Ryan
In the interest of keeping it simple, you need to reload for this rifle. There are some brands and loadings of commercial ammo that will function the rifle correctly, but most are too hot, and use powder with too slow a burn rate. I replaced the gas block screw on one of my rifles with an set screw with an angled bevel filed on one of the sides to provide a level of adjustment for many different loads. Problem is, unless you stick with one brand, you find yourself spending more time adjusting than shooting. So...I ended up pulling the adjustment screw out and replaced it with the original screw and hand loaded for the rifle instead.
My Recipe is:
Winchester case
Winchester Large Primer (non magnum)
36.5-37 grs of IMR 4895
Hornady 140 gr Interlock Bullets.
With this loading, my rifle regulates to the sights as far as elevation is concerned. Minor windage adjustments may be necessary.
This load clocks around 2550-2600 fps and functions the rifle and action perfectly without beating the heck out of the cases (The solid ejectors on these rifles is very hard on case rims, and can severely dent them if the load is too hot). My load throws the cases about 10-12ft. and without damage to the rims, which is far less than the 30ft. where most commercial loadings end up.
Most of the problems the AG42b encounters are from these too hot commercial loadings that put excessive pressure on the extractor and ejector, as well as the safety/dis-assembly block at the rear of the receiver. If you have the tool kit, and it's complete, you'll find a small rectangular tin that contains two spare extractors, and springs, 1 or 2 extractor pins, and a spare firing pin and spring. There should also be a flat sheet metal type of "pick". This is the tool for changing out the extractor. I believe the Swedish Ag42b manual that has been translated, (and available on the net) shows how it is used.
The rear sight drum can be regulated for both spitser and round nose bullets, by reversing the sight drum after removing the adjusting knob. again, the manual should show how this is done. There should be a "half circle" type pin wrench in the kit. This wrench is used to loosen or tighten the smooth nut at the muzzle, which lessens the tension of the spring just to the rear of it, so that the windage screw on the front sight can be easily adjusted, and for cleaning the muzzle end of the barrel. After any windage adjustments or cleaning, the nut is replaced and tightened.
This should cover most of your questions.
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