Printable View
Hello all
Adi manual indicates 40gn ar2209 is a compressed load with a 140gn AMAX.
40gn ar2209,checked on two beam scales,looks like this in my once fired HDY brass.
With a 140 eldm loaded at 2.800" there is space inside the case,nowhere near compressed.
Ar2209 is lot # mem5675.
Whats going on?Attachment 128686
They got it wrong. I'm using Lapua brass and there's no way 40 grains is compressed in any normal sense of the word. I went up to 42 grains and there was still room for the powder to move around at 2.840 C.O.A.L.
With a projectile as long as the 140 Eld-M it pushes down into the powder, but it displaces into the shoulder region so no crunchy noises.
Hi
Did you get pressure signs above 42gn?
MARK
Didn't go above 42 grains. Based on all the research I had done that would be getting very warm in Lapua brass so I stopped there. As it happens 41.5 shot an outstanding group so I was happy with that.
Somewhere around the place is an article about pressure signs in small primer brass. The short version is that once you can see pressure signs you're way over-pressure.
Heres me thinking 40.5gn is pushing the envelope...
and it could be depending on your barrel dimensions/ fouling/ powder batch/seating depth/primer type/ ......
I'll start low.
Definitely not compressed. Powder charge can vary a lot depending on the particular rifle. In my Tikka T3x I load 44.6 grs of AR2209 with the 143 ELD-X for 2,800 fps in Lapua cases. The rifle has a long throat and longer than normal M+ magazine. Bullets are seated well out and don't intrude past the neck shoulder junction. That load is warm but not hot in my rifle. It would be dangerous in some 6.5 CM rifles with a shorter throat and loaded to fit in a shorter magazine.
42.4gr AR2209, 143gr ELD-X, 2.850" COAL, CCI BR4 primer... works for me. 2760-2800fps depending on temp and altitude.
At 43gr I saw mild ejector stamps, so backed off.
The Lapua SR brass has been extensively tested at some warm, hot and silly hot loads. One of the tests I can put my finger on now is the 6.5 Guys on YouTube who loaded the brass at 43gr with the ELD-X and repeatedly fired until they got to 20 reloads, and no untoward brass outcomes at all so they gave up. IIRC they then went waaayyyy over a sensible load just to see if they could break it.... nope. And it was still accurate.
Now obviously none of this is written to encourage you to do anything stupid, but it does shed some light on what I think is now well understood and that is the early LR brass load data was very conservative, certainly in terms of how standard pressure signs are exhibited on the SR brass.
However, without a proper measuring regime how do we know what the actual chamber pressure is!
In this article, some of the US comp shooters' loads are detailed. Scroll down for the 6.5 loads, you'll see the loads are all "up there" no matter which powder, for velocities in the 2750-2850fps range.
https://precisionrifleblog.com/2019/...oor-load-data/
The article on working up to pressure signs, and what to look for, is this one:
https://www.primalrights.com/library...nding-pressure
I was using 41.5 grns in LApua SP brass for 140 grain ELDM's
Swapped over to W760 and 139 scenars ....same charge same results
42.40 2209, 140eldm, but My tikka also has a long throat. only doing about 2715fps and still under max pressure.
