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M4 Receiver Optic Rail - Why it sucks with Picatinny 1913 spec Optic Mounts (Pics)


Duggan

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You're probably right about the source of the extrusion. Big names that do it right like LMT probably do everything in house.

 

I'm going to bust Surefire's balls on why they decided to deviate from the mil spec standard on their M80 rail. Their bottom rail is within spec, but the sides are not.

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Guest cleefurd

Machined our 1st test part around noon. Almost surreal to see a correct rail in position. Can't describe how "wrong" it makes the O.E.M. part look. No offense to Benelli, not their fault Joint Services review partys approved the present part.

 

 

 

 

Correction on the "Transverse" designators (engraved #'s in the bottom of the grooves). The screw locations dictate as follows;

  • T11
  • T9
  • T7
  • T5
  • T2
  • T0

Unless we offset them to the far left then we could put

 

  • T12
  • T10
  • T8
  • T6
  • T4
  • T2
  • T0

as is customary.

 

Any suggestion/preference?

 

Centered is traditional, but staggered numbers

Off-set allows typical numbering in unique location.

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Guest cleefurd

BTW;

 

1. Flexed receivers will NOT occur or we will replace it.

2. It won't shred a receiver in any way.

3. No axial cut, full height, full length.

4. May have a mounting boss/s for a heat shield (and or) handguards we have on our R&D shelf.

 

The mounting boss/s consists of a centered axial hole as seen from the front that does not interfere with any geometry or mounting slots. Inert presense unless utilized.

Edited by cleefurd
Design mod
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Machined our 1st test part around noon. Almost surreal to see a correct rail in position. Can't describe how "wrong" it makes the O.E.M. part look. No offense to Benelli, not their fault Joint Services review partys approved the present part.

 

 

 

 

Correction on the "Transverse" designators (engraved #'s in the bottom of the grooves). The screw locations dictate as follows;

  • T11
  • T9
  • T7
  • T5
  • T2
  • T0

Unless we offset them to the far left then we could put

 

  • T12
  • T10
  • T8
  • T6
  • T4
  • T2
  • T0

as is customary.

 

Any suggestion/preference?

 

Centered is traditional, but staggered numbers

Off-set allows typical numbering in unique location.

 

I'd go staggered in order to keep a consistent and recognizable T markings.

 

The odd numbers and skipping 2-3 at a time is just weird IMO.

 

That said, T-markings are of little real concern to me ... but my preference would most certainly be for the offset, every other T marking.

 

ETA - Also, congrats on making a successful, properly made replacement part! I know a lot of us cannot wait to get ahold of these ... thank you so much for your continued hard work Kip!

 

ETA2 - We want pics!

Edited by Duggan
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Guest cleefurd

We won't paint fill them so they won't be conspicuous.

 

The 1st sample part one was the centered pattern that begins 0-2, then skips 3 and 4 to finish out odd numbers.

 

Off-setting them all to the left allows all even numbers

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We won't paint fill them so they won't be conspicuous.

 

The 1st sample part one was the centered pattern that begins 0-2, then skips 3 and 4 to finish out odd numbers.

 

Off-setting them all to the left allows all even numbers

 

 

Am I the only one that thinks on such a short piece of rail, the T markings are unimportant?

 

Sorry if I get totally shot down on my opinion, but I would not feel at any loss if the rail did not have them. On such a short piece of rail, you know if your optic is a bit fore or aft of it's position last time. Just about as easily as remembering "the foot goes between "X" and "X".

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Am I the only one that thinks on such a short piece of rail, the T markings are unimportant?

 

Sorry if I get totally shot down on my opinion, but I would not feel at any loss if the rail did not have them. On such a short piece of rail, you know if your optic is a bit fore or aft of it's position last time. Just about as easily as remembering "the foot goes between "X" and "X".

 

I agree, as previously stated it is not of major importance to me, however if one is going to put T-marks, one should put them in a uniform order ... not skip random digits like a crackhead. :)

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We won't paint fill them so they won't be conspicuous.

 

The 1st sample part one was the centered pattern that begins 0-2, then skips 3 and 4 to finish out odd numbers.

 

Off-setting them all to the left allows all even numbers

 

I just wanna one ASAP. Use your best judgement.

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If you're going to do them, I'd recommend offset with consistant even-number markings.

 

Kip: Did you say that you're putting mounting bosses in the rails (as needed) in order to allow us to use these as replacement rails on some other commercially available accessories? Or am I misunderstanding the intent of these bosses?

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Guest cleefurd

The boss is a discreet hole in the front of the rail, not visible from the top or sides. That hole acts as a locating point for a heat shield and/or alternate handguard arrangement that may be made available down the road. There if you ever need it, out of mind if not.

 

As for the "T" markings; the M4 Carbine has them, and "Wpn Data Book" entries help an armorer "know" where to re-position a sight system when doing work on assorted armory guns. Since some of these may wind up in a military armory****(see note), the 2111/2112's (armorers) tend to find the feature useful. A number is often easier to recall than say... 4th slot from the front, errr wait or was that the fifth slot from the rear even with the sight edge... etc. You get the point.

 

We got off the crack (same crack Benelli was on with the totally random screw spacing) and shifted to the left, "T" numbers 0-12 by twos.

 

Pictures by Monday of a non-anodized sample.

 

****Note ; not all armories/repositories store tactical wpns with optics attached, but shotguns are an exception since MANY Marine armories still store shotguns in strong-boxes and not racks.

Edited by cleefurd
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The boss is a discreet hole in the front of the rail, not visible from the top or sides. That hole acts as a locating point for a heat shield and/or alternate handguard arrangement that may be made available down the road. There if you ever need it, out of mind if not.

 

As for the "T" markings; the M4 Carbine has them, and "Wpn Data Book" entries help an armorer "know" where to re-position a sight system when doing work on assorted armory guns. Since some of these may wind up in a military armory****(see note), the 2111/2112's (armorers) tend to find the feature useful. A number is often easier to recall than say... 4th slot from the front, errr wait or was that the fifth slot from the rear even with the sight edge... etc. You get the point.

 

We got off the crack (same crack Benelli was on with the totally random screw spacing) and shifted to the left, "T" numbers 0-12 by twos.

 

Pictures by Monday of a non-anodized sample.

 

****Note ; not all armories/repositories store tactical wpns with optics attached, but shotguns are an exception since MANY Marine armories still store shotguns in strong-boxes and not racks.

 

The rail will fit perfect.

It will mount using my stock screws/lock washers

It will be compatible with LaRue mounts.

It will be priced fairly.

It will be of equal or superior material quality when compared to the OEM rail.

Kip will produce it, and thus attatch his reputation to its performance.

 

This is fact. This is plenty enough. I will buy when available.

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The boss is a discreet hole in the front of the rail, not visible from the top or sides. That hole acts as a locating point for a heat shield and/or alternate handguard arrangement that may be made available down the road. There if you ever need it, out of mind if not.

 

As for the "T" markings; the M4 Carbine has them, and "Wpn Data Book" entries help an armorer "know" where to re-position a sight system when doing work on assorted armory guns. Since some of these may wind up in a military armory****(see note), the 2111/2112's (armorers) tend to find the feature useful. A number is often easier to recall than say... 4th slot from the front, errr wait or was that the fifth slot from the rear even with the sight edge... etc. You get the point.

 

We got off the crack (same crack Benelli was on with the totally random screw spacing) and shifted to the left, "T" numbers 0-12 by twos.

 

Pictures by Monday of a non-anodized sample.

 

****Note ; not all armories/repositories store tactical wpns with optics attached, but shotguns are an exception since MANY Marine armories still store shotguns in strong-boxes and not racks.

 

I knew you'd make the right decision. Crack kills!

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Guest cleefurd

Top side only so far, ends not yet cut to length, nor is the bottom radius applied. They will be bead blasted (like the one on the far right) and then tumbled prior to anodizing to ensure proper "satin" texture to resemble OEM finish.

P6080028_ca1c1.jpg

P6080025_4d264.jpg

Note numbers along left edge.

Lets see it!
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Very nice!

 

Have you considered making a steel replacement handguard bracket (the one captured by the magazine tube) that indexes with the boss on the rail?

 

This may help with torsional forces for when the usual suspects mount a big heavy optic. For military units who are mounting night vision and thermal imaging scopes, this added support would be welcome.

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Very nice!

 

Have you considered making a steel replacement handguard bracket (the one captured by the magazine tube) that indexes with the boss on the rail?

 

This may help with torsional forces for when the usual suspects mount a big heavy optic. For military units who are mounting night vision and thermal imaging scopes, this added support would be welcome.

 

I would think that the threads of the screws on the rail would be ripped from the reciever before enough rail movement occured that the keeper would restrain it just due to tolerances. No way could the keeper be made to tolerances as tight as screw threads. It would be impractical.

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It has to be made like a rag pad with wings at the front to limit leakage... Er, torsional twisting.

 

Those aluminum threads are very easy to strip unfortunately. The receiver itself flexs very easily too.

 

Benelli really screwed up by not installing the bolts from the inside of the receiver. Then it could have the threads into the picatinny rail, or into a bolt. Then if you did strip the screws, you'd only need to replace the rail rather than do costly repairs to the receiver. The bolts wouldn't be able to fall out from the inside while the barrel is installed either.

 

Or do it right and have the rail apart of the receiver like the on an A3 or A4 AR15 upper receiver.

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It has to be made like a rag pad with wings at the front to limit leakage... Er, torsional twisting.

 

Those aluminum threads are very easy to strip unfortunately. The receiver itself flexs very easily too.

 

Benelli really screwed up by not installing the bolts from the inside of the receiver. Then it could have the threads into the picatinny rail, or into a bolt. Then if you did strip the screws, you'd only need to replace the rail rather than do costly repairs to the receiver. The bolts wouldn't be able to fall out from the inside while the barrel is installed either.

 

Or do it right and have the rail apart of the receiver like the on an A3 or A4 AR15 upper receiver.

 

The rail on the M4S90 was almost an afterthought it seems.

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The rail on the M4S90 was almost an afterthought it seems.

 

It really does seem that way ... like they put all the effort in the ARGO system, and then as an afterthought said "hey we should probably slap a rail on top too".

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It really does seem that way ... like they put all the effort in the ARGO system, and then as an afterthought said "hey we should probably slap a rail on top too".

 

Yeah, I really don't understand it. EVERYTHING about the M4 is built with almost no room for improvement, except for the rail. Which is horrid.

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I was looking inside the receiver earlier. Seems they did the rear sight right. Screws from the inside, and screws from the outside. The inside screws are massive compared to the rails. They're also on the thickest portion of the receiver.

 

Sure, the receiver is milled out in the front for the barrel. So it would have required a thicker receiver.

 

They screwed it into 0.128" of aluminum.

 

Afterthought? Absolutely.

Edited by StrangerDanger
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I was looking inside the receiver earlier. Seems they did the rear sight right. Screws from the inside, and screws from the outside. The inside screws are massive compared to the rails. They're also on the thickest portion of the receiver.

 

On the picatinny rail, they even milled out the meat on the furthest to the rear screw. They screwed it into 0.128" of aluminum.

 

Afterthought? Absolutely.

 

All signs certainly point to that.

 

Oh well, at least "we" are taking steps to remedy the situation, and by "we" I mean Kip is graciously providing his expertise to assuage our whining.

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