View Full Version : B5 Sopmod stock extremely tight on buffer tube
I just purchased a B5 sopmod stock (mil-spec) from DSG Arms for my Daniel Defense MK18. I was able to get the stock on the buffer tube (mil-spec), but it is extremely difficult to move it between the different positions compared to the Magpul MOE that came on the rifle. I wanted to check with the knowledge base here to see if I was possibly doing something wrong (which is likely) before I contacted DSG or B5 about the stock. Thanks in advance!
disclaimer: I used the search button and Google prior to posting, but could only find this topic discussed about early model B5 sopmod stocks
DD is known to have slightly larger receiver extensions than most. You are not the first to report a problem.
DD is known to have slightly larger receiver extensions than most. You are not the first to report a problem.
Thanks, I didn't realize DD had a larger buffer tube. Guess that is what they mean by Mil-Spec+ :sarcastic:
IIRC there are tolerances for the tube just like everything else. So you may have gotten one that was at the higher end. If you move the stock back and forth on the tube it will wear a little and become easier.
I'm having the same issue is the OP. My CTR moves back and forth without any effort, but I cont. hardly move the Sopmod :(
Should I apply little grease or lube some kind?
I have two B5s. One on a Vltor tube and one on an HK. They're both a tight fit, I think B5s just are on the small end of the tolerance. The Vltor was much less tight than the HK was to start, but after a few days, the stock moves just fine on the HK. Spend some time working it back and forth like you would a leather holster. It will be fine. No lube needed or advised.
Ditto on it being a B5 issue. I've had three, one of which was super tight. Another local guy had same problem. Never had same issue with the dozen other make stocks in my experience. I just live with it. Prefer it to a rattling non-locking MOE.
My B5 SOPMOD fits very snug on my BCM RE, much tighter than the M4 stock that came with the RE. A little dry-lube inside the stock helped. As above, I prefer a snug fit to a rattle.
filthy phil
12-03-13, 08:10
IIRC there are tolerances for the tube just like everything else. So you may have gotten one that was at the higher end. If you move the stock back and forth on the tube it will wear a little and become easier.
Good to hear I have same issue with a 6920
I ordered one as well during the sale from DSG and mine is extremely tight on a BCM. I briefly searched and saw a post on TOS regarding some guys having the same issue a few years ago. They blamed it on B5 producing the first batch out of spec (too tight) because the government gave them the wrong specs, blah blah blah.
Anyway, I spent a few minutes sliding it back and forth and it has loosened up slightly, so I didn't look into it any further.
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SilverBullet432
12-03-13, 10:47
DD is known to have slightly larger receiver extensions than most. You are not the first to report a problem.
Never heard such things
SpeedRacer
12-03-13, 10:55
They can definitely be snug, but become what i believe is perfect after muscling them back and forth a few times. I'll take solid lock up over quick collapsibility any day.
I got one the sale also. It fits, albeit tight, on all my extensions except for my DD. I can't even get it on that one at all.
Thanks for all the replies. I will put it back on and try to break it in.
My brother had the same issue with a B5 on a BCM RE, we ended up sanding the inside of the stock out a bit and it's still really tight...
Could it be that was an older model? As far as I know that issue was fixed. I have B5 stocks on every carbine I own and with the exception of one they are smooth. After I worked it a few times it was fine.
My brother had the same issue with a B5 on a BCM RE, we ended up sanding the inside of the stock out a bit and it's still really tight...
I own one B5 Stock, it is a Bravo model, and the first time I installed it it was a rather tight fit on the lower. That said, it did wear in and I have not had any issue with it since.
The one I bought at that sale (FDE) fits like a glove. Have no idea who made my RE.
As far as I am concerned I will take the tight fit and plan to pick one up soon.
Could it be that was an older model? As far as I know that issue was fixed. I have B5 stocks on every carbine I own and with the exception of one they are smooth. After I worked it a few times it was fine.
I believe the packaging on mine had a date of 4/13 - presumably the date of manufacture/packaging.
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my B5 SOPMOD was very tight at first on my BCM, but it loosened up over time.
I had an original/pre-release one that was very tight. I wrapped a broomstick with some fine grit sandpaper and lightly hit the inside of it. Took a few seconds and it worked perfectly.
They do break in without help, though.
Berserkr556
12-07-13, 07:18
Better tight than loose. I like my stock to fit tight and my B5 SOPMODs are snug with no wobble. If I wanted a loose stock I would have just went with the standard stock.
I had to return the B5 Bravo I purchased a week ago. I have a Spikes buffer and it was considerably loose and rattled quite a bit. I purchased the CTR and it locks up perfect and is silky smooth. Bad part is I really liked the B5 cheek weld and design, just didn't jive with the Spikes.
I snagged one of the $49 enhanced sopmods from dsgarms on black friday, and it is extremely tight on my Vltor A5 receiver extension. I also have two BCM carbine receiver extensions that it simply will not fit over. Almost makes me think that dsgarms was getting rid of old inventory.
I also have a sopmod bravo, and it is super loose on all my receiver extensions. So loose that it will probably fit on a commercial receiver extension.
Plastic molding can be a pain in the butt, but still...you'd think they would run a little QC on their products.
I sent a request to DSG Arms to return the SOPMOD. I put it back on my rifle and tried to extend/collapse it numerous times to loosen it up. No luck what so ever! It was so tight collapsed that I had to put my foot on the back of the pistol grip and pull with both hands to get it extended again. I removed it and decided it wasn't worth messing with.
I sent a request to DSG Arms to return the SOPMOD. I put it back on my rifle and tried to extend/collapse it numerous times to loosen it up. No luck what so ever! It was so tight collapsed that I had to put my foot on the back of the pistol grip and pull with both hands to get it extended again. I removed it and decided it wasn't worth messing with.
I'm considering doing the same. Please let us know what they say.
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NeoNeanderthal
12-07-13, 19:47
My b5 was slightly loose on my BCM receiver extension. So i took a few pieces of black electrical tape (one at a time) and put them on the receiver extension. Tight as a tiger now. I like it difficult to move because i only adjust it of someone else is using my gun. It still slides but it takes a little force.
IIRC there are tolerances for the tube just like everything else. So you may have gotten one that was at the higher end. If you move the stock back and forth on the tube it will wear a little and become easier.
I lube mine just a bit.
Just got one as well and I find it to be "snug". I would much rather have it fit tight than be a sloppy rattle trap.
that's funny because both my friend and I have B5s that actually have a small amount of slop in them (you can hear some wiggle if you shake the gun)
My recently purchased B5 Bravo also fits a little loose on my BCM RE.
that's funny because both my friend and I have B5s that actually have a small amount of slop in them (you can hear some wiggle if you shake the gun)
Might be the buffer weights you're hearing.
The first one I got was so tight I had to beat it onto my DDV7. Then I had to use a rubber mallet to get it off. A few passes with a brake cylinder hone and it was good to go. My second one worked just fine on all my rifles including that DD.
I'm considering doing the same. Please let us know what they say.
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DSG has been great! Called them this evening, about 10 minutes before closing, to inquire about my return request as I had not heard back. Gave the guy my info and he stated he had approved the return and I should have received an email with a pre-paid return label. After telling him I hadn't received the email he verified my contact info and said he would call me tomorrow after looking into it. While talking he stated they had been having problems with B5. He didn't explain and I didn't ask because I knew he probably wanted to leave work. I will ask him when he calls me tomorrow.
While I am disappointed my SOPMOD didn't work out I am extremely impressed with DSG. For those of you that ordered your SOPMOD from DSG and are having similar issues, I am sure they will take care of you if you decide to return it or exchange it. He did mention they are currently out of stock, so if you go the replacement route it might be a bit of a wait.
skijunkie55
12-11-13, 06:42
If you can get the stock onto the RE there is no need to return it... It will break in over time. Mark @ B5 did confirm in one of these other threads that there is an issue with tolerance stacking on certain receiver extensions, especially the DD ones.
Below was my quick fix without sanding. - just in case you have thoughts on returning the stock.
Polymers / plastics get softer with heat. I used a hair dryer on the stock for about 3 minutes a day for a week. Heated the stock up, worked it on and off the RE, now it is absolutely perfect with no slop whatsoever.
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