New to the Forum; just registered today. I've been reading these forums and hoped I could get some help from someone more experienced than myself
I'll start this off by saying I'm relatively new to reloading (been reloading rifle for around 3 years), newer to pistol reloading (been reloading pistol for around 1 year), and I just bought a 10mm 3 weeks ago so I'm very new to reloading 10mm. Like most here I didn't pick up a 10mm to shoot .40 s&w power loads; I want the hot stuff (within reason).
I decided last week to see how fast I could push a 180 grain XTP with Power Pistol. I intended to load the 180 grain XTP over 9.4 grains PP @ o.a.l of 1.26", then increase by 0.1 grain increments until I either saw pressure signs in the brass or achieved 1400 fps, whichever came first (I had previously safely loaded up to 9.4 grains PP). I am using new starline brass and Winchester primers, firing out of a Rock Island Armory 1911 5". Below are my results:
180 grain XTP @ 1.260" O.A.L. (5 shots each)
9.4 grains Power Pistol
Average velocity: 1292 ES: 57
9.5 grains Power Pistol
Average velocity: 1308 ES: 48
9.6 grains Power Pistol
Average velocity: 1319 ES: 21
9.7 grains Power Pistol
Average velocity: 1290 ES: 35
9.8 grains Power Pistol
Average velocity: 1292 ES: 66
I stopped at 9.8 grains, although my brass never showed signs of over pressure aside from slightly flattened primers. No case bulges, excessively flattened primer, primer piercing, etc. I loaded up to 10 grains, but did not fire past 9.8 as the dropping velocities made me nervous. I also note the relatively large ES.
This brings up several questions:
1) Why would my velocities decrease as my powder charge increased?
2) I am more experienced in long range rifle reloading and have never crimped rounds on my bolt guns. These 10mm rounds were all without a crimp. Could that be affecting my ES and velocities? Is crimping mandatory when developing hot loads?
3) Are there any suggestions on how I could get to 1400fps? change powder? different crimp? etc. Is it possible that ~1300fps is the limit with my gun for a 180 grain XTP?
I realize that these are very hot loads, but the thing that makes me want to keep pushing it is the brass seems fine. I've read several of the posts on this forum with some reaching velocities into the 1400's (albeit they were probably using 6" barrels). I'm not trying to push my luck too much, but just cant wrap my head around why my velocity would decrease as my powder charge increases.
your responses will be appreciated!