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Started by txcas, February 17, 2010, 01:54:37 AM
Quote from: Cold Trigger Finger on January 21, 2016, 08:45:56 PMGain twist rifleing does help mitigate peak pressure. At least one of our 6.5 predessors ( the 6.5 Carcano) had gain twist rifleing. And from the records of ruptured cases and failures to extract , the 265 Mannlicher, could have used it also. With the powders of the day , even 2200fps with a 160 gr bullet under tropical conditions proved too much for the brass to handle. In modern times , the 460 Smith and Wesson had to have gain twist rifleing to function in the XVR ,with safety and dependability. There may well be others. Like the 454 Casul that could use it but FA went with a slow twist. There are no doubt others, but those come to mind. I think all 6.5s should have gain twist rifleing . Just makes for a nicer transition from dead still to ?how many thousand rpm , in a split second. No wonder some bullets blow up in mid air .
Quote from: dadajack on January 21, 2016, 09:01:31 PMI think those thin jacketed varmint bullets blow up regardless of how fast you get them to their terminal RPM. Although, there could be some tearing of the jacket in the barrel from the rifling that compromises the integrity of the bullet. But, I think a 22-250 with a 35 grains varmint bullet will detonate outside the barrel with a fast enough twist even if you used polygonal rifling and gain twist if the rate is fast enough. So, the twist rate can, indeed, influence peak pressure, but does that mean you retain the same muzzle velocity, or would the MV also drop enough to be statistically relevant to cartridge performance. Also, I wonder how fast we could get the 6.5 Creedmoor going safely witth a gain twist barrel? Could you imagine how much that barrel would cost? To go from 0-8" twist in 26" or less? I wonder if there is a minimum barrel length necessary to stabilize the bullet at the final twist rate. I mean, surely you can't just have one or two calibers of final twist rate at the end of the barrel and call it good, can you?I didn't realize the 454 Casull could benefit from gain twist. I know it is high pressure, but... Aww hell. there I go again. Talk to you guys later.
Quote from: Denver Steve on February 06, 2016, 10:24:27 AM+1 on the carcano and gain twist rifling. My dad has an old 6.5 carcano that i would like to get into reloading for him. Bartlein also offers a gain twist rifling for their barrels but i believe they call it their t-style rifling. Heard nothing but good things about it from the few people i have talked to that have shot them.
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