I use mag length & longer in my AR, mag length for when I need to use the mag, usually use a 75gn Hornady in RG case with 24 gns for mag & 77gn Sierra in a Lapua case with around 24gns but single loaded with my single load platform mag.
I use mag length & longer in my AR, mag length for when I need to use the mag, usually use a 75gn Hornady in RG case with 24 gns for mag & 77gn Sierra in a Lapua case with around 24gns but single loaded with my single load platform mag.
Pistol & Rifle Shooting in the Highlands with Strathpeffer Rifle & Pistol Club. <StrathRPC at yahoo.com> or google it.
No longer Pumpin Oil but still Passin Gas!
Oh, shock horror!!! I'd better burn it all.
Pistol & Rifle Shooting in the Highlands with Strathpeffer Rifle & Pistol Club. <StrathRPC at yahoo.com> or google it.
No longer Pumpin Oil but still Passin Gas!
Its interesting that you are almost 10% less capacity. I wonder what affect its having on pressure.
If you weigh the 77gr bullets it doesn't say 79gr by any chance
What cases are they? Thick brass?
Lots of places on the net I can see people using 24gr with col ~2.260/5 and no one mentions compressed loads.
Are you using the regular SMKs (9377) or the tipped version (7177) which are slightly longer so the same col will push the bullet back in the case.
I'd like to try the 90s or the 95s but need a 1:6.5 twist. Time to get a Valkyrie
Hi again! Bullets are definitely 77gr regular SMK; brass is Remington and measures up as it should. Like you, I can find loads of references to 24gr with COL 2.260.
I have gone with 22.5gr and can just hear a slight crunching as I seat the bullet.
Perhaps I'm just nervous, but will see how they perform next week.
Have just also loaded 175gr TMK for the .308. Local component vendor says to bung in 44gr N140 and seat to 2.800 COL. No way........ That exceeds the published maximum and in any case the bullet won't go in with that much powder unless a lot of force is used. Perhaps my idea of a "compressed" load is rather less adventurous than some others, but I prefer not to have to hammer the bolt open after a shot.
It is a mystery.
OUCH
44gr of N140 was my standard long range load for 155gr SMKs (I'd use 41gr at 100 yards, 3MOA lower but softer on the shoulder). Interestingly the Viht online says that is too much. It was below the what sierra published in the loadall book I had. Don't shoot it any more.
For the 175s that looks way over. Perhaps they are thinking of the 155s?
Be safe
For the public consumption regarding AR loads....or what we find works.
We dont have the benfit of thousands of pounds of gas to start the extraction, so load for accuracy (unless you are going long range) or you may well find that you wont be getting the bolt open if the case decides not to spring back. GGG brass works well as it is quite hard. Because we cycle rapidly they get hot but need to feed well, so most of us FL resize and use the cases 2-5+ times. I will often use a batch for matches 5 times then drop them to practice for a few loads, but the CSR scene is awash with 5.56 GGG once fired at circa £50 per thousand (or an H83 box full). Penny a load...peanuts.
I load mag length and crimp. I shoot CSR so expect circa 1MOA prone mag rested, this is good out to 600, you may want more but with a 4x scope from some very dodgy positions, 1MOA at 100y is better than the 36mm at 30m acceptance required on the L85
You will find that with most loads, putting a 77 grain bullet into the case at mag OAL will compress the load. I have not seen any pressure issues to date with 77SMK/24.6Gr RS52 or 75PPU HPBT 24.7Gr RS52 and I am well on my way to barrel no 3.
I literally copied the meplat to head dims of an RG SS109 round and took that as a datum. The RG bullet is quite pointed so it does make the same load with HPBTs look a bit duimpy but they feed well without catching bullets on the feed ramp and splines. Many mistake damage caused by ejecting a live round as damage caused by loading. The bullet can get dragged between 2 splined and get gouged on the way out, as cn the case necks.
As regards sizing, I screwed up a new die setting which cause me to get case head seps in a comp. I got away with it but scrapped the lot on firing. I then took fired round and litterally kissed it with the die until it fed well and checked it in a Dillon head space gauge where it registered as bolt action (longer than semi auto). It has been fine ever since.
I now keep a broken case extractor in the butt...on the grounds that a bit like baldricks bullet, if I own one, I wont need it
Why RS52 and not Varget, IMR4894, N140? Well N140 works, but RS52 gives progressive pressure (rather than the spike of N140) and good velocities. The other 2 are difficult to find and make you grow 2 heads.
STM and nice clean brass also aids movement in the mags and loading. Mine will (and should) fully chamber under its own steam, even when hot.
Also, I find the spring, bold carrier bearing surfaces, gas horn, bolt rings, cam pin and the rear of the locking splines respond well to a bit of molly grease (the black airgun stuff).
Love your ARs, they will keep going.
I shot my BAR10 for the first time on Sunday. Being braked it showered the firers either side with bloody bark chips but it dont half go well. One for CSR society only though I think
I'm a maggot in another life you know
All loads need working up. I would start with an arbitrary 42 ish and either do a ladder test ro work up on .5gr incerments then fine tune. FWIW these figures are arrived at using specific barrels, barrel lengths, bullets etc. A hell of a lot can change when you put a Barnard action, heavy Lilja 3 groove barrel and Plama brass together with RS52 and a 155gn bullet. Mostly over HME if you are shooting FTR People tend to obsess over flat trajectories, whereas given we mostly shoot at known ranges (hunters excluded, I get that) then a best load would either be for accuracy/comfort, or staying supersonic if over 800 yards.
I'm a maggot in another life you know