Posted: 10/11/2019 3:03:30 AM EDT
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125gr Speer TNT
16gr VV N32C Sized, trimmed, flash hole uniformed, virgin Hornady .308 brass (ID 0.305", loaded OD 0.337") CCI 200 OAL 2.700" +/- 0.005"; at least 0.12" jump Pre-'64 Winchester Model 70 Target with 27" Obermeyer 5R 1:10, Redfield apertures, bipod and rear bag support. Bore was moderately cleaned last week before 60 rounds in a match, and 5 rounds right before this test yesterday. Attached File Temperature in the 70s-80s, 5-15mph tailwind, partly cloudy. F1 Shooting Chrony set just shy of 15ft from the muzzle. I have not tested the calibration, but believe it to read 100-150fps fast. 1st string: Shooting position wasn't quite right. 1816, 1860, 1859, 1854, 1862, 1853, 1858, 1856, 1851, 1836 Avg: 1851 fps ES: 46 fps SD: 13 fps Minus the outlier - Avg: 1854 fps ES: 26 fps SD: 7 fps Attached File 2nd string: Shooting position mostly fixed, bench is a little high. 1784, 1853, 1846, 1845, 1845, 1833, 1856, 1862, 1862, 1855 Avg: 1844 fps ES: 78 fps SD: 22 fps Minus outlier - Avg: 1851 fps ES: 29 fps SD: 9 fps Attached File Combined: Avg: 1847 fps ES: 78 fps SD: 18 fps Minus outliers - Avg: 1853 fps ES: 29 fps SD: 8 fps It might like a little tweak, but it could clean the MR-31 with a high X-count as is, so it's not worth the patience. @Reorx |
VERY nice iron sight / open sight shooting... especially with a "reduced" load. I get pretty good consistency/groups with reduced loads but have never been able to get great consistency / groups. With my "regular" loads, I get sub moa groups and single digit SDs but with reduced loads, my SDs are typically in the 20s and group size is 1.5 to 2 moa... and my sights are a fixed 10x chunk of glass!!!  Admittedly, I don't spend a lot of time/effort developing my reduced loads - maybe that has something to do with it!
Cheers! |
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Quoted:
If the vertical in those groups is an issue for you, push the bullet as far out as possible into the rifling. I'm not sure how much shank is on those bullets. An eighth of an inch is a lot of jump. The base is about 2/3 in the neck and as far as I like to go for mag fed rounds. I tried a split neck case and barely neck sized case, with a rod in the bore to help prevent sticking in the leade, but couldn't get the neck to hold on to the bullet on extraction, except once which was 2.82". Nothing in the neck. |
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I used Da's open vent Garand at the MBAR match today.
-Speer 130gr HP -17gr VV N32C -CCI 200 -RP and Winchester .270 cases necked up. -OAL 3.100" Best target of the day. After shot #7, I got a little excited and thought clean. When setting up #8, I lost the muscle memory in the shoulder; where the stock was and how firm. So I had to mentally reboot. My heart still felt the anxiety. Attached File I'll measure the mean radii when I get home. Summary target. The windage is stock 1 MOA, so it was easier to "safe side" the right half by setting my natural point of aim a smidge left. I can't see rings, but I can approximate their scale on the FSP. Attached File |
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The subsonic load request thread next door got me to go down a small rabbit hole that tied to another interest of mine regarding .22LR and twist.
Using the JBM calculator, it seems anything propelled up to 1100fps or slows over distance to <1400fps - the transonic zone - has a greater wind drift than subsonic or very supersonic. I'm curious if that's true. Anecdotes or links regarding that would be appreciated. I'm considering comparing some 180/190gr bullets and ~10gr N32C in the 900-1000fps range. I bet the SD of velocity will still be good, but I'm not sure about wind control besides having a couple floor fans next to the muzzle and <25yds further downrange. |
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M1 Garand with Criterion barrel and light accurizing - skim bed, handguard fiddling, NM elevation with 0.5 MOA hood. The adjustable gas plug had the screw removed. The trigger's 2nd stage break is similar to a long roll 1911 trigger. He wore out the original buttplate, so I put a new one on the night before the match. Two sandbags for front support, left hand hooked on the sling swivel for rear support, as I believe the spirit of rules dictates.
I used some leftover Hornady 150gr FMJBT/16gr N32C for sighters. Their locations are the pasters on the summary target above. I switched to the 130s for record. Group 1 The high outlier is from not holding as firmly in the shoulder. Dad crossfired in the X with his M70. 
Attached File Group 2 About the same as Group 1, but without causing an outlier. Attached File Score 1 One of the guys teased "You gonna come a click right?". "I dunno, it's MOA clicks." I let it be, but the first shot was further left than call, so I moved it a couple clicks right, forgetting how big MOA can be, went out the other side, so I came back one click and "safesided" using Natural Point of Aim a smidge left. I was having some difficulty with the brightly light range and targets. Attached File Score 2 I settled on using one eye, and turned the hood 0.5 MOA up. I need about 15fps lower velocity.
Attached File Score 3 I had a major bathroom visit beforehand and that seemed to affect my NPoA and focus. 
Attached File It isn't worth trying to find the Summary target holes in OnTarget. I won by a comfortable margin. Out Of Competition, Dad was close with his M70 (from the OP). 2nd place was a Swedish Mauser, and 3rd was either an M1903A3 or slightly sportered Krag. |