7.62x39 AR build

[smee78]

Hey everyone

I'm building a 7.62x39 ARand wanted to see if anyone else out there has one and what there experience with them have been. I will be running a 16" barrel with a carbine gas system and will be putting a scope on it. I'm aware that mags can be somewhat of a problem and I have heard of a few bolts breaking but I'm not to worried about that. I have 2 of the ASC 10 rounders and 2 Frankenmags so that shoud help with that problem. I mainly wanted to use this setup for hunting so anyone out there with info please pass it on.

 

[doofus47]

I have a bushmaster M4/A3 upper that has been mated to both a CavArms lower and a Palmetto State Armory lower. Neither has had an issue with extraction. Feeding is the usual point of pain.

+The mag issue is a common sticking point. I bought extra power springs from Wolff.
+If you plan on shooting lots of steel-cased ammo, you will need to mod your firing pin to allow for a few thousands (.003 to .007) more extension to set off the steel-cased primers. Various companies also sell 7.62x39 specific bolt/firing pin combos. Buy a couple solutions; you might lose an extractor along the way.
+Make sure that whatever upper you get has generous feed ramps.
+I I have a Burris FastFire 3 reflex scope on my upper. It co-witnesses with my fixed A2 sight. The sight height is standard. I'm sure that other red dots would work equally well.

Fun stuff. Tell us how it works out.

 

[smee78]

Thanks Doofus47 for the info, I was afraid that after 200 views that no one was going to share any info. The barrel and upper I am using both have M4 feed ramps so I should be good there, Have you had to do any mods to get your running? I will be reloading so I will mostly be shooting brass ammo so I hope that fixes any FP problems. I will keep thing updated as this build goes on.

 

[doofus47]

I didn't have to do anything dramatic.
I swapped out my hammer spring for a higher power hammer spring from Wolff. That took care of the majority of fail to fire issues when shooting steel cased ammo. I still have a few and I am probably going to swap the bolt to see if that resolves the few that are still failing to ignite. This isn't a battle rifle, but inconsistency does drive me batty. I swapped magazine springs as well.

I took mine deer hunting a few years ago. I plan to again this year, if I draw. The M4 platform with 7.62x39 umph makes a terrific brush gun.

 

[Mobuck]

I had a A2 Colt 7.62x39 upper for several years, then swapped it for a new Olympic flat top 7.62 upper. The magazine issue is easily solved by getting some C-Products mags. FWIW I sold my "frankenmags" to buy C-P mags. I use C-P in both 7.62 and 5.45 cals.
The Colt upper shot best with Remington 125 grain .3095 diameter bullets. The new Oly is a .311 bore so I plan to feed it primarily Hornady .312 V-Max bullets. For best results, make sure you know the bore diameter of your upper. It will save you time and wasted components.

 

[smee78]

Thanks Mobuck, I that is something I will have to check into before I get into reloading for this gun.

 

[smee78]

I think I am going to use the Rock River Arms Operator A2 stock, has anyone used this and how did you like it? I want something that will give a good cheek weld but not be to expensive.

 

[smee78]

Well here it is, after a long wait I finally got it together. My friend had it out at his place and put a few rounds through it, said it felt light and ballanced and feed brass and cheap steel ammo just fine. I cant wait to get it out and put some rounds down range.

P.S. the bore on this one is .311 so any load or bullet info wold be ageat.

 

[Nathan]

Doesn't someone make a lower which uses AK mags? After my research on the subject, I think I would definately use that lower.

No mention of it as a separate piece for sale.

 

[Knight cadet]

I recall seeing an AR lower once that took AK mags. That would seem to be the way to go. I would also think that a gas piston upper would be desirable since so much of the 7.62x39 uses dirty burning powder and DI systems don't do well with that.

 

[tahunua001]

I don't own one but my brother built one. he's snapped the extractor and had to pretty much replace the entire LPK because he went the cheap route. now he'll only shoot brass cased ammo and he claims about the same accuracy as his AK, which I am not impressed with at all. I hope you have better luck with yours.


I am a little odd. I am becoming a huge 6.5mm snob. I am in the process of building a 6.5 grendel which has superior ballistics to any 30 caliber that can fit in the AR15.

 

[Mobuck]

"he's snapped the extractor and had to pretty much replace the entire LPK because he went the cheap route."
I can see how steel cased ammo MIGHT be blamed for a broken extractor but how can the type of ammo get the blame for problems with the lower?

 

[tahunua001]

did I use the words "steel cased" in my post. I was not referencing steel cased ammo in my post although he was using tula at the time of the breakage. the LPK had nothing to do with ammo it had to do with a poorly made LPK.

 

[doofus47]

nice looking firearm, Smee!
Give us some details. Did you have to mod anything or have any special points of pain?

 

[smee78]

This one was a simple bolt together, nothing painful about it. My friend that is playing with it said he was able to zero it in with a few shots and its holding just under a 1/2" at 100yrds with open sights. I'm good with that and that was with cheap steel case (i think Wolf) ammo. I plan to reload with this gun, using Whichester ammo to start with and reloading the brass afterward, I hope if I can get it to stay about where its at I will be happy, the barrel is cut 311 so my bullet selection will be a little limited but I am building this gun for hunting so I dont need tons of different rounds for shooting paper, just one that works well. I was able to keep the cost down on this build, I got a few pieces on sale here and there, the barrel was Advanced ResearchOrdnance barrel, grade 4150 chromium-molybdenum alloy steel and Melonited, it has m4 feedramps and is 16". The bolt is a Palmetto Armory full auto BCG with a model 1 sales x39 bolt, the rest is just parts and pieces (Plametto lpk, upper & lower reciever, RRA front sight,Yankee Hill rear) . The stock is a RRA Operator A2 Stock, I wanted a fixed stock with a good cheek weld for hunting so I splurged a little for this one. I also went with flip up sights so I will be able to run a scope once this one is broke in. I may swap out the fwd grip for something later, this one I just had laying around so I used it. Thanks everyone for the help, mainly Doofus47.

 

[smee78]

I finally got to take my X39 AR out to shoot and man what a blast we had, a bunch of us all got together out at a friends house and had a can/plastic bottle dance, they were moving all over the place. I did not do any bench work to see how tight I could get it to shoot but minute of can was great, I had no miss feeds or mag problems with the ASC (10 & 20 rounders), and I loaded the mags with mixed ammo everything from brass Winchester to steel Wolf and it ate them all with no problems. I really like this gun and thanks to everyone who shared there experiences with it, next step will be to get hunkered down with it and see what I can get with some nice handloads.
Thanks again.

 

[doofus47]

Apparently, yesterday was a National Take-your-7.62-AR-to-the-Range day.
I got out as well. My buddy actually did most of the shooting with it to re-sight the irons and FF3 to 50 yards. It took him about as long as it took me to do the same with my new Adams Arms/shadow ops .223 AR. He had one FTE which I blame on me putting my brass catcher over his ejection port. Once I cleared the port, he ran clean.
He loved it and I only got it back after he ran out of ammo.
We're going to head up to the hills to scare some cans later.
Happy shooting.

 

[tahunua001]

deleted

 

[TMD]

Doesn't someone make a lower which uses AK mags? After my research on the subject, I think I would definately use that lower.



No mention of it as a separate piece for sale.

Sadly RRA only sells this as a complete gun. For the life of my I don't know why they wont sell the lower separately.

 

[smee78]

"For the life of my I don't know why they wont sell the lower separately."


Because they want to sell a complete gun VS a stripped rec.