260AI roll call

[Fast14riot]

what is twist on your 260? very nice

All my barrels are 1:8 twist.

 

[Fast14riot]

So, talking with a buddy who just got into 260AI, re: measuring shoulder bump. What comparator diameter are y'all using? I've always used my custom 0.355" diameter comparator for mine.

 

[JLT]

So, talking with a buddy who just got into 260AI, re: measuring shoulder bump. What diameter comparator diameter are y'all using? I've always used my custom 0.355" diameter comparator for mine.

I use the .400" comparator.

 

[Bill Norris]

So, talking with a buddy who just got into 260AI, re: measuring shoulder bump. What diameter comparator diameter are y'all using? I've always used my custom 0.355" diameter comparator for mine.

I use the Stainless Steel Sinclair # 40A insert from Brownells.

 

[Fast14riot]

Did a narrow powder charge test at a 600 yard match today. 45, 45.1, 45.2 of N555 under the 153.5 LRHT. Weird winds by the end of the day. Last match there were 4 flags pointing in 4 different directions and dust devils rolled across the infield. Flags literally pointing at each other.

Only have 156 rounds on the gun now, its settling in nicely. Last match I shot 45.2gr and it showed a bit of vertical. Dropped points were usually straight out the top. Heavy mirage as they just did a controlled burn at the entire range, so pure black ground on a 93° day.

Managed to grab top honors as well. Last match we did no sighters just for fun, which made everyone wait for someone else to shoot first, lol!

Still need to do a tuner test at long range, but should have it dialed in and groups shrunk down once the barrel settles in in the next 100 rounds or so.

 

[Fast14riot]

I've got a buddy who spun up two 260AI barrels, one at 24" for a hunting gun and a 28" heavy barrel PRS match gun. He's been working with N160 and Berger 156 in Alpha brass in the match gun. Still hasn't hit max yet, but numbers are looking good so far. I didn't get pictures of his targets, but I think he's between nodes and can go either up to 46.8gr (carefully) or down to 44.6gr.

 

[swd]

I've got a buddy who spun up two 260AI barrels, one at 24" for a hunting gun and a 28" heavy barrel PRS match gun. He's been working with N160 and Berger 156 in Alpha brass in the match gun. Still hasn't hit max yet, but numbers are looking good so far. I didn't get pictures of his targets, but I think he's between nodes and can go either up to 46.8gr (carefully) or down to 44.6gr.

View attachment 1693182

I’ve seen some of his targets and it’s showing lots of potential even using the bloke of gunsmith that did the work..

 

[Fast14riot]

Yeah, he's close, I've been chatting with him about it. I think a little more testing and he should have it dialed in solid.

 

[Fast14riot]

I’ve seen some of his targets and it’s showing lots of potential even using the bloke of gunsmith that did the work..

I told him to be skeptical, he uses a 3 jaw chuck, lol!

 

[Fast14riot]

Finished the day with 322 rounds on the new barrel, chronographed a 22 shot string to see where its at with my old load of 45gr N555 under a 153.5. Came in about 15fps faster than where I like it to be. This was in a 1000y match. I'm loading a narrow powder test for shooting a 600y match tomorrow. Getting it dialed in for the Western State Regionals long range match at the end of next month, then fine tuning it for SWN in February.



All thing considered, its a solid load, but had more vertical than i would like. Dropped points out the top and bottom with perfect wind calls. Did some coarse tuner testing today too, but will try more tomorrow as well.

All in the pursuit of a perfect score!

Trust, but verify.

 

[swd]

Finished the day with 322 rounds on the new barrel, chronographed a 22 shot string to see where its at with my old load of 45gr N555 under a 153.5. Came in about 15fps faster than where I like it to be. This was in a 1000y match. I'm loading a narrow powder test for shooting a 600y match tomorrow. Getting it dialed in for the Western State Regionals long range match at the end of next month, then fine tuning it for SWN in February.

View attachment 1694817

All thing considered, its a solid load, but had more vertical than i would like. Dropped points out the top and bottom with perfect wind calls. Did some coarse tuner testing today too, but will try more tomorrow as well.

All in the pursuit of a perfect score!

Trust, but verify.

There was a ton of vertical in today’s conditions every time it switched to coming from the left. I got bit by it once and watched pretty much everyone get bit by it too, LOL. You had to stop and wait at any hint of that switch..

 

[Fast14riot]

Did today's powder test at a 600y match, also a new lot of powder. This one is fast! My previous load above at 2760 was 45gr of N555. I had 5 rounds of that left as a base line, loaded 22 rounds each of 44.7, 44.8, 44.9. I chronographed 44.8 and it was coming in at 2793 but had ok waterline. The group of 4 up at 1 o'clock was 44.6 just to get an idea.




44.7 shot ok, but was still faster than I liked. A bit more vertical.




44.9 got really ugly with vertical and I was fortunate to keep things centered up enough to not really drop many points. For those who aren't familiar with the MR1-FC target, the x ring is 3" (half moa) and 10 ring is 6".




Finished out the day with a respectable score, enough for a 1st in F/class but got more testing to do in the next 5 weeks before the Western States long range.

Also got my buddy out with both of his 260AI and he's been running too fast as well and not getting the numbers he should. Told him to back down to 2800 or less and he should be fine.

 

[msalm]

Just ran across this thread and GREAT READ! Several weeks ago I finished a 260AI build for my nephew that wanted an accurate rifle for an informal local shoot with friends. It’s on a really nice private range and is anything from 220 yards to 700+. 26” Muller barrel (from when he was at Rock Creek), Mack Bros action, and a McMillan A5 Carbon stock. Load development was with 136 Scenars as I had a bunch, H4831 in two round increments up to 48gr. He smoked his buds after we zeroed at 100 and I just ran a basic chart for the (slow) velocity of 2820. The target was a dartboard (picture target) at 420 yards, best 4 out of 5 shots. He had 2 50’s, a 25 and one squeaked high at 12 o’clock for a 20. He was 100 points ahead of the next shooter. He said the guys got kind of quiet, but they were impressed.

Anyway question is, has anyone thought about trying the new 144gr Lapua match target bullet? Any recommendations on loads to try? I think he’s at about 20 rounds through this rifle so far but I got 300 of those in and pretty interested in trying them out. I’ll be following this thread…might even build myself one…

 

[Fast14riot]

Just ran across this thread and GREAT READ! Several weeks ago I finished a 260AI build for my nephew that wanted an accurate rifle for an informal local shoot with friends. It’s on a really nice private range and is anything from 220 yards to 700+. 26” Muller barrel (from when he was at Rock Creek), Mack Bros action, and a McMillan A5 Carbon stock. Load development was with 136 Scenars as I had a bunch, H4831 in two round increments up to 48gr. He smoked his buds after we zeroed at 100 and I just ran a basic chart for the (slow) velocity of 2820. The target was a dartboard (picture target) at 420 yards, best 4 out of 5 shots. He had 2 50’s, a 25 and one squeaked high at 12 o’clock for a 20. He was 100 points ahead of the next shooter. He said the guys got kind of quiet, but they were impressed.

Anyway question is, has anyone thought about trying the new 144gr Lapua match target bullet? Any recommendations on loads to try? I think he’s at about 20 rounds through this rifle so far but I got 300 of those in and pretty interested in trying them out. I’ll be following this thread…might even build myself one…

Glad the information is helpful! Is he planning on staying with H4831? I'll have to look at the bearing surface on those bullets and crunch some numbers, but my gut feeling it running them around 2900-2950 should be about right.

I went right to the 153.5 because I would have to run the 144 really hot to gain the BC back from velocity vs the long pointy 153.5 with a 0.33BC.

 

[msalm]

I really like the looks of that Lapua offering…we shall see. Also, not stuck on 4831, but he’ll shoot whatever I load for him…. I have quite a few other powders, so if there’s a better option I’ll use it.
Pic of his 420yard target, definitely room for improvement, but we haven’t even started playing with this yet.

Trying out the Maven RS SFP 4-24 scope. Really quite nice optics and I get a 20% military discount.

 

[Fast14riot]

4831 has always been great in the 260. Same for 4350. Anything within or around those burn rates has potential to do well. I shot RL23 for a long time as well as H4831. I currently shoot N555, my buddy is using N160.

Are you loading LRP or SRP brass? I've found that the slower powders like N160, H4831, N555 are a little more sensitive to primer choice in small primer brass. When I used Ginex small primers with RL23 they worked fantastic (especially for old brass because they are just a little larger diameter), but switched to N555 and the Ginex was going click-bang giving me the slightest hang fires. Just enough I could hear the firing pin fall before going bang. Went back to Rem 7-1/2 primers and all is good. Still getting low single digit SD over 22 round strings. The chrono data above is for 22 rounds with a SD of 4.0. ES is a little high but I was out of my node still, so once that comes back it'll come down some, too.

I did a little digging around for dimensions on the 144 Max Range OTM, its going to be very close to the Sierra 142smk length, so 1:8 twist will be ideal. With 4831 i would work up to 48gr +/- 0.5gr depending on your brass. Lapua, Peterson, Alpha I would probably expect to see pressures around 47.5gr or so. With Rem, Win or other thin wall brass potentially could go to 48.5 (carefully, of course) depending on freebore and bullet jump. H4350, I suspect topping out around 45gr.

Can get you better load info if I have your case volume in gr/H20, jump, etm...

 

[Bill Norris]

4831 has always been great in the 260. Same for 4350. Anything within or around those burn rates has potential to do well. I shot RL23 for a long time as well as H4831. I currently shoot N555, my buddy is using N160.

Are you loading LRP or SRP brass? I've found that the slower powders like N160, H4831, N555 are a little more sensitive to primer choice in small primer brass. When I used Ginex small primers with RL23 they worked fantastic (especially for old brass because they are just a little larger diameter), but switched to N555 and the Ginex was going click-bang giving me the slightest hang fires. Just enough I could hear the firing pin fall before going bang. Went back to Rem 7-1/2 primers and all is good. Still getting low single digit SD over 22 round strings. The chrono data above is for 22 rounds with a SD of 4.0. ES is a little high but I was out of my node still, so once that comes back it'll come down some, too.

I did a little digging around for dimensions on the 144 Max Range OTM, its going to be very close to the Sierra 142smk length, so 1:8 twist will be ideal. With 4831 i would work up to 48gr +/- 0.5gr depending on your brass. Lapua, Peterson, Alpha I would probably expect to see pressures around 47.5gr or so. With Rem, Win or other thin wall brass potentially could go to 48.5 (carefully, of course) depending on freebore and bullet jump. H4350, I suspect topping out around 45gr.

Can get you better load info if I have your case volume in gr/H20, jump, etm...

47.5 gr. H-4831 is where I stopped with Lapua brass and 140 gr. class bullets. The loads above that were not as accurate especially out at 600 - 700 yds.