Wringing out the 190 gr. GC Loverider ......
Range conditions were mostly good except that the light was so bright with the afternoon sun reflecting off the snow that it made the image in the scope too bright. The light orange dots were washing out in the bright light hence I had to darken some of the aiming points.
Accuracy was nothing to brag about. The Loverider did not fail, but it didn't do anything noteworthy, either.
All of today's cases used a 0.354" neck expansion mandrel for maximum neck tension. All received a moderate crimp (this particular crimp die will bulge the cases if I crimp too hard).
I tried tweaking the powder charge. Quickload had predicted 1414 fps @ 30 ksi and I did not attempt to exceed that velocity by much. Then I tried different primers.
I could see the crosshairs wobble at least an inch, sometimes two inches, as I squeezed the trigger. The M29-357 is light on the muzzle end due to its aluminum shroud and the scope being slid all the way back to deal with the eye relief problem, so the muzzle does not want to sit still. So the guy behind the trigger is adding at least an inch, maybe two inches to the groups. That said, at no point did the 190 GC act like it wanted to shoot one ragged hole.
The 190 GC spit a GC today. The GC fit could stand to be tighter. Primer comparison:
-- 83 ES average with WSPM primers
-- 5.75" average with WSPM primers (2 groups)
-- 58 ES average with CCI #550 primers
-- 4.2" average with CCI #550 primers (3 groups)
-- 51 ES with CCI #500 primers
-- 5.5" with CCI #500 primers (only one group)
-- CCI #550 was 49 fps slower than WSPM with same 15.6 gr. charge.
-- CCI #550 was 25 fps slower than #500 with same 15.8 gr. charge, however the #500 load was seated 0.005" deeper so it was not an apples-to-apples test.
Based on this limited data it looks like CCI #550 might be the best choice, but there isn't enough apples-to-apples data to be sure.Case Capacity:
I have a confession to make -- I've been shooting mixed brass.
In fact, I've been shooting mixed brass in the 357 forever, and it hasn't been an issue until now. But because I'm not happy with the M29-357's velocity variation, I'm looking closer at anything that might cause velocity variation. Here is a sample of case capacities. I only measured one of each type case.
-- 27.4 gr. H2O nickel R-P
-- 26.3 gr. H2O nickel WW
-- 27.2 gr. H2O brass Federal
-- 26.5 gr. H2O brass WW
-- 27.4 gr. H2O brass GFL
-- 27.4 gr. high
-- 26.3 gr. low
-- 26.9 gr. average
(There's two or three more brands in the mix but I did not have empties of them to measure today.
How much velocity variation is that causing? Thanks to Quickload, it's easy to estimate. QL says today's 15.8 gr. charge would produce 1441 fps in the nickel WW case but only 1393 fps in the nickel R-P case, a 48 fps spread! Oops!
So in theory, I could reduce my ES by 48 fps if my cases were uniform.
Of course, even if I segregate cases by brand, there will still be variation from case to case (unless I want to shell out for Lapua cases
The next step will be to measure the capacity of 10 cases of each type, to estimate how much variation there will be if I segregate cases.Observations and Things To Try Next Time:
-- nothing rattled loose today. The ocular lens lock ring stayed put, and the rear scope base screw seemed to stay snug.
-- I started out using 1.617" COL but occasionally a nose would drag on the barrel. I'm guessing that I forgot to allow for excess headspace. Say there is 0.005" excess headspace, then the 1.617" cartridge could protrude 0.002" from the 1.620" long cylinder. I switched to 1.612" COL and did not experience any more nose dragging.
-- to help with the wobbling muzzle, I could replace the aluminum shroud with a brass shroud? Or make a brass or steel "sled" that screws to the shroud?
-- I like a 190 gr. weight for the 357 -- it's about as heavy as you can go without losing a lot of velocity -- but the gun does not seem excited about the Loverider design.
-- so I will recut some of the bore-riding bands to make them full diameter bands. Also recut the check shank a little larger while I'm at it.
-- but first I want to shoot the 190 GC into the water tank to see if it has anything interesting going on.
-- continue investigating case capacity variation. Possibly segregate cases.
-- possibly make a "sled" that screws to the shroud, to reduce muzzle wobble.