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Posted: 4/8/2006 8:59:15 PM EDT
I just got my CMT upper to go with my Stag lower but I can't get the two together. I'm having problems pushing the take down pin through. It goes through the lower fine with the upper off and it slides easily through the upper by itself. When I try to get it through the upper and lower to close the rifle it just won't go.

What do I do ?
Link Posted: 4/8/2006 9:13:26 PM EDT

Originally Posted By madrhythm:
I just got my CMT upper to go with my Stag lower but I can't get the two together. I'm having problems pushing the take down pin through. It goes through the lower fine with the upper off and it slides easily through the upper by itself. When I try to get it through the upper and lower to close the rifle it just won't go.

What do I do ?



How does the alignment of the takedown pin holes look? Do the holes from the upper and lower line up? Do the upper and lower close completely together?
Link Posted: 4/9/2006 2:22:50 AM EDT

Originally Posted By QUIB:

Originally Posted By madrhythm:
I just got my CMT upper to go with my Stag lower but I can't get the two together. I'm having problems pushing the take down pin through. It goes through the lower fine with the upper off and it slides easily through the upper by itself. When I try to get it through the upper and lower to close the rifle it just won't go.

What do I do ?



How does the alignment of the takedown pin holes look? Do the holes from the upper and lower line up? Do the upper and lower close completely together?




What he said (+ uh-oh sounds like someone's upper is off)


Got a buddy with an AR you can try it on?
Link Posted: 4/9/2006 5:04:50 AM EDT
Sounds like the upper can't be fully seated on the lower. I had something like this happen to me. The tab(piece that the rear take down pin goes through) on the upper receiver is to thick to go all the way into the lower receiver. It could be out of spec and may have to be narrowed or the area in the lower rec is to narrow. I had a new Stag upper to install on a OLY lower wouldn't fit. In my case I had another lower and it was a perfect fit so I used that one instead.
Link Posted: 4/9/2006 5:49:15 AM EDT
When you put the upper on the lower, push the upper receiver toward the buttstock. The buffer sticks out a little thus pushing the upper and lower off alignment. Stag / CMT guns are very tight when new, don't be affraid to apply a some pressure when pushing the pins in (but ensure that the pin / hole are properly aligned)

The best way assemble the rifle is to put the buttstock on the ground, put the upper on the lower, hold onto the handguard while applying rearward (or downward) pressure and push in the front pin (with my Stag's, I generally have to give the front pin a hard slap with the palm of my hand to get it in).

Once the front pin is in, you may have to squeeze the upper and lower receivers together to get the rear pin in. I have had to do this with ALL of my Stag / CMT guns.

When taking the upper and lower apart (when the guns are new) I have to use a tool to push the pins out as the pins are very tight.


Stag / CMT are tight guns but they will go together. On a recent Stag that I purchased I put some oil / grease on the take down pins because the fit was very tight. With use the parts will break in and be easier to put together and take apart.

Link Posted: 4/9/2006 7:46:59 AM EDT
Thanks guys I'll try it right now let ya know.
Link Posted: 4/9/2006 7:56:08 AM EDT
Ok, USMC03's suggestions got me about 3/4 of the way through, but it just won't go all the way.

Should I tap it with a light hammer or just ask GTS for a new one?
Link Posted: 4/9/2006 8:07:54 AM EDT

Originally Posted By madrhythm:
Ok, USMC03's suggestions got me about 3/4 of the way through, but it just won't go all the way.

Should I tap it with a light hammer or just ask GTS for a new one?




Like I said:

How does the alignment of the takedown pin holes look? Do the holes from the upper and lower line up? Do the upper and lower close completely together?
Link Posted: 4/9/2006 8:16:54 AM EDT
The holes appear to line up correctly. The upper and lower do close completely. They actually fit together very tightly. They stay frimly together even when the take down pin is not in.
Link Posted: 4/9/2006 8:31:27 AM EDT
After carefully inspecting the takedown pin holes I have discovered that the holes don't line up, but only by the smallest of margins. It was actually hard for me to see it, but I could feel it when I ran the tip of a small punch across the joints.

Any fix or do I send it back?
Link Posted: 4/9/2006 9:00:40 AM EDT

Originally Posted By madrhythm:
After carefully inspecting the takedown pin holes I have discovered that the holes don't line up, but only by the smallest of margins. It was actually hard for me to see it, but I could feel it when I ran the tip of a small punch across the joints.

Any fix or do I send it back?



Well sending it back depends on how much they are off. If the holes are off set by only a few .001’s making it difficult to install the pin I personally would lube up the pin good and try again by hand to install it. This may require tapping with a rubber mallet. Anodizing can take up a few thousands of an inch and after being shot a few times the lower to upper fit would loosen up.

It’s hard to really tell with out actually being there to see first hand exactly how far off the receivers are. If you feel uncomfortable with the fit and think that damage could result by “forcing” the receivers together then contact the dealer where you purchased your parts.

This is just my personal opinion. As an aircraft mechanic for 21+ years it’s easier for me to have such things in front of me to be able to assess the situation.
Link Posted: 4/9/2006 9:24:47 AM EDT
Which pin are you having trouble with?


On 2 of my Stags when I first got them I had to take a small rubber mallet and tap the REAR take down pin (the one closest to the buttstock) to get it in.

A little lube on the pin it's self may help.


In looking at one of my Stag's when I have the front pin in, the rear pin looks to be out of allignment. I have to squeeze the upper and lower together with my left hand and tap the rear with a small rubber mallet to get the pin started. (this is on my newest Stag).

It will take SOME force, but not an excessive amount.


If the upper or lower is OUT of spec, no amount of force will fix the problem. But in my experience, new Stags are tight and take a little more force to get the pins in and out due to them being build to tighter tolerances. Your milage may vary



Link Posted: 4/9/2006 9:13:53 PM EDT
It's the rear pin that is giving me trouble. I'll try a rubber mallet in the morning, see it I can tap it through.
Link Posted: 4/10/2006 4:28:32 AM EDT
Link Posted: 4/10/2006 7:31:17 AM EDT
Well, I got it to go through using a mallet. It was a VERY tight fit. Thanks for all the hints.
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