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8/16/2022 4:37:09 PM
Posted: 6/18/2022 2:14:10 PM EDT
I got one of the luth-ar a1 sight kits, and it seems those are the only thing I can find available.  I put it together and the aperture is extremely stiff to move, and appears to be drilled off center.  Is there a better option somewhere I'm not seeing?
Link Posted: 6/18/2022 2:27:27 PM EDT
[#1]
check the EE here, or GunBroker for GI parts...and forget the commercial junk
Link Posted: 6/18/2022 2:39:11 PM EDT
[Last Edit: 556Cliff] [#2]
It's actually probably due to the flat spring pocket on the modern manufactured A1 type upper, if that's what you're using? They aren't machined correctly to allow the flat spring to compress correctly.

Also, the flat springs are hit and miss on their sizing. If you get an undersize flat spring pocket and an oversize flat spring it can make the fit even worse.

I have a bunch of modern (Brownells) A1 type uppers with the undersize flat spring pocket and I have a bunch of NOS Colt A1 rear sight kits from the The Amherst Depot. All the included flat springs where oversized and would not compress in the out of spec flat spring pockets. I ended up having to buy a bunch of flat springs from RRA which were on the smaller side and they would fit, but they needed to be pre-compressed to actually be able to thread the windage screw through the rear aperture due to the shallow out of spec flat spring pocket... The pocket is out of spec in both length and depth.
Link Posted: 6/18/2022 3:55:52 PM EDT
[#3]
Discussion ForumsJump to Quoted PostQuote History
Originally Posted By 556Cliff:
It's actually probably due to the flat spring pocket on the modern manufactured A1 type upper. if that's what you're using? They aren't machined correctly to allow the flat spring to compress correctly.

Also, the flat springs are hit and miss on their sizing. If you get an undersize flat spring pocket and an oversize flat spring it can make the fit even worse.

I have a bunch of modern (Brownells) A1 type uppers with the undersize flat spring pocket and I have a bunch of NOS Colt A1 rear sight kits from the The Amherst Depot. All the included flat springs where oversized and would not compress in the out of spec flat spring pockets. I ended up having to buy a bunch of flat springs from RRA which were on the smaller side and they would fit, but they needed to be pre-compressed to actually be able to thread the windage screw through the rear aperture due to the shallow out of spec flat spring pocket... The pocket is out of spec in both length and depth.
View Quote


It's a pre-brownells nodak upper but I guess they are probably the same?
Link Posted: 6/18/2022 4:05:04 PM EDT
[Last Edit: 556Cliff] [#4]
Discussion ForumsJump to Quoted PostQuote History
Originally Posted By psychotr:


It's a pre-brownells nodak upper but I guess they are probably the same?
View Quote


It's possible, but I'm not sure when these started to be machined incorrectly. All I know is that all my Brownells uppers purchased since 2017/18 were machined incorrectly in that area. And any slick side/A1/C7 type upper that's been made available since has had reports of the same issue with very difficult rear sight installation and overly stiff adjustments.

It's also possible that the location of the windage screw hole in the upper plays a part in all this.
Link Posted: 6/18/2022 4:58:48 PM EDT
[#5]
slightly squashing the spring with some pliers can help
Link Posted: 6/18/2022 6:05:16 PM EDT
[#6]
I have one of the Luth rear sights that was very hard to move. I took it apart and it had 2 flat springs stuck together.
Link Posted: 6/18/2022 8:16:44 PM EDT
[#7]
Same problem, flattening the spring helps.
Link Posted: 6/18/2022 8:34:23 PM EDT
[#8]
Link Posted: 6/18/2022 8:45:52 PM EDT
[#9]
One of the apertures being off-center is correct per the TDP. That's a built in allowance for the flip up/down movement on the screw
Link Posted: 6/18/2022 9:47:07 PM EDT
[Last Edit: coctailer] [#10]
No selling in tech
Link Posted: 6/19/2022 3:21:44 AM EDT
[#11]
One of the aperture is supposed to be slightly off center
Link Posted: 6/19/2022 7:56:33 PM EDT
[#12]
I just checked the TDP. The L aperture should be offset 0.007" to the right (when viewed from the rear)
Link Posted: 6/19/2022 10:25:27 PM EDT
[#13]
Discussion ForumsJump to Quoted PostQuote History
Originally Posted By mcantu:
I just checked the TDP. The L aperture should be offset 0.007" to the right (when viewed from the rear)
View Quote


Neat, I didn't know that.  It is the L aperture.  I'm somewhat surprised I can notice .007"


Link Posted: 6/19/2022 10:27:29 PM EDT
[#14]
Discussion ForumsJump to Quoted PostQuote History
Originally Posted By mike_nds:
We cut our flat spring pockets to the same depth as my sample Colt uppers.

It’s one of my specific checks for each inspection.

As others have said, giving the spring a squish before helps.

Also, run your screw through the aperture before you try to install. I’ve had apertures from Luth with bad threads before.
View Quote


I don't think it is binding up on the screw, I will try to smush the spring down and get the tension reduced as you and others have suggested.
Link Posted: 6/20/2022 8:39:15 AM EDT
[#15]
Discussion ForumsJump to Quoted PostQuote History
Originally Posted By mike_nds:
We cut our flat spring pockets to the same depth as my sample Colt uppers.

It’s one of my specific checks for each inspection.

As others have said, giving the spring a squish before helps.

Also, run your screw through the aperture before you try to install. I’ve had apertures from Luth with bad threads before.
View Quote


Yeah, never had an issue with Nodak or Colt receivers, actually I've never encountered this issue at all. That's probably because I've never used any of the newer stuff like Brownells or LuthAR receivers.
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