Figured I would get out this morning and test the loads I had loaded up in my 338 AM as I am waiting for the guy in the brown truck to bring me a little overnight package containing very pertinate tooling that I broke yesterday [img]/ubbthreads/images/graemlins/frown.gif[/img]!!
Shut the lathe down for a day but will be back up and running this afternoon, I hope!!!
Anyway, I ordered in 8 lbs of VV 20N29 to test in my 338 Allen Mag. It is really intended for use with the 350 gr ULD RBBTs but I was curious about the 300 gr pills as well so I started there in the testing.
The load consisted of the following:
300 gr SMK
TTI formed cases
The powder charge I used started at 144.0 gr and I stopped at 154.0 gr increasing one grain at a time. I stopped at 154.0 gr as I was starting to get some powder kernal popping when I seated the bullet. Not alot but enough to make me stop increasing the load.
Temp this morning was in the mid 60's with 25% humidity.
I set up at 200 yards and sent the first three shots down range. Nothing great in group, about 1", last two were cutting each other though.
Let the barrel cool and made a scope adjustment since I remounted the Nightforce NXS 3.5-15 on the rail since I am still waiting for my IOR 35mm low rings to come in to replace the high rings. Another story, not happy with IOR service.
These two were under 1/2" but still about an inch farther to the right then I wanted. Made a scope adjustment and let the barrel cool again.
For the last 6 shots, 149.0 gr to 154.0 gr I shifted to a clean target and fired them all at the same target square. This was the group ol Black Sunshine made for me at 200 yards with 6 different loads!!
Again, pic quality sucks, my apologies, I am beginning to think its my camera??? You get the idea though.
Velocity wise, It seems 20N29 is a bit slow for the 338 AM. Here are the velocities I got with each load level:
144.0 gr...........3244 fps
145.0 gr...........3364 fps
146.0 gr...........3378 fps
147.0 gr...........3383 fps
148.0 gr...........3388 fps
149.0 gr...........3399 fps
150.0 gr...........3398 fps
151.0 gr...........3431 fps
152.0 gr...........3440 fps
153.0 gr...........3454 fps
154.0 gr...........3470 fps
With another grain I am sure this load would be right at the 3500 fps level but consistancy may suffer with the cracked powder from the compressed load. I may test and see because obviously the powder shoots well and pressures are MUCH lower then either H-50BMG or WC872. With these two powders, to reach 3500 fps you need 148.0 gr and 149.0 gr respectively and there is significant primer cratering and a decent extractor mark on the case head. The primer pockets are still very tight with these two powders at this velocity and bolt lift and extraction are effortless.
20N29 however shows dramatically less cratering and just the very slightest shadow line of an extractor ring, no bright spot at all really.
As far as matching burn rate perfectly to the case capacity I would say H-50BMG, WC872 or US869 are a bit better choices for the 300 gr SMK, BUT for a much lower pressure load that still offers 3500 fps performance and fine accuracy, 20N29 seems to be as good as any in the 338 Allen Mag.
I suspect that this powder will really come into its own with the 350 gr ULD RBBT where I suspect it will be the powder of choice for the heavier pills offering right at 100% load density with good top chamber pressures.
Will test that soon and report back.
Still for this test I am very happy, holding near 1/4 moa at 200 yards with six differnet loads is not to bad. Would someone like to evaluate my ladder test target and point out my vibration nods???? [img]/ubbthreads/images/graemlins/grin.gif[/img] Damn smart ass gunsmith!!
Hopefully the brown truck gets here soon, have to get back to accurizing before I have some customers riot [img]/ubbthreads/images/graemlins/grin.gif[/img]!!!
Will post more soon.