bld451 Posted May 15, 2017 Report Share Posted May 15, 2017 One of my hunting buddies was wanting a "little more" than his 300 blackout would give with a 150 grain bullet and we started tossing around ideas. He wanted 30 cal but didn't want to go AR-10. There are several options, but each has their issue. One uses a proprietary case and loaded ammo is available, but costs about $1.50 each. Standard 7.62x39 seems to have some feeding issues and a fairly sparse selection of good hunting bullets. Wilson has one that seems to beat the blackout, but not by much, and the ammo cost is an issue again (this will sound funny later). There are several wildcats that have been used successfully, but we didn't want to trim, size, blow out shoulders, etc and then load a .25C bullet to fireform, etc. I suggested a 7.62x39 Ackley improved, and kind of chuckled inside. Well, in talking over the Ackley treatment with him, I started to convince myself that it might actually be a good fit for an AR15. As it turns out, he thought so too. Able to fire readily available and cheap (for now, at least) ammo which you could reload to somewhat better performance, shoot a great variety of .308 cal bullets in a .308 bore, case stretch would be greatly reduced (no trimming for a while), new body taper feeds great out of available and cheap Grendel and standard 7.62x39 magazines, body taper reduces bolt thrust and wear on the weaker bolt, new reamer cleans up 300 BLK chambers. We had to investigate. I felt funny re-visiting this, as the russian cartridge has been one of the most altered cases in shooting history, and what we were going to do was old news. However, there was not a whole lot on the web about anyone using it in an AR.... so..... We came up with a design, ordered a reamer and we're off! Well, we found ourselves in the shop a couple weeks ago Saturday chambering the second rifle and prepping for a range day with our new 308x39 American AR's. I guess we were really just itching for a project. (slightly more expensive than a LOT of Grendel or Arrow brass...) As it turns out, I think it will be as good as we were hoping it would be. We had an issue with small gas port size on the rifle, and ended up single loading it to fire factory x39 ammo, but accuracy was as good as the original chamber (2" at 100) and we only lost about 60 FPS fireforming. The carbine was a little overgassed as it was a blackout in its previous life and had a big port in the carbine location, but it worked great! Even with the blunt round nose soft point PPU brass case ammo, it fed from C-products 7.62x39 30 rd magazines over 90%. We don't have dies yet, so I made a neck sizer and we took loading gear to the range so we could at least fire some reloads. We don't have the ideal barrel yet to really wring it out, but I think we are looking at 2600 easily with a 125 from a 20" barrel. Pretty fun project. We may yet find out why this hasn't been a "thing"........ Don't know 'til you try. Quote Link to comment Share on other sites More sharing options...
bld451 Posted May 15, 2017 Author Report Share Posted May 15, 2017 Sorry, the title should have said "our stab at a short 30 cal AR15". Apologies if you were looking for 308 Win info...... Quote Link to comment Share on other sites More sharing options...
98Z5V Posted May 15, 2017 Report Share Posted May 15, 2017 Very cool. Quote Link to comment Share on other sites More sharing options...
Robocop1051 Posted May 15, 2017 Report Share Posted May 15, 2017 Let me try to find some source material... i met a guy who actually has a .308x39 chambered barrel, and he hand loads brass x39 casings with .308 projectiles. To my recollection, he's getting 1MOA or better. Ill find my info and bring it back here. Quote Link to comment Share on other sites More sharing options...
Matt.Cross Posted May 15, 2017 Report Share Posted May 15, 2017 I like it!!! Quote Link to comment Share on other sites More sharing options...
Sisco Posted May 15, 2017 Report Share Posted May 15, 2017 Be careful, the military is reportedly looking for a larger cartridge so you never know where this may lead. Seriously, a great project. I always wondered why more research into the advantages of 7.62x39 and into fixing it's disadvantages hasn't been done in the U.S.. Keep us informed! Quote Link to comment Share on other sites More sharing options...
Robocop1051 Posted May 15, 2017 Report Share Posted May 15, 2017 So reading up... I guess it doesn't matter much. a .308 proj in a Russian SAAMI barrel (and vise versa) might only be off by .001 in actual measurement. It looks like POF and Faxon are already prepping for this by making all their barrels slightly undersized. Giving optimal performance to SAAMI cartridges, and damn good performance on .308x39 hand loads. Quote Link to comment Share on other sites More sharing options...
Robocop1051 Posted May 15, 2017 Report Share Posted May 15, 2017 I also remember an old member loading Sierra 125gr flat bottom proj's and getting nearly 2600 fps in his 300Blk. I'm pretty sure Hornady makes one too. Quote Link to comment Share on other sites More sharing options...
Robocop1051 Posted May 15, 2017 Report Share Posted May 15, 2017 I miss having @Jgun around. He was a smart guy. (This is for 300Blk, but the concept is similar) Quote Link to comment Share on other sites More sharing options...
bld451 Posted May 16, 2017 Author Report Share Posted May 16, 2017 Thanks for the replies. I hope Jgun is still doing his thing. I understand stepping away. Did the same a while back from a couple other forums. 2600 from a B.O. with a 125 is pretty good. He talked about extractor marks. I would have liked to see some of that brass. "extractor marks" sometimes means you are yielding your brass. You've got to be careful up there.... We're not going to load to 60K PSI+ sike some do with Lapua brass and the like. I am fairly confident we can get good velocity at 50-55k. Given the large rifle primers and factory x39 brass from various makers, we'll keep it reasonable. We should know more in a week or two. Barrel blanks coming this week. Quote Link to comment Share on other sites More sharing options...
bld451 Posted June 1, 2017 Author Report Share Posted June 1, 2017 Got to do a little testing Monday AM with the new 24" barrel. .308 caliber with .111 port at the rifle position. We are likely going to end up with a 20" but wanted to see real numbers on the chrony, and since the blank was a 25", why not. Hopefully soon we will have apples to apples comparisons with 24, 22, 20, 18 and 16 lengths with same loads. We're thinking we might only lose maybe 10-15 fps per inch when we start cutting the barrel. The .111 port was still a little small in the longer gas system, but it's getting there. Going slow with opening the port. We need to balance the need to cycle the factory ammo that will have lower pressures because of the chamber size and the desire not to over-gas the higher pressure reloads. I tested a limited number of loads because there was limited time to prep and only an hour or so to shoot. RL-7 and H335 were the powders loaded for this trip. I'm not going to publish charge weights at this point, but velocities were decent without any signs of pressure and half shot 2" or better. Might be more room to work, but I need to spend a little more time with it. These were averages of three shot strings to get an idea, and I hope to be a little more deliberate for accuracy next time. I apologize for the abbreviated data, but it's what I have right now. 110 Nosler Varmageddon w/ H335 = 2635 FPS avg next to least accurate load (2-4") 150 Sierra Gameking SPBT W/ H335 = 2485 FPS avg least accurate load (3-4") 150 Sierra Gameking SPBT W/ RL-7 = 2500 FPS avg Most accurate load (.75-1.75") 165 Hornady FB SP W/ RL-7 = 2290 FPS avg Second most accurate load (1.5-1.75") Quote Link to comment Share on other sites More sharing options...
98Z5V Posted June 1, 2017 Report Share Posted June 1, 2017 (edited) Be careful on that port - the max you can go is 0.125". That the size of the gas port in the gas block. If you have to take the port diameter beyond that 0.125", then the port in the gas block will have to go up, too - you can get to it through the rearward set screw hole in the set screw gas blocks - you'd lose the threading in that set screw hole, so you'd have to up the size of the set screw, then recut some thread. Not a huge job, but more to do. Another limit you'll have it the hole in the end of the gas tube - that can't go up very far, because of the diameter of the tube... Gas tube material should be 303 stainless, so it's easy to rip it up. I'll get a pic of a gas tube port in a second, and upload it here. Pic coming up - not much to work with here... but there's a little... Edited June 1, 2017 by 98Z5V Quote Link to comment Share on other sites More sharing options...
bld451 Posted June 1, 2017 Author Report Share Posted June 1, 2017 Yeah, I'm hoping it will make it with .125. We may in the end go with the carbine port location for the reasons you mentioned. Carbine port might work better anyway, as it can be used with any length handguard. With this port, two of the reloads locked the slide back, and maybe half the others cycled, so I think we are close. Hopefully .014" or less close.. Either way, we intend to find the right combination that will work 100% with both. We're pretty confident this thing will work as envisioned. Just need to work out the details. We were happy to see 2300 fps with the 165's, and Quickload tells us we can hit 2400 reasonably. That is a pretty nice bonus of this round if it proves true. We are heavy for caliber guys, so were tickled with that. The Nosler long range accubonds and Ballistic tips should expand out to 300-400 yds reliably if their upset velocity specs are accurate. Quote Link to comment Share on other sites More sharing options...
washguy Posted June 1, 2017 Report Share Posted June 1, 2017 (edited) Very Kewl .... me and my buddy have been shooting 762x39 since 1992 from our colt sporter 762"s...and have never had any problems with feeding...we bought a metric $hitload of that Russian ammo that's in the white brick and comes in the wooden case...remember When Clintoris banned the stuff and we have the ammo that was stamped hunting ammo I guess while still in transit....so yeas I know that 762 is min of man and not gonna win any target contests,but my buddy has been on two heli hunts in the last six months using the sporter with that bimetal hunting ammo and the heli pilot who sees all these hi dollar rifles is most impressed by my buddies kills...last month he went and killed 14 hogs and 2 coyotes out of the copter.....he sez that the Roosky ammo rolls those hogs hard....of course he chooses to take his son over me to go heli hunting...well crap! Wash Edited June 1, 2017 by washguy Quote Link to comment Share on other sites More sharing options...
GRA Posted June 1, 2017 Report Share Posted June 1, 2017 20 minutes ago, washguy said: Very Kewl .... me and my buddy have been shooting 762x39 since 1992 from our colt sporter 762"s...and have never had any problems with feeding...we bought a metric $hitload of that Russian ammo that's in the white brick and comes in the wooden case...remember When Clintoris banned the stuff and we have the ammo that was stamped hunting ammo I guess while still in transit....so yeas I know that 762 is min of man and not gonna win any target contests,but my buddy has been on two heli hunts in the last six months using the sporter with that bimetal hunting ammo and the heli pilot who sees all these hi dollar rifles is most impressed by my buddies kills...last month he went and killed 14 hogs and 2 coyotes out of the copter.....he sez that the Roosky ammo rolls those hogs hard....of course he chooses to take his son over me to go heli hunting...well crap! Wash This is definitely something I want to do and I was going to take my 7.62x39 AR when I go. Quote Link to comment Share on other sites More sharing options...
bld451 Posted June 1, 2017 Author Report Share Posted June 1, 2017 That's on my Bucket list. Who are you using for the heli hunts? Do they do half days, or hourly? Probably a half day with the safety briefing, etc....... Fun stuff. Quote Link to comment Share on other sites More sharing options...
Robocop1051 Posted June 1, 2017 Report Share Posted June 1, 2017 I want to build up a badass UTAS XTR-12 for a Heli hunt and launch some wicked Federal flight control (9 pellet) 00 buck at some oinkers!!! That would rain down a hell storm of lead death. I gotta talk to UTAS about sending me an upper. I totally plan to build a 26.1 inch "firearm" with a UTAS upper.... even if I have to leave it at Tom's house (fuk u Cali!!!) Quote Link to comment Share on other sites More sharing options...
washguy Posted June 1, 2017 Report Share Posted June 1, 2017 10 hours ago, bld451 said: That's on my Bucket list. Who are you using for the heli hunts? Do they do half days, or hourly? Probably a half day with the safety briefing, etc....... Fun stuff. Hey Bld I don't know the guys name its all done thru my friend...the guy actually there are two of them tow the choppers to my buddies deer lease where there are like 10 to 15 guys on the two leases owned by the same ranch....well over 10 thousand acres...so its really a neat deal 600 bills an hour split 2 ways is an awesome deal...the safety report goes like this my buddy told me this is the pilots briefing...lol do not touch the controls...if you cause us to crash and we live thru it..I will kill you myself if you shoot the skids its 7 thousand bills ,and you have to buy em in pairs....if you shoot the cockpit glass its over 50 thousand to replace....do not even think about shooting any of the rotors period! okay...lets go kill some stuff ! The pilot plays heavy rock n roll over the headphones while you are killing pigs...my buddy sez the tunes really add to the excitement ! He is going to do another hunt and this time there will be room for me...there better be ! The better hunts are the ones where the trees havnt leafed out yet...theres no where for em to hide Wash Quote Link to comment Share on other sites More sharing options...
98Z5V Posted June 2, 2017 Report Share Posted June 2, 2017 15 hours ago, Robocop1051 said: I totally plan to build a 26.1 inch "firearm" with a UTAS upper.... even if I have to leave it at Tom's house (fuk u Cali!!!) I am completely alright with this plan - you know it will be well cared for, just like one of my own children. Quote Link to comment Share on other sites More sharing options...
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