AR XTC/Match Irons

[adv_rider]

So this weekend the match upper from forum member 10at6 arrived. I gave it a good clean and set it aside until this evening.

Went to put the scope on it to see how the balance was and ... wait, ah dip. Weaver rail. Booo.

Guess I need to rethink my scope mount setup.

For now the upper has to endure wearing an extra ultradot I had from my wadgun. Too bad the red dot is not the right tool. Nice low profile and very light. Oh well, it will at least get me through some function tests.

 

[jelenko]

Weaver rail.

Interesting. I didn't know there were any AR uppers with Weaver rails.

In any case, picatinny mounts should work on a Weaver rail.

 

[adv_rider]

The rail cross sections may be compatible, but the lug spacing is way off. I measure the 'presumed' weaver rail lug spacing as 2 1/8 inches.

 

[adv_rider]

Ok, no idea how I got the measurement in my prior post this morning, but it is definitely a weaver style rail with slots about 1 inch apart. Cross section is the slightly different as well compared to picatinny.

Hmmmm.

(Best ignore the out of place red dot)

 

[adv_rider]

Wonder what my options are at this point. I'd like to swap the stac (in a cantilever mount) as needed between uppers, so a picatinny base makes the most sense.

 

[jelenko]

I'm not an expert, but I don't think that's a Weaver rail. My understanding is slots in weavers are ~ .4 inch apart.

Personally, I would get a new upper receiver and move everything to it.

 

[adv_rider]

My understanding is there is no set standard for spacing between weaver slots.

Upper receiver is already in the side charger config, so kind of a shame to dump it.

 

[Jeff Porter]

Burris AR Signature QD PEPR cantilever mount uses a single lug on the clamp base. I have my STAC in one and use it on weaver and pic rail receivers. Might have needed to open up the weaver groove with a file but it wasn’t much.

 

[VA_XTC_Shooter]

Ok, no idea how I got the measurement in my prior post this morning, but it is definitely a weaver style rail with slots about 1 inch apart. Cross section is the slightly different as well compared to picatinny.

Hmmmm.

(Best ignore the out of place red dot)

you could have slots milled in the the top to picatinny specs

 

[adv_rider]

That was going to be the plan, but the rail is also about .6 inches higher than a standard a4 picatinny height above the receiver. I think an adjustable stock would cope fine, but it still is more weight up high.

 

[adv_rider]

I think my 2 best options are:

1. Get a new upper receiver, have it modified for side charging, swap everything over.

2. Essentially get the weaver rail block cut off just above the top of the receiver, get a picatinny blank cut to the correct height, drill and tap for installation of replacement picatinny from the top. I could also keep the cut off portion of the old weaver rail and reinstall if I ever came into irons for a weaver base.

#1 is cleaner, but I assume more costly. Also I have never disassembled an upper and there may be tricks with the older design handgaurd tube.

#2 gives more flexibility and may be cheaper, but more of a chance to turn out jenky. Also wondering if a m-lok rail would work since they are low profile. Honestly I have stayed willfully ignorant of ar accessories and rails, so not sure if picatinny optics bases work on mlok.

 

[Walt Krafft]

That looks like an A2 receiver that had the handle cut off and the rail added. Stripped uppers are pretty cheap. Get a new one.

 

[adv_rider]

Is there a company that sells stripped side charging uppers that aren't hot garbadge? I only see Bear Creek Arsenal and I'm not doing that...

Otherwise 265 for a modified side charging upper receiver and bolt carrier from woa... They don't list just a stripped side charging upper but I could always ask.

 

[jelenko]

Is there a company that sells stripped side charging uppers that aren't hot garbadge? I only see Bear Creek Arsenal and I'm not doing that...

Otherwise 265 for a modified side charging upper receiver and bolt carrier from woa... They don't list just a stripped side charging upper but I could always ask.

WOA might be willing to sell you just the upper. I would want to ask them if you could return the upper if the bolt/handle you have doesn't fit. I've found that all modified bolts/handles aren't in exactly the same place on the bolt.

Keystone Accuracy might be willing to do the cut in a new upper that you sent them. I know he can, just not sure what work he's accepting these days.
@Walt Krafft Are you aware of other gunsmiths who would make the cut on an upper?

@adv_rider Whoever does the work on the new upper, you should send them the bolt with the handle.

PS. I would agree about Bear Creek.

 

[adv_rider]

Thank you all for the help and advice. This is new territory for me and I greatly appreciate it.

Another option is Fulton Armory - they are 30 min away and sell stripped flat top uppers for 175. In theory I could make an appt, verify my bolt fits and walk away with the stripped upper.

Not sure if that is a reasonable price, but it seems pretty straightforward.

 

[adv_rider]

So yet another complicating factor. Looks like the barrel is not cut for m4 feed ramps?

 

[mdkeeler3]

Is there a company that sells stripped side charging uppers that aren't hot garbadge? I only see Bear Creek Arsenal and I'm not doing that...

I still have a few heavy wall upper receiver's already milled for a side charging handle. I still run iron sights on all my spaceguns with this upper.

SELLING - AR-15 Parts (Upper Receivers, BCG's & Handguards)

I am helping my gunsmith and friend liquidate some surplus AR-15 parts he no longer needs. He is not on-line or in any of the forums, but he does communicate by e-mail. These are all new high-quality parts. 1) Heavy wall forged upper receivers machined for a side charging handle with complete...

forum.accurateshooter.com

 

[Rtheurer]

So yet another complicating factor. Looks like the barrel is not cut for m4 feed ramps?

before the sky is falling... Does it matter? Have you shot it yet to confirm that it is causing some issues?

 

[VA_XTC_Shooter]

So yet another complicating factor. Looks like the barrel is not cut for m4 feed ramps?

You're fine. Your upper doesn't have cuts to match the M4 ramps in the barrel extension anyway, so you wouldn't really gain the M4 ramp "advantage"
I don't have M4 ramps and haven't had a stoppage because of it.

Now, if you are concerned about that extension in a new upper with M4 ramps, yeah, you could have issues. But that's when you just take a dremel to your standard ramps. The cone shaped stones, diamond stone, a couple of cratex bits and you are golden. That's how they are polished anyway.

 

[adv_rider]

Sooo .... lots of different tangents on this thread. I'll do my best to summarize:

Match upper config (as is)
-Appears to be an A2 upper receiver with the handle cut off and replaced with an integrated weaver optics rail
-Upper is cut for side charging bcg and has a side charging bcg
-Barrel/receiver is for the standard rifle profile (not M4 profile extensions and ramps)

Problem:
For sights I was planning on using a recently purchased STAC III scope in a cantilevered mount. This will not work with the weaver rail. Furthermore the weaver rail is ~0.6" higher than a normal flat top rail, so cutting slots into the weaver to accommodate the picatinny optics mount puts everything quite high. Forgetting the poor head alignment for a moment, I did sometest holds and was able to notice the weight higher up. Maybe I'd adjust, but it was noticeable. At 6'2" I don't need more weight up high.

The proper option appears to be to replace the upper receiver with a true flat top w/ picatinny. This introduces a new set of problems:
-no guarantee the current side charging bcg will fit/work. Since I will be using an adjustable buttstock going to need a side charger receiver.
-new upper receiver is going to have the m4 feed ramps. This would be the 'bad' situation in the diagram VA_XTC_Shooter posted
-while unlikely, I suppose headspace issues could also be introduced.

These problems are not insurmountable, but you get the idea.

Now, to be honest I have not shot this yet, but all I have to mount for sights is an old ultradot. I doubt I'll be able to determine accuracy potential with that, though benchresting it should give me a clue. PO said the upper does very well and I trust them. Discussion on the thread has been very helpful in understanding potential fixes and scope ... and hopefully avoiding further mis steps.

Shame on me for not really understanding what I was getting, but I had never heard of an AR with weaver rail and I think the PO presumed I was going with irons. To be fair I thought I'd be going with irons when I started this thread, but after test driving the scope on my service rifle I don't want to go back!