My friends SI Defense build.

planeflyer21 · March 28, 2013

Don't sweat it...it isn't a "gap between the receivers".

It's a "tactical credit card holder" for when you need more accessories immediately.

Jon

Robocop1051 · March 28, 2013

I have a positive and a negative response to this.

Pos:

The gap shouldn't affect the function or accuracy of the rifle.

Con:

I wouldn't buy a pair of pants with one leg longer than the other. Sure it does the right function, but it looks bad. Nope! I'd be an unsatisfied customer. Email those pics with the gap back to SI-D.

To me it looks like their upper take down hole needs to be adjusted.

Robocop1051 · March 28, 2013

For the record;

My SI-D 2nd gen does NOT have that gap. In fact, the parts are machined so tightly together, they practically snapped closed/open when I first got it.

planeflyer21 · March 28, 2013

Robo...you're up early. <laughs>

Jon

MONTANA308 · March 28, 2013

Ya that dont look right here is my SI

matched set

Robocop1051 · March 28, 2013

Robo...you're up early. <laughs>
Jon

Baby hours are rediculous.

planeflyer21 · March 28, 2013

Baby hours are rediculous.

Wait until you find yourself operating on these hours in 5 years...just so you can have "Robo Time". :binkybaby:

Jon

NoFail · March 28, 2013

Well okay then ... Can I say "fornicate"!!!!!

So I'll tell him what you guys think. This sucks large donkey size for sure, and I'm the one who told him to go for the SI because they do quality poop. I didn't mean real poop, fornicate!!

Thanks guys.

MONTANA308 · March 28, 2013

I'd call SI or email Chris the manager the pics i hope they make things right. that looks really bad. The stuff I have baught from them has all been really great stuff.

Robocop1051 · March 28, 2013

Trust in SI-D. They will make it right. Remind your buddy that perfection takes time.

phunk · March 29, 2013

First I would figure out the source of the gap, and see if I could fix it myself.

What do you think is creating the gap? It would be either the take-down pins location in reference to the mating surfaces is slightly off, so the surfaces are not accomplishing full touch-down.... or what I would suspect is much more likely, there is an extremely minor mismatch in the radius of the mating surface that curves upward near the buffer. I would suspect that they are touching in that spot before the flat area can touch-down fully in the rear. A radius like that, is going to be a pain in the ass for manufacturing a clean mating surface, and the tighter you want them to fit, the harder it will get to make them fit right. Sometimes even miscalculating the thickness of the material finish can take a perfect fit pair of parts and make them a no-go.

With the front take-down pin already installed, does the rear take-down pin feel like it requires any extra effort to insert? If you have only the rear pin inserted, and the front pin out, can you make them sit perfectly flush holding them together? Then lastly, with no takedown pins in, can you make them sit perfectly flush?

NoFail · March 29, 2013

Thank you robocop & phunk. With no pins they mesh perfectly. The set is back in Jason hands now. I had not tried to see what happens with just one other other pins by itself. Except with front pin inserted & swinging the upper down to position I think they did mesh well, if I remember, and then upon inserting rear pin the gap would present itself. The curve at rear does not seem to be touching with lower when the pins are inserted because I think upper is lifted up, by the rear pin, from lower when pins inserted.

So I sent Chris an email with pic asking for assistance. Waiting for reply.

Edited March 29, 2013 by NoFail

phunk · March 30, 2013

ah, that sounds like it might not be correctable without replacement. without having it in front of me, i have hard time deciding if its enough to bother me if it were mine. with most, if not all, of my guns, you can see light between spots of the slide/frame, and my SIG AR15 i can see light between the upper and lower.

phunk · March 30, 2013

Here I have attached pics of my sig m400 for comparison. Without bright light source behind it, looks great. With a flashlight, I can get light thru anywhere from the receiver extension up to the ejection port door

98Z5V · March 30, 2013

...because I think upper is lifted up, by the rear pin, from lower when pins inserted.
So I sent Chris an email with pic asking for assistance. Waiting for reply.

Could you charge it? Would the bolt carrier come all the way back, and into the receiver extension? If so, upper and lower center bore were okay, which would mean that it was okay.

I can get light to come through any upper and lower combo, even a couple maatched sets. It's gonna be there, to some extent.

I guess the only real test of it would be long-term testing. If the upper and lower center bore were off, you'd have some weird buffer face wear. At a minimum. Maybe even receiver extension wear, on the inside. Kinda like what you'd see with carrier tilt on a piston gun.

Edited March 30, 2013 by 98Z5V

NoFail · March 30, 2013

I don't know, 98, & I could have used my BCG to check it too, didn't Know to think of it. He doesn't have the BCG yet. Ill see if I can get his receivers back here so I can try that, good idea.

Thanks, phunk!! There is a lot more light showing through his than on yours. If you look at pic I posted, you see in front that there is no light and as you look front to back the gap increases as it progresses to the back. That makes me think the rear pin is holding rear of upper up, because either the upper hole is offset too low or the lower hole is offset too high.

unforgiven · March 30, 2013

If you drilled them out to alingnment would thier be a pin to hold it together??? Like a tensioning pin. <dontknow>

Robocop1051 · March 30, 2013

If you drilled them out to alingnment would thier be a pin to hold it together??? Like a tensioning pin. <dontknow>

It all depends on how techie the owner is, but it could be done. I think the issue is with the upper, and not the lower. An aluminum plug can be made and installed in the take down hole. (A guy did that here already with a bad 80% drill.) Then just re-drill the hole to match the lower.

If I remember correctly, the process involves some machining skill, a bit of metallurgy knowledge and a small quantity liquid nitrogen.

NoFail · April 1, 2013

It was late morning west, er, left coast when I emailed Chris and explained everything. No response yet. Not really my business as far as he's concerned, I think. If I don't hear from him tomorrow ill advise friend Jason to email Chris.