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Posted: 10/27/2009 8:21:18 AM EDT
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Thanks everyone in advance for the help.I'm having a problem with the accuracy of a 6.5 Grendel I've put together.No, it's not my first build, several others have turned out to be tack drivers.I have used better parts in everything, and I do know shooting basics.Now the problem....
Barrel is a 24" that I purchased from AA a while back and it included the bolt.Everything has been checked and I cannot find anything obvious.At 100 yds groups are about 3" average with Lapua 123 gr bullets and new Lapua brass.At 200 yds groups average 6", I did notice that with hotter loads ( higher fps) group size seems to get a little better but it still sucks.I find no info as to what the twist is, but I've been thinking of trying the Lapua 108 gr...maybe twist is too slow for the 123 gr?Has anyone run into this? This barrel was purchased back when the big scare was on and I waited quite a long time for it, maybe it's a turd? Any suggestions? |
| There are things to try that arent Grendel specific. Find out what your twist is, but I doubt that's the problem. Yes try a different bullet, or a still hotter load (if you can safeelty), or a lighter load. Try some manufactured ammunition. Assuming everything is put together right, you may have a bad barrel/crown, or you may just have hit the "shit spot" for your barrel with the load you're using. |
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exhog,
Your barrel likely has a 1:9" twist. If you are making up your own loads make several sets of 5 rounds and vary the pounder between sets by 0.5 gr. find out which shoots best and fine tune from there. Other things to check are neck tension and seating depth (jump to lands), etc.... If you are looking for specific Grendel reloading information you would be better off checking 65grendel.com. T |
| what kind of powder are you using? My 20" shoots 2-3" groups at best with BL-C2 using 120 Nosler BT and 123 Sierra Match kings. Both are sub MOA with TAC powder. Also I get better groups with Wolf MPTs and AA 123 Scenars than with Black Hill 123 Sierra Match Kings round. Don't know what Black Hill uses for their powder but that stout load will not shoot worth a crap in my Grendel. |
Bullets are Lapua 123gr and recently 108gr.Have tried H4895 and AA2520, 2520 was a stouter load( close to factory load) and did shoot a little better, maybe 2" group.However I still consider that unacceptable for long range shooting.I would be dancing in the streets with 1/2" groups...
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I never got good results with the 123s. However, I have gotten good results with the 108s. Look through some of my posts on the 65grendel reloading section. I have done a lot of testing.
I think people have this impression that the grendel is superbly accurate. It isn't any more accurate than a lot of other cartridges. Plus, there are very few people tinkering with them compared to .223 or .308. That means less chances of finding that magic pet load. I had really good results with the 120smk, but the BC isn't as high as the other bullets. The 108s are where it's at in my book. I cannot remember any of the loads off the top of my head. I have been focused on bullseye pistol for the past couple of years, so my rifle shooting has taken a backseat. |
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Quoted:I think people have this impression that the grendel is superbly accurate. It isn't any more accurate than a lot of other cartridges. Plus, there are very few people tinkering with them compared to .223 or .308. That means less chances of finding that magic pet load.
Good point. The accuracy part of the Grendel equation comes from the high BC of the 6.5mm slugs, MAINTAINING accuracy in the wind and at range. Gotta get that CQB accuracy in place first. At least before we get to the quantum aerodynamics that will eventually catch up with us. Wasn't the sweet spot for that cartridge supposed to be around 129 or 130 grains? |
| No puskrat, 123gr is the ideal supposedly. My 22" Lothar Walther loves 120gr bullets. I have found no real difference between any of the various 120gr bullets I have tried and shoot consistent 1" groups at 100yds with the shitty stock trigger. I suspect when I upgrade the trigger things may tighten up a bit. Try the 120gr SMK's. |
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Speaking of scopes, what kind of scope and rings do you have on it.
I assume tis a flat top. I heard a gunsmith say one time that he had fixed more rifle barrels buy changing the scope than any other method. If that is not the problem, some other things you might want to try are.. Bed the barrel into the receiver. Make sure the barrel nut is tight. If everything is right and square and the scope is good then you could have a bad barrel, IE the lands could be rough. Good idea IMO would be to run some the tubbs 50 bullet kit through it to smooth it out. That should cut the groups in half if it really is a barrel problem. That said I never could get any of my Ar15s to shoot like any of my bolt action rifles but then again they were all hunters so I did not really care. 3/4"-1" group seems like it was about average for most of my AR15s. |
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Hmmm, some good points brought up and thanks.Scope is a new Bushnell 6500 tactical 4.5-30 with a Burris PEPR mount on a flattop ,could be the scope of course new doesn't mean it's good and I will check it.As far as accuracy, I have an AR in .223 that I put together with similar parts that groups under 1/2" at 100 yds all day with 55gr or 69gr.I may try the scope off that one just to eliminate it.I too have always read that in the 6.5 the 123gr bullets are THE pill, but I will try some 120gr smk's.One thing that I did notice that's peculiar....with the 123gr/H4898 load it grouped high/left about 3".With the same pill but AA2520 it grouped maybe 2" but LOW RIGHT about 5" away from the first group with no adjustments made to the scope....?????????
Anybody? 
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Quoted:
No puskrat, 123gr is the ideal supposedly. My 22" Lothar Walther loves 120gr bullets. I have found no real difference between any of the various 120gr bullets I have tried and shoot consistent 1" groups at 100yds with the shitty stock trigger. I suspect when I upgrade the trigger things may tighten up a bit. Try the 120gr SMK's. Where did you get this barrel???? I wanted a 22" but could not find one.... |
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You sure you are squeezing them off ?
Is it possible the ramps could be damaging the bullet. Thats a really nice scope. Trying to figure out what is wrong is really tough when having these sorts of problems. My dad bought a 6.8 mini, new, and it would not group. On a cold barrel It would shoot the first two shots low and left and the third bullet would hit high and right about 5-6" from the first two. I was convinced it was the scope, tried another one, nope. Honed the rings too nope. Next I figured it had a barrel problem. Ran a box of tubbs bulelts through it, nope. TRied a third scope, nope. We finally boxed it up and sent it back and they replaced the barrel, bolt and a few more items. I think it might have had a crooked chamber or something. At any rate when we got it back it would shoot 3/4" To solve a problem like you have, you have to start with the simple things first and eliminate each one until you find the problem. Find a good accuracy load too for testing. First I would check to make sure the bullets are not getting damaged on the way in. Next check the rings are tight. Next make sure the rings are parallel. That can cause problems too if they are too far out of alinement. Next I would check the barrel nut and make sure its properly torqued. If you remove it bed the barrel when you reinstall it. Next I would try a different scope just to eliminate that. I have gotten brand new leupolds that were bad. After that I would suspect a barrel problem, extension or bolt problem. You could try some tubbs bullets too, but that could be just a waste of $ like it was for me. What you are going through is a real PIA. |
Guys, thanks for the good suggestions...I will try a few things more just to eliminate those from the issue.Seems I'm not the only one with some problems in this cartridge, but I do intend to solve it, I still feel even with some headaches this cartridge does hold promise.When/if I solve it I'll be sure to post updates but in the meantime please keep suggestions coming in!
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Well IMO the Grendel is not an inherently inaccurate round. Just the opposite.
It was shot in competition as a 6.5mm PPC for years before BillA got hold of it and the PPC rounds are accurate. One guy over at 6mmBR had a 1000 yard target rifle set up for a 6.5G. I really think that the problem is more like the grendel round in an ar15. Maybe the bullets are getting dinged on the way in. Maybe its something else, who knows. That said I read over at the 6.5G forum that Bill A beds all of his barrels and that is supposed to help with accuracy. Explained why, but I cant remember now. After I read that I started bedding my AR15 barrels. |
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With blue locktight, but it is a specific locktight.
Cant remember the number. Dont use red or any other type if you are not sure as you might not be able to remove it. You put it on the mating surfaces where the barrel extension goes into the upper receiver, then assemble. Just dont get any on the barrel nut threads. Go to the 6.5G forum and ask over there. They can probably help you with better info. I would check the bullet tips first to make sure they are not getting damaged. |
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An update so far.....I emailed AA and explained what I was experiencing with this barrel.They want me to send it back to them ( which I will do) so they can examine it.I think we may be on to something here, and I also have to give a big PLUS to AA for responding to me and showing that they do care.
I will update further on this as I'm sure I'm not alone, or at least some may be interested in the determination here.I also want to thank everyone again for all the help and suggestions.I have helped many here ( or at least tried to) and it's nice to see that as a group there is considerable "brain trust" at work. 
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