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Discussion Starter #1
I've figured out what the Sig 556 likes best but my new LMT is still going through the testing phase.... So far I've tried the 55, 62, 75's and some Black Hills 77 gr. HPBT Match but still have not found the "magic" bullet that will perform consistently/accurately from it.
Wouldn't it stand to reason that a barrel with a 1:7 twist would prefer a heavier bullet? Should the 77 gr. have performed far better then the 55?
I've seen some 80 gr. but they call for match chambers or something to that effect. How high weight wise can I go with commercial/military ammo?
I have three different barrels a 10.5", 14" and 18" for this LMT and so far none of them like what I have fed it...... :cry:
Maybe I'll get lucky with the 69 gr. bullets? Would it be uncommon for it to prefer a 69 grain vs. a heavier bullet considering the 1 in 7 twist?



Thanks.......
 

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szuppo

It sure sounds like you have tried a lot of combination's, my question would be are you hand loading or buying manufactured rounds? In my little bit of experience, I only get really good results in my .308 with either very high quality manufactured rounds or hand loads, with hand loads being clearly better.

I am just now starting to reload, but I had been fortunate enough to have a friend that did and he spent some time at the range with me going through powder charges, powder types, primers, etc. It is a very consuming thing, at least it was for him, but he was also scary good with his Remington 700

I would have to ask, what kind of results are you getting? And what are trying to achieve?
 

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Discussion Starter #4
I'm using manufactured ammunition, mostly Hornady and Black Hills.
The best I've been able to get is 2.5" groupings at 100 yards.
In my 556, which for some reason shoots the cheap PMC 55 grain really well and yields 1.5" groupings of 10 shots at 100 yds consistently.
I'd like to do that or better with the LMT however it seems to not like what I've fed it thus far. I'm getting 3" or better with the various ammo I've tried and it is very inconsistent.
I am hoping that the 69 gr. I have on order are what it likes. :?

What is the heaviest bullet out there that can be used?
 

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The heaviest and best bullets that you can reload for your 556 with a 1:7" twist are the Hornady 75 grain BTHP, the Prvi 75 grain BTHP, the Sierra MatchKing 77 grain BTHP, tthe Swift Sirocco 75 grain BTHP, and the Nosler Competition 77 grain BTHP.

Do not try the Hornady AMAX 75 grain with the plastic tip, they are too long. Also, do not try any of the 80-90 grain bullets as they are all also too long.

Here is some good info for review:

http://www.shootingtimes.com/ammunition/st223_120606/
 

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Agreed,
the 75gr A-Max, 80gr SMK and heavier weight 22 caliber bullets were meant to be shot from rifles with throating for these bullets as well as being shot one at a time, not fed from a magazine.
 

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szuppo

I can see why you are upset, I would think that you should be able to achieve better results than that, unfortunately I am not sure where to tell you to go from this point.

Did you buy the LMT new? If not it could be that you have copper fouling in the barrel if the previous owner was not fastidious about cleaning it, if that is not the case....

Sadly despite 22 years in the military I am new to the repeating rifle life. I always had someone else to look after them for me, I probably should have been more involved, it would have made now a lot easier. So I cannot say what else might be causing the problem. I will say that I have had problems with sights and optics over the years that caused similar problems.
 

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Discussion Starter #8
The LMT was purchased new and has three different barrels for it. The accuracy isn't horrible, I jsut expect better and think it is only a matter of finding what these barrels like.

I appreciate all the info.
 

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In a previous post, you mentioned that you had three different barrels. Would your LMT be of the MRP variety? If so, check that the barrel is tightened to spec, if you haven't already done so. That might be the cause of the rifle's lack of mechanical accuracy.

Leb
 

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Bullet Weight ?

I've now tried 52gain SMK's, 53 grain Hornady Match, 60 grain Hornady spire points, 62 grain steel core, and 69 grain SMK's. My Sig 556 shoots it's tighest groups with the 52 grain SMK's. go figure. :roll:
 
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