Just got finished testing a batch of 7mm Allen Magnum rounds loaded with the 200 gr ULD RBBT in the 26.5", 1-9 twist Shilen #4 barrel.
I started with 94.0 gr, increased by 1.5 gr up to 100 gr and then by 1.0 gr up to 104 where I stopped.
Here is the target from the testing, this was at 100 yards, hay bails were in the way for my 200 or 300 yard shooting allies!!!
Shots 1-3 were shot at the middle square, 4-6 were at the right and 7-9 at the left. I would also like to point out that shot number 7 was my fault. I have been nursing a pretty serious pinched nerve in my right shoulder/neck area and it got away from me on that shot, flinched like a little girl. Had I not I suspect that three shot group would be as good or better then the 4-6 group.
Once velocity got to +2950 fps in this barrel, the groups really tightened up, dramatically so in my opinion. I was glad to see the extremely consistant velocity increase with each increase in powder charge. Seemd this bullet and powder are a good match for this case volume!!
Velocity wise I was happy as well. My original predictions were to hit 3200 fps in a 30" Lilja 3 groove barrel. This shorter barrel hit 3140 fps with the 104 gr load. Still I wanted to see how the primer pockets were holding up so headed back to the bench and popped the spent primers out and reprimed the cases. The 104 gr load felt EXACTLY like the 94 gr load.
There was a slight pull on the bolt handle needed to extract the cases. From past testing with the other Allen Mags I am 100% confident that this is because the cases were not partially full length sized and more importantly, I did not reanneal the case necks before loading these more serious loads.
In past testing, these two things totally eliminated the slightly sticky case extraction and also allowed slightly higher velocity potential as well. We will see. I will not test higher until I get the Redding Full Length Sizing dies in stock so I can partially size the cases to correct this problem and so I can get an accurate idea of case extraction.
Still, 3140 fps with a 200 gr ULD RBBT in a 26" barrel is enough to make me smile.
Group 4-6 measured .778" ctc. Shots 8 and 9 were .521" ctc and I suspect had I not flinched on shot 7 that group would have also been in the 3/4 moa range.
Certainly not amazing but for this bullet in this twist barrel in this light of a barrel, I will take it anyday of the week!
I will second what ss7mm posted about rifle torque with these bullets, at +3000 fps it will lay the rifle on its side if you are not doing your job. The Holland QD brake helps alot but there is no way around this.
More testing to come at longer ranges. Please to not take this test as saying the 200 gr ULD will work in any 1-9 twist barrel, it may well not. Hell, it may shoot 10" groups at 300 yards in this barrel, I will test and report my findings.
It does however tell us that there is a decent chance that this bullet may be usible in factory, large cased 7mm rounds!! WHat a boon that would be to 7mm shooters.
Nuff playing for today, back to work I go!!!