Your posts suggest inconsistency of groups, if that is the case. What are you changing? Are range conditions changing? Scope problems and torque/contact points are change issues. Loads that are the same, normally perform the same. Barrels usually are consistent, until fouling or wear occur. I have seen some odd bench bag/rest setups cause major group problems.

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Plant 1,

I have mostly been working with IMR 4064, H4895, AR-Comp, W748, N135 and PP2000 MR

I have tried CCI BR2's, 34's and 200's for the most part. Those three primers show very little difference over my Lab Radar. There is a myth out there that the 34's are a mag primer. B.S.!!

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holy cr@p... it wont shoot 168 MK's over H4895?

somethings reeeeeeeeely wrong here.

be interesting to see your follow up after the range report.

Made it to the range yesterday. I trimmed all the cases a bit shorter than normal, pulled the suppressor adapter and did an experiment with shooting a group with an entirely different BCG.

No luck.

My dad gave me an old 16 inch barrel DPMS barrel a long time ago. I did not believe it was worth the trouble of even putting on a rifle. It has a carbine length gas system and took me 2 days to get what seems like 2lbs of copper out of.

I put it on the 2nd upper receiver i bought trying to solve the accuracy problem with this rifle. HA!!!

It ended up shooting decent. It does less damage to the brass than the rifle length 20 custom barrel does.

I actually shot MOA groups with it with 168's with both IMR 4895 and H4895.

At this point i am putting the high dollar crap away and just going to shoot this junker 16 inch DPMS barrel with the DPMS BCG.

When i can get a control group with it, if i can???

I will start adding and removing parts and components from the old rifle to see where the problem is.

The SAGA continues!!

Somewhat of a side note, with the DPMS re-build.

I did not grind on the barrel nut to ensure the gas tube was not touching. I also did not fret over the somewhat restrictive feel of the gas tube going into the gas key.

I also need to see decent results the next 2 range trips at least to believe this shoots ok.

Too many times have i had a good session, only to return for disappointment.

Over the years, I've had quite a pile of DPMS barrels, and only 1 or 2 could be considered duds, and several were amazing, including a couple I have now.

One of my regrets is not buying a few of their 204 barrels when Midway had them for $200 for years.

Sounds like you're on the right track. I'm reluctant to offer any more advice since everything has been a dead end so far, but it's worth noting that I have noticeably shrunk groups by tuning gas blocks down to barely function. It sounds like the custom barrel has a much too large port.

Any improvements or positive progress?

Well.... I took it out to the range. The two days prior i spent hours and hours trying to remove hard carbon from the barrel.

I must have done 15+ or so extended scrubs with JB, and another 15-20+ scrubs with Kroil and a brush. I actually wore out the 2nd brush.

The directions on the JB container say to shoot the rifle and warm it up, before continuing on with a stubborn barrel. I will do that this go round.

I fired 3 decent looking groups of < 1.5 inches, The 4th group of H4895, +0.2 grains gained 8fps average and strung the bullets into a 3 inch, straight vertical group.

I then was all done with that combo, and switched to 165 grain Nos BT's. Nothing shot well after that.

I suspect copper, or carbon built up some place and ruined all shots after the 3rd group.

This time of year i don't have that much time to shoot.

I am somewhat spooked i am going to harm the barrel with this much scrubbing. After 30+ frustrating cycles, the patch comes out fully black. No sign of improvement or trend.

It seems the carbon is almost as hard as my head is. My dad took immaculate care of all of his barrels. Except for this one. It seems it was never cleaned. I am not sure if he purchased it second hand or not?

I am happy with the velocity the 16 inch DPMS barrel gives. I am shooting these 165-168 grain bullets between 2450-2500 and the brass looks fine.

Somewhat better than my fancy 20 inch custom barrel spits out running between 2500-2550.

Hornady brass seems a bit too soft for the AR308 platform. My range pick up Lake City Nato brass has worked the best by far.

The Starline brass has a good base for this platform also. I just can't get it size consistently.

Yesterday a nice fella was blasting away with his new 308 rifle. he let me pick up all 82 pieces of Lake City Nato 2021. Lucky me!!!

After quite a bit of fussing and fiddling, I have landed on a combo that shoots consistently. After many 10 shot groups, and many more 7-8 shot groups.

The combo is 42 grains of Reloader 15, CCI 34's and 165 grain Nosler Ballistic Tips.

I am not sure yet which mod made the rifle start to shoot repeatable. Though i am certain it was either changing upper receivers to one that clearly has a better fit, and or getting that JP bolt out.

This rifle with the regular gas block and the above load throws brass straight forward with a DPMS bolt.

With the JP bolt it throws the brass out the 4 o'clock, and into the next county over. I will do a BCG shoot out down the road.

I am now running the SLR bleed off block, and the rifle runs great!

I researched gluing the barrel in pretty heavily. I ended up going with shim stock. The barrel fit was already really good. I used 0.001 SS. After freezing the barrel, and heating the upper, they are married together.

I shot several 10 shot groups prior to, and several after, and did not notice anything.

At this time i am very pleased with the last 5, ten shot groups all coming in right at 1.25 inches. Over and over.

I feel confident playing with other combinations now.

I no longer hate the 308!

Well I am happy to know my AR10 experience matches yours. I did the smart thing and sold all my AR10 stuff! I had no trouble getting my AR10 to shoot well but I had a very bad time getting it to function reliably. Nothing like my AR15 experience.