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Joined: Fri Nov 10th, 2017
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Back when the 45GAP came out I was one of the early adopters. About 9 months after I had gotten my gun I confirmed with RCBS that my 45acp dies would work for the GAP. I had about 2k in spent brass and the rest of the components on the shelf.
I contacted Speer and talked to one of their reloading experts on possible loads for 45GAP. They were still working on load data and the expert suggested I use 10% below max data for 45ACP+P as a max powder charge, look for overpressure signs, especially the "Glock Smile". If I was getting a Glock Smile on the spent brass I was about 15% over what should be a max powder load.
This kind of freaked me out because of the pressure spikes that can happen with the faster powder Speer was recommending. The Speer expert also told me the GAP specs were throttled back to 45ACP+P values or slightly below to keep people from trying to load the hotter GAP ammo in their ACP's so there was little chance of a blowout.
All but one of my early loads fell right in line with what eventually got published. The one that didn't was too low at almost a grain lower that the recommended starting load. I was also trying to make my GAP ammo more consistent with ACP standards and not the ACP+P. I couldn't have done this without a chronograph.
____________________
Tony
NE ATL
'04 XLT regular cab 3.slo stepside
Semi retirement