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The Range
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crimp pressure
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<blockquote data-quote="Blitzfike" data-source="post: 1470852" data-attributes="member: 807"><p>Internal ballistics is a VERY complex issue. Increasing the crimp can certainly increase pressures. Not very many folks have access to pressure test gear so the next best thing is a chronograph. You can see the results of changes fairly soon in your bullet velocities. I have experimented with changing powders, primers, crimp, bullet lube and a variety of other factors in trying to wring the most out of pistol caliber ammo in carbines. I've found that using slower burning powders with lead bullets lubed with a moly/wax lube can give me 300 fps more velocity than standard loaded jacketed bullets. I started doing this for my son and his Beretta 40 carbine. I have been able to duplicate it for my Hi-point 40 carbine as well. Pressures appear to be in the normal range as measured by case expansion and primer flatness. In order to get the same velocities with more normal powder selections, I see case expansion and primer flattening to a great extent. The powder I ended up using is Accurate #7. Pretty slow for a small capacity case. Bullet seating depth plays a large part is pressures as well. I like Accurate #5 for my more robust pistol loads, but you have to be very careful with is as you can see pressure spikes pretty quickly with bullet setback. (bullets getting pushed further into the case as they are chambered and rechambered in auto pistols.) I tend to use a fairly heavy crimp with #5 to help guard against that. The crimp has much less effect on pressures than the reduced case volumn does. Blitzfike</p></blockquote><p></p>
[QUOTE="Blitzfike, post: 1470852, member: 807"] Internal ballistics is a VERY complex issue. Increasing the crimp can certainly increase pressures. Not very many folks have access to pressure test gear so the next best thing is a chronograph. You can see the results of changes fairly soon in your bullet velocities. I have experimented with changing powders, primers, crimp, bullet lube and a variety of other factors in trying to wring the most out of pistol caliber ammo in carbines. I've found that using slower burning powders with lead bullets lubed with a moly/wax lube can give me 300 fps more velocity than standard loaded jacketed bullets. I started doing this for my son and his Beretta 40 carbine. I have been able to duplicate it for my Hi-point 40 carbine as well. Pressures appear to be in the normal range as measured by case expansion and primer flatness. In order to get the same velocities with more normal powder selections, I see case expansion and primer flattening to a great extent. The powder I ended up using is Accurate #7. Pretty slow for a small capacity case. Bullet seating depth plays a large part is pressures as well. I like Accurate #5 for my more robust pistol loads, but you have to be very careful with is as you can see pressure spikes pretty quickly with bullet setback. (bullets getting pushed further into the case as they are chambered and rechambered in auto pistols.) I tend to use a fairly heavy crimp with #5 to help guard against that. The crimp has much less effect on pressures than the reduced case volumn does. Blitzfike [/QUOTE]
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