Sorry to resurrect this, but I bought a bunch of NSA .254 38.5grn slugs, and I cannot get them to seat in the magazine. Are
The opposite. This is what prevents jams and gives you a good seal for the air. The tighter fit prevents the slug from moving. If you take a slug and seat it in the barrel you should have to use force to push it through the rifling. The mag on the GK1 is actually rifled. Years ago I thought the pellet/slug should be able to move through the barrel with as less friction as possible. Makes sense, right. Well you'll be losing fps because the air will be going around the slug. My avs slugs actually have fingernail marks on the base from pushing them in. 42 grain AVS and you'll never have a jam again. Im sure there are other pellets/slugs just as good. One more tip - you dont want to be shooting a heavy slug (38 grains and above) on low power setting.
Agree with all of this. I have found the sweet spot to be NSA 33.6grain to get through a full mag at around 50 FPE very consistently and they shoot better than AVS and everything else ive tried. I hear Altaros ATP smooth (the bigger diameter) work very well but they are too heavy to get through a full mag without too much power/fps spread.