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View Full Version : Range Report: 7.62x39 SOTA Arms Upper on 80% lower


sharxbyte
05-14-2012, 11:29 PM
Good news and bad news. First the good: IT WORKS :D! Pretty well too. I was getting about 10" groups offhand at ~100(+) yards shooting irons with a standard a2 rear sight (small aperture) and an Armalite a2 gas block mounted front sight with a KNS crosshair sight post. It ate all of the Tula steel case HP I fed it, fed reliably 98% of the time (I think I had 2 fail to feed's early on) A couple or 3 of the rounds needed to be shot twice, but I blame that more on Tula than on the gun. They all went off after the second try. The ASC Mag's are excellent. No double feeding, and it only failed to eject twice (see below)


http://i208.photobucket.com/albums/bb197/mugglle/gunz/Group25yds.jpg

5 shot group @ 25 yards Irons after I finished dialing in.

Had a ton of fun shooting all sorts of stuff on a friend's property (they have a nice pile of junk and we set it up and put orange target stickers to shoot at)

Had a few 25 yd targets for me to get sighted (My buddy's SKS and my brother's AR15 were both already sighted), a helmet on a broomstick and some bottles at 50 and 60 yards, and halfway up the hill we were shooting into, we had 2 toilet seats/lids, a rusted barrel lid on a chair, a knee board (the kind you tow behind boats) and a fan, all with orange target stickers at 100(ish, it was slightly more) yards.


Bad news: After 300ish rounds, the bolt lost some lugs. I sent an email to SOTA requesting a replacement and return shipping provided if they want the broken one back. Fortunately the only part damaged was the bolt, and not the barrel/gasblock/feed ramps/firing pin. At least one of the broken lugs got stuck in such a way that the bolt would not close all the way and It was a pain to remove the upper. Come to think of it, one of the lugs might have broken early on and caused the bolt not to lock open 100% of the time when the magazine was empty. Near the end (When I finally realized something was wrong) I had 2 FTE's in a row, and that was when I noticed the broken lugs (and subsequently when I realized that the bolt wouldn't close)

EDIT: Apperantly this is a problem with 7.62x39 bolts in general, because the bolt face is opened and weakens the web between the lugs. Looking at LMT, Colt, and anyone else who sells bolts that dont have a lot of break reports.

http://www.c3junkie.com/m16/762/all.jpg
^Courtesy of amphibian @ http://www.ak47.net/archive/topic.html?b=3&f=121&t=455539

Will update when I receive a reply to my email.

In the mean time, here's some broken bolt porn:

http://i208.photobucket.com/albums/bb197/mugglle/gunz/IMG_20120514_192211.jpg

http://i208.photobucket.com/albums/bb197/mugglle/gunz/IMG_20120514_192444.jpg

http://i208.photobucket.com/albums/bb197/mugglle/gunz/IMG_20120514_192458.jpg

http://i208.photobucket.com/albums/bb197/mugglle/gunz/IMG_20120514_192722.jpg
Only bad thing here are the little pieces of broken bolt lugs.


So overall, besides the defective bolt, the gun is a lot of fun to shoot, relatively accurate, and seems to be great quality. Did I mention it looks great (http://www.calguns.net/calgunforum/showthread.php?t=560086)?

EvoXRiley
05-15-2012, 8:45 AM
thats a pretty good busted up bolt head. glad nothing worse happened. in the big picture tho, what good a a broken gun after 300 rounds?!

PolishMike
05-15-2012, 8:49 AM
Sorry, but AR's are not suited for 7.62x39.

I'm surprised you are willing to touch ANYTHING from that company after that bolt failed like that. In my opinion your hands and eyeballs are not worth the few dollars you save on ammo.

So in 300 rounds you had:
Failure to Fire
Failure to Feed
Catastrophic malfunction

and you want to keep trying?????

TheExiled
05-15-2012, 9:17 AM
Sounds like that short outing about sums up that setup.. :eek:

NorCalK9.com
05-15-2012, 10:03 AM
Shoulda got an ak!
You wouldnt of had the following probs.
Failure to eject.
Failure to fire.
Or.
Broken teeth.
Btw what are teeth doing in a gun lol

sharxbyte
05-15-2012, 10:05 AM
could have just been a lemon; Others have had good results... Ya I'll keep trying.



Broken teeth.
Btw what are teeth doing in a gun lol

bolt teeth (corrected to "Lugs")

FourLoko
05-15-2012, 10:10 AM
holy crap

I don't even know what bolt is in mine but I should figure out my round count. My 7.62x39 upper still won't feed reliably. After extensive research and testing it's been determined that I need my gas port drilled one size up.

zfields
05-15-2012, 10:11 AM
Yikes, thats one F'd up bolt.

zfields
05-15-2012, 10:12 AM
Sorry, but AR's are not suited for 7.62x39.

I'm surprised you are willing to touch ANYTHING from that company after that bolt failed like that. In my opinion your hands and eyeballs are not worth the few dollars you save on ammo.

So in 300 rounds you had:
Failure to Fire
Failure to Feed
Catastrophic malfunction

and you want to keep trying?????

^ this.

ThemBastards
05-15-2012, 10:42 AM
Sucks to hear... Not to pee on your fire but to keep hope alive in others- my upper still hasn't had any issues 800 rounds in(M1S not Sota Arms). Good luck on your replacement and keep everyone posted on Sota arms' responses.

MUKAK
05-15-2012, 10:48 AM
damm that sucks!! and here I was thinking about getting me a 7.62 upper to play with.. but after seeing this i think i made up my mind on NOT GETTING IT!!!!

AK build Party here i come

Reverend Clint
05-15-2012, 12:12 PM
i hope mine doesnt do that, ordered a barrel and bolt carrier group from them.
how long did it take them to ship?

sharxbyte
05-15-2012, 12:30 PM
took about a week and a half from purchase date and another week and a half to ship, so expect 3ish weeks

winxp_man
05-15-2012, 12:34 PM
I have a buddy that has the 7.62x39 in the same platform. I hope his will be ok. He hasn't fired it yet but we will see. I will let my buddy know about this. Thanks for the post with info.

sharxbyte
05-15-2012, 12:52 PM
Honestly the break looks more like a cheap bolt than something caused by the 7.62x39 round. considering that the rest of the upper isn't visibly marked, and the bolt has that kind of damage, its either a cheap bolt, or a lemon.

PolishMike
05-15-2012, 1:01 PM
Honestly the break looks more like a cheap bolt than something caused by the 7.62x39 round. considering that the rest of the upper isn't visibly marked, and the bolt has that kind of damage, its either a cheap bolt, or a lemon.

Exactly and they will replace it with another cheap bolt that has the potential to INJURE THE SHOOTER.

Why are you even considering this?

sharxbyte
05-15-2012, 1:15 PM
Exactly and they will replace it with another cheap bolt that has the potential to INJURE THE SHOOTER.

Why are you even considering this?

Other than damaging the upper receiver, how would a bolt failure cause the shooter injury? I understand that hypothetically this is a remote possibility with a violent explosion, but from what I've been reading, older bolts have been known to have lugs (I think that's what they are called?) break. Just after a whole lot more wear. Please enlighten me.

http://www.ar15.com/forums/t_3_118/568866_Ever_Break_An_AR15_Bolt_While_Shooting___Ho w_Common_Is_This_.html

PolishMike
05-15-2012, 1:41 PM
Other than damaging the upper receiver, how would a bolt failure cause the shooter injury? I understand that hypothetically this is a remote possibility with a violent explosion, but from what I've been reading, older bolts have been known to have lugs (I think that's what they are called?) break. Just after a whole lot more wear. Please enlighten me.

http://www.ar15.com/forums/t_3_118/568866_Ever_Break_An_AR15_Bolt_While_Shooting___Ho w_Common_Is_This_.html

Well if the bolt is that bad how can you be sure the rest is safe?

SOTA is known for issues.
http://www.ar15.com/mobile/topic.html?b=3&f=4&t=567672
http://www.300blktalk.com/forum/viewtopic.php?f=136&t=79652

There is absolutely a risk of injury. I would not touch their stuff.
You already had one catastrophic failure. There is no way to be confident that in the next 300 rounds whatever breaks stays in the gun.

Edit: And yes, AR bolts are known to shear lugs in the 30-40 THOUSAND round count. Not the first couple hundred.

sharxbyte
05-15-2012, 2:32 PM
Also suggested that they refund the price of the BCG. If that's the only defective part, I can buy another from someone else and hopefully have better results.

ThemBastards
05-15-2012, 2:45 PM
Exactly and they will replace it with another cheap bolt that has the potential to INJURE THE SHOOTER.

Why are you even considering this?

If you have a tire blow out on you do you sell your car?

sharxbyte
05-15-2012, 3:23 PM
Talked to Olympic arms and they sell a complete bolt (supposedly manufactured specifically for 7.62, and reinforced) for $67.60, and a stripped version for $55.90. Working on digging up an LMT lobster claw(tail?) bolt, or a colt, but Colt is closed now, and LMT's have been out of production for a while.

PolishMike
05-15-2012, 3:28 PM
If you have a tire blow out on you do you sell your car?

The bolt is not a tire! It is the engine.

If the engine blows up driving off the lot then YES I DO

deadcoyote
05-15-2012, 3:34 PM
I hate to be another guy peeing in the cheerios here but I would also be fairly hesitant to trust another BCG from the same company that sold you one that basically disintegrated in a few hundred rounds.

sharxbyte
05-15-2012, 3:51 PM
That's why I'm looking into other companies... Unfortunately most of the companies who used to make the bolts that weren't breaking (or people haven' been complaining about, LMT, CMT, Colt) aren't making bolts anymore. Can't find them used at the moment either.

sharxbyte
05-16-2012, 12:20 AM
I just took my upper out and it performed well for about 300 rounds,
when the keyed parts of the bolt broke off. I wasn't abusing the
rifle, just shooting it normally, and all of a sudden I had my first
fail to eject. I popped out the round and removed the magazine, but
was unable to remove the upper the normal way because one of the
teeth from the bolt (the only one I recovered) was stuck near the feed
ramps. Eventually got it out, separated the receivers and removed the
bolt to assess the damage. fortunately the bolt was the only defective
part and the only part damaged. I will attach photographs of the bolt
and damage. I would be happy to ship the defective part back providing
shipping is covered.

The original order details are below.

*******

Of course we will pay shipping. We absolutely would like to get that one back to run some metalurgy on it. That should not happen! You let me know what you would like to do. We can send you a replacement bolt minus the extractor for you to change and keep shooting. We can send you another bolt carrier group. We can do the refund for the BCG. In all cases we would like to get that bolt back though. Let me know what it is that you would like to do.

Thanks
Sota Arms Sales

This is what I received from them. Considering the bad news, its good to know that they are eager (at least on paper) to help, as opposed to hiding, not claiming responsibility, or refusing to replace it. Here was my response:
I would be happy to return the bolt and I understand your eagerness to examine the product. I was researching for more than 5 hours today, and it seems that this is a very common problem among 7.62x39 bolts due to the fact that they have a wider bolt face to accommodate the larger diameter round. This in turn results in less material between the lugs, and in combination with the more severe pressures of the 7.62x39, this can cause breaks. Only two companies seem to have addressed this, and they seem to have stopped producing bolts for this round. I would look into 6.5 Grendel bolts, with less (somewhere in the neighborhood of 11 thousandths of an inch?) Head space. Basically, a redesign of the bolt with stronger material, reinforced at the common break points, and with some stress relief measures. for obvious reasons I can't name brands, but you might get some ideas off Google. "enhanced 7.62x39 bolt ar 15" might help. There are plenty of people looking for replacement bolts for this round, in ar 15. If it can be designed to take the stress demanded of it, a re design would be a well spent investment. Happy customers and all that.

As for me, I would appreciate a replacement bolt, but for the reasons mentioned above, it probably will be nowhere near a permanent fix, and it's likely to happen again. Go ahead and ship the bolt along with replacement postage, and I'll baby it, and send back the broken one minus extractor. I'd also appreciate updates on if and when you pursue my above suggestion for a more permanent solution. Rigorous stress testing is something your clients will most definitely be doing, and it would be ideal to far exceed their expectations.

Have a good evening, and I Hope to hear from you soon

ott1
05-16-2012, 12:53 AM
Probably should've gotten the bolt from AR15Performance. You probably know this already.

http://www.ar15performance.com/inc/sdetail/3255/339

Thicker webbing.

They're currently out of stock. Was told that they may have more mid June.

sharxbyte
05-16-2012, 3:13 PM
Just got an email from LMT, and they apparently have some still in stock... Might be worth picking up a couple. Will update with price per unit

Full Clip
05-16-2012, 5:59 PM
Sorry, but AR's are not suited for 7.62x39.

That comment really doesn't make a lick of sense.
Is 5.56/.223 the only "suited" caliber for an AR?
What about .300 Whisper?
5.45x39mm?
6.5mm Grendel?
9mm?
6.8 mm Remington SPC?
.204 Ruger?
.22 LR?
300 AAC Blackout?
.458 SOCOM
.50 Beowulf?
And the other twentysomething calibers that ARs come in?
Yeah, do away with them all... just because a crap-quality 7.62x39 bolt fails. Must have been the "un-suited" caliber's fault...

FMJBT
05-16-2012, 10:01 PM
That comment really doesn't make a lick of sense.
Is 5.56/.223 the only "suited" caliber for an AR?
What about .300 Whisper?
5.45x39mm?
6.5mm Grendel?
9mm?
6.8 mm Remington SPC?
.204 Ruger?
.22 LR?
300 AAC Blackout?
.458 SOCOM
.50 Beowulf?
And the other twentysomething calibers that ARs come in?
Yeah, do away with them all... just because a crap-quality 7.62x39 bolt fails. Must have been the "un-suited" caliber's fault...

I believe he is refering to the amount of metal that must be removed from the bolt face to accomodate the larger 7.62x39 cartridge base. It's removing metal from directly under the bolt lugs, kind of like chipping away at the foundation of a house, except that the foundation of a house isn't holding back 50,000+ psi of pressure. As the diameter of the cartridge base increases, the safety margin of the bolts ability to reliably hold back all that pressure time after time proportionally decreases.

sharxbyte
05-16-2012, 11:21 PM
Hello
We are quite familiar with those issues on this bolt. We are also familiar with the Grendel. You are correct in the fact that it is head spaced different. The bolt face is moved backward .011. That also helps with the "knife edge" extractor. We have run many many 7.62 bolts and have not seen this. I know it can be a common thing but typically at this point we want to see the metalurgy on it because we should be beyond that catastophic failure.

We'll have another bolt coming your way!

Thanks
Sota Arms Sales

Update

MrPlink
05-17-2012, 12:55 AM
Sorry, but AR's are not suited for 7.62x39.

I'm surprised you are willing to touch ANYTHING from that company after that bolt failed like that. In my opinion your hands and eyeballs are not worth the few dollars you save on ammo.

So in 300 rounds you had:
Failure to Fire
Failure to Feed
Catastrophic malfunction

and you want to keep trying?????

truth

Shoulda got an ak!
You wouldnt of had the following probs.
Failure to eject.
Failure to fire.
Or.
Broken teeth.
Btw what are teeth doing in a gun lol

more truth

PolishMike
05-17-2012, 6:54 AM
That comment really doesn't make a lick of sense.
Is 5.56/.223 the only "suited" caliber for an AR?
What about .300 Whisper?
5.45x39mm?
6.5mm Grendel?
9mm?
6.8 mm Remington SPC?
.204 Ruger?
.22 LR?
300 AAC Blackout?
.458 SOCOM
.50 Beowulf?
And the other twentysomething calibers that ARs come in?
Yeah, do away with them all... just because a crap-quality 7.62x39 bolt fails. Must have been the "un-suited" caliber's fault...

AR's are not suited for 7.62x39 by design. Having a straight 90 degree magwell prevents the use of any good magazines. Most of the other calibers you listed feed fine with a straight magazine. 7.62x39 does not. It needs a curve right away to feed reliably.
That comment had nothing to do with the broken bolt but with the shear design of the gun.

sharxbyte
05-17-2012, 7:59 AM
The magazine comment only USED to be true. This is no longer the case. Both of my mags fed almost flawlessly.

And for those of you insisting on the fact that should have bought an AK, I didn't. That's just the way it is. It's on my "buy" list, but i haven't gotten there yet. I have this, and I'm going to do my best to make it work, then get proficient with it. Maybe I should have gone with an AK, but I don't see anyone volunteering $500 to get me one now.

And FYI, the LMT bolts are $155 a pop.

PolishMike
05-17-2012, 8:01 AM
The magazine comment only USED to be true. This is no longer the case. Both of my mags fed almost flawlessly.

You stated multiple failures to feed in the first 300 rounds. That is not "almost flawlessly" that is absolutely unacceptable in a serious carbine.

sharxbyte
05-17-2012, 8:11 AM
I'll take 1%, especially if all of them were in the first 30 shots.

I'm seriously considering getting an LMT bolt and credit carding it. Amphibian over on AR15.com/AK47.net as of November 2011, finally broke the extractor, but not the bolt, and he's apparently running it full auto. From what I can tell he's been using it since at least 2008.

zfields
05-17-2012, 1:39 PM
Malfunction amnesia at its finest.

Sent from my Incredible 2 using Tapatalk 2

sharxbyte
05-24-2012, 2:09 AM
Got the replacement bolt in the mail today from, along with a reply from Amphibian on AR15.com. He still hasn't broken his LMT bolt, so that's where a portion of my next few paychecks will be going.

I'll shoot this until it breaks and have the LMT as backup, hopefully getting a refund of 50-100 when I decide I don't want another replacement. hopefully the broken bolt I send back to SOTA will help them to improve their design.

sd_shooter
05-24-2012, 6:57 AM
I used to think I wanted a 7.62x39 AR, and what's worse, it would have been my first AR :eek:

Looks like it's something for those with lots of time, money and patience.

Hmmm, gotta give my AKs a hug!

ThemBastards
05-24-2012, 8:55 AM
AR's are not suited for 7.62x39 by design. Having a straight 90 degree magwell prevents the use of any good magazines. Most of the other calibers you listed feed fine with a straight magazine. 7.62x39 does not. It needs a curve right away to feed reliably.
That comment had nothing to do with the broken bolt but with the shear design of the gun.

My ASC straight mags feed just fine....


Seems to be a lot of hatred towards the bastard child of the russian round and the american weapon system. Sharxbyte after seeing all the work you put into your stripped lower I hope your new bolt works out for you and you have a nice long relationship with your gun.

Reverend Clint
05-24-2012, 10:23 AM
finally getting my barrel and bolt from sota... over a month after i ordered it. I think they forgot since i emailed them about taking 3 weeks and they literally shipped it an hour later.