Thread: HK M1s90 +surefire spacer tube help

so i bought a surefire forearm from some guy on ebay. he said this "worked as intended" but he did not have the Spacer Tube that fits between the receiver and the forearm , which also goes around the magazine tube. Surefire no longer has these either. what can i do ... make it out of wood? does any body have the dimensions on this thing or another solution.

If you're game I'll make you one out of aluminum, but you'll need to get me a picture and some dimensions

I'm guessing this is what you're talking about: ImageShack® - Online Photo and Video Hosting

it looks like it's just a cylinder with a specific ID and OD of a certain length. If it's under 1.5" I have a 5gal bucket of 1.25" aluminum rod cut-offs.

Measure the diameter of your magazine tube (maximal diameter), the inside diameter of where the spacer is supposed to go, and the length between the fore-end and the receiver.

ya thats it exactly. that little black spacer tube thats to the right of the forearm in that picture. Ill bring home my calipers and get that measured up. what would the charge be for a service like that.

If it's just a cylinder... don't even worry about it. You're on your own for anodizing though. Seems you may not be the only person looking for this part, so I'll just write it off as product development.

ill get all the measurements this weekend, and take some photos of the older forend and parts. Thank You so much. !!!!!!!

No worries man, was hoping you would have dimensions today, I'm out in the machine shop.

sorry i could not get these sooner to ya but this is the best i could come up with.


for the custom part


Outside Dia . so it fits inside the forearm 1.355 ''
Inside dia. so it fits around the mag tube 1.100 ''

2.5 inches in length.


im pretty new at taking measurements on anything besides a bullet so i hope i did a good job.

I suppose we'll find out soon enough. I won't have time to get to it tonight, but I'll probably get it done over the weekend. PM me your mailing addy (don't care where as long as you get it)

Also, just for quick reference, what's the max dimension on your receiver? I don't want to make the spacer so it sticks up over the receiver, and what is the distance between your barrel and mag tube?

Receiver width is 1.460 inches wide


The tightest gap between the barrel and the mag tube looks to be 0.050 inches (but I measured by sticking as much paper in-between the gap and measuring the paper, the problem could be that the barrel flares out for about a ½ inch before it meets up with the receiver. do you need me to take some pictures?

Hopefully I got it all, I'm bubblegumed and totally spaced out on taking the picture, I'll get it in the mail later this week.



I made the inside a bit tight so it won't rattle, if you have any issues getting it in there, just grind it out with some sandpaper. I made the outside a bit undersize as I didn't have the right sized stock and I roughed the outside up with sandpaper to deburr it and make paint stick a bit better if you want to paint it.