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Post by Lee Martin on Dec 24, 2018 16:08:29 GMT -5
Backup .30 Stingray – Load Development _____________________________________________ I broke in the lead on my backup .30 Stingray barrel today. It took about 20 rounds and the blue went away. Load development was done without the tuner using four charge weights and three seating depths per (jam, -10, & -20). The wind was nasty. Flags spun and pine trees swayed. But I found a node at the same combination I shoot in my primary Stingray. 33.0 grs of LT-30 at jam minus 10 thou printed good. The air kept switching from head winds to tail winds giving a half-bullet of vertical. These were my two 3-shot groups with that load:    I hoped the wind would calm enough to for a five shot group, but it actually picked-up. I stuck five into the paper, shooting fast on one condition. I think I can shrink it in milder conditions.  33.0 @ jam-10 is solid. Next time I’ll install the tuner and center the node. -Lee www.singleactions.com"Chasing perfection five shots at a time" |
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Post by squigz on Dec 27, 2018 17:12:37 GMT -5
So, what you're saying is that there's 11 shots in those 3 pictures? Hell, it looks like one of my good shots after 10 of my normal!
Fantastic shooting!
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Post by Lee Martin on Jan 2, 2019 20:54:04 GMT -5
Match #50 Black Creek Winter League, Match #2 IBS VFS 100 yard _______________________________________ I had another good match at Black Creek on Saturday. The wind wasn’t blowing hard, but gave enough abrupt shifts to cause dropped points (and missed X’s). My friend Chris and I were the only two that managed to stay clean.   A view from behind a fellow competitor’s gun:  -Lee www.singleactions.com"Chasing perfection five shots at a time" |
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Post by leftysixgun on Jan 2, 2019 22:14:37 GMT -5
Lee, congrats on your win.
I dont shoot the bench game but would you please explain what Jam-10 means. Does it mean you know what length you need to seat against the lands and then you increase the OAL by .010” thus jamming the bullet into the lands by that .010”?
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Post by Lee Martin on Jan 2, 2019 22:40:40 GMT -5
Jam minus 10 is essentially 0.010" deeper on seating depth than jam length. In my gun, the ogive gauge measured 2.425" after the bullet was seated long and jammed into the lands. This is done using a dummy round with the bullet seated long (ex - 2.440"). The bolt lugs are lubed, the case is chambered, extracted, and measured. At 2.425", the bullet was pushed back 0.015". So 2.425" is the jam length. If the micro seating stem was at say #50 for 2.440", jam would be #35. To achieve jam minus 10, the stem is lowered another 0.010" to #25. -Lee www.singleactions.com"Chasing perfection five shots at a time" |
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Post by Rimfire69 on Jan 3, 2019 10:50:46 GMT -5
Wow, incredible shooting.
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Post by leftysixgun on Jan 3, 2019 13:29:13 GMT -5
Hahaha, wow, thanks Lee. Thats definitely not what I thought it was. Thats for explaining it to me and everyone else.
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mbruce
.240 Incinerator
Posts: 15 
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Post by mbruce on Jan 5, 2019 15:44:34 GMT -5
Jam minus 10 is essentially 0.010" deeper on seating depth than jam length. In my gun, the ogive gauge measured 2.425" after the bullet was seated long and jammed into the lands. This is done using a dummy round with the bullet seated long (ex - 2.440"). The bolt lugs are lubed, the case is chambered, extracted, and measured. At 2.425", the bullet was pushed back 0.015". So 2.425" is the jam length. If the micro seating stem was at say #50 for 2.440", jam would be #35. To achieve jam minus 10, the stem is lowered another 0.010" to #25. What neck tension do you typically need to go deeper on seating depth than jam length? Thank you |
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Post by Lee Martin on Jan 9, 2019 21:08:21 GMT -5
mbruce - there’s no set jam length. It’s determined by the combination of bullet ogive and neck tension. For a given bullet, higher neck tension increases jam length. Lighter neck tension decreases it. -Lee www.singleactions.com"Chasing perfection five shots at a time" |
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Post by Lee Martin on Jan 9, 2019 21:11:07 GMT -5
Match #51 Black Creek Winter League, Match #3 IBS VFS 100 yard _________________________________________ When I scheduled the Winter League at Black Creek, I had to run consecutive weekends. I worried this would hurt turnout, but for the 2nd week in a row it was well attended. Good friend Wayne France and I ran neck and neck all morning, both ending with 250-22X’s. He got me on the tie breaker however; his first match was 50-5 and mine was 50-4. But I’m pleased with 2nd and another “screamer” decal, shot through a lot of wind.  -Lee www.singleactions.com"Chasing perfection five shots at a time" |
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Post by bradshaw on Jan 10, 2019 4:31:37 GMT -5
mbruce - there’s no set jam length. It’s determined by the combination of bullet ogive and neck tension. For a given bullet, higher neck tension increases jam length. Lighter neck tension decreases it. -Lee www.singleactions.com"Chasing perfection five shots at a time" ***** This and Lee’s previous explanation clearly answer the question of mbruce. These posts also illuminate why a marksman or markswoman keeps notes. Bench rest ammo typically has less NECK TENSION than field ammunition. We’re talking bolt rifles, which write their own rules of perfection, permitted by the highest chambering leverage of any action type. This whole section in Lee’s archive is worth reading a few times. And thanks to mbruce for the evocative question, David Bradshaw |
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Post by Lee Martin on Jan 15, 2019 20:01:02 GMT -5
Barrel Tuners – Part 2 ________________________________ 33.0 grs of LT-30 @ jam-0.010” was a solid node. This was proven shooting the gun without the tuner. Last weekend I installed the tuner by shouldering it, then backing out one half turn. It was locked and a three shot group was fired. It looked decent, but gave slight vertical. The tuner was turned out 1/4” (circumference movement, not total travel). Another three shot group was made. This was repeated until the vertical went away, netting a tight cluster. The tuner was marked with a Sharpie dot on its back edge. Additional 1/4” movements were made and eventually the vertical returned. At that point I had come off the node. I continued moving the tuner out until the node reappeared. Each time the ends of the node were designated with black dots. Key takeaways: • The tuner doesn’t have to be moved much to affect the group • Nodes spanned 3/4” of rotation • The node appeared twice in less than one full turn • POI is slightly altered by tuner position • The shape of the group can be changed by the tuner. I purposely don’t want flat, horizontal tunes. Left-to-right spread is exacerbated when shooting into cross-wind (the condition I typically pick. Head and tail winds are tough to hold off on because the flag views are narrow). • The tighter grouping node was selected by moving the turner in between the dots. For that condition, it approximated the middle of the node. Bukys TSI Tuner:   First end of a node:  Middle of the node. This is where I locked the tuner:  Tail end of the node:  This is a typical in-between nodes group. Fastest point of barrel deflection leads to major vertical:  Example of a flat/horizontal tune:  Vertical tune, about a half bullet total spread:  -Lee www.singleactions.com"Chasing perfection five shots at a time" |
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Post by bradshaw on Jan 15, 2019 23:33:43 GMT -5
Lee.... a graphic tutorial, excellent. Looks like you can measure the length in thousandths between nodes, or half-nodes. Not sure how the length of adjustment corresponds with barrel harmonics----for instance, how many times do sounds waves bounce back and forth the length of the barrel in one node?
It goes to show that there is nothing arbitrary about sharpshooting: not in the rifle or pistol; not in the bullet, not in the shooter.
David Bradshaw
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Post by Lee Martin on Jan 24, 2019 21:20:23 GMT -5
Match #52 Fairfax Rod & Gun Club Winter League, Match #3 IBS VFS 200 yard ___________________________________________________ Big wind kept the competitor count low for the 3rd installment of the Fairfax Winter League. 25 – 30 mph gusts forced us to steer the bullet into the 10 ring @ 200 yards. If you weren’t comfortable holding 3 – 4” off the mothball, this wasn’t the day for you. At times there was sustained 2 - 3 ring push, sometimes more. Complicating this was the wind rapidly changed direction. The only calm part of the day was the warm-up. And by calm, I’m talking 5 – 10 mph air. I started my sighter on a manageable right-to-left and stacked 4 shots into less than 1/2”. Under those conditions at 200 yards, the load showed promise. That gave me enough confidence to aggressively hold off throughout the match. I also picked up on direction changes early. As streamers dropped and vanes turned, I shot. Put another way, I waited until the wind began a 180 degree transition and pulled the trigger on changeover. It worked in the warm-up, on record sighters, and fortunately on record bulls...for the most part that is. It’s a tad hard to describe, but here goes. Red = right-to-left, Green = left-to-right (these are the colors of the wind flag vanes). Sunday, when there was say 15 – 20 mph red, you had to hold 3 - 4 inches off at 4:00. The wind pushed the bullet left and up. Hard green was 3 - 4 inches off at 10:00. Mild green, like I experienced in warm-up, was 3/4” outside the 10-ring at 10:00. So if I had a good condition, I’d hold there. Similarly, mild red was 3/4” outside at 4:00. The problem was, it rarely eased. Instead we saw a lot of hard red to hard green and vice versa. When hard red appeared, I held mild green and waited. Just as the majority of the flags turned from red to green, I fired. It worked pretty well but the key was to do it fast. Again, as the streamers began to fall and the vanes turned, I shot my mild hold. Benchrest is like any other sport. There are days when your eyes and brain really connect. Other days they don’t and you’re left guessing. I’ve experienced both and felt lucky to have the former Sunday.   -Lee www.singleactions.com"Chasing perfection five shots at a time" |
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Post by Rimfire69 on Jan 25, 2019 7:34:19 GMT -5
Fantastic shooting again Lee.
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