60gr Tmk 223 won't group. Help

1shot2kill

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I've tried 3 different powders over 300 rounds and the best I can get is 2" @ 100 yards
I really want these to work considering I have 1200 of them
Gun: Aero M4 enhanced builder set
WOA 18" SPR Rifle length 1/7"
Timney trigger
JP BCG
JP Rifle length captured buffer assy
Powders tried:
Ramshot Tac
CFE223
AA2520
All cases are LC17
CCI 400 primers
seating depths used 2.250-2.285"

Ramshot tac produces single digit SD 26.0-26.3

any help would be appreciated
 

MarshallDodge

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Have you tried other bullets in that rifle, like a 69 grain or 77 grain BTHP?

I like TAC but I would try a little faster powder. Can you get you hands on some H322 or H335?
 

st1650

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Not that it would really matter for accuracy but I'd go with thicker primers like CCI BR4s, 450s, or Fed 205M-AR on a gasser (or Rem 7 1/2 if you can find them - loved them in my gasser)

For powder, why not try varget and/or XBR ? Sierra says Varget 20.2 – 23.6 grains (but you can probably go all the way to 25). For XBR probably 21.0-24. You gotta watch out with XBR thought ... you get no pressure sight then up the charge and get pressure signs pretty quick.


Why not also try maybe a fairly early to tune load like the 77 SMK or Lapua Scenar 77 over varget to establish a baseline - maybe there's something wrong with your barrel or something ? Cause if you can't get a classic 77 smk or scenar 77 to shoot less than 1 moa, then there's definitely something wrong with your scope, mount or barrel.
 

1shot2kill

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77 smk & 75 hpbt under 25.2gr of AA2520 is my pet load and my rifle loves it.
The reason for the 60tmk was they were .12 a piece on sale when I bought them 2years ago or so
 

rweaver00geo

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Is the tac charge high to anyone else? I only have the hornady data in front of me and it max's out at 24.7 with the 60/62 class weight bullets. (tmk not included).
All the powders you mentioned are spherical and may work better with a magnum, or rem 7 1/2. But you obviously got the 2520 to work with the 77gr with out a magnum primer. Primer change and possibly try one stick powder?
 

rweaver00geo

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One more thought, have you checked the seating depth in respect to the lands? If not with one of those fancy tools that I dont own, the split case method perhaps?
 

1shot2kill

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One more thought, have you checked the seating depth in respect to the lands? If not with one of those fancy tools that I dont own, the split case method perhaps?
I have checked seating depth but I want to run these out of a magazine as it is a ar15.
Ramshot lists max load for the 5.56 62gr @ 26.2 I was keeping a close eye on cases, primers & ejection patterns while working up.
 

Mr Tibbs

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I've tried 3 different powders over 300 rounds and the best I can get is 2" @ 100 yards
I really want these to work considering I have 1200 of them
Gun: Aero M4 enhanced builder set
WOA 18" SPR Rifle length 1/7"
Timney trigger
JP BCG
JP Rifle length captured buffer assy
Powders tried:
Ramshot Tac
CFE223
AA2520
All cases are LC17
CCI 400 primers
seating depths used 2.250-2.285"

Ramshot tac produces single digit SD 26.0-26.3

any help would be appreciated
Have tried the CBTO method instead of OAL ?
 

ICU22250

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    Are you loading everything at the top end of the charge weight? Maybe back off a bit and see what you get.. It almost sounds like a build issue on the rifle, maybe the barrel nut or something not torqued to spec or something of that nature.. Try some factory match grade ammo like some prime or hornady stuff just to see if the rifle wants to shoot to begin with. 2 inch groups is the best you get out of 300 rounds, that just isn't right, something is wrong and im not sold that its your loads is all.. JMO...
     

    1shot2kill

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    Are you loading everything at the top end of the charge weight? Maybe back off a bit and see what you get.. It almost sounds like a build issue on the rifle, maybe the barrel nut or something not torqued to spec or something of that nature.. Try some factory match grade ammo like some prime or hornady stuff just to see if the rifle wants to shoot to begin with. 2 inch groups is the best you get out of 300 rounds, that just isn't right, something is wrong and im not sold that its your loads is all.. JMO...
    All factory ammo shoots great it's literally just this bullet & that's what has been driving me nuts.
    Also I worked up loads with all 3 powders listed.
     

    st1650

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    I don’t know ... you wouldn’t have that much of a problem selling those 60gr TMKs and just buying 77 smks.
     
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    st1650

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    Seirra doesn't list that bullet for .223 AR15.
    I don't know about the 60gr TMKs, but the 80 gr ELD-M for me, wouldn't shoot unless it was loaded .010" off the lands. It was very depth sensitive and I had to load them extremely long at 2.525". Even at 2.515" they wouldn't group any better than 1 moa.
    Obviously it was a bolt gun load.
     

    ICU22250

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    Another thought is, would the 60's perform well in that fast twist 1:7? What grain factory fodder that shoots great did you shoot? I know, I'm probably reaching here...
     

    1shot2kill

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    40 grain up to 77 shoots great.
    I’m trying to attach a picture from my phone of the last time I went out.
    Bottom right is 55gr American eagle
    These were all shot round robin.
     

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    n0glock

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    I would call Sierra they may have an idea what is going on. Had an issue with Speer TNT's years ago and a quick call and the issue was solved.
     

    1shot2kill

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    I would call Sierra they may have an idea what is going on. Had an issue with Speer TNT's years ago and a quick call and the issue was solved.
    I contacted them Friday and the guy I spoke with wasn't sure either.
    The only thing he could say was 25.8 was max 223
     

    ICU22250

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    What kind of brass are you loading with? Mix brass, premium brass? Also what are you charging your loads with?
     

    FCS

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    60 TMK, I’d suggest H322, VV N-133 or N-135, AA2015, Benchmark or similar powders that are a little faster than what you’ve tried.
    I know, easy for me to say and not so easy to find any of the suggested powders.
     

    ICU22250

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    60 TMK, I’d suggest H322, VV N-133 or N-135, AA2015, Benchmark or similar powders that are a little faster than what you’ve tried.
    I know, easy for me to say and not so easy to find any of the suggested powders.
    I run N133 with Nosler 40 grain ballistic tips myself...
     

    1shot2kill

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    60 TMK, I’d suggest H322, VV N-133 or N-135, AA2015, Benchmark or similar powders that are a little faster than what you’ve tried.
    I know, easy for me to say and not so easy to find any of the suggested powders.
    I agree I'd love to try some of those but at this point if I cant get them to shoot with the 3 great powders I have I don't think they'll shoot.
    Also Sierra recommended a overall length of 2.250" Which put the ogive inside of the end of the case
     

    Chickentoast

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    I found the TMK's much more finicky than SMK's, but was able to get the 69's and 77's to shoot, albeit in a 9 twist. I have a feeling your twist might just be too fast. Save 'em for your next barrel?
     

    Snuby642

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    Ogive in the case mouth on a 60g bullet at 2.25?

    Do you have pictures of any of them?
    Maybe next to a 55g fmj for a comparison.
     

    EM_556

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    Just for curiosity sake, what twist barrel is this being used in? And how is accuracy?
    16" DD CHF barrel. 1:7 twist. Accuracy 3/4-1" at 100yards with a 1-6 scope. I think I could shoot it better with a larger scope but not needed for the application. I think I was getting around 2850-2900fps.
     

    ICU22250

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    16" DD CHF barrel. 1:7 twist. Accuracy 3/4-1" at 100yards with a 1-6 scope. I think I could shoot it better with a larger scope but not needed for the application. I think I was getting around 2850-2900fps.
    That's great, well, that answers my question whether or not the 1:7 is too fast for the 60's or not... Sorry OP, I hope ya get it figured out...