Buying the components I'll need to reload for my Krag and these gas checks are totally new to me. I want to use lead bullets because they are cheaper and apparently Krags like them, but I see lead bullets with and without gas checks (presumably the later come without the gas checks but provide the option of installing them). I need bullets sized to about .311 or .312 since my bore slugs to .3108 and I have come across a few expensive jacketed ones sized to .312 but they are roughly $30 per 100 which means I will seldom be shooting my Krag. But I did find these on midway;

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$68 per 500 is a lot more to my liking, I'll actually be able to afford to shoot my Krag. They are on the heavier side, round nose and sized just a bit larger than the bore. But at what point or fps do I definitely need a gas checked lead bullet? Can I get away with the above for fun at the range? This is in a real 1899 Krag carbine that I want to punch paper at 100yards. Thanks