time on my hands...
GregT
Hayward. Wi
