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9/22/2017 12:11:25 AM
Posted: 6/18/2003 11:20:26 AM EDT
I was running a few rounds through a 16" upper I built yesterday on my 80% lower. After a few rounds I noticed sluggish cycling and ejection, then the bolt hung up after a stovepipe. I have about 1k through this lower and have put 2 to 3 hundred rounds through this upper with zero malfs prior to this.

Upon inspection I noticed a large gap between upper an lower than a sickening sight of cracks on both sides through the takedown pin holes angeling towards the back. This allowed the back end to spring enough to cause the bolt carrier to bind. The rear end is still attached amazingly being a cast lower you would think it would just break right off immediately.

I beleive the culprit is a fixed tele-stock I just bought, I have had it on this lower for about 150 rounds, it is the kind that uses a full length tube that extends to the rear of the "sliding" butt and has a steel insert to make the internal length the same as a standard carbine tube. I carefully examind the buffer tube ring on the lower and it has an indentation from the carrier key impacting it.

Shouldnt the buffer have been long enough to prevent this? or is it the fault of a worn out recoil spring?

Being that the rear end of the lower has not completely detached, should I just cut grooves perpindicular to the cracks and JB Weld steel pins in? or should I try to find someone to weld it? any other possible repair ideas?


Link Posted: 6/18/2003 11:23:08 AM EDT
I suggest getting a competent welder and have it welded, then heat treated. got pics?
Link Posted: 6/18/2003 11:30:35 AM EDT
I'll try to get some pics tonight and post tomorrow. Heat treat? This is a casting straight from the mold, I didint think that treating was necessary.
Link Posted: 6/18/2003 11:32:03 AM EDT
heat treat AFTER it's welded.
Link Posted: 6/18/2003 11:34:26 AM EDT
Any thoughts on why this buffer and spring aloowed the key to impact the lower? what is the depth (inside) of a standard carbine buffer tube?
Link Posted: 6/18/2003 11:40:41 AM EDT
which buffer do you have installed? the shorter one is for the CAR length the fake tele's should have regular A2 sized components.
Link Posted: 6/18/2003 11:43:12 AM EDT
this stock came with a CAR buffer, I measured the internal lentgh and it is considerably shorter than a standard A1/2 tube and will not accomadate the longer buffer.
Link Posted: 6/18/2003 4:28:13 PM EDT
[Last Edit: 6/18/2003 4:30:47 PM EDT by bgenlvtex]
I'd take the pieces out of the lower,finish breaking it in two and throw it in the scrap metal pile like the piece of crap that it is. Then I'd spend $100-$120 on a quality FORGED stripped lower of my choice. I'd replace the buffer tube,buffer and spring and shoot/inspect for futher malfunctions. YMMV
Link Posted: 6/18/2003 4:40:42 PM EDT
Wouldn't T&M for a decent weld job, heat treat and re-coloring/anodizing cost as much as a stripped lower?
Link Posted: 6/18/2003 8:02:43 PM EDT
Just measured my buffer tubes. Car 7" deep fixed 9.75" deep There was 3/16" clearance between the buffer tube and key with the bolt carrier all the way back.
Link Posted: 6/19/2003 4:33:50 AM EDT
bgenlvtex and yellobelli, Actually this lower is not a piece of crap, it did not completely break through after nearly 30 rounds in this condition. If you read my initial post carefully you will see that this started life as an 80% lower, i.e. no paperwork as I built it personally, it is worth a lot more to me than ANY factory stripped lower regardless of who made it. My refinishing will go as far as another quick spray paint job with Krylon ulta flat black, this is not a show piece, it is a working gun with obvious advantages having been home built. Oldguy, Thanks for the measurement on the CAR tube, I believe (if memory doesnt fail me) that the tube I have is deeper and is most assuredly the culprit. I have the lower back burnered for now till I can get someone to weld it, plenty of welders arounf here in the sticks but few can do aluminum. Heinou as it may sound, I might still JB Weld the hell out of it to get it running (worst case scenario), looks arent importatn as long as it functions and is durable. Thanks for you help guys, still open to discussion on alternate repair methods. Jeff
Link Posted: 6/19/2003 4:58:25 AM EDT
JKH: I don't think anything in my post alluded to the fact that the lower was a "piece of crap." My comment was basically raising the issue of cost comparison. Since the lower has personal significance to you, then cost doesn't enter into the equation. Get it welded, finish it up and have fun. I'm not sure where you are in the "sticks" but call the local marine shop and see if they know of a good aluminum welder. Seems the easiest way to find a good Al welder anymore is to hit the marinas and such.
Link Posted: 6/19/2003 5:12:43 AM EDT
yellobelli, I apologise if it apears I took umbridge at your post, I just wanted to clarify what this is as there are definitely some pieces of "crap" cast lowers out there. I live in south western New York state, very rural and very poor. Actually it make for great hunting and many, many places to shoot as the population is very low and there are many farms and forests. I am blessed with having a very good professional job being that the median income here is $34,500 and the averag welfare rate per town is 18%. There is a small machine shop in my town, I will give him a try, actually he reamed and lathe threaded the buffer tube hole on this for me, $25 out the door! Again, I apologise for my bruskness. Jeff
Link Posted: 6/19/2003 7:00:09 AM EDT
[Last Edit: 6/19/2003 7:05:12 AM EDT by neilfj]
JKH, you said that the tube was longer than the measurements of 7" provided by oldguy. If the A2 buffer won't fit, my guess is that the spring is too short or the steel insert is in the wrong location. The combined length of the buffer along with the fully compressed spring should be of sufficient length to prevent the bolt carrier from retracting deep enough into the buffer tube so that the carrier key doesn't strike the tower. Another option for repair, which will look like crap, is to cut a couple strips of metal to use as straps to bridge the crack. Drill and tap in at least 4 locations (2 on each side of the crack) and use 4-40 screws. There should be enough 'meat' in that area to use 1/4" screws, maybe even 3/8" if your lucky. You'll still have to resolve the buffer problem though. Like I said, this will look like crap, but its an option. Another option, if you can find a steel/brass rod thin enough is to break off the tower and drill it and use the rod as a dowel to told the parts together. Make the holes larger than the dowel and use JBWeld to glue them in place, along with JBWeld along the seams. The difficult part of this process would be getting the holes centered and properly located so that the 2 pieces line up perfectly. The good part of this method is that you could use a total of 6 dowels..2 on each side wall and a couple on the bottom. This should give you plenty of strength and won't be as noticable as other methods.
Link Posted: 6/19/2003 7:31:00 AM EDT
I will be heading home for lunch soon and will measure the tube again. I like the dowel idea, perhaps I could also leave the tower in place, drill and tap and countersink for cap screws and install them with red loktite. I'll see about welding but if worse comes to worse I think your dowel idea or a variation thereof would be best. Thanks Jeff
Link Posted: 6/19/2003 3:18:57 PM EDT
The piece of crap comment was mine.My appology. You asked"My lower just cracked,what to do" I offered my opinion in no uncertain terms and it's still my opinion. There are fairly large chunks of steel reciprocating at high speed within inches of your face and they are dependant on that lower receiver being structurally sound,this doesn't concern you? I read your post that the lower started life as an 80% cast lower....so.....it broke. I have no fear of yellow sheets.I do fear guns in my face that fail inches from my face. YMMV
Link Posted: 6/19/2003 5:46:14 PM EDT
Holy cow! yellobellii I offer my profoundest apologies, I was totally in error in not reading the posts carefully as to author, again I am sorry for casting aspersions your way. As to the other gentleman, Yes there are steel parts reciprocating but not at profound velocities, when the bolt carrier starts its rearward motion it is within the buffer tube and captive. For there to be any true danger the entire rear with the stock and buffer would have to fall off first to allow the carrier to be expelled directly out under recoil (thats if I fired it after this occured), I would have to be blind and without feeling to not notice such a scenario, even the guy that had the Hesse break like this did not have a catastrophic event. Anyway, I have decided to experiment. I started repairing one side tonight by cutting a groove perpindicular to and bridging the gap just below the takedown pin hole (with enough room for clearance), I then drilled holes at either end and made steel pins with 90 degree hooks at both ends out of 1/32" round spring steel, the ends were bent so that it had to be tapped down into the holes putting tension on it to draw the pieces together (of course I have the lower securely clamped in a vice bringing the pieces tight together in the proper location), the groove was cut a bit oversized and then filled with JB Weld then the "staple" was put into place and tapped home. I smoothed out the JB Weld and after minor sanding and painting it will be invisible, after this side cures completely I will do the other in the same manner. Over top of the pivot pin holes I will slice grooves in the top with a dremel cutoff wheel and do the same thing with thinner spring wire (maybe a piece of cutoff guitar string), I will not make the hooked ends as this will only need to prevent movement of these thin areas. I believe this will do the job, I tried to pull the broken tower away from the rest of the receiver but I could not perceive any movement so it appears the crack did not extend into the solid area where the thumb web goes. Now I have another vexing situation, I installed the upper that was on this lower onto a Cav arms lower I got today, when I retract the carrier group it binds and sticks approximately 9/10ths of the way back and stays unless I squeeze the upper down tighter on the lower at the rear (only slight pressure), then it will release. I tryed a different carrier and it alleviated the condition marginally, this upper has not exibeted this on other lowers just this Cav-15 lower. Any thoughts?
Link Posted: 6/19/2003 5:49:19 PM EDT
Shoot! oldguy, I fogot to mention that I measured the tube, exactly 7". I am beggining to think I may have had it out one turn to many and that allowed the key to impact, I havent tryed the assembly with the carrier yet to see how far out it does or doesnt protrude but will tomorrow.
Link Posted: 6/22/2003 4:11:59 PM EDT
Your logic escapes me. Why exactly would you try to repair something that could injure or maim you? As you have stated, you are not financially in dire or close to desparate straights. You made/finished one lower - you can do the same thing again. Yes, both myself and most members of these boards can understand your reluctance to purchase a new 'forged' and documented receiver, so buy a used rifle at a show! Or make a new one. We are not at war, the hoards (foreign or domestic) are not cresting the ridge. It is in no way vital that you salvage this lower!! Your saftey is more important! Just because both you and another member came away unscathed doesnt mean you'll get lucky again. Some words given to me by a SF veteran before my first experience with the elephant come to mind, [b]"Put your faith in God. Put your trust in God, but don't tempt fate - it pisses him off."[b] Dont tempt fate - it's just not worth it.
Link Posted: 6/22/2003 6:09:30 PM EDT
4gma, Thank you for your concern although I do not consider there to be ant real potential for serious harm from this receiver, it is essentially a non stressed item. Yes I could buy or build another but the spirit of WECSOGing is deeply ingrained in me, I come from a line of engineers, tool & die makers and inventors so it is a compulsory gene that drives me to find solutions and correct problems. I do not see myself as tempting fate, rather tempting God, Actually I have a highly developed sense of personal destiny as a believer in Christ under doctrine, I know precisely where I will be going and know that God is in control and I will not die one second before my appointed time, that applies to all people fo course, believer and non believer alike. Thanks again for your concern but all will be well, actually half of the repair is completed with steel inserts on each side (which would be sufficient alone), I will be adding more to the top rails above the takedown pin holes to either side and will actually have a stronger unit than before the crack. besides, if I can trust my plastic lowers (Cav arms and Carbon 15 with a Hesse on the way) I certainly will be able to trust this.
Link Posted: 6/27/2003 10:54:17 AM EDT
I believe I have success! I finished the "stapeling" process on either side below the take down pin holes, that removed all movement by itself. over top of the pin holes from the top plane of the lower, I dremeled out channels and JB Welded steel reinforcement pins in place. Zero movement of crack. I reinstalled the standard A2 butt assembly until I figure out why this happened with the fixed telestock (made by ASA by the way), I think that either the buffer is to short or the spring so I could use a buffer measurement from a known good specimen. This should hold, the only thing I can think of that would break this is maybe a .50 caliber upper which I dont have and wouldnt put on this lower anyway. Thanks for your help, I will try to post an update after several hundred rounds. Jeff
Link Posted: 6/27/2003 11:25:37 AM EDT
I liked the staple method. Sounds like the staples they use for surgery. I'd like to hear how it works out after you've tested it.
Link Posted: 6/27/2003 11:30:40 AM EDT
I should have left them exposed for the full "Frankengun" effect.
Link Posted: 6/27/2003 3:20:23 PM EDT
Originally Posted By JKH: Now I have another vexing situation, I installed the upper that was on this lower onto a Cav arms lower I got today, when I retract the carrier group it binds and sticks approximately 9/10ths of the way back and stays unless I squeeze the upper down tighter on the lower at the rear (only slight pressure), then it will release. I tryed a different carrier and it alleviated the condition marginally, this upper has not exibeted this on other lowers just this Cav-15 lower. Any thoughts?
View Quote
Yep, from this page [url]http://www.roderuscustom.tzo.com/cgi-bin/ib3/ikonboard.cgi?s=3efcd0030450ffff;act=ST;f=11;t=128;hl=buffer+tube[/url] and the quote is (by user OSI): "FYI, I had a Cav-Arms lower which did not mesh with the upper and I had to shave about 1/16th off the top of the bolt carrier to make the gun function, but once it was done, the rifle would shoot fine." Hmmm, this is only the second time I have heard about the Cav lowers and b/c's that sstuck when retracted.
Link Posted: 6/30/2003 4:49:23 AM EDT
mikr, I worked on mine last night, this one flat top upper bound terribly and my varmint upper would bind only if holding it in the offhand position, now the flat top barely binds if I hold it without supporting the forend (it will not bind then). Its really difficult to tell where the binding occurs on these so it takes a lot of assembly/dissasembly, etc. Mine is one of the blems and I have read of other with the same problem, evidently when they slipped in the clamps (?) of the fusion welder it also caused problems with the buffer are, mine actually looks flatened out on top. As for my JB Welded cracks (with staples), I ran 90 rounds through it the other day when I had a chance wit 2 different uppers, the last 30 rounder I pounded out as fast as I could pull the trigger (yippee!), so far no signs of movement. I still have to check out the fixed telestock by inserting the buffer, spring and carrier to see how far in it goes. Either I had it to far out (which I doubt as I have built a few of these) or the buffer and or spring is to short. Otherwise my old closet gun is back in business and rady for a new paint job, this time with Krylon ultra flat black camo paint.
Link Posted: 6/30/2003 5:22:09 AM EDT
I want to see pictures..........
Link Posted: 6/30/2003 5:53:53 AM EDT
Ok, will get some this afternoon or tonight an post tomorrow, I have to warn you though, I havent cleaned up any of the JB Weld.
Link Posted: 7/1/2003 12:13:14 PM EDT
[Last Edit: 7/1/2003 12:21:56 PM EDT by JKH]
Here are pics; [img]http://www.imagestation.com/picture/sraid67/pc591808a69e6a3a5bdb5ef22419f303d/fbc9b946.jpg[/img] [img]http://www.imagestation.com/picture/sraid67/p5038d7c1d8b4fff0fc428ccf1b5f9869/fbc9b91b.jpg[/img] [img]http://www.imagestation.com/picture/sraid67/p6f60b014ed4d2304a33b3a246dc42a8a/fbc9b8f0.jpg[/img] Dont laugh, it works! Later I will sand it out and re-paint it, I stripped it when I made th repairs.
Link Posted: 7/2/2003 4:56:44 AM EDT
Well guys, stupid is as stupid does. I checked the telestock with the buffer, spring and the bolt carrier, it stops the carrier about 3/16" short of the tube. I had removed this stock after the initial installation to spray flat black paint on the very shiny aluminum buffer tube (looked pimpy), evidently I did not pay close enough attention and had it backed out 1 thread too many. Live and learn. I have an ACE skelton stock I am using on another lower and will not bother with a fixed tlestock again unless I can use the real thing legaly. Thanks you all for your helpful suggestions, at least I didnt crack my nice forged lower and can live with the repairs to my other as it is ugly to begin with.
Link Posted: 7/7/2003 7:08:09 PM EDT
if no one has told you this yet...your Cav Arms lower binding is easy to fix by using a half-round file to take some material off the top of the buffer tube until it slides freely. i've had to do this on one of my lowers when using an ASA 9mm upper receiver.
Link Posted: 7/8/2003 4:20:39 AM EDT
Thanks, I did some research and came to the same conclusion, lower now works fine.
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