Side Rails Delete

1076 Views 18 Replies 8 Participants Last post by [email protected]@X, 2 mo ago

[email protected]@X

Discussion Starter · 3 mo ago

Ever since I became an owner of an SCAR17, I wanted to remove the 9 & 3 o'clock factory rails. I have a forward choke style foregrip and these 2 rails just limits this type of grip.
I recently purchased a Lancer Systems, carbon fiber handguard, which I installed this past weekend. I really like the feel & look plus it removed some of the fat as well. I really hope it lives up to my expectations.
Now more than ever, I would like to remove these rails, add a Railscales Karve index/stop with some strategically placed grip tape.
In order for me to do that, I will need to acquire 2 replacement screws to replace the 2 (T25) factory "Barrel Extension Screws".
Does anyone on here know the thread pitch for these 2 screws?
Although the factory yoke/collet that these screws on to is no longer needed with this handguard, it is replaced by another collet needed for the installation.
Therefore these 2 support screws are still needed for this handguard.
I will need a shorter screw, preferably with a flat head.

Blue Rectangle Wood Font Brick

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1KPerDay

· #2 · 3 mo ago

This guy @Rego Systems will know for sure.

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[email protected]@X

Discussion Starter · #3 · 3 mo ago

1KPerDay said:
This guy @Rego Systems will know for sure.

Thank you broda!

Reactions: 1

Kansas boy

· #4 · 3 mo ago

M5 x 8mm Torx flanged button screws are what I use. You can get them from AccuGroup.

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[email protected]@X

Discussion Starter · #5 · 3 mo ago

Excellent... Kansas boy!.. I did see your old post on deletion of rails as well.
M5 is what I was looking for..
Thanks
I glanced @ Rego Systems alternative (which I was unaware of) and I'm impressed at their hardware & end result finish.

Reactions: 2

Rego Systems

· #6 · 3 mo ago (Edited)

Thank you all for the mention. Yes the OEM front barrel support screws are M5x0.8mm (thread diameter and pitch), I don't recall the actual length but it's probably around 8mm.

The SCAR receiver has a unique angle countersink for those screws. So I had to design completely custom screws to allow them to fit flush with the SCAR receiver, and I had to use a different thread size/pitch for them to fit in this space and meet strength requirements. So because of this the Rego custom front barrel support screws will only work with the rest of the Rego forend kit.

If I can help in any other way just let me know.

-Brett

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Kansas boy

· #7 · 3 mo ago

[email protected]@X said:
Excellent... Kansas boy!.. I did see your old post on deletion of rails as well.
M5 is what I was looking for..
Thanks
I glanced @ Rego Systems alternative (which I was unaware of) and I'm impressed at their hardware & end result finish.

Cool, I did what I could with what I had then. If I get another SCAR, I'm getting a Rego forend for it.

Reactions: 1

[email protected]@X

Discussion Starter · #8 · 3 mo ago

Rego Systems said:
Thank you all for the mention. Yes the OEM front barrel support screws are M5x0.8mm (thread diameter and pitch), I don't recall the actual length but it's probably around 8mm.

The SCAR receiver has a unique angle countersink for those screws. So I had to design completely custom screws to allow them to fit flush with the SCAR receiver, and I had to use a different thread size/pitch for them to fit in this space and meet strength requirements. So because of this the Rego custom front barrel support screws will only work with the rest of the Rego forend kit.

If I can help in any other way just let me know.

-Brett

Brett,
Thanks again for your assistance all the information provided.

Reactions: 1

Robe

· #9 · 3 mo ago

I also installed a Lancer carbon fiber forend and liked it. But, I too stumbled upon the Rego System forend and now have one of those. I like the Rego System product because it is pretty similar to the Lancer. Just as slim. Fit is very similar. Lightweight. Many of the same great features but in an aluminum forend. The real Rego advantage is the hardware kit that comes with the Rego forend. it is a great addition. My favorite system by far.

Reactions: 2

ShootingSight

· #10 · 3 mo ago

Screws used on the SCAR and wrench size are:
1 – M5x10 for the top of the rear trunnion – 3mm Allen
9 – M4x6 for the sides of the rear trunnion, the guide rail, the case deflector – 2.5mm Allen.
4 – M4x8 for the ‘teardrops’ and front sling plate – 2.5mm Allen.
4 – M4x12 for the side rails – 2.5mm Allen.
2 – M5x12 T25 Torx for the bottom rail – T25 Torx.

All of these are standard 90 degree taper heads.

The 6 screws for the barrel extension (4) and the front of the side rails (2) use a 60 degree head taper. T-25 Torx, M5x0.8mm. The threads are 4.75mm long below the taper.

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[email protected]@X

Discussion Starter · #11 · 3 mo ago

ShootingSight said:
The 6 screws for the barrel extension (4) and the front of the side rails (2) use a 60 degree head taper. T-25 Torx, M5x0.8mm. The threads are 4.75mm long below the taper.

You are "The Man"!!.. The 60° head tapper is what I needed, to find the 2 replacement units.
Thanks for sharing your knowledge..

Grinder

· #12 · 3 mo ago

ShootingSight said:
Screws used on the SCAR and wrench size are:
1 – M5x10 for the top of the rear trunnion – 3mm Allen
9 – M4x6 for the sides of the rear trunnion, the guide rail, the case deflector – 2.5mm Allen.
4 – M4x8 for the ‘teardrops’ and front sling plate – 2.5mm Allen.
4 – M4x12 for the side rails – 2.5mm Allen.
2 – M5x12 T25 Torx for the bottom rail – T25 Torx.

All of these are standard 90 degree taper heads.

The 6 screws for the barrel extension (4) and the front of the side rails (2) use a 60 degree head taper. T-25 Torx, M5x0.8mm. The threads are 4.75mm long below the taper.

And though he doesn't mention it, Art's SCAR screw sets are top notch

Reactions: 1

ShootingSight

· #13 · 3 mo ago

Note, the 60 degree taper is not an industry standard metric screw - I sell replacements for the OEM, but had to have them custom machined. 60 degree screws do exist, but I have only ever found them in imperial thread sizes.

[email protected]@X

Discussion Starter · #14 · 3 mo ago

ShootingSight said:
Note, the 60 degree taper is not an industry standard metric screw - I sell replacements for the OEM, but had to have them custom machined. 60 degree screws do exist, but I have only ever found them in imperial thread sizes.

Thx. for the heads up... I might end up just getting button heads or maybe some 45° flat heads w/countersunk finishing washers.

icantpickaname13

· #15 · 3 mo ago

ShootingSight said:
Screws used on the SCAR and wrench size are:
1 – M5x10 for the top of the rear trunnion – 3mm Allen
9 – M4x6 for the sides of the rear trunnion, the guide rail, the case deflector – 2.5mm Allen.
4 – M4x8 for the ‘teardrops’ and front sling plate – 2.5mm Allen.
4 – M4x12 for the side rails – 2.5mm Allen.
2 – M5x12 T25 Torx for the bottom rail – T25 Torx.

All of these are standard 90 degree taper heads.

The 6 screws for the barrel extension (4) and the front of the side rails (2) use a 60 degree head taper. T-25 Torx, M5x0.8mm. The threads are 4.75mm long below the taper.

To clarify here the front side rail screws are 8mm in total 4.75 below the taper. How long would you recommend to purely remove the rail completely and replace with a proportionally shorter screw?

ShootingSight

· #16 · 3 mo ago

Here is my drawing of the the FN bolt (unofficial):

Slope Font Schematic Parallel Pattern

Here is an industry standard 8mm bolt. Thread length is the same, and I have modified some in the past, by putting them in a rotary fixture in a grinder, and changing the head angle. They fit, but I do not know if the wall width between the bottom of the socket well and the tapered face starts getting thin and compromising strength.

Another approach would be to machine a conical nut with a female 90 degree taper on one end, and a male 60 degree taper on the other, to screw on to a regular bolt, though the bolt head would stand proud at that point.

Font Parallel Symmetry Circle Pattern

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[email protected]@X

Discussion Starter · #17 · 2 mo ago

Thank you for the heads up. Ideally the 60° angle flat heads are ideal for a delete, but unfortunately Rego systems won't sell these alone. I ordered these to try them.out Low Profile Screws M5 (10 Pack)
I'm hoping the low profile head won't be uncomfortable or get in the way..

Rego Systems

· #18 · 2 mo ago (Edited)

[email protected]@X said:
Thank you for the heads up. Ideally the 60° angle flat heads are ideal for a delete, but unfortunately Rego systems won't sell these alone. I ordered these to try them.out Low Profile Screws M5 (10 Pack)
I'm hoping the low profile head won't be uncomfortable or get in the way..

Hello Max, just to offer some clarification, it’s not a matter of me being unwilling to sell the screws alone.

The issue is that custom flush Rego screws are a completely different thread size and pitch then the OEM M8x0.8mm screws. The Rego screws will not thread into the OEM front barrel support. They will only work with the Rego bridge that attaches the SMR forend to the receiver.

Unfortunately creating a complexly flush forend for the SCAR couldn’t be achieved with off the shelf parts. It required that I design several custom pieces of hardware that work together as an integrated system. This is why the Rego forend kits come with 17 individual components, 13 of which are CNC machined specifically for the SMR kit.

If there is anything else I can do to help with your project please let me know.

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[email protected]@X

Discussion Starter · #19 · 2 mo ago

Rego Systems said:
Hello Max, just to offer some clarification, it’s not a matter of me being unwilling to sell the screws alone.

The issue is that custom flush Rego screws are a completely different thread size and pitch then the OEM M8x0.8mm screws. The Rego screws will not thread into the OEM front barrel support. They will only work with the Rego bridge that attaches the SMR forend to the receiver.

Unfortunately creating a complexly flush forend for the SCAR couldn’t be achieved with off the shelf parts. It required that I design several custom pieces of hardware that work together as an integrated system. This is why the Rego forend kits come with 17 individual components, 13 of which are CNC machined specifically for the SMR kit.

If there is anything else I can do to help with your project please let me know.

Yes! You're right and my apologies, my mistake.
You did mention that thread pitch was completely different.
This screw is important since it holds the sub-brace in place..
As far as the other 4 rear-ward screws & spacers for the rail delete, do you have these available for purchase individually?

Thx..

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