Team,

 

Some of you are connected with me on Farcebook might have seen the latest project I've come up with to keep myself off the streets, and out of gaol.

 

Mainly because I can, and possibly to develop a product for commercial sale, I'm looking at an M-Lok compatible accessory rail for my Marlin 336.

After all, I'm thinking that if I want an accessory rail for this weapon, surely others would like it as well?

 

As to why? Well... if you mob recall my latest update on The Mistress in the Studboard (https://www.lightfighter.net/to...-marlin-336-in-30-30) I want to mount a Magpul AFG on the fore-arm.

 

The short version why I'm going for M-Lok over Keymod rail standard:

  • I'm looking at mounting Magpul furniture and accessories, so thought to stick with the system that's designed for the accessory range I'm planning on using.

  • M-Lok is a great deal easier to fabricate with the facilities I have access to. This also makes it a damn sight cheaper in terms of machining operations.  M-Lok also fits within the limited real estate a bit easier.

  • Due to my experience in industry and limited engineering, I have some doubts about Keymod holes.

 

Now, I've done my usual project research with everyone's favourite research tool: Google.

I've also downloaded the Magpul FAQ/info sheet on the M-Lok idea. Really nice document.

 

So, in order to move forward with this project, I need some data.

 

  1. What are the accurate dimensions of the M-Lok slots and their spacing?

The Magpul FAQ lists the M-Lok slot dimensions and spacing as “approximate”.

 

  1. What is the length of the T-Nut used?

I need to calculate the clearance needed between the fore-arm rail and the barrel/magazine tube.

 

  1. What is the wall thickness of the rail/fore-arm?

Research so far of free-float M-Lok compatible fore-arms for AR-15 series suggests 0.29inches (or 7.366mm). I'm wondering if I can reduce that wall thickness down to 6 or even 5mm, since my application isn't free-float, I'm planning on using conventional barrel band anchor.

 

So far, I'm looking at doing some designing, and then to convert the design to 3D format for CNC machining. Along the way, I'm planning on using a mate's 3D printer for prototyping of the layout I want.

I'm still trying to work out if I want a tri-rail (slot rails at 3, 6 and 9 o'clock), or a five-rail layout (slot rails at 1:30, 4:30, 6, 7:30 and 10:30). Still doing some scribblings on paper. More to follow on this one.

 

I'm even thinking about whether to include sockets for push-button sling swivels.

 

Look forward to any assistance you can provide. 

=======================
Forward!
Where we are, where we belong, where we should be.

  

Location: Back in Bris-Vegas, wondering at the bright lights of the big smoke

Original Post

I have a few polymer M-Lok hand guards, from Magpul, and the thickness can vary, I think. 

 

When I ordered some spare T-nut sets from Magpul, they came with two different length sets of mounting botls: one longer than the other. I ASSume that this is to make certain that they will accommodate all of the potentially various wall thicknesses of other manufacturers' hand guards.

 

For example, even on Magpul's polymer MOE SL hand guard, the thickness of the side M-Lok slots seems to be different from the bottom M-Lok slots, which also have an aluminum heat shield behind them.  I base this upon how large of a gap I needed to have between the T-Nut and the bolt, when mounting accessories to the hand guard.

 

I ASSume that this is to make certain that they will be compatible with various manufacturers hand guards.

 

I am sure that this can vary even more, on solid aluminum hand guard sets from other manufacturers, as well.

 

I am sorry, but don't I have the tools to accurately measure the T-nuts, for you.

 

 

I am really interested to see what you are designing!

                                                                                             ____________________________________________________________

                                   

                                                                                              "Hokey religions and ancient weapons are no match

                                                                                                 for a good blaster at your side."        -Cpt. Han Solo

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Joined: 3/20/05 4:14 PM        Location:  North Carolina

Thanks mate!

Knowing that there are long and short T-nuts helps a fair bit.

I may have to bite the bullet earlier than I thought and buy the furniture (like the AFG) I want to see how much clearance I need.

=======================
Forward!
Where we are, where we belong, where we should be.

  

Location: Back in Bris-Vegas, wondering at the bright lights of the big smoke

I apologize if my explanation was misleading, but the Magpul T-nuts themselves are all the same standard size.  

 

It is actually the treaded bolt/screws, which fasten to the T-nuts through the M-Lok slots to the accessory, that are of different lengths.

 

Meaning that, no matter how thick the hand guard is, the T-nut will still interface correctly.

 

This is what allows for the various thicknesses of hand guard, I think.

 

I will try to put up some photos for you, tomorrow.

                                                                                             ____________________________________________________________

                                   

                                                                                              "Hokey religions and ancient weapons are no match

                                                                                                 for a good blaster at your side."        -Cpt. Han Solo

                                                                                            ____________________________________________________________

 

Joined: 3/20/05 4:14 PM        Location:  North Carolina

OK, so here are some photos, that might help you out, Mick.

 

This is an M-Lok hand stop that I got from Arisaka Defense (an awesome piece of kit, by the way):

 

 

I comes with a standard, Magpul T-Nut, but a very long mounting screw, which is needed for the hand stop, due to its unique design characteristics:

 

 

Here is the hand stop, attached to a six o'clock M-Lok slot on a Magpul MOE SL polymer carbine hand guard:

 

 

Inside of the hand guard, the T-Nut is correctly locked, perpendicularly, into the M-Lok slot, with very little of the screw's threads protruding:

 

 

 The length of the fastening bolts, can vary from each manufacturer's accessories or hand guards, depending on the specific application.

 

For example, the very long Arisaka supplied screw is on the left, and in the center and on right, are two different length screws from Magpul.

 

 

Note that the depth, or thickness, of all of these T-nuts is the same.  

 

In fact, I think that this is because Magpul is the sole manufacturer of the T-Nuts, in order to ensure their universal compatibility.

 

 

 

 

So, I guess what I am trying to convey is, I do not think that it really matters how thick or thin your hand guard is (Z dimension) because longer or shorter screws can be used.

 

Since the T-nut is standardized, it will work with any M-Lok slot that is made to the specified shape (X and Y dimensions).

                                                                                             ____________________________________________________________

                                   

                                                                                              "Hokey religions and ancient weapons are no match

                                                                                                 for a good blaster at your side."        -Cpt. Han Solo

                                                                                            ____________________________________________________________

 

Joined: 3/20/05 4:14 PM        Location:  North Carolina

Beauty!

 

Thanks mate, that helps a bloody great deal. Gives a really good idea of how much stand-off I need to account for.

 

I owe you a beer, old son.

=======================
Forward!
Where we are, where we belong, where we should be.

  

Location: Back in Bris-Vegas, wondering at the bright lights of the big smoke

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