I really do really hate posting failures but since I started this I guess I need to...
Monday, I knurled up another set of Lehigh .500x350 grain bullets. I had decided I wanted to shoot them from my Knight Mountaineer with a Western Kit installed. I use #11 Mag or RWS 1075+ caps a NECG adjustable peep mounted on a Warne scope block.
One of the questions asked was if I would get the same velocity shooting the same powder load I was shooting the last time, but instead of igniting it with a 209 primer - using a percussion cap.
That was the only really successful part of the shooting trip. The velocities were greater than the 209 ignited powder loads but that small difference can be attributed to the longer barrel on the Mountaineer (3" longer). The load was 120 grains of T7-2f. I will suggest to you that 120 grains of powder with a 350 grain bullet is more than I would normally use with cap ignition. During the shoot I also made a mental note - not one of the #11 caps survived enough to offer me anything to tip out of the breech area. When I opened the bolt to get the cap out is was gone or I might find a very small piece on occasion.
Shot (120 gr. T7-2f)
#1 1885 fps
#2 1876 fps
#3 1848 fps
#4 1870 fps
Shot (110 gr. of T7-2f)
#5 1765 fps
#6 1785 fps
#7 1748 fps
With the Ultra Lite I was averaging 1800 fps with a 120 grains of T7-2f. So really cap versus primer - same 0 same 0 with a know good powder.
Now the failure... and I believe I know the reason. This particular rifle shoots Bull Shop lead conicals very accurately. I sighted it in using a Bull Shop .503x400 gr. LGP last fall and it proved to be a great round for the rifle.
Monday, I did notice that when I loaded the knurled Lehigh, they loaded very well through the crown and down the first third of the barrel, then after that the weight of the Range Rod would slide the bullet and sub base down to the powder. I really did not think much about it at the time.
I loaded and shot the first four shots through the chrono. I did notice that the bullet were hitting the top of the target even though I was aiming at the center. I was OK with that as the rifle was sight in with 100 grains of T7 and lead conical.
After shooting the first four, I was really OK with the velocities, but when I walked out to the target the disappoint level went very high. At 50 yards the four shot group was approximately 3-4" - terrible but what was even worse was that fact that 3 of the 4 shots tumbled through the target. Really made a mess of the plywood backer board - but it was painfully obvious that the bullets tumbled.
I took 3 more shots with a reduced powder load and suffered the same results. One of the 3 final shots was so tight getting through the crown - I did have to use a short starter to get it in, yet after the first third of the barrel it went down with a two finger push. This could be the one bullet that did not tumble in the group.
In my mind at that time - I was really disappointed with the outing and more importantly the barrel. I even hesitated writing this post... I will also say when I got home and cleaned the bore I really tried to feel the difference in the bore size. Yet with a patch and cleaning jag going down the bore I really could not feel any difference. It truly felt the same size all the way down. At that point I decided to push a .458 sabot and projectile through and out the breech. I pushed 3 different bullets and sabots through and once again could not feel a thing, not felt difference at all. Next I got a box of Bull Shops and pushed three of those full bore lead conicals through. The loaded snugly in the crown, no short starter needed, and pushed through what I would call normally. It did get some what easier the last 2/3rds of the barrel but certainly enough to hold the bullet on the powder.
So my conclusion... I believe when I was shooting the knurled .500x350's the bullet slid several inches up the barrel on ignition - never starting to rotate. Some rotation occurred in the last 1/3rd of the barrel but certainly not enough to stabilize the bullet. Also since this is a solid brass bullet the ignition could not cause the bullet to obturate to the bore - so it was slip city.
With the Bull Shops, all of this is a moot point since the ignition does cause the bullet to obturate and fill the bore - hence they stabilize just fine.
Now I really wish the bore on my Mountaineer was SAAMI deminsions - but then again it is not a centerfire it is a ML and when shooting ML bullets -non of this matters - it shoots lights out...
