DA Socom 18 bolt/receiver lug issue

S

smeagol

Member
Rating - 100%
20   0   0
Location
Nova Scotia
Hello nutterz! I'm usually more of a creepy lurker than a poster, but I'm so excited about this new purchase, it was either poop my pants or post something. Since I'm running low on skivvies and Xmas isn't for another 5 weeks, best to post...

Recently purchased a DA socom 18 from canam. Took it out cleaned it up and gave it a once over best I could based on all the info on here and the greater interwebs. This thing looks great and shoots even better! What an idiot for not getting one sooner f:P: And yes, yes, I should have bought 2.

Only problems I found:
slightly loose op rod guide
the gas lock could be a tad tighter
what looked like very little or no left bolt lug contact
Bolt disassembly went smooth but when trying to reassemble it it seems the extractor spring and plunger are a little longer than it should be as I had to push it back quite a bit to push the extractor back in.

At the range fired a bit of the norc ammo from the package deal and also some factory loaded Federal .308. Got one or 2 split necks with the norc ammo and a few flattened primers with the federal.

Used an rcbs precision mic to check the headspace. The Federal brass averaged a little shorter than the norc steel cased stuff (around .002" shorter I think) which was just under 7.62 NATO field reject, something like 1.642 or 1.643". I don't have the numbers or photos with me, I am out of town for a few days, but will post after I get back.

Later on I checked the contact in the bolt lugs that I coloured with a red sharpie before firing and found there was no contact on the left lug. I'd say 30-40% contact on the right lug. Didn't have any feeler guages handy so I checked with a light underneath, and it looked like a friggin canyon between the receiver and left lug. I'll check it end of the week with a buddy's guages and post the results.

I'm a newb to this platform but I would guess lapping this in would cause way too much headspace if my memory and rough estimates are correct. Also, dpending on the gap, lapping might even grind through all the surface hardening on the right lug.

The sights are nice and tight, and all they needed from being what appeared to be centered at factory was a few clicks up and left. I'll adjust them right next time out. Time and boom boom will tell if they stay tight :ar15:

I guess I might be calling canam to see what they think after I finish checking everything, but I'm sure if there is an issue, they will step up as they always seem to in the past. The rest of the gun is fine (unless it is the receiver out of spec causing the lack of contact with the bolt lugs?) so would it be a new bolt or would they send a whole new gun? Meh, premature question at this point I suppose.

All in all a sweet shooter though. Glad I finally picked one up and hope I get it sorted soon!

Play safe!

Chad
 
Last edited:
OK, the cases measured:

Steel norc 10 cases avg 1.6425

Brass Federal 5 cases avg 1.6410

Here are the primers, norc and flattened federal

6.jpg

4.jpg


Still haven't gotten hold of the feeler guages to measure the gap at the left lug. A closer look it seems the receiver might be the issue: there looks to be a ridge near the outer wall, possibly left over from grinding down the face of the left locking lug? Thoughts on this?? Can anyone say if they have seen similar on other receivers?

1.jpg

2.jpg


Here's how much the right lug is bearing:

3.jpg


Thanks all

Chad
 
Last edited:
smeagol said:
Still haven't gotten hold of the feeler guages to measure the gap at the left lug. A closer look it seems the receiver might be the issue: there looks to be a ridge near the outer wall, possibly left over from grinding down the face of the left locking lug? Thoughts on this?? Can anyone say if they have seen similar on other receivers?

1.jpg

2.jpg


Here's how much the right lug is bearing:

3.jpg


Thanks all

Chad
Click to expand...


All my M14s and garands seem to have the wear mark in some form in another .. As for that ridge, if the lug of the bolt is resting on it when its in battery i would carefully remove it ..
 
If your not gretting proper lug engagement send it back. Or you can play the bolt lottery on the ee. Why take a chance? If you bought it new get hold of Can am and see if they will replace the rifle for one that is closer to spec.
 
Noob question:
When you mark the bolt lugs with red marker do you then have to fire the rifle a few times ( and if so how many ) to get a good idea of lug engagement? Or can you simply manually cycle the action a few times.

Reason being is I just got my canada mom socom 18 in the mail yesterday

Thanks
 
smeagol ... i'd approach the retailer with the problem .. if they do nothing, then i'd check the bolt to make sure its all up to spec .. if you can't find a norc replacement, you can alway order a fulton from either armtac or brownells ( only do that if your willing to lap ... and definitely buy a manual and read about it before hand )

wait till 45king and tacteacher post on it ... maybe they can help

here some sorta related stuff on m14forum ... think these are posts 45 made ?
http://m14forum.com/gunsmithing/98237-m14-headspacing-quick-simple-cheap-pretty-darned-accurate.html
http://m14forum.com/gus-fisher/86960-mounted-my-first-fulton-armory-bolt-chinese-m14.html
http://www.milsurps.com/showthread.php?t=24124
http://www.milsurps.com/showthread.php?t=9080
 
Last edited:
Here's a shot of the left lug fit, with a light underneath to highlight. Note that the lug on the receiver side appears to be not parallel to the bolt lug (gets further apart as it nears the outside of the receiver). Also note the ridge in the corner there. It looks like (and this photo doesn't show it very well, the light drowns it out and exagerates the gap) the receiver lug was milled on an angle because it was too close otherwise, but it was milled way too much and now its too far.

7.jpg


No luck getting a set of feeler guages, but 2 strips of printer paper together are tight at the inside and snug-ish at the outside of that gap. Calipers show the 2 strips at .008". I know that's prob not very accurate but screw it, it's hillbilly accurate. So the math looks like this i suppose:

Lap the bolt in and minimum headspace (prob much longer in reality) sits around 1.650" and that is just to get the left lug to start contact. I don't know how much more it'll add to then lap the left lug in completely, given the slight angle the receiver lug appears to be at.

Again, I am new here to this platform, and while I have read everything I could find, my head is still up my arse. I take it I am risking lapping straight through the hardening on the right bolt lug by doing all that, not to mention getting a loooooong headspace?

I will be contacting CanAm and hopefully they can replace it, otherwise it'll be a shopping I will go for a fix (or sending it to someone with more know how than me!)
 
48206 said:
Noob question:
When you mark the bolt lugs with red marker do you then have to fire the rifle a few times ( and if so how many ) to get a good idea of lug engagement? Or can you simply manually cycle the action a few times.

Reason being is I just got my canada mom socom 18 in the mail yesterday

Thanks
Click to expand...

If you are going to cycle it by hand, use a little rearward pressure on the top of the bolt with a thumb to make sure the bolt is contacting the receiver lugs and rubbing while your cycle it. And make sure you don't jame up your thumb!
 
ya get hold of Canada Ammo. Good find by the way. They may not like having to replace it but they always do the right thing
 
millwright said:
ya get hold of Canada Ammo. Good find by the way. They may not like having to replace it but they always do the right thing
Click to expand...

Email sent to them. I have had nothing but great experience with CanAm, their customer service is fantastic. I just hope that if they do decide to replace it, it's before the 24 that are still in stock are gone! I won't be able to wait till next shipment now that I've got the bug. If I have to wait, I'll likely buy a full size and my wife will kill me before I can enjoy either!
 
your light from underneath really shows the problem ! i've heard of the norc bolts being abit on a slant or out of spec

ok heres what it says in kuhnhausen -the receiver front locking lugs must engage both front bolt lugs. Surface engagement at each should be at least 75 to 80% before lapping and 90 to 95% after lapping.

if you put a spent casing in the chamber and close it... does it still sit with that much gap ? you should be able to see a little bit of wear on the receiver in the lug recess if it was at all touching... ( which doesn't look to be the case )

CanAm will hopefully clear it up .. .. keep us informed
 
dimeN said:
your light from underneath really shows the problem ! i've heard of the norc bolts being abit on a slant or out of spec

ok heres what it says in kuhnhausen -the receiver front locking lugs must engage both front bolt lugs. Surface engagement at each should be at least 75 to 80% before lapping and 90 to 95% after lapping.

if you put a spent casing in the chamber and close it... does it still sit with that much gap ? you should be able to see a little bit of wear on the receiver in the lug recess if it was at all touching... ( which doesn't look to be the case )

CanAm will hopefully clear it up .. .. keep us informed
Click to expand...

I don't believe the bolt lug is slanty, I think its the receiver lug, almost like it was milled too big then over corrected at a slant which left that ridge in the corner.

That's the gap, as tight to the rear as she goes, even with something in the chamber. Not a bit of wear on either face of the left lugs that I can see. And the red sharpie is still there.
 
You need to have a round in the chamber to see contact. The bolt is usually a little loosy-goosey so you really can't go by that.

Try cutting an empty case in half. Throw your trigger spring in the case then but everything in the chamber. This should give back pressure to the bolt and give you a better idea of how the lugs contact.
 
You must log in or register to reply here.
Back
Top Bottom