MK262
- Thread starter Army of One
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I have tried N540 with 77 SMK and 80 ELD in a 24" bolt gun. No chrono data yet as I'm still looking for pressure signs as I turn it up.
On edit. It may not be the best for an AR gas system.
On edit. It may not be the best for an AR gas system.
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Yeah, I got it for .308s but ran out of N140 and wasn't shooting much .308 so I figured I'd give N150 a go in my .223 bolt (26") and get great results, 24.7 gives me 2950 with 75s and <1/2moa. Just hammers. Might be too slow at 2.260 in an 18" barrel though, I dunno. I'll try and report back.
Nice, curious to hear your results. VV don't have any data for N150 and Hornady 75 BTHPs (of which I have lots) but they do for 77gr Nosler CCs (max 25.6gr) and 77gr Berger OTMs (max 25.2gr) and I've always found the data for CCs and SMKs to be pretty interchangeable with the 75 BTHPs. I'll try and get out and do some testing in the next couple days as well. I'm just about out of all my 75gr/8208 carbine ammo so I need to get on it, haha.
I got to do a bit of load dev with 75gr BTHPs loaded at mag length (2.260 COAL) today. First I shot a 5rnd control group with my current load which is loaded long.
24.7 N150 @ 1.935 BTO: 5rnds = 0.18 moa @ avg MV of 2935 fps
Then I moved on to rounds loaded to AR mag length of 2.260 COAL (I've het to measure what the actual seating depth difference is but it's sizeable). I planned on shooting 2x 3 rnd groups of each charge weight and then looking at group size as a composite of both groups but I just ended up shooting 1x 6rnd group instead.
23.8 N150: 6rnds = 0.40 moa @ avg MV of 2837 fps
24.1 N150: 6rnds = 0.38 moa @ avg MV of 2864 fps
24.4 N150: 6rnds = 0.50 moa @ avg MV of 2891 fps
24.7 N150: 6rnds = 0.26 moa @ avg MV of 2923 fps
25.0 N150: 6 rnds = 0.29 moa @ avg MV of 2934 fps
I'm kinda surprised that the avg MVs are basically the same at the 2 different seating depths as I expected the rounds loaded at 2.260 to be moving faster and to show more signs of pressure (which they didn't). I'll grant that the sample sizes aren't large enough to be statistically significant but I still thought I'd see more of a difference.
For my uses with my trainer .223 bolt gun, it's a wash between 24.7 and 25.0, 24.7 is ever so slightly tighter but 25.0 has an ES about 5fps lower (44.8 vs 39.0). Neither is really important for a gun that is very rarely shot past 700. I'm sure I could tighten up the ES if I cared by throwing the charges on my Auto throw/trickler but I don't really care to do that for .223 and just throw the charges on a manual thrower and am ok with +/- 0.12gr of variance. I figure I'll stick with 24.7 cause there is never any harm in going with the lighter charge. I'll try 24.7 in an 18" gas gun tomorrow. It's not a precision barrel (keeps 24.4 N150 inside 1.50moa @2650fps) but I'm interested in seeing what kind of speed I get with this load. I've got a 20" Krieger Hbar coming for a different build and I'll try this load in it as well and report back.
24.7 N150 @ 1.935 BTO: 5rnds = 0.18 moa @ avg MV of 2935 fps
Then I moved on to rounds loaded to AR mag length of 2.260 COAL (I've het to measure what the actual seating depth difference is but it's sizeable). I planned on shooting 2x 3 rnd groups of each charge weight and then looking at group size as a composite of both groups but I just ended up shooting 1x 6rnd group instead.
23.8 N150: 6rnds = 0.40 moa @ avg MV of 2837 fps
24.1 N150: 6rnds = 0.38 moa @ avg MV of 2864 fps
24.4 N150: 6rnds = 0.50 moa @ avg MV of 2891 fps
24.7 N150: 6rnds = 0.26 moa @ avg MV of 2923 fps
25.0 N150: 6 rnds = 0.29 moa @ avg MV of 2934 fps
I'm kinda surprised that the avg MVs are basically the same at the 2 different seating depths as I expected the rounds loaded at 2.260 to be moving faster and to show more signs of pressure (which they didn't). I'll grant that the sample sizes aren't large enough to be statistically significant but I still thought I'd see more of a difference.
For my uses with my trainer .223 bolt gun, it's a wash between 24.7 and 25.0, 24.7 is ever so slightly tighter but 25.0 has an ES about 5fps lower (44.8 vs 39.0). Neither is really important for a gun that is very rarely shot past 700. I'm sure I could tighten up the ES if I cared by throwing the charges on my Auto throw/trickler but I don't really care to do that for .223 and just throw the charges on a manual thrower and am ok with +/- 0.12gr of variance. I figure I'll stick with 24.7 cause there is never any harm in going with the lighter charge. I'll try 24.7 in an 18" gas gun tomorrow. It's not a precision barrel (keeps 24.4 N150 inside 1.50moa @2650fps) but I'm interested in seeing what kind of speed I get with this load. I've got a 20" Krieger Hbar coming for a different build and I'll try this load in it as well and report back.
Tried 24.7gr N150 in my 18" gas gun yesterday. Shot a 10 rnd group side by side with a 10rnd group of what has been my go to load (22.8 IMR8208XBR). Both groups were identical in size with 9/10 rounds inside 1.5 moa and the 10th opening them up to 1.88 moa. The 8208 load is kinda slow (2590 yesterday) and the n150 load is 100 fps faster (so 2690) with no added pressure signs. Given how well 24.7 N150 shoots in my bolt gun and that it matches the accuracy my gas gun is capable of but at a faster speed than 8208 (2590fps) or N140 (2650) I'll be shooting this load as a common load between bolt and gas guns which is nice from a logistical point of view. I'll see how it does in the Krieger Hbar when I get that build put together.
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