Babies first AR build finished (260 Rem) *first range report*

[nuclear_shooter]

Just finished putting together my first AR build! Basically a JP 260 barrel on a MKM MATEN. Here are some pics of the build:









And here is a really crappy picture of the finished product. Bipod mount is still in the mail, and its dark it my apartment.



I'd like to thank all the great guys on the forum, I couldn't have done it without you guys! Special thanks to ORD and BusterB for helping keep picking some of the components. Unfortunately, this is a really busy two weeks for me so I don't think I'll be able to get out and shoot it until nearer the end of March.

Edit: figured I'd add it weights 13.4 lbs with scope and empty mag.

 

[LRRPF52]

Very slick build. That Mega MKM is a clean, excellent evolution of upper receiver and handguard interface for the Stoner system.

What charge handle are you thinking about? BCM large latch or a Raptor should go well with this fire stick. Do you have brass, bullets, powder, and dies? Any loads planned for it?

.260 Rem is a great cartridge. I like the 130gr going just over 2800fps, VLD's and Norma GT's. Also shoots 139gr Scenars and 142gr SMK's well, but I have a Bartlein barrel.

 

[nuclear_shooter]

Very slick build. That Mega MKM is a clean, excellent evolution of upper receiver and handguard interface for the Stoner system.

What charge handle are you thinking about? BCM large latch or a Raptor should go well with this fire stick. Do you have brass, bullets, powder, and dies? Any loads planned for it?

.260 Rem is a great cartridge. I like the 130gr going just over 2800fps, VLD's and Norma GT's. Also shoots 139gr Scenars and 142gr SMK's well, but I have a Bartlein barrel.

Thanks, I'm really happy with the way it came out so far. I just ordered the BCM Mod3 for this one. I have one on my AR-15 as well, and like it a lot. With that huge SWFA SS ocular housing, its almost impossible to grip the handle.

As for loads, I'm not sure yet. I got 100 pc of Lapua brass and some 140 gr AMAX's but I have read some people have issues with the heavier bullets in semiautos. Only suitable powder I could find was RL-17. I also have some 123 Scenars on the way. I will probably try some 140s in some once fired brass a friend gave me. I normally try to stay away from the VLD bullets because they like to be crammed into the lands (or close to it). I will probably post on the reloading forum soon about this more specifically.

 

[eclipse57]

That is an exceptionally nice looking rifle.

I don't shoot the 260, so I hope you post a range report here so I can see how it shot for you and how you like it.

The BCM mod3 is the way to go as you obviously well know.

Enjoy!

 

[nuclear_shooter]

That is an exceptionally nice looking rifle.

I don't shoot the 260, so I hope you post a range report here so I can see how it shot for you and how you like it.

The BCM mod3 is the way to go as you obviously well know.

Enjoy!

Will definitely post results, but don't hold your breath. I've got a big meeting next week and then spring break. Expect to shoot her around mid March.

 

[FALex]

Did you run the JP LMOS BCG by chance?

 

[nuclear_shooter]

Did you run the JP LMOS BCG by chance?

Nope, quite the opposite. Got a DPMS BCG with a Slash's 10oz buffer.

 

[hlee]

You may want to put your level to the rear of the paralax knob so that you can see it from behind the rifle...

 

[nuclear_shooter]

You may want to put your level to the rear of the paralax knob so that you can see it from behind the rifle...

Had it this way on my 700 and it worked fine. Its actually held above the knob so you can still see it. I like having it far forward because when I shoot with my normal glasses its harder to focus on when its closer.

 

[LRRPF52]

I had my .260 Rem chamber cut by GA Precision, and they know what they are doing when it comes to gas guns and accuracy with this caliber. Jeff asked me what bullets I was planning on shooting, and I told him the 139gr Scenar. It shoots that bullet so well, I am tickled, but it also shoots the 142gr SMK just as well in the first set of load development I did with both of them.

It also shoots the 130gr VLD the same, which is my favorite bullet with it. The 130 VLD beats the 140's for me for drop and drift at 1000yds, because of speed, and the BC's are pretty close. I like the 22" .260 Rem AR10/130gr VLD combination a lot. It's a lazer with very fast follow-up. I use it to shoot 4"x4" explosive targets when we do the demo for the precision rifle clinic up at BoomerShoot each year, and it's literally fun to just ride the gun as you index it on target after target at 400yds and make them detonate as fast as your skills will let you push yourself.

It's kinda boring shooting IPSC sils with it, unless you put them way out there.

 

[nuclear_shooter]

I had my .260 Rem chamber cut by GA Precision, and they know what they are doing when it comes to gas guns and accuracy with this caliber. Jeff asked me what bullets I was planning on shooting, and I told him the 139gr Scenar. It shoots that bullet so well, I am tickled, but it also shoots the 142gr SMK just as well in the first set of load development I did with both of them.

It also shoots the 130gr VLD the same, which is my favorite bullet with it. The 130 VLD beats the 140's for me for drop and drift at 1000yds, because of speed, and the BC's are pretty close. I like the 22" .260 Rem AR10/130gr VLD combination a lot. It's a lazer with very fast follow-up. I use it to shoot 4"x4" explosive targets when we do the demo for the precision rifle clinic up at BoomerShoot each year, and it's literally fun to just ride the gun as you index it on target after target at 400yds and make them detonate as fast as your skills will let you push yourself.

It's kinda boring shooting IPSC sils with it, unless you put them way out there.

How far do you jump those 130s?

 

[FALex]

How far do you jump those 130s?

+1 on that...I am running the 139 Scenars at 2700 out of my LRP-07. Scenars don't seem to mind a jump. Curious to shoot something like a 123 out of it also, but the Scenars run really well.

 

[nuclear_shooter]

+1 on that...I am running the 139 Scenars at 2700 out of my LRP-07. Scenars don't seem to mind a jump. Curious to shoot something like a 123 out of it also, but the Scenars run really well.

Interesting. Heard some of the gap guys saying the 140's were causing issues (burst primers, loose primer pockets after one shot). Interesting to see that you don't have that issue. What powder?

 

[FALex]

Well, mind you, these are 139 Scenars and are not jammed (like VLD's need). I get loose pockets on my brass after 2 loads shooting 140's out of my bolt, but I jam them.

To answer your question, I am running 41.5 H4350.

 

[nuclear_shooter]

Cool, I believe the issues were with 142 SMK and 140 AMAX's which probably weren't jammed. Full thread here: http://www.snipershide.com/shooting/snipers-hide-reloading/238509-gap-10-260-blowing-primers.html He blames the primer hole on the DPMS BCG, but I'm pretty sure the JP bolts have the same hole.

 

[nuclear_shooter]

I finally got to take this beast out today and shoot it! I loaded up 40 rounds with a (light) 40 gr RL-17 and 123 scenars. After getting the gas adjusted and zerod I shot a few 5 shot groups. I'm really pleased with the results so far. I shot a .8" group with horizontal stringing (I had full adrenalin going from the excitement and wasn't doing the best trigger control) and my friend and much more experienced shooter shot a .5" group. We were battling some pretty heavy headwinds which were physically moving the targets making shooting groups hard, but without any load development I'm very pleased! I didn't get to chrono these (again, wind) but my next step will be an OCW. If quickload is right these were somewhere around 2750, which for a 123 is pretty light. Hoping for something more like 2900.

 

[LRRPF52]

How far do you jump those 130s?

I load them to 2.805" COL IIRC. My throat is cut for VLD's & the Scenar loaded to mag length for a gasser. Berger also updated their findings on jump with the straight VLD"s a number of years ago, and basically said there are several seating depth nodes that are rather large increments. You can have some jump with VLD's and still get accuracy, but you just have to find the seating depth node.

Another issue with VLD's is manufacturing variance in the ogive, since the radius is so long and hard to keep consistent, even for the best bullet makers. That said, my very first time shooting the .260 Rem with 130gr VLD's at 1000yds gave me a 9.25" group, with a purposely ignored wind speed change. I was aiming at a boiling bullseye with a Vortex 2.5-10x44 PST while laying in the bed of our truck, off a bipod and rear bag. Instead of holding into the wind more for my 3rd shot, I used the same aiming point, as I had no clue if I was even hitting the target.

When I drove out to see the results, I'll be darned if I didn't have a 9.25" group, with the first two rounds within 4.5" of each other. The trajectory at 1000yds was still very flat, as I used a cardboard box for a crib mattress to see the entry and exit. There was no more than 10 degrees of angle on the terminal trajectory at that range, which was freaking scary compared to .308 Winchester.