Accuracy problem.

[rcoodyar15]

Coming soon.
The owner of the upper is in no rush, and as this is pro-bono, I have to slip it in between "real work" as able.
Will keep everyone updated as the checks are completed.

thanks for the update. I am always curious about problems like this. never know when it will happen to you. Nice to know another thing to look for.

I will keep watching!

[Sgt_Gold]

Tag for info.

[mtdawg169]

If you seriously want to have it diagnosed, you can send the upper to me. I can do a safety inspection, test fire, diagnostic, and corrective action; all recorded.

Sincerely, let me know.

This is one of the most awesome things I've seen here on M4C in a while. Nice move Jack.

[BufordTJustice]

This is one of the most awesome things I've seen here on M4C in a while. Nice move Jack.

It's sacrifices like this by members with serious real world knowledge (like Jack) that truly adds to this community.

[ryantx23]

Tag to follow

[Zim]

Tag to follow

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I just finished installing a CMR, and the Noveske low profile gas block was definitely contacting the rail. I had to take a few whacks at it until it looked good, and it still might not have enough clearance. It's definitely a finicky rail when it comes to gas blocks.

[Reconinforce]

Awesome forum. Pretty cool how people help each other out. Way to go. Interested to see how it all goes.

[Failure2Stop]

Alrighty...

Schedule and weather came together to be able to get initial data points.

Prior to going out, since late update, I cleaned the operating parts, chamber, and bore.
The bolt, bolt carrier, and charging handle were a little tacky, and there was build-up in the barrel extension.
The bore wasn't terrible, but a little scrubbing pulled out a lot of fouling.
I did not de-copper.
General clean-up and lube, light coat of lubricant in bore.

Environmental:
77 degrees F
29.89 in Hg
12.5 ft
95% relative humidity
0.073 lb/ft3

Sunny, shooting to the South (0900-1030)
No wind.

Setup:
Harris HBR Bipods, directly attached to sling swivel on HG.
DIY rear squeeze bag.
US Optics 1-8x
LMT lower, A5 RE/buffer/spring, KAC 2-stage trigger.
El-Cheapo Bushnell Spotting Scope
Dunkin Donuts Iced Coffee, less cream, less sugar
Mint Skoal (not pictured)



Conduct:
Rough bore-sight of optic.
50yd intial zeroing using PMC 55 gr.

First Group:

First shot was the one close to the center dot at 11:00.

Groups 2 and 3:

Group 2 was PMC 55 gr (!, right?)
Group 3 was Mk 262 Mod 1
Group shift is due to optic adjustment/zeroing (I forgot the adjustment values and over-adjusted for group 2).

Moved target back to 100 yards (actually closer to 95 than 100, but no big deal for this).

View through USO 1-8:


Mk 262 Groups:



Just for gigs, I shot some PMC too:


I am inclined to believe that there is contact between the gas block and inner bottom portion of the handguard; normally I see a larger difference between PMC and precision ammo, even with "service" grade barrels.

I will be removing the handguard and checking precision with a test tube after confirming barrel nut torque.

[Koshinn]

You must have some of that pmc 55gr supermatch ammo!

[Failure2Stop]

You must have some of that pmc 55gr supermatch ammo!

I double and tripe-checked the ammo after seeing that group, hah.

Just proves that if you shoot enough of anything, you can show a group that is wholly mis-representative of actual capability.