AR help - please :)

[92G]

This is the cam pin

Cam Pin AR15

Cam Pin AR15

bravocompanyusa.com

perhaps you mean the firing pin retaining pin?
who the F made your BCG?
good luck

 

[enbloc]

"Cam Takedown Pin", not "Bolt Cam Pin".

Davey has an older large-hole Colt lower fitted with a late-style small hole upper...

 

[92G]

There is no such thing as a cam takedown pin, but then again why let that stop the imagination.

 

[mac1911]

There is no such thing as a cam takedown pin, but then again why let that stop the imagination.

i think its because of the cam like lobe on the front pin/screw for the large hole lower to small hole upper install. ?

here is another style

Colt AR15/M16 Receiver Offset Adaptor Pin

www.eabco.net

 

[daveyburt]

both the bolt cam pin, and the front take-down cam pin were changed.

sschevy went through it all: Full BCG check, headspace check, tube alignment, gas rings, ejector, buffer tube stuff.... full inspection. Then those two new parts and some grease.
He also threw in a set of handgards which were much nicer than mine.

-so, we eliminated a couple of obvious issues.
We shall see what comes next....

thx again to Mr SS!

 

[Lank]

Just curious if you lubed it good. ARs like it wet.

Astroglide doesn't cut it in AR's

 

[daveyburt]

Astroglide doesn't cut it in AR's

You're right! - you totally have to use PornHub brand

 

[daveyburt]

@sschevy
Update: It runs! mwah, ha, ha, ha, ha.

It appears as though the lower's front take-down cam pin may have been culprit.
Threw a few different mags at it as well. All worked fine.
Played the shoot one, clear one game for a mag or two. Then shot a few, cleared one for the next mag and so on.
I still need to feed it some more but, for now looks like problem solved.
sschevy also changed the bolt cam pin as the firing pin had a little friction through there - and greased the bolt a bit.
Maybe it was a combination of the three things that let it run but, it's running.

But, I'm still wanting to get that big pin upper as this cam pin seems to add too much possibility of variance to the fit.

Thanks all - especially SSchevy - for the advice, info and assistance!!!

 

[enbloc]

I love a happy ending...

 

[daveyburt]

all different kinds!

 

[enbloc]

all different kinds!

Yep. What's that old saying? "A bad happy ending... is still better than a Good Day at Work..."

 

[cathouse01]

I’ve found that using something like the Accu Wedge helps make up for any slight variance in the fit of the adapter pivot and tightens up the whole upper/lower interface. Here is a knock off from Amazon:

View: https://smile.amazon.com/vnt-Receiver-Buffer-Hunting-Accessories/dp/B08HWK2S1J/ref=sr_1_1_sspa?crid=QOUPBQMNEOJ0&dchild=1&keywords=accu+wedge&qid=1607714336&sprefix=accu+wedge%2Caps%2C552&sr=8-1-spons&psc=1&spLa=ZW5jcnlwdGVkUXVhbGlmaWVyPUEyWTc0VzExQlhWMTlFJmVuY3J5cHRlZElkPUEwMTUxNzExMjlRNDlYT1RTMDExUiZlbmNyeXB0ZWRBZElkPUEwMjI0NDc0MVJFVlZNRUFBWE0wOCZ3aWRnZXROYW1lPXNwX2F0ZiZhY3Rpb249Y2xpY2tSZWRpcmVjdCZkb05vdExvZ0NsaWNrPXRydWU=

 

[cathouse01]

You do have one other option if all you plan to use are mil-spec uppers. A good gun smith who knows their aluminum welding can weld up the old large pivot pin hole and then re-drill the lower for a standard mil-spec pin. So you end up with a pre-ban lower that will accept standard mil-spec uppers. However it will no longer accept its historically accurate Colt large pivot pin uppers.

 

[mac1911]

You do have one other option if all you plan to use are mil-spec uppers. A good gun smith who knows their aluminum welding can weld up the old large pivot pin hole and then re-drill the lower for a standard mil-spec pin. So you end up with a pre-ban lower that will accept standard mil-spec uppers. However it will no longer accept its historically accurate Colt large pivot pin uppers.

then you just need a few of these

Colt Receiver Adapter Offset Bushing

Please view details for more information.

www.jsesurplus.com

Just be careful with any big hole small hole combo.
The fit and install can bit pressure on the pivot that can crack the ears if tilted open.

 

[daveyburt]

Just be careful with any big hole small hole combo.
The fit and install can bit pressure on the pivot that can crack the ears if tilted open.

Thx!
This is exactly why I want out of the large hole/small hole game.

 

[daveyburt]

You do have one other option if all you plan to use are mil-spec uppers. A good gun smith who knows their aluminum welding can weld up the old large pivot pin hole and then re-drill the lower for a standard mil-spec pin. So you end up with a pre-ban lower that will accept standard mil-spec uppers. However it will no longer accept its historically accurate Colt large pivot pin uppers.

good to know that's an option too.

I kinda don't want to ruin the original pre-ban config tho.

 

[jpm]

You do have one other option if all you plan to use are mil-spec uppers. A good gun smith who knows their aluminum welding can weld up the old large pivot pin hole and then re-drill the lower for a standard mil-spec pin. So you end up with a pre-ban lower that will accept standard mil-spec uppers. However it will no longer accept its historically accurate Colt large pivot pin uppers.

That's something I would not do with a pre-ban Colt. Too valuable to be screwing around with like this. Buy one with a small front pin (they do exist) and sell the large pin, that's what I ended up doing.

 

[cathouse01]

That's something I would not do with a pre-ban Colt. Too valuable to be screwing around with like this. Buy one with a small front pin (they do exist) and sell the large pin, that's what I ended up doing.

I actually agree, just stating it as an option. Other thing I didn’t point out was that if you weld and re-drilled, you’d probably have to refinish the entire lower to make it look right, which would make it even less historically accurate. But there are folks who don’t care about history, they just want a pre-ban that can have all the evil features.

 

[jpm]

I actually agree, just stating it as an option. Other thing I didn’t point out was that if you weld and re-drilled, you’d probably have to refinish the entire lower to make it look right, which would make it even less historically accurate. But there are folks who don’t care about history, they just want a pre-ban that can have all the evil features.

Didn't even think about the finish aspect! Good point. I think at that point cerakote would be your best option.