07-12-2018, 12:02 AM
grayfox Wrote:I've settled on MI handguards myself, I like them.
On that 2450 ft/sec load... sst's as I recall don't really like to be up close to the lands, they shoot better at about 2.245, which is not even the 2.260 standard. You might try that. Also it might just be me but 2450 for a 22" barrel sounds kinda slow. nothing wrong with slow if it's accurate. If you're at the TAC limit then for sure get one of the better powders. I'd kind of expect sst's to get more like 2500+ even up to 2550+ for a 22", depending of course on the barrel specifics. My 20" Howa gets 2525 easily on sst's, 2510 on eldm's, no pressure signs, accurate, single digit sd's. I don't consider it a fast barrel more like a medium one.
Ejector marks (did I write about this?) sometimes are a result of being scraped by the sharp edge of the ejector during bolt rotation and may not be pressure signs per se. The Grrr is a mild pressure cartridge so a better way to see about over pressure is to measure the case diameter just above the web, use a mic, a caliper won't be fine enough... compare to unfired. It's after 10 pm so my brain is shutting down but there are some threads that talk 0.001's on this for info. LRRPF52 and JAS and I think Sneaky did a lot of pressure tests on Grendel loads maybe they might chime in.
On the record-keeping, record them all, good bad or indifferent. Xls rows in a spreadsheet are cheap after all! dates, MV, loads, brass, SD, etc etc. You'll want to go back thru them at some point so go ahead and write them down. Heck I even have a separate tab for each grendel, again Xls space is cheap.
Hornady black 123 is a sort of "regular guy-proof load" commercially, in 20" about 2400-2425 ft/s so yours should be higher, but SD ought to be good, anyway it's a chance to get some independent data/verification on your barrel. not foolproof but a definite data-point on performance, that's what you want to look for. Once we get some MV/SD performance data we should be able to narrow down where to look for MV-nodes -- that's when you'll find accurate loads.
Gray Fox,
I was able to make it to the range today and try out CFE223 and AR Comp for the first time with 123SMKs at 2.260 COAL. All of the CFE223 groups were terrible with an average groups size of 1.30 so I didnt upload a picture. The AR Comp had two great groups with low standard deviations. Well see if I can reproduce these loads next time out. If history repeats itself I will not but Im remaining hopeful.
The groups on the top row were shot with a $100 Bear Creek 16 300 Blackout using Hornady 150 soft points and Lil Gun powder as a comparison. These groups can be repeated and this budget barrel shoots sub MOA.
The links below show the groups and crono data
https://www.flickr.com/photos/68382999@N...ted-public
https://www.flickr.com/photos/68382999@N...ted-public