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Old February 25, 2012, 12:35 AM   #53
Bart B.
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Join Date: February 15, 2009
Posts: 3,825
Then there's those whose bullets are so lightly held in case necks they can be pulled out by hand. And they shoot very accurate. Some benchresters do it and they win matches.

Talked with a guy years ago who ran some tests measuring how much extraction force it took to bullets that and varing amounts of neck tension in uncrimped cases as well as other with varying amounts of crimp. Cases with varying amounts of neck tension had the smallest spread of forces to pull the bullets from each batch. Crimped cases had wider spreads of force required.

One thing often done by military teams shooting match ammo to improve vertical shot stringing at long range. 7.62 and 30 caliber arsenal match ammo has specs for the extraction force to push/pull a bullet out of their case necks. Regular crimped service ammo has about 60 pounds spec'd but for the uncrimped match ammo it has to be at least 20 pounds but I've never measured any with more than 40. The extraction force spread of both is quite a bit. Folks would use a Lyman Nut Cracker tool with a seating die for the cartridge at hand then use it to just barely seat the bullet deeper to break it loose from the asphaltum sealant. Reseated rounds had a much smaller extraction force spread and shot better scores due to a smaller vertical shot spread.

This seems to fly in the face of Lee's belief that increasing a bullet's extraction force (which crimping does) improves anything regarding accuracy.

How many folks have measured the force needed to pull bullets out of case mouths?
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