TO all. I got out this morning to do a bit of my personal shooting as well as test a couple other rifles for customers.
Many of you wanted to see some better pics of my 510 Allen Mag so I took some.
I was just shooting some fireforming loads in Virgin cases as well as in some semi formed cases which I had annealed so the shoulder would sharpen up properly so I can send a few off to get dies made.
I was only shooting at 100 yards but the virgin fireforming loads simply refused to puch groups larger then 3/8" for three shots. Now these loads are tripping the chrono at only 2400 fps so they are VERY easy to shoot. The load I used for these was 215 gr H-50BMG under the 750 gr A-Max.
For the semi formed cases I poured some more powder to them using 240.0 gr H-50BMG under the 750 gr A-Max. When I held the big rifle steady they shot just as well as the lighter loads but I was shooting off the bipod which flops side to side quite easily. When the reticle would roll to the right, the shot would be slightly to the right, when she rolled left the shot would print slightly to the left.
THese heavier load averaged 2745 fps for 10 shots. There was more velocity variation then I like to see but the load density is MUCH lower then it really should be. When I get serious about doing load development I will be starting with US869 and VV 20N29 which should both improve load density dramatically.
Just comparing the load data for H-50BMG to US869 with the 750 gr A-Max. Hodgdon lists a max load of 233.0 gr for H-50BMG and 250.0 gr for US869.
Now in real life, if you put 233.0 gr of H-50BMG in a match rifle chambered for a 50 BMG you would probably not get the bolt open. I have found absolute max with this powder and bullet in most 50 BMG rifles will be in the 215 to 222 gr range max. Seeing that the 510 AM will comfortably take 240 gr of powder shows how much case capacity has increased.
Hodgdon also lists that US869 will produce from 125 to 150 fps more velocity then H-50BMG with the 750 gr A-Max and even better with the heavier bullet weights!!!
Here are the pics.
Here is a pic of a six shot group I shot with the 2745 fps load.
Considering my crude bullet seating system this is much better then I ever expected. OAL varied as much as 25 thou. I am making tooling right now to correct this problem until the dies get in. Still, just shy of 3/4" for six shots at 100 yards with a 750 gr bullet at just under 2750 fps is a pretty good start.
I will probably put the rest of the 510 AMs testing on hold until I get the dies made and get through the big game rifle rush for customers which I am in the middle of right now!!
More to come soon though.