New AR Build!

slimjim · Posted: Sun Nov 21, 2010 7:58 pm Post subject: Re: New AR Build!

A shooting buddy just helped me run some JB paste through the barrel as Dawgdad recommended and chased it with fine polish. Its ready to go and I'm just going to start shooting it. I've got 40 V-max, 50 HP, 55 FMJ, 69 SMK, 75 A-max, and 77 SMK to shoot through it this week. We will see how it does.

Dawgdad · Posted: Mon Nov 22, 2010 8:05 am Post subject: Re: New AR Build!

Occams Razor--- (look that one up if you dont know it Wink

) before you blame a bad barrel from a custom manufacturer with a solid reputation... Where would you look first on model 70 that was not shooting well?

Check the scope the mounts make sure every thing is right in the barrel nut area. Try the reduced powder 77 load that is a known 1 moa shooter in about any AR platform with a 1:8 or faster twist. Use Some Black Hills match ammo..
If all that checks out then go to the crown on the barrel and then maybe bore scope the thing.

You did have a lot of fluting done. Do you think that might be and issue? Hate to spend more of your money but if it does not settle down to sub MOA in the next hundred rounds or so, I would consider Cryo treating it in case the fluting has caused a stress that changes poi as it heats up.

slimjim · Posted: Mon Nov 22, 2010 5:50 pm Post subject: Re: New AR Build!

Dawgdad, all good suggestions. Scope has been great and used on other ARs before I placed on this one. Since installed on the new AR, POI has been consistent all three sessions at the range. Fiocchi 69gr SMK is match ammo but I know its not as good as Black Hills which a can try after this next session if things aren't looking up. Cryp, wow, hope things don't come to that but I wouldn't rule out your suggestion. Just a note, the barrel hasn't had enough rounds down it fast enough to heat-up at all. Always been cool to the touch so far.

Just for now, I did the JB Paste and I'm going to wait to see what the results of the next session are. I finished all my loads just and hour ago.

Thanks again for you suggestions. They have helped me prepare for the next round.

Dawgdad · Posted: Mon Nov 22, 2010 6:34 pm Post subject: Re: New AR Build!

Cryo is really not that expensive - The place that does it (300 below) is about three blocks from where I work and I get a note about 3 for one specials once a year. If it comes to it we could get up a few barrels to try there for about $65 each.

slimjim · Posted: Mon Nov 22, 2010 7:56 pm Post subject: Re: New AR Build!

Dawgdad wrote:

Try the reduced powder 77 load that is a known 1 moa shooter in about any AR platform with a 1:8 or faster twist.

Dawgdad, what load recipe is this? I currently have some 77 SMK loaded with 24.0gr of TAC. Your reduced powder load for 77gr sounds like it would be less than that.

Dawgdad · Posted: Mon Nov 22, 2010 11:10 pm Post subject: Re: New AR Build!

24.0 RE - 15 or 23.8 Varget 2.250" about 2650 fps

slimjim · Posted: Wed Nov 24, 2010 12:04 am Post subject: Re: New AR Build!

It was a gorgeous day so I headed to the range to try all the suggestions. Rifle shot different this time out, could have been the JB Paste scrub. Here are the 5-shot groups from four different ammo. I did shoot 7 with the 40gr V-max just to make sure how it was grouping because it was the best last time out and wasn't shooting as well this time. Top row was with the gas turned off and manually cycling the action. Bottom is with the gas on in semi-auto.

Some observations.
- Boy this gun doesn't like 55 FMJ. My M&P loves it.
- Big difference in how 69 SMK group this time out compared to last
- This is my first bull barrel. I didn't expect such varied results. Glad the 77 SMK show good promise.
- I found it counter-intuitive that with the gas on, all average velocities were faster.
- I threw in my shots from my .270 for reference. Shot as well as chambered's 7mm-08 today. I always shoot 2 when I go to the range to build confidence in the rifle's consistency.

Anyone's comments would be appreciated. Also, why faster with the gas on? I did shoot gas on last so maybe the barrel was still getting faster.

slimjim · Posted: Wed Nov 24, 2010 12:12 am Post subject: Re: New AR Build!

I did shoot the Hornady 75gr A-max with Varget and IMR 4064. 4064 didn't shoot well enough to even post the results. Significant shift in groups with Varget. COAL was 2.39". I still need to improve my measurement technique but the rifling starts around 2.40 COAL so I'm pretty close to the lands. Looks like I should work some more loads up around 24.2 grains. Will have to get some 77 and 80gr SMKs.

Elvis · Posted: Wed Nov 24, 2010 12:20 am Post subject: Re: New AR Build!

thats a dead varmit group now. heres hopeing it keeps inproving from here on for you.

slimjim · Posted: Wed Nov 24, 2010 10:33 am Post subject: Re: New AR Build!

Is JB Paste that good? I shot 65 rounds yesterday. Just cleaned the gun and the copper fouling was less than the previous 5 shots I accomplished before the JB Paste and polish treatment.

Ah, the fun of learning a new rifle!

Dawgdad · Posted: Wed Nov 24, 2010 11:16 am Post subject: Re: New AR Build!

Quote::

I think i posted earlier that I hit the throat with al ittle JB paste and gave the barrel a few licks while I was in there and...... I took it out and shot 40 rounds through it! Cleaned it saw how easy it cleaned and smiled. Saw how good it shot and smiled more.

Now you know my secret...The less I stcik a rod and jag in my barrel the better off it is.

fnuser · Posted: Mon Nov 29, 2010 6:57 pm Post subject: Re: New AR Build!

got all my components assembled for my 6.8 but guess what I forgot, the little roll pin that holds the gas tube in the block. oh well that was going to be way to easy. Went ahead and ordered some ammo midway had S.S.A. 115 gamekings under $20. Anybody reloaded their brass before?

slimjim · Posted: Mon Nov 29, 2010 7:25 pm Post subject: Re: New AR Build!

fnuser wrote:

guess what I forgot, the little roll pin that holds the gas tube in the block.

If you get anxious to shoot it, just install the gas block so it is oriented to block the port, e.g., install it 45 degrees off axis. Then shoot it like a straight pull bolt action.

slimjim · Posted: Mon Nov 29, 2010 7:25 pm Post subject: Re: New AR Build!

fnuser wrote:

guess what I forgot, the little roll pin that holds the gas tube in the block.

If you get anxious to shoot it, just install the gas block so it is oriented to block the port, e.g., install it 45 degrees off axis. Then shoot it like a straight pull bolt action.

slimjim · Posted: Fri Dec 10, 2010 7:07 pm Post subject: Re: New AR Build!

Stopped at the range today on the way home from hunting. Temp was 68 degrees with variable winds 5 to 12 mph from right rear shoulder to left rear shoulder. I had worked the OCW for 69gr & 77gr Sierra Match King with Varget and I was confident in the new loads I selected so I skipped the 100 and 200 yard ranges and went to 300. I dialed in 15 clicks per the ballistic table and let loose. Both bullets did well but I've found what the rifle likes. 77gr SMK and Laupa brass! Here are my groups from today's range time. Did I say this was 300 yards!

Thanks for all the tips Dawgdad!!