Uneven Erosion of Barrel Lands -- Cause?

[David Milisock]

I don't know if you can improve the accuracy of an AR much by changing how you clean. They run a little differently than the bolt guns and match guns I usually shoot. The basic answer is if it is delivering accuracy you are happy with then stick with your current approach. If you want to tighten up groups then you'll have to experiment.

My LR BR rifles will shoot 1/2" groups and better at 300 yds in good conditions. The way I clean doesn't seem to make a huge difference, as long as I don't go too long between cleanings, get the barrel too dirty, speed it up, and put it out of tune.

I run the same cleaning procedures with my bolt rifles and get improved groups over the AR but the same consistency. My bolt rifles are in general factory rifles with custom barrels and I don't shoot the best grouping loads. I choose loads that are a compromise between group size and high velocity because the groups are close in size but the velocities are significantly faster, (up to 500 FPS) providing much flatter trajectory and wind drift due to reduced time of flight for varminting. The slower velocity can average 7/8" at 300 yards instead of 1 1/16" but the load just sucks in trajectory and wind drift over terraced farm fields.

It's always been my judgement that to improve the accuracy of these rifles I'd need to spend the time and money to improve the furniture bedding and machining of the action and barrel. I use moly and that improved the shot string count and has worked for decades over 2 barrels.

 

[INTJ]

I run the same cleaning procedures with my bolt rifles and get improved groups over the AR but the same consistency. My bolt rifles are in general factory rifles with custom barrels and I don't shoot the best grouping loads. I choose loads that are a compromise between group size and high velocity because the groups are close in size but the velocities are significantly faster, (up to 500 FPS) providing much flatter trajectory and wind drift due to reduced time of flight for varminting. The slower velocity can average 7/8" at 300 yards instead of 1 1/16" but the load just sucks in trajectory and wind drift over terraced farm fields.

It's always been my judgement that to improve the accuracy of these rifles I'd need to spend the time and money to improve the furniture bedding and machining of the action and barrel. I use moly and that improved the shot string count and has worked for decades over 2 barrels.

More likely you'd need to take your load tuning to the next level, and it probably isn't worth it in a varmint or big game rifle. I know I don't try to tune my hunting rifles to the level I tune my competition rifles.

As long as bedding isn't terrible and machining isn't gross, the effort needs to be in the barrel and tuning.

 

[David Milisock]

More likely you'd need to take your load tuning to the next level, and it probably isn't worth it in a varmint or big game rifle. I know I don't try to tune my hunting rifles to the level I tune my competition rifles.

As long as bedding isn't terrible and machining isn't gross, the effort needs to be in the barrel and tuning.

I agree, I've stated that I picked a compromise load based on best group at highest velocity. The group is not bad about 3/16" larger at 300 yards, but the best range groups are just awful field loads they are way too slow to handle wind. I shoot today on many of the farm fields I hunted 50 years ago, except in the last 15 years or so the fields are now terraced to reduce erosion. The change produced eddy currents in the wind that quite frankly vastly changed the doping problem, similar to skipping rocks over a pond.

A 400 yard field where I used to use my 223 all the time, now routinely forces me to move to my 6MM as the normal temperature changes increase the wind speed and makes changes in the direction and also the eddy currents. Forget going to heavy weight 22 caliber projectiles the added trajectory and increased time of flight make them useless. I went with moly coated 40's at 3,900 FPS, the range groups are not as good but in the field 300 to 350 yard head shots on chucks are easily done and on calm days 400 yard body shots are something I don't shy away from. That load requires that I use one lot of brass only.

The 6MM Remington is handled the same way, load picked for velocity first group second, a 75 grain VMAX moly at 3,900 FPS. When the range gets to 600 or the wind is dicey the 6MM keeps my in the field longer.

 

[Shooter13]

It's expensive reading this forum!

LOL you're just now finding that out?????

 

[divingin]

I'm not sure what coating is on the Dewey but it's pretty good a tough stuff.

Nylon.

 

[gunsandgunsmithing]

Nylon.

Is that what it is? I really had no idea, just that it's some kind of hard plastic.

 

[divingin]

Is that what it is? I really had no idea, just that it's some kind of hard plastic.

G&G; It's on the Dewey website: "We offer Nylon Coated Rods, Stainless Steel and Brass Rods as well."

 

[jackieschmidt]

Getting back to the OP’s original inquiry, I am betting on the throat never being truly aligned with lands and grooves from the beginning.