Today I tried a new bullet. Since the "Extreme" Loverider (XLR) seemed to be just a little shy of support, I split the difference between the Extreme Loverider and the Regular Loverider and called it the "Aggressive" Loverider (ALR), because it's more aggressive than a regular Loverider but not as aggressive as the Extreme Loverider. The only difference is the GtoB -- the ALR's GtoB is 1.3, halfway between the XLR's and the Regular's. You have to look closely to notice that the ALR's bands are just a little bit longer than the XLR's bands. The theory was that the longer bands should provide a little more support.
Since the ALR is nearly the same as the XLR, and since the XLR shoots nearly the same (1.24" average) as the regular Loverider (~1.2" average), I expected the ALR to shoot about the same 1.2", too. But it had other ideas.
There was outside mirage making the target jiggle 1/4", and a 0 - 10 mph wind that often changed speed and direction. I have not had much luck with range conditions lately.
I started with the same 34.8 gr. LVR load that I used last time with the XLR.
From left to right:
-- the first target on the left was a mediocre 1.20", about what I expected, especially considering the mirage.
-- second target, I tried RL15. Previous powder tests in the original throat had RL15 shooting just as well as Leverevolution. But a lot has changed since then, a different throat and a different seating depth. Well, today it did not like RL15 ! That seemed strange.
-- third target, back to Leverevolution but I dropped the charge to 34.4 gr. Nonetheless the velocity went up, not down. Velocity variation improved, yet vertical dispersion increased. That seemed strange. In mid-group, the bolt release stuck in the open position. It had given me problems sticking a while back and I thought I had fixed it by cutting more clearance inside the stock where the bolt release was rubbing. Something must have shifted? It's not good when bedding-related things shift. I checked the action screws -- tang and forward screw still tight, middle screw still just snug. However, I noticed that I could free the bolt release by backing the middle screw off one turn. Something must be flexing when the middle screw is snugged? So I cut more clearance for the bolt release and assembled the middle screw 1 1/2 shy of snug -- basically the middle screw is just sitting there, not putting any force on the action.
-- 4th target, a repeat of 34.4 gr. LVR with the sticky bolt release situation fixed. Less lousy, but still lousy.
The ALR bullet was cut with a snug fitting check shank, whereas the XLR check shank tends to be a little loose. Nonetheless 3 out of 41 ALR bullets lost their checks today. 2 of the errant checks happened during the 1st 4 shots. The 3rd errant check happened with RL15. I have no explanation for the errant checks, other than to say that it does not correlate to check fit. Conclusions:
-- today was a Murphy's Law day when nothing seemed to go right.
-- there is no great love for the ALR bullet, but I don't know why, since it is very similar to the other Loverider bullets.
-- I may need to experiment with action screw tightness. Otherwise I don't know what I can do about the bedding. It already has pillar & Devcon bedding. However,the M700 action design doesn't have a lot of bedding area at the tang and hardly any bedding area in the middle, plus the M700 is a flexible action by benchrest standards.
-- the errant gas checks are still a mystery.Where to go from here:
-- other than action screw tightness, I am out of ideas with this snug 1/2 degree throat. It does not seem to be as accurate as the original 1 degree throat.
-- the throat experiments so far have demonstrated that small changes in the throat can make a big difference in accuracy, so I am inclined to focus on the throat. This throat was deliberately cut on the tight side and I am worried that it may be too tight, so I may try recutting it just a tiny bit deeper. It's easy to cut it too deep and spoil accuracy, though. If it were a cheap barrel then firelapping would be an option to gradually open up the throat, but I am reluctant to firelap this top-of-the-line barrel.
-- other than using epoxy to glue gas checks on, I don't know what to do about the errant gas checks. Some days it doesn't seem to correlate to anything.