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Discussion Starter #1 (Edited)
Hi folks,

I have an LWRC 68 that’s been nothing but trouble. It wasn’t stabilizing anything I could find (factory loads). 120 SST’s, 115’s, 110’s, 100’s... I was getting wild 4-5 inch groups. I sent it back to LWRC and they replaced the barrel. The new barrel still isn’t stabilizing. Same bad groupings.

I got a reloading press and finally got some 85s, 95s and 115s to try (as soon as the range opens). I also got the Hornady modified case, OAL tool and bullet comparator set.

My question is - how long is too long for jump to lands? I tried both a 95 gr TTSX and a 115 Sierra MK with my new tools. My CBTO is 1.960 and 1.9440, both of which put my COAL out to 2.440 and 2.400 (when jamming the bullet into the lands with the modified case and OAL tool). If I am loading to 2.295, I have a long jump...

I have read a bunch of posts where folks are pushing out to 2.35 or so with modified mags - to get to .010 from the lands. I am no where near that. Even if I loaded one at a time, the 2.4 lengths don’t give the neck much bullet to hold on to.

Is this why my 68 won’t stabilize?

Just out of curiosity, how does this compare to your rigs?

Thanks,

MB
 

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This isn't the first time I've heard LWRC owners express accuracy concerns. I have no experience with an LWRC Upper. Their website gives little detail. Twist rate is what stabilizes a bullet not jump to the lands. If the bullets are not stabilized, the paper holes would be oblong. I assume this is a gas piston system which can disturb a barrel during actuation compared to a direct impingement.

I have had 6.8mm barrels with COALs of 2.420" for 100/110 AB to touch the lands. Lately some manufacturers are shortening freebore to improve peformance with factory ammo. Adjusting COAL is a power "lever" to improve accuracy. Tryi adjusting COAL in 0.015" to 0.030" increments to see if you get a better grouping. Sometime a bullet/powder combination is more accurate with a longer jump. I also check scope and mounts for issues, even try a different scope & mount for verification. I've even found some muzzle devices can degrade accuracy.
 

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60901
 

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And a better example. I do load long with CavityBack modified magazines.
60902
 
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Discussion Starter #5
I’ve loaded 50 rounds - still working on charge weights. I’ll crawl into adjusting COAL after I find some happy charges.

95gr BARNES M/LE TAC-TX 6.8MM
COAL 2.240
H322 28.6-30.5 gr
New Starline brass
CCI BR4 sm primers
 

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Discussion Starter #7
This isn't the first time I've heard LWRC owners express accuracy concerns. I have no experience with an LWRC Upper. Their website gives little detail. Twist rate is what stabilizes a bullet not jump to the lands. If the bullets are not stabilized, the paper holes would be oblong. I assume this is a gas piston system which can disturb a barrel during actuation compared to a direct impingement.

I have had 6.8mm barrels with COALs of 2.420" for 100/110 AB to touch the lands. Lately some manufacturers are shortening freebore to improve peformance with factory ammo. Adjusting COAL is a power "lever" to improve accuracy. Tryi adjusting COAL in 0.015" to 0.030" increments to see if you get a better grouping. Sometime a bullet/powder combination is more accurate with a longer jump. I also check scope and mounts for issues, even try a different scope & mount for verification. I've even found some muzzle devices can degrade accuracy.
Thanks. I’m definitely poking holes, but they’re 2.5” up/left, then 4” down, then 3” left. It’s just not grouping. I’ve removed all muzzle devices. I’ve used huge heavy muzzle devices. Used bags vs bipods. I’ve never had one that didn’t behave like this.

I am suspicious of the input of the piston. LWRC told me that the rifle spec was 1.75 moa. That isn’t what I want to hear for a $2600 rifle. Really hoping I can load my way out of this disappointment.
 

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Discussion Starter #8
This isn't the first time I've heard LWRC owners express accuracy concerns. I have no experience with an LWRC Upper. Their website gives little detail. Twist rate is what stabilizes a bullet not jump to the lands. If the bullets are not stabilized, the paper holes would be oblong. I assume this is a gas piston system which can disturb a barrel during actuation compared to a direct impingement.

I have had 6.8mm barrels with COALs of 2.420" for 100/110 AB to touch the lands. Lately some manufacturers are shortening freebore to improve peformance with factory ammo. Adjusting COAL is a power "lever" to improve accuracy. Tryi adjusting COAL in 0.015" to 0.030" increments to see if you get a better grouping. Sometime a bullet/powder combination is more accurate with a longer jump. I also check scope and mounts for issues, even try a different scope & mount for verification. I've even found some muzzle devices can degrade accuracy.
Forgot to confirm - I have also swapped optics with other known good optics and gotten this optic to behave on other rifles. I have leveled It and used torque drivers to 30# per larue (they’re the LT111 QD). It’s all tight. A good place to check - it shoots like that...
 

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Why H322? Why not AA2200? Cant help on the LWRC. Have read several threads with accuracy issues from them, plus the stated 1.75 moa spec.
 

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I'm going to get bashed for this but it needs to be said . If the manufacturer has very little confidence in it shooting better than a junk barrel why waste money and time trying to do what they can't with their product ? Sell it to someone who is more into show than go and build ( or have a friend build it ) a 6.8 with a ARP barrel . Then you can come on here and show off your 1/2 moa groups .

Sent from my moto g(7) play using Tapatalk
 

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Ben, this sounds like a bad scope mount to me but if you have changed scope and mount and it still shoots the same, you have ruled that out. When you reload, do you separate your brass by manufacturer then develop a load with only the same manufacturers brass? I've seen groups bounce around like this when a reloader mixes their brass.
 

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Discussion Starter #13
Ben, this sounds like a bad scope mount to me but if you have changed scope and mount and it still shoots the same, you have ruled that out. When you reload, do you separate your brass by manufacturer then develop a load with only the same manufacturers brass? I've seen groups bounce around like this when a reloader mixes their brass.
agree. It shoots like a loose scope. I have ruled that out however.

I’ve only fired factory ammo to date. I got into reloading for many reasons, this being one burning reason. I have brass from many head stamps, but bought fresh starline brass to work from.
 

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Discussion Starter #14
Ben, this sounds like a bad scope mount to me but if you have changed scope and mount and it still shoots the same, you have ruled that out. When you reload, do you separate your brass by manufacturer then develop a load with only the same manufacturers brass? I've seen groups bounce around like this when a reloader mixes their brass.
I bought the 224 Valkyrie upper. Want to see if it shoots with the same optic and lower. Then it will be certainly the upper/chamber/barrel/crown or load. I’ve heard a theory it’s over pressured. I want to try all the options and then ask LWRC one last time.
 

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I bought the 224 Valkyrie upper. Want to see if it shoots with the same optic and lower. Then it will be certainly the upper/chamber/barrel/crown or load. I’ve heard a theory it’s over pressured. I want to try all the options and then ask LWRC one last time.
And a better example. I do load long with CavityBack modified magazines. View attachment 60902
you might have a trigger pull might be a little to much
 

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My LWRC Six8 piston performs best with the Federal XM68 ammo with 90 gr Gold Dots. I'm thinking .75" groups. I've got a spare upper with a DI ARP barrel on it. .5" groups. The Six8 Piston is a nice AR, but I had to switched out the trigger on mine. The original trigger was pretty bad like most milspec triggers I've tried. Not sure if its the piston, the barrel or both that make it less accurate than my ARP barrel.
 

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deputy bruce and Ed make a good point. The trigger makes a significant difference. I noticed when I put a good match trigger in my ARs I could start calling where the crosshairs were when the shot broke.
 

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I've never had an AR do that even with cheap budget guns, but i have never had a piston gun either. Heck even my old mini 14 shoots better than 1.75moa. I do see where a trigger might help but not likely enough to tighten groups by 3moa.
That being said I would check the piston system doesnt look like its hitting the handguard, then remove the handguard & check to make sure the barrel is tight (see below *) and manipulate the piston to ensure the it isn't rubbing something during the stroke. As H has said before pistons tend to create more issues than they solve. If it is over pressured you may be able to try a heavier buffer if the piston isn't adjustable.


* I had a 308 AR once that i torqued the barrel nut to spec and bedded it with loctite and allowed it to dry. Then at the range the POI kept moving on me. Turns out the barrel nut had a burred thread on it that bound up and allowed the barrel, once heated and loctite broke, the slightest bit of wiggle. I tore it down and dremelled the bur off and put back together and its fine now but something that may be overlooked.
 

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I had a 308 AR once that i torqued the barrel nut to spec and bedded it with loctite and allowed it to dry. Then at the range the POI kept moving on me. Turns out the barrel nut had a burred thread on it that bound up and allowed the barrel, once heated and loctite broke, the slightest bit of wiggle. I tore it down and dremelled the bur off and put back together and its fine now but something that may be overlooked.
Same here. Every AR10 barrel I've installed required a lot of torque or it would move a little. The Six8 barrel nut requires a special barrel wrench if I'm not mistaken. Fortunately I haven't had to mess with mine.
 
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