Accuracy Issues

[varminthunter]

To begin this, I recently purchased a new AR15 upper. This is a 24" SS Bull barrel with a 1:8 twist. I cleaned the barrel before shooting and when through the normal shot-clean for the first 25 rounds and then after every 25 rounds. I have fired almost 150 rounds through this barrel and so far the best accuracy I have seen is a 3" group at 100 yards. I have tried 55gr, 62gr and 75gr rounds, all producing approx. the same results give or take a 1/2" +-. These round have been everything from FMJ, Soft Point and Hollow Point rounds.

I ran my borescope down the barrel and to me it looks like rust spots all up and down the barrel, but I'm not 100% sure. What are your opinions of the attached borescope images. Some of this maybe copper fouling, so I think I will pickup some cleaner for this to clean the barrel.

I should mention that I purchased this upper through M&A Parts Inc.

 

[Rabbitkil]

I would use some bore paste and polish the barrel then try again with the break in process

 

[mike243]

Looks like cooper fouling

 

[backyardtndeer]

I am not familiar with m & a parts. I don't think that is rust. May try iosso bore paste and brush it real well.

 

[DaveB]

Questions:
1. Handloads or factory?
2. Have you looked at your fired brass, particularly primers. Any signs of overpressure? case neck ? any bulge near extract points?
3. Are you firing from a rest and if so make and model

I'm at exit 15 on I-40, we is neighbors. PM me

 

[varminthunter]

Questions:
1. Handloads or factory?
2. Have you looked at your fired brass, particularly primers. Any signs of overpressure? case neck ? any bulge near extract points?
3. Are you firing from a rest and if so make and model

I'm at exit 15 on I-40, we is neighbors. PM me

Factory loads, not over-pressure signs on any of the cases. All shots fired from a bench rest and with little to no wind.

Howdy Neighbor

 

[DaveB]

Slide by. I'll spot you 25 rounds of 223 loaded with 25 gr of H335, Fed GM205MAR primers, 55 gr Armscor FMJ.

My son shoots these at 100 yards into a cloverleaf with an Axis bolt. You will see if something else is amiss with your rifle. My thought is the jump is too long since the groups are consistent. Just one more thing, let someone else shoot the rifle and take you out of the equation.

You have a good trigger?

 

[varminthunter]

I'm running a Franklin Armory BFSIII trigger, have had my Son-in-law and grandson both shoot the rifle with the same results. Ok maybe a little worst. I checked the headspace and seating depth on the rounds fired, 5 to 6 thousands jump not bad. Could be better with hand loads. I use the same ammo in my DPMS and Armalite rifles and will shot a 1" group or slightly better out of both rifles. The original Anderson 16" carbine upper shots really good with the same ammo also. I really thinks it has something to do with the upper and not so much the ammo or shooter. It's a bull barrel, which the crown is not recessed, didn't really like that but it is what it is. The lands and groove don't all start at the same point in the barrel like one would expect.

 

[varminthunter]

I'm thinking that maybe I will take the barrel in and have an 11 degree crown put on it, this might help. Right now though the crown is in good shape with not nicks or dings.