Problem Child: Does good upper and lower receiver exist for 6.5Cm in Ar-10

[200mfromocean]

I built a gibbz arms upper and lower ar-10 side charger a few years ago. I could never rely on it no matter matter how much more money I threw at it and how clean it was maintained. I also had difficulty trusting the aero precision uppper and lower witth same 24" lilja barrel and 20" pencil barrel, while my old old 24" RPR runs circles around it. One issue issue is that the it feeds to low. Magpuls sit higher and run the best on most of my ar-10.

Anyway is there a suitable ar-10 upper and lower for 6.5 CM? My objective is a field rifle with dust cover and forward assist that will run hunting bullets.

 

[Hecouldgoalltheway]

Well hmmmm. Let me start by saying what nobody else wants to be the first to say:


Your previous uppers and lowers had zero to do with your issues. You had gas system or feed issues.

If you want to buy one that will always feed and never cause an issue, buy an LMT, a Geissle, a pof, or a DD. Then you won't have to do anything but shoot it. But, if you want to do it on a budget, the upper/lower are about the least impactful part of the system.

 

[M4orturnate]

⬆this

 

[redneckbmxer24]

Buy a Seekins or LMT. Done.

 

[Precision Underground]

I built ours on a Mega Maten set and would trust it with my life any day. But as someone else said, it’s very likely a gas system issue not a receiver issue.

 

[Hardholder439]

You haven't supplied nearly enough info for anyone to actually help you although I 100% agree it is not your receivers.

My first build was Aero Upper and lower, Criterion 20" .308 barrel, rifle length gas system, pre-assembled CA compliant carbine lower, Geissele trigger and SLR adjustable gas block. Failures to feed and eject right out of the gate. Re-positioned the gas block one way and it got worse. A little back past the starting point and it was better but not right. Tapped it back approximately .015" and it's been reliable ever since. Barrel and bolt purchased through Fulton Armory so they checked headspace.

2nd build was on Aero upper and lower, Krieger 6.5 Creedmoor 26" barrel, rifle length gas system, JP high pressure bolt (a must), heavy buffer, Tubb recoil spring, Geissele trigger, SLR adjustable gas block and a cheap ($400 Primary Arms scope) I nailed the gas block positioning and the rifle shoots sub 1/2 MOA with Hornady 140 grn ELD match ammo. 100% reliability. The only issue, if you can call it that was the headspace with my barrel bolt combination was SAAMI minimum. My go gauge would not go. When checked, the go gauge was over SAAMI minimum by .002" as measured with an RCBS Precision Mic. To trouble shoot the issue, I tried chambering 20 rounds of Hornady factory 140 grn ELD match ammo. Cartridges that chambered were SAAMI minimum or less. Anything over and the bolt would not close. This was checked with the barrel off and the bolt disassembled.

More info would help others help you.

 

[200mfromocean]

I had issues with 6.5 CM also with Aero upper and lower, I switched it to 308 BA barrel and 3/4 or better with 150 hndy interlock or similar weight ammo.

The current one(gibbz upper and lower) has JPI bolt, special recoil spring, adjustable gas block. I had trouble getting bolt to close and got light hammer strikes with S&B 129 softpoint which my RPR loves.

Anyhow I will probably go with one of the aforementioned upper and lowers that were suggested. IF any of them work well with Lancer AR-10 mags that would be great. Problem wiith lanser ar-10 mags is they sit a little lower than magpul. Yes, I have tried with magpul.

 

[GUNNER10]

I've built up a couple really nice 308 AR's in the past and while they were both great, one had a Krieger, one had a Noveske, I have gotten away from doing builds as its really not hard to find the configuration that you are looking for out of a factory gun and generally speaking there are less issues that can be associated with tolerance stacking from all the different manufactures.

I've been shooting LMT MWS and have zero issues. I picked up a factory 6.5cm barrel for it a couple years back and it shoots really close to my old krieger.

 

[Jigstick]

Buy a Seekins builder set

 

[RUTGERS95]

sounds like someone thought you could just slap various parts together, ala ar15, and thought they could get a reliable 308........

sell it off, buy LMT, have fun

 

[wade2big]

Buy a Seekins builder set

Those haven’t been a available for a couple years now. Is Seekins selling the SP10 sets again?

 

[Clayman]

Anyway is there a suitable ar-10 upper and lower for 6.5 CM? My objective is a field rifle with dust cover and forward assist that will run hunting bullets.

My Zev tech billet set has a phenomenal fit and finish. Would highly recommend. It's paired with a proof research barrel and jp fmos enhanced bcg.

22" rifle +2 gas length, slr sentry adjustable gas block.

Sig 140gr otm

 

[mrtoyz]

Seekins or LMT. As good as it gets.

 

[Jsp556]

I had a matrix set that the mag catch was too high and caused feeding issues.

 

[lte82]

My Zev tech billet set has a phenomenal fit and finish. Would highly recommend. It's paired with a proof research barrel and jp fmos enhanced bcg.

22" rifle +2 gas length, slr sentry adjustable gas block.

Sig 140gr otm

The Rifle +2” is where it’s at when using slower powders for 6.5mm or 6mm. When AR10s were (briefly) getting popular for high power competition, guys were doing +3” or even +4” with the 243 win and longer 26” barrels.

 

[solson]

Those haven’t been a available for a couple years now. Is Seekins selling the SP10 sets again?

They are currently listed on their site as a backorder option, no info as to how long to fulfill that I'm seeing, but they are letting you place the order. I checked a few months back and it was listed as out of stock, so progress I guess.

 

[HerCoStarNTheBeaverPictur]

I built on roam receivers and have had zero issues but I agree with above, the receivers are very likely not your problem

 

[200mfromocean]

I’ll probably get in line for seekins builder set given all the fancy parts already, ie jp bch & silent capture sping etc. My existing gibbz set must begeared for 308. Thr angle is likrly too low to feed many of the 6.5 bullets. On my last trip the bolt would not fully close on first round. I have about 1000 edx 143 projectiles and a big pile of cleaned brass.

 

[Hardholder439]

I’ll probably get in line for seekins builder set given all the fancy parts already, ie jp bch & silent capture sping etc. My existing gibbz set must begeared for 308. Thr angle is likrly too low to feed many of the 6.5 bullets. On my last trip the bolt would not fully close on first round. I have about 1000 edx 143 projectiles and a big pile of cleaned brass.

Bolt would not fully close on the first round. Did you check headspace with a go gauge prior to assembly? What was the headspace measurement on the cartridge that would not chamber? (Revisit my earlier post) The receiver isn't the issue. You are looking in the wrong place. Failure to feed, the cartridge isn't making it into the chamber. Bolt not closing is a different issue. Which is it?

 

[Huskydriver]

Let's see... As far as receivers go decide if you want dpms or Sr25 cut.

If you want a fa, that will limit your Sr25 cut options down but there are some good ones.

+2 gas system is the easy button esp with a agb.

Sfp bolt

You are in business

 

[200mfromocean]

Bolt would not fully close on the first round. Did you check headspace with a go gauge prior to assembly? What was the headspace measurement on the cartridge that would not chamber? (Revisit my earlier post) The receiver isn't the issue. You are looking in the wrong place. Failure to feed, the cartridge isn't making it into the chamber. Bolt not closing is a different issue. Which is it?

No, I did not check headspace with a go gauge. I was always getting scratched bullets when feeding. I’ll have to post a pic. The last one whom took a look at the issue said the magazine is not coming high enough when seated. This is a 6.5 CM barrel. Maybe its an issue with bolt and or install. Had a similar issue with lilja pencil barrel (cant remember receiver) where hornady factory ammuntion was getting stuck in chamber, and when i pulled bolt back gunpowder would fall back all over.