Went out this morning, had a little time to test some of my own stuff. I wanted to load up some of these huge 350 gr ULD RBBT Wildcat Bullets that Richard sent me for testing in the Kahn.
Basically I was running blind, where do you find load data or even reference data for a bullet like this???
I decided to start with AA8700 as it would offer me the shallowest pressure curve of the powders I had on stock in the event I estimated a starting load to high!
I started at 90.0 gr with an OAL of 3.830" which is roughly 0.075" off the lands, again a precautionary measure to control pressure. My concerns were not warranted.
These were with Virgin 338-378 Wby brass as well.
At 90.0 gr the shoulder was not completely blown out and the neck and shoulder were smoked heavily.
I jumped to 95.0 gr and the shoulder angle sharpened up better but still not totally crisp. I was simply finding the working range of this bullet and powder combo, really had no interest in velocity at this point.
I loaded up 100.0 gr of 8700 under the same OAL and this time the shoulders sharpened up nicely with a good gas seal on the neck as well, no smoking.
On my 300 gr ULD loads at 3050 fps I can see just the very faint starts of an extractor mark onteh case head. This load was still very clear, in fact the primers were round as round could be.
I jumped another 5 grains to 105.0 and fired this case, again no faint extractor mark at all.
At this point I had 6 virgin cases left so I figured if I took another 5 gr jump I would have to be in the working pressure range of this bullet cartridge combo.
Loaded up the gear and headed out to my 100 yard range for velocity and accuracy testing. See the whole reason for the test was to see first of all if the bullets would land on point with the 1-10 twist and secondly, what velocity potential was possible in a heavy rifle.
Well with everything set up I touched the first round off and at 100 yards it landed exactly where the 300 gr load prints. THis is a common occurance with the V-Block rifles at ranges under 300 yards or so.
Velocity was just under 2780 fps, I was very happy.
Shot two ripped down range and the bullet hole did not increase in size, at least not from what I could tell through the 16x SS scope. This velocity dropped just under 2740 fps.
Let me say at this point that the 300 gr ULD fired in this rifle at 3050 fps is nothing but a warm and fuzzy experience, these loads, while certainly not punishing, are noticably heavier in recoil.
I fired shot three down range and could now see that the bullet hole had gotten slightly larger, not much though. The velocity of this shot was just over 2740 fps. The average for the three was 2753 fps.
The velocity spread is I am sure from the jump to the rifling so I am not concerned with this being able to be tightened up dramatically. This is also not a full tilt load.
When I rechamber the fired case, it chambers easily with no resistance. This is a trick you learn shooting the 50 BMG. If a freshly fired case will rechamber with little down pressure on the bolt, your running in the 55,000 psi range. The bolt dropped on these fired cases with no resistance.
I am predicting that this rifle will be able to drive this bullet at at least 2800 fps comfortably and possibly 2850 fps with top end loads but I doubt I will push the rifle that hard, there is no need.
Out to 1000 yards, the 300 gr ULDs are flatter shooting but the 350s have an edge in wind drift and certainly energy when you get out past the 1/2 mile mark.
From 1000 to 2000 yards the 350 really starts to catch up in drop but retained velocity and wind drift are piling on the advantage as is the energy advantage.
At 2800 fps this bullet should stay super sonic out to around 2400 yards. The 300 gr load will hit 2200 yards so there is a net gain of a solid 200 yards which I personally feel is significant at these ranges.
All this is with a B.C. of .975. Richard says the B.C. will be in the high .900 range so this is just a number I picked and used. I will be testing for this as well here soon and will report.
I will not say the 350 gr ULD is more accurate then the 300 gr ULD but I will say I have shot groups in the .1"s with both bullets in the Kahn so obviously they can shoot. I have only shot one group on paper to date with the 350 gr ULD Wildcat bullet and it is the one above, pretty decent start!!
Later, I will keep posting teh results I get from this huge 338 bullet. One thing is for sure, the 1-10 twist will stabilize them in the 2700 fps range.