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Mega MaTen, JP, 6.5 Creedmoor build done

BgBmBoo

Gunny Sergeant
Supporter
Full Member
Minuteman
Well I decided to put together the Mega Maten upper/lower set I had laying around. But I was not interested at all in a .308...after years of shooting slippery, high BC, "hot rod" cartridges. The .308 is just a turd to me...sorry .308 fans.

I was on the fence about a .260, 6CM, or 6.5CM. I ruled out the .260 for a few reasons, but mainly due to having to seat the long heavy bullets deep in the case to get them to fit in a mag.

Next was the 6Cm, and I was/am excited about that chambering, but GAP has a pretty long lead time on a barrel and bolt.

So...a few phone calls later to my buddies at JP Enterprises and my credit card had me a 22" bolt & barrel kit, 15 1/2" handguard, low mass bolt carrier, and a silent capture op spring. About 12 days from order to at my door.

Next came a trigger. Went with a AR Gold two stage. I have had good luck with them in my AR's, so figured go with what ya know.

Stock is a Magpul PRS and grip is a Ergo.

Slapped it all together and screwed the barrel on today. Topped it off with a Bushnell HDMR G2 in a JP 24mm base...time to hit the range!

So after a bunch of delays I made it out to the range around 3:00 and got setup.
I had a few boxes of Hornady 140gr Amax's. And after three shots to get zeroed I shot a few 5 shot groups at 100 yards.

Right away I could tell this rig wanted to shoot. First five shots were about 3/4".
The rifle was cycling very harshly and the bass was getting dents in the side from being slammed into the brass deflector. So I started cutting back the gas (adjustable gas block). It was very obvious it was WAY over gassed.
Another 5-6 rounds and I had it dialed I thought. Musc smoother cycling and less violent cycling. No more dents in the cases. Oh...and I was getting a avg. of 2675 FPS according to my cheapy chronograph.

I shot another five shot group and that yielded about 1/2" group. Pretty darn good for factory ammo and less then 25 rounds behind a new rifle.

Well with that out of the way time to stretch its legs. Went out to 600 yards. 4.3 mils had me nailing a 12" gong round after round....boring!

Dialed in 10 mils and lined up on the 1000 yard steel. First shot high and 3 1/2" mils right....oh...look at the wind flag. Winds moving pretty good out there.
Came down to 9 mils and held 3 1/2 mils into the wind....boom......ping. Let 4 more go and had no problem hammering the gong.

Loaded up another 5 rounds and let my 16 y.o. son take turn. He was able to keep 3 out of five on the steel.

I did have to open the gas up a bit. I think once some carbon built up it needed a bit more. It failed to lock the bolt open a couple of times.
Seems to be where it wants to be now. one thing...this rig is VERY sensitive to the adjustable gas block. And in the wide open position how it shipped, was waaaayyyy over gassed. Have I ever mentioned I will never own a AR type rifle without a adjustable block!?!?

Anyways....a few "peeves". One the JP bolt carrier is not notched for the dust cover detent. So I can not close the dust cover. Not a big deal but worth mentioning.
Next while DPMS mags fit and work flawlessly so far, I have two A.S.C mags that will not fit into the rifle. Which kinda sucks as they have more "room" in them so you could seat bullets a little longer. The DPMS ones has the tip of the Amax's right against the front of the mag.

Other then that...a fun rifle and round so far. I would have included pics of my 100 yard groups, but I forgot them on the target stand....

Take care,Stan













 
Re: Mega MaTen, JP, 6.5 Creedmoor build done

Beautiful set up. I have been dreaming of something eerily similar. How does the low mass BCG and silent spring feel? Does it greatly reduce recoil or hardly noticeable?
 
Re: Mega MaTen, JP, 6.5 Creedmoor build done

Nice rifle! I just built almost the same thing. Mine has a 22" and a Geissele in it though. I almost went with the jp.

IMG016_zpsf7a199a1.jpg
 
Re: Mega MaTen, JP, 6.5 Creedmoor build done

Nicely done Stan! It's good to know where my money is going next. I'll have to check it out next time you shoot, let me know.

Darin
 
Re: Mega MaTen, JP, 6.5 Creedmoor build done

Nice rifle. I just built one with all the same components except a Geissele national match trigger and Atlas bipod. Shopping for a scope but really holding out for the new upcoming HDMR2. My thunderbeast 30P-1 is at my dealer and paperwork has been submitted. Hoping to have both these items before spring of next year.
Glad to hear yours shoots well, hopefully mine wiill too.
 
Re: Mega MaTen, JP, 6.5 Creedmoor build done

Thanks folks.

MP...I have used the JP low mass operating system in almost all my AR's. I have one of the silent capture springs in a 14 1/2" AR and now with this build I would recommenced them.
They run very smooth and...well...silent!

Yep...hope to make the next shoot Darin. Just need to get some ammo together. Might have to shoot the factory stuff until I get the dies and bullets in.

Post up with pics and range report when you get it finished Wolf.

Marm...I had this HDMR on hand so I figured I should use it. I too am looking forward to the new Bushy products.
I have a 18" JP CTR-02 that needs some glass and am thinking one of there new 1-8X scopes would be just right for it.

Take care,Stan
 
Re: Mega MaTen, JP, 6.5 Creedmoor build done

Very nice sir. 6.5 CM is pretty cool round, it seems as if they are breeding around here. I started with one... now, my son has a TRG in 6.5, I have a Surgeon and an AI, and built a AR.

I took a garden variety AR10T, bought a GAP barrel and bolt for it, went thru a couple fore-ends till I found one I liked, that of course isn't available often, Badger. The thing shoots great, except for two small itty bitty issues.

Like yours, it is way overgassed. I mean WAY over. It rips the top out of the sheet metal mag follower in the stock mags, on an empty mag. And first round is usually not in the group with the rest of the mag, and I am thinking the bolt isn't seating the same from hand as from the cycling. Suppressed, it was even worse, although a ball to shoot.

As such, it has sat in the safe for a few months, as I never remember to order the adjustable gas block. I just got two in this week, one for this rifle and an extra for just in case. I'll report back after changing the block out, how it shoots.

Like that JP stuff, pretty nice parts! Great customer service there too.
 
Re: Mega MaTen, JP, 6.5 Creedmoor build done

Hi Mike.
The adjustable gas block will make a HUGE difference. Like I stated above, before I adjusted this one the cycling was very violent and harsh. I would guess with the can on yours that it has to be even worse.
I ended up with the adjustment screw almost all the way in (gas almost off).

It now runs VERY smooth with a very "linear feel" to it.

I have owned a large number of JP AR-15 upper based builds and got very spoiled by the adjustable block. I will never own a AR style rifle without one.

Take care,Stan
 
Re: Mega MaTen, JP, 6.5 Creedmoor build done

I was about to pull the trigger on a JP barrel, but did not really get any feedback on performance...I ended up having APA build me one.

Man, if I would have known how these barrels would shoot, I would have opted to go this route

Nice build
 
Re: Mega MaTen, JP, 6.5 Creedmoor build done

If your ever wanting feedback on JP products you will have much better luck (and feedback) on the three gun forums.
I have owned A LOT of JP products and with no disappointments. Their barrels are no exception. Plus I really like their barrel profiles (light(er) weight) and the heat sinks....they stay much cooler and cool faster then bull barrels.

Take care,Stan
 
Re: Mega MaTen, JP, 6.5 Creedmoor build done

Nice looking rifle. Didn't know the JP BCG did not allow for the dust cover to be closed.
 
Re: Mega MaTen, JP, 6.5 Creedmoor build done

The JP bolt carrier is designed for their LRP-07 (large frame AR) that has no dust cover and so it (the JP bolt carrier) has no "notches" or cutout for the dust cover detent. I could just replace the bolt carrier with a DPMS,etc, if it bothered me that much.
But I like the low mass carrier so I will use it and not worry about the dust cover.