Rails Archives

The short answer to that question is “No” but then when someone asks if they can use some Picatinny mount on a Weaver rail it becomes “It depends”. Why is that?

Well, the Picatinny rail does have a true military specification – “MIL-STD-1913″ that lays out the details but nothing like that exists for Weaver rails – when writing this post, I did some digging and I can’t find an authoritative width of the rail, the recoil slot is about 0.180” but their spacing, number and depth can all vary.

The reason that Weaver rings and mounts can typically fit a Picatinny rail is that the recoil slots are 0.206″ wild and spaced 0.394″ apart. However, if you are using rings that were on a Weaver rail, while the bolts or recoil bars may fit the Picatinny slots, the spacing between the mounts may need to be adjusted.

There are plenty of posts out there with more details but I would tell you to only use Picatinny rails and mounts going forward if at all possible. The reason is that because there is the published MIL-STD-1913 specification, the interoperability of parts from different vendors is far, far more likely.

This is the Picatinny Rail / MIL-STD-1913 cross-section view.
It is from the Wikipedia entry about the MIL-STD-1913 Picatinny Rail.

This side-view shows the details of the recoil slots.
It is from the Wikipedia entry about the MIL-STD-1913 Picatinny Rail.

I was unable to find a US DOD direct link for the MIL-STD-1913 but I did find two sites hosting scanned copies – BiggerHammer and EverySpec

Some Photos

What inspired me to sit down and write this is my working on a 5.56 Polish Beryl right now. The actual Beryl optics rails are a both rare and cost a fortune. While there are Picatinny versions out there, I have two of the older Weaver rail design they started with and am lucky that my ADM and Vortex mounts all surprisingly fit – it’s always nice when things work out in a good way.

At first glance, you’d think it was a Picatinny rail with the slots going the whole length. It’s actually a Weaver rail. Weaver rails can have dramatically different numbers of slots and spacing.

The top is a RS Regulate Picatinny rail. The bottom is the Beryl’s Weaver rail. You can see the difference in the recoil slot spacing. By the way, RS Regulate is my favorite AK scope mount hands down.

That is the bottom side of an American Defense Manufacturing (ADM) mount and my goto scope mounts these days when I want quick connect levers. The recoil bar is what may or may not fit a Weaver rail. Now this only has one lever and bar – One piece scope mounts will likely have two recoil bars and the spacing between them could compound fitting challlenges.

The Vortex UH-1 and Crossfire red dot on an ADM base both fit the Beryl rail.

In Closing

Weaver and Picatinny rails are different. In general, you can use Weaver mounts on a Picatinny rail but you may not be able to put a Picatinny mount on a Weaver Rail.

In my case, I got lucky and could mount the red dots no problem. A mount with two screws/contact points may or may not line up – that will just depend on many factors in terms of the spacing between the recoil bars, size of the bars, etc.

Bottom line, go with Picatinny rails and mounts going forward to maximize your ability to move components around.

For more information:

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I like to heat treat my entire lower rails before I install them. Some guys just heat treat the tip but I go for overkill. When I would get flats and rails from AK-Builder for whatever I was doing, I’d do all the lower rails at once and store them oiled in a bag for later use.

The process is simple, I heat them up with a torch to dull to medium orange, which comes out to around 1500-1600F. Some guys use magnets and stop the heathing when magnetism is lost, some use marker/applied heat indicators – there are many ways to do it. I tend to use my sheet metal/jewelers oxy-acetelene torch. It is known as a Meco Midget and the thing is awesome for sheet metal work. I’ve had mine for over 10 years and never had a problem. I have a giant Journeyman II set but find it too big and cumbersome for stuff like this.

Tin Man Technologies (TM Tech), who I got mine from years ago and you will need to search around for it or find what some call a jeweler’s torch

Next, quench the parts in room temperature used engine oil. It works great for me. I have an old navy fuse can with a lid glued to a piece of wood that I use for this purpose.

After that, I anneal them by putting them in a flat pan, pouring in some brake fluid with some paper towel exposed, lighting the towel and then letting it all burn it off, which is about 500. It’s messy and you want to do it outdoors for sure – I let it all burn off and then air cool. Some guys put them in a toaster oven at 500F for 5-10 minutes and let them slowly cool down by turning the oven off. That works too.

Here the rails right after the brake fluid is finished burning off – you can see some of the soot that is generated:

When you weld the rails in with a spot welder, just be careful not to ruin the heat treat by letting a tong get up against the ejector tip and heating up. I’ve done it twice over the years. One time I didn’t notice and had to repair a peened over ejector and the other time I saw the discoloring of the tip and did a spot hardening of the ejector tip while it was in the receiver.

At any rate, I’d then oil everything and put them in a ziploc bag for future use. I would sand the backs of the rails prior to installation to get good spot welds.

While I use OA for a lot of my work, MAPP works just fine too.