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+--- Thread: AR-COMP \ 120 gr SMK \ Starline Data (/showthread.php?tid=21123)
AR-COMP \ 120 gr SMK \ Starline Data - AlaskaGrendel - 04-27-2020
EDITED:
Hello Grendel Forum. It has been many many years since I have posted anything (like before the old forum went away and before Grendel was SAAMI approved). Honestly, the knowledge bank in this forum is immense and really has everything you need to know whether brand new or kicking it up a notch.
Now....into the weeds with some data on load development at least with the 18" Criterion hybrid barrel
Chamber measured out @ 1.726 (averaged after measuring 15 times using Hornady tools) to the lands based on the ogive measurement of 120 SMK.
New Starline @ 1.510. The WFT trimmer just barely kissed these, some just polished.
CCI 450
120 gr SMK (as the universal testing standard and a great bullet)
COAL of 2.235 with an ogive measurement of 1.700
AR-Comp and a Magneto speed. Started quite low and worked up and I'm confident I can work up (MAYBE A LITTLE) higher. 5 round ladders.
Environment: about 43 degrees and maybe 50 ft above sea level
25.3 Gr \ 2305 avg \ SD 5.2
25.6 Gr \ 2332 avg \ SD 7.0
25.9 Gr \ 2367 avg \ SD 17.0
26.2 Gr \ 2396 avg \ SD 9.4
26.5 Gr \ 2430 avg \ SD 9.2 - .77" group which is dandy by my standard.
26.8 Gr \ 2464 avg \ SD 7.4
27.1 Gr \ 2486 avg \ SD 9.0
27.4 Gr \ 2510 avg \ SD 4.3 - 4 rds touching with a flyer. Flyer ruined it and it was the operator...
27.7 Gr \ 2534 avg \ SD 8.8
28.0 Gr \ 2548 avg \ SD 10.2
I'll work it up a little higher but 27.4 is likely my load.
Primers were perfect. In fact, these loads were too light to cycle my rifle reliably using an Armaspec SRS H2 bufffer. To confirm that was the problem, I dropped a few old factory rounds (123 gr SST) which were much harder in the recoil department, cycled everything just fine, and gave a 5 shot string of 2400 fps average. Conclusion there is that AR-Comp is quite soft shooting aka slow, not as gassy? Perhaps a buffer swap to an SRS H1 and re-shoot 27.3-.5.
My untrained eye is seeing something kind of interesting, however. Maybe its nothing, but I am seeing the same thing with 69 gr SMK's. It really appears that 2500 FPS +/- about 50 fps on either side is where the Sierra Match King bullets like to fly. Really interesting with a Chronograph to watch. Who knows.... its fun.
AR-COMP \ 120 gr SMK \ Starline Data - BluntForceTrauma - 04-27-2020
Welcome back and thanks for taking the time to do such a good report!
AR-COMP \ 120 gr SMK \ Starline Data - Grendelshooter - 04-27-2020
Great thread!
AR-COMP \ 120 gr SMK \ Starline Data - A5BLASTER - 04-27-2020
Welcome back.
My 120 gold dot load are is 28.6 grains of ar-comp. Like you ar-comp won't reliable cycle the action till I'm in the 27.8 range.
28.6 grains is safe in both my 12.5 and 12 inch grendels and was safe in 4 diffrent AA fluted 16 inch barrels as well.
Funny thing is my 123 nosler CC load for my wildcat 264 cal upper is 28.6 as well.
AR-COMP \ 120 gr SMK \ Starline Data - Jetpig - 04-30-2020
120g SMK, 27.3g AR Comp, 2880fps, 4/5 shots touching at 200 yards. First one, a flyer, operator error.
My go-to load!
AR-COMP \ 120 gr SMK \ Starline Data - Lemonaid - 04-30-2020
Jetpig Wrote:120g SMK, 27.3g AR Comp, 2880fps, 4/5 shots touching at 200 yards. First one, a flyer, operator error.
My go-to load!
Jetpig, if 2880 fps is not a typo you must have a very long barrel!
Please tell more!