6.5 Creedmoor Large Frame AR Build Questions

[kentuckyMarksman]

Ok, so I'm putting together my first Large Frame AR. I've assembled numerous AR15s, but I have no large frame AR experience. I've been buying parts, thought I'd get some input on the parts I still need to purchase before making a mistake. So to start off, this is what I have already purchased:

1. ZEV Large Frame billet receiver set
2. 16" ZEV Handguard
3. DPMS Rifle Buffer Tube
4. Magpul PRS Gen3 Stock
5. Geissele SSA-E Trigger
6. Geissele Lower Parts Kit (the receiver set uses a standard AR15 lower parts kit)

Now, these are the parts I'm thinking about purchasing

7. JP Enterprise Low Mass Bolt Carrier
8. JP Enterprise AR-10 Standard Silent Capture Spring Builder Kit
9. JP Enterprise 6.5 Creedmoor 22" barrel w/ +2 gas system - includes headspaced High Pressure Bolt
10. SLR Adjustable Gas Block
11. +2" gas tube
12. Area 419 Hellfire Self Timing Muzzle Brake

I think that covers everything. I'm new to large frame ARs, I think all the above parts will work well together, but I don't have any experience with it. What are your thoughts on the parts above? Would these be good parts to go with?

 

[Jgunner]

I did something similar with 2a zanthos set. All lightweight, jp moving parts, but an ultralight smoke composites stock and handguard. 22” fluted barrel, +2 gas system. I just picked the parts i wanted and it shoots really good for a gasser.




Usually 3/8” at 100 but only gone out to 1208 yards, 6.5x47. Velocity was slow, i need to kick it up. 6.5cm should be a hot ticket with good loads.

 

[kentuckyMarksman]

Great! Thanks for the reply!

I had someone suggest I true the upper receiver. With it being a ZEV billet receiver set, I assume it would be pretty precisely machined as is and wouldn't need truing. I've trued small frame AR uppers with good success. What are your thoughts?

 

[sam4886]

I would do it just for peace of mind.

Your parts list looks great...all high quality stuff.

 

[Flatwater618]

+1 on truing up the receiver...I have found that it almost always helps. With the 2A sets I've noticed that it seems more square, less important I guess with those.

May want to consider a Superlative Arms adjustable gas block also. I have switched over to those and have "perceived" (one of those, I think I feel things) less carbon build up in the receiver and on the bolt with SA's design. Customer feedback has been similar as well. Especially when shooting suppressed if that's a consideration for you...

 

[padom]

Never trued a quality upper. Some do. Results downrange for me say no need.

I would swap that SLR to a Superlative Arms AGB. JP low profile AGB is nice too. And I cant stress enough the JP SCS Heavy builders kit. I've built 20+ 6.5cm gassers. You'll want the heavy and tuned with springs to prevent early unlock so your brass isnt being beat to shit with that JP LMOS carrier.

Other than that, your list looks good. Also, if you're putting this together yourself, you'll need a Geissele reaction rod to install that barrel properly.

 

[Flatwater618]

+1 for the reaction rod...

 

[kentuckyMarksman]

Thanks for the input! Yes, I'm planning on using a Reaction Rod for the install.

I'll look into the Superlative Arms gas block, sounds like it's probably the way to go. Thanks for the tip on the Heavy SCS System.

 

[Jgunner]

I have a master of arms adjustable titanium gas block, i would not buy again, slr gas block on my ar15’s have been phenomenal.

Sergeant of arms uses slr and they make a bunch of accurate gassers, but its for sure an adjustable gas block.

 

[Darqusoull13]

Thanks for the input! Yes, I'm planning on using a Reaction Rod for the install.

I'll look into the Superlative Arms gas block, sounds like it's probably the way to go. Thanks for the tip on the Heavy SCS System.

You might also consider a full JP Barrel Kit. You've already got most of the parts listed and it might be a reasonable option to save a bit buying everything as a package.

 

[Primus]

A quality forged or billet upper shouldn't require facing . MEGA/Zev are good to go but you still want to check just to confirm.

If not, This is an invaluable tool that will fix most issues quickly.

BROWNELLS AR-15/M16 UPPER RECEIVER LAPPING TOOL | Brownells

Cold-rolled steel lapping tool chucks into a 3/8' hand drill to easily “square” the upper receiver face on your AR-15. Helps ensure precise mating of barrel and receiver for added accuracy. Coat face of receiver with aluminum-oxide lapping compoun...

www.brownells.com

 

[kentuckyMarksman]

A quality forged or billet upper shouldn't require facing . MEGA/Zev are good to go but you still want to check just to confirm.

If not, This is an invaluable tool that will fix most issues quickly.

BROWNELLS AR-15/M16 UPPER RECEIVER LAPPING TOOL | Brownells

Cold-rolled steel lapping tool chucks into a 3/8' hand drill to easily “square” the upper receiver face on your AR-15. Helps ensure precise mating of barrel and receiver for added accuracy. Coat face of receiver with aluminum-oxide lapping compoun...

www.brownells.com

Thanks! I actually own that tool for AR15s, but not large frame ARs. I do plan on picking one up for large frame ARs, haven't really looked for one yet though.

 

[Primus]

Also if you don't already have the reaction rod, don't buy it. Brownells sells a similar one you can grind the flats down to put in a vise. I LOVE G stuff, but all of their tools are all a rip off and something similar can be had elsewhere much cheaper. Their tools are rediculously priced. CNC warrior is a good source as well.

 

[rpoL98]

for muzzle brakes, might want to take a look at the Precision Armament M4-72 (7.62 version). pretty effective, and with a 22" barrel, it's far enough forward to not clear off your bench from the blast. The benchmark testing by TTAG compared it with other brakes for recoil effectiveness, comes out pretty good, although that test is dated by now.

I also use the Precision Armament muzzle device shims, available in 5/8" and 1/2".

PTG makes a AR-10 large frame lapping tool.

you could assemble your upper, final torque and everything, and then look to see if your barrel is dead-centered in your handguard. if it isn't perfect (use a ruler with 64ths graduations, or calipers), then you have a candidate for upper receiver face lapping. I lap all of mine, AR-15 and AR-308, just to save me the trouble, and usually lap several stripped uppers in a session to take advantage of setting it all up.

I have the Geissele AR-10 reaction rod, use it frequently, one of my better investments. if you get somebody elses, whatever, don't get one made out of aluminum, the splines that engage the barrel extension lugs just won't hold up with repeated use.

 

[Primus]

The origional was made by KAC for the sr25/sr15 with the proprietary barrel extensions. G ripped off the idea for standard ar15 BEs. Then Brownells ripped off both. They all work the same so grab whatever is in stock and cheapest. I own one of each and use them all.

They all are superior to the other vise blocks that don't support the barrel and you run the risk of shearing the pin or torquing the reciever out of square.

 

[bfoosh006]

Pacific Tool and Gauge makes a great 308 sized lapping tool.

And I still say do it... Lol

You'll spend 30 bucks on ammo and wonder if you should have...

 

[Primus]

PTG has been pretty spotty last couple years can you actually order one and get it shipped in a reasonable time. They are a few hours south of here.

 

[kentuckyMarksman]

PTG has been pretty spotty last couple years can you actually order one and get it shipped in a reasonable time. They are a few hours south of here.

True! I ordered some headspace gauges from them and ended up waiting about 4 months for them to ship...

 

[akg102]

Parts list looks great! Anything beyond what you have listed will be personal preference. I've had both the SLR and SA gas blocks -- they all work.

 

[Pusher591]

Anyone shooting a big frame 6.5 Creed without an adjustable gas block?

My newly built one pierced primers on the only test Ammo I had (Factory Berger 140 Hybrids) but I kind of figured that since it’s pretty hot and I was running a softer buffer set up. 5.6 ounce buffer and JP heavy spring in it now and a few different selections of ammo are up next.

Just curious if anyone has had success running a fixed gas block with FGMM or Hornady 140/143 factory ammo

 

[Flatwater618]

Anyone shooting a big frame 6.5 Creed without an adjustable gas block?

My newly built one pierced primers on the only test Ammo I had (Factory Berger 140 Hybrids) but I kind of figured that since it’s pretty hot and I was running a softer buffer set up. 5.6 ounce buffer and JP heavy spring in it now and a few different selections of ammo are up next.

Just curious if anyone has had success running a fixed gas block with FGMM or Hornady 140/143 factory ammo

Yes...but for $100 put a Superlative Arms gas block on and you can tune it perfectly to whatever load your shooting. They are very durable and reliable...no worries there.

 

[Darqusoull13]

Anyone shooting a big frame 6.5 Creed without an adjustable gas block?

My newly built one pierced primers on the only test Ammo I had (Factory Berger 140 Hybrids) but I kind of figured that since it’s pretty hot and I was running a softer buffer set up. 5.6 ounce buffer and JP heavy spring in it now and a few different selections of ammo are up next.

Just curious if anyone has had success running a fixed gas block with FGMM or Hornady 140/143 factory ammo

Hornady 140 is pretty conservative and has been my preference. With a JP heavy SCS it should be better. However as others mentioned adjustable gas is amazing for really dialing the operating system in to be super smooth and reliable.

 

[broncoaz]

May want to consider a Superlative Arms adjustable gas block also. I have switched over to those and have "perceived" (one of those, I think I feel things) less carbon build up in the receiver and on the bolt with SA's design. Customer feedback has been similar as well. Especially when shooting suppressed if that's a consideration for you...

I don’t understand the benefit of the Superlative Arms AGB venting gas rather than just blocking it like the SLR and others. Either design should be sending the same amount of gas to the BCG, one is venting at the block and the other is sending that gas down the barrel with the rest. I run gas blocks under the handguards, so venting it there seems like it would make things hot and dirty. I have 2 rifles with SLR blocks, but if there’s a proven benefit over the SLR I’m all ears before I build my next one. Cost isn’t an issue, but the threads on other forums seem all over the place on these.

 

[TACC]

A quality forged or billet upper shouldn't require facing . MEGA/Zev are good to go but you still want to check just to confirm.

If not, This is an invaluable tool that will fix most issues quickly.

BROWNELLS AR-15/M16 UPPER RECEIVER LAPPING TOOL | Brownells

Cold-rolled steel lapping tool chucks into a 3/8' hand drill to easily “square” the upper receiver face on your AR-15. Helps ensure precise mating of barrel and receiver for added accuracy. Coat face of receiver with aluminum-oxide lapping compoun...

www.brownells.com

Great info right there

 

[Flatwater618]

I don’t understand the benefit of the Superlative Arms AGB venting gas rather than just blocking it like the SLR and others. Either design should be sending the same amount of gas to the BCG, one is venting at the block and the other is sending that gas down the barrel with the rest. I run gas blocks under the handguards, so venting it there seems like it would make things hot and dirty. I have 2 rifles with SLR blocks, but if there’s a proven benefit over the SLR I’m all ears before I build my next one. Cost isn’t an issue, but the threads on other forums seem all over the place on these.

I don't think there's an issue with either SA or SLR and theoretically I agree with you...bleed off or restricting the gas port shouldn't make that much of a difference. Both SA and SLR are great companies and both produce a robust product.

In my experience (YMMV), I witnessed less fouling with the SA gas block over the SLR. Maybe it's the difference between venting rather than restriction of the gas port? Can't say for sure. But, especially when firing suppressed, there was a marked difference between the two styles with regards to fouling on the BCG and within the upper itself. I've run both on 300BLK, 6.5 Grendel 308 and 6.5 Creed...same result of less fouling with the SA bleed off style. Reliability has been identical between the two, so given I ended up with less fouling I just stuck with SA.

As for the venting, I've never noticed it being substantial to the point that it resulted in a heating up or carbon buildup on the handguard...could be position of where I hold as well, you may have a different experience if you go the SA route but so far they have worked very well for me.

 

[Flatwater618]

Great info right there

+1 for the Brownells lapping tool...

 

[lennyo3034]

I don’t understand the benefit of the Superlative Arms AGB venting gas rather than just blocking it like the SLR and others. Either design should be sending the same amount of gas to the BCG, one is venting at the block and the other is sending that gas down the barrel with the rest. I run gas blocks under the handguards, so venting it there seems like it would make things hot and dirty. I have 2 rifles with SLR blocks, but if there’s a proven benefit over the SLR I’m all ears before I build my next one. Cost isn’t an issue, but the threads on other forums seem all over the place on these.

Not me, just found on YouTube. Essentially he did not see any significant difference other than velocity with the bleed off function vs restriction.

 

[Flatwater618]

Not me, just found on YouTube. Essentially he did not see any significant difference other than velocity with the bleed off function vs restriction.

Good video and explanation, thanks for sharing. Agree 100% a piston system is cleaner for sure.

As for the DI systems...again, just my take based off what I’ve seen, but I felt that there was a greater difference in fouling between the two than what he says in the video with a restrictive setup vs a bleed off system. Could be my old eyes or 1 too many bourbons while cleaning the carrier lol. But I did feel there was enough of a difference to make the change to SA.

In the end, use what your comfortable with, I think either option will serve you well!

 

[kentuckyMarksman]

So I'm planning on ordering a barrel kit from JP Enterprises that includes a adjustable block, gas tube, and muzzle device. Leaning towards the heavy Silent Capture Spring system with the low mass bolt carrier. Does that seem like a good choice? Like I said, I have no large frame AR experience and just want to make sure my parts work together.

 

[Darqusoull13]

So I'm planning on ordering a barrel kit from JP Enterprises that includes a adjustable block, gas tube, and muzzle device. Leaning towards the heavy Silent Capture Spring system with the low mass bolt carrier. Does that seem like a good choice? Like I said, I have no large frame AR experience and just want to make sure my parts work together.

All what I'm running in this JP 6.5 with a compensator. They work quite well in my rifle.

 

[Daherc]

I don’t have too high end of a build, but I am running the SA gas block in mine. It’s pretty nice compared to some of my other adjustable gas blocks. I do not run a high pressure bolt, and I have not had any of the common issues with my primers. I run some rather hot hand loads through mine as well.

I have a billet receiver set from Live Free Armory and I never trued the receiver. Maybe I should have, but I still get 0.26” five shot groups at 100 yards. I’ve also hit 6” gongs at 1,000 yards as well.

I think the parts on your list are going to produce a sweet setup.

What glass are you going with?

 

[kentuckyMarksman]

Thanks for the input!

I have a spare PST Gen2 5-25x that I'm going to put on there for now. I'm thinking I'll eventually put a Razor on there.

 

[padom]

So I'm planning on ordering a barrel kit from JP Enterprises that includes a adjustable block, gas tube, and muzzle device. Leaning towards the heavy Silent Capture Spring system with the low mass bolt carrier. Does that seem like a good choice? Like I said, I have no large frame AR experience and just want to make sure my parts work together.

Great choice. If you want something smaller and effective put a APA Little Bastard break on there. The only other option I would go with outside the JP barrel setup would be a Bartlein from Craddock. Send them your JP or Rubber City High Pressure bolt and have them do a custom Bartlein for you headspaced to your bolt with +2 gas. Other than that, JP is going to be your best off the shelf option.

I don’t have too high end of a build, but I am running the SA gas block in mine. It’s pretty nice compared to some of my other adjustable gas blocks. I do not run a high pressure bolt, and I have not had any of the common issues with my primers. I run some rather hot hand loads through mine as well.

I have a billet receiver set from Live Free Armory and I never trued the receiver. Maybe I should have, but I still get 0.26” five shot groups at 100 yards. I’ve also hit 6” gongs at 1,000 yards as well.

I think the parts on your list are going to produce a sweet setup.

What glass are you going with?

Your gun shoots 1/4moa groups at 100yds? Or you shot one 1/4moa group? That would be the most accurate large frame gasser ever seen....?

 

[Daherc]

Great choice. If you want something smaller and effective put a APA Little Bastard break on there. The only other option I would go with outside the JP barrel setup would be a Bartlein from Craddock. Send them your JP or Rubber City High Pressure bolt and have them do a custom Bartlein for you headspaced to your bolt with +2 gas. Other than that, JP is going to be your best off the shelf option.


Your gun shoots 1/4moa groups at 100yds? Or you shot one 1/4moa group? That would be the most accurate large frame gasser ever seen....?

This is the target. This was during test load development. Also after barrel break in. 130gr ELD-M over H4350. 0.258" group at 100 yards. maybe it was a 4 shot group. I can't remember.

 

[Kango]

I don’t have too high end of a build, but I am running the SA gas block in mine. It’s pretty nice compared to some of my other adjustable gas blocks. I do not run a high pressure bolt, and I have not had any of the common issues with my primers. I run some rather hot hand loads through mine as well.

I have a billet receiver set from Live Free Armory and I never trued the receiver. Maybe I should have, but I still get 0.26” five shot groups at 100 yards. I’ve also hit 6” gongs at 1,000 yards as well.

I think the parts on your list are going to produce a sweet setup.

What glass are you going with?

Are you running the GB on bleed off or restrictive mode? Also what is your buffer/spring setup?

 

[Daherc]

Are you running the GB on bleed off or restrictive mode? Also what is your buffer/spring setup?

I am running my gas block slightly restricted. I am running a carbine spring and buffer in a rifle stock. I bought a spring spacer. I believe it came from Spike's. My 308 rifle buffer and spring would not allow bolt lock back on am empty mag.