Sunday, June 26, 2011

TWS Gen.II AK Scope Mount

I finally got the Gen. II TWS scope mount and peep sight that I ordered from Dallas Shooting Supplies a few days after Christmas.  Harummph!!  It came in about the 20th of May.  I'm not exactly sure, because I wasn't home and they didn't supply a tracking number.  I believe that I got the latest version with the "spacer" for the .308 Saiga rifles.  My intention was to mount it on my Interarms Tantal (Polish AK-74, more or less, with some unique differences).

How Does It Work?
The TWS Gen. II scope mount is a railed dust cover.  Wait a minute, don't start groaning just yet, this one's pretty clever, and seems to work really well! 

The cover is held in place in front by a hinge pin that passes through the front of the mount, and the holes where the pin for the rear sight used to reside.  That pin fits tight too.  The tab that the hinge pin goes through is attached to the dust cover with two socket head screws.  The overall length of the TWS mount, from rear sight bracket to stock trunnion, can be adjusted with these two screws in order to help make the mount fit individual rifles.

A tab, bent in on the right side of the cover works as a spring to maintain the lateral alignment of the rail.

Top: Right, rear corner of TWS dust cover mount.  Bottom: Inside, rear of railed TWS dust cover.

An angled surface on the bottom edge of the take-down button supplied with the rail interacts with the cover, like a wedge, to hold the cover tight against the stock trunnion.  Recoil only helps to snug the mount down tighter.

Crude attempt to show the angle of the button on the TWS guide rod.

The TWS dust cover mount is held tight to the receiver every which way.  The barrel is press-fit and pinned into the barrel trunnion, which is firmly riveted to the receiver.  The rear sight and optic mounted on TWS mount should stay aligned with the barrel.

The TWS mount will fit most stamped and milled 5.45mm, 7.62x39mm, 7.62x51mm (Saiga), and .223Rem AK variants.  It will not fit Yugo's, because their dust covers are half an inch shorter than most AKs.  It will not fit Saiga shotguns, because the shotguns have different barrel trunnions and rear sights.

It doesn't attach to the tang of stock trunnion, so it will work with AK pistols, underfolders, and rifles with side-folding stocks.

I believe there are plans for a Yugo version.


The TWS mount is supposed to hold a zero, and return to zero even after you flip it up and lock it back down, through the simple machine elements described above.  For the most part, it does.  After sighting in, I flipped the mount/dust cover up, and unseated the take-down button/recoil spring guide, and then I buttoned everything back up again and vigorously racked the bolt carrier a few times.  I did this return-to-zero test a couple of times.  The first 2 or three shots would go a little bit to the right before the recoiling bolt carrier fully seated the take-down button/recoil spring guide against the rear of the dust cover/mount.  After those first few rounds, the bullets would start going through into 10-ring again.  At 12 paces the difference was maybe half an inch for the 1st round.  I can live with that.

This testing was done without fitting the recoil spring guide to the stock trunnion.  Return-to-zero may be better now that it’s fitted -- more on this when I get to installation.

First Impressions
Initial inspection was very positive.  I was happy to see that the font size of the engraving was not as large as on some of the prototype and beta-test mounts.  I also was a little surprised at how nice the mount looked.  I wasn't sure exactly what I'd get from a small company.  The mount looks very nice, and there's no machining marks on the outside of the unit.  Every other slot in the rail has a number machined (maybe laser engraved?) on it.  I'm very pleased. 

Please note that my Interarms Tantal has a grey finish.  Keep that in mind as you look at the picture of the mount on my rifle.  The grey rifle finish is the oddball, not the finish on the TWS mount.  I actually really like the grey/black two-tone look. . . I just need Duracoat the silver Aimpoint.

The mount didn't come with any instructions.  Having read through the forum thread, and seen a YouTube video on how to remove an AK rear sight, I knew what I had to do.  That TWS Gen. II Scope Mount thread currently stands at 69 pages, and it's still going.  The mount should come with an instruction sheet, it's not a simple drop-in/bolt-on installation.  I was able to get the mount installed in 25-30 minutes, with a lot of that time spent fighting to get the hinge pin installed against the sight spring pressure.  Like I said, the pin fits tightly, and forcing everything into place took some real effort.  Removing the rear sight from my rifle was not as easy as shown in the video either, so that took maybe 3-5 minutes, instead of about 2 seconds as shown.  Getting the recoil spring removed from the Tantal take-down button/recoil spring guide, and reinstalled on the button/guide supplied with the mount was easier than I had expected, but remember, there were no instructions included, and I was working on prior knowledge from reading 50+ pages of forum posts.  Without knowing what to do, it would have taken a whole lot longer.

I did get the mount installed on the Tantal without cutting or filing anything.  It should be noted however, that fitting the TWS recoil spring guide may be necessary or even required in some cases.  The Gen.II mount worked pretty well on my rifle with no modification, but I don’t think stoning/filing the bottom of the TWS recoil spring guide hurts anything, and I’ll feel better knowing that there’s nothing to keep the mount from locking down snug.

Stock TWS spring guide.  Note that both screws are showing.

Romanian Spring Guide.  See how far back it goes?

TWS spring guide with the bottom filed/stoned down some. Note only one screw fully exposed now.

The rail sits very low, allowing some micro red dot sights to co-witness with the iron sights if you get the TWS peep sight.  With a real Aimpoint Micro, the iron sights show in the lower 1/4 of the tube.  Heights of the tubes of the Aimpoint micro clones often sit higher up and may not allow co-witnessing with the iron sights.  By all accounts the Bushnell TRS-25 micro red dot sight will co-witness, and runs $75-90 some places.  The Primary Arms Gen.7 Red Dot, with the non-removable mount, may also co-witness, but the TRS-25 seems to be more common on the TWS Gen.II Mount.  The Primary Arms Micros that I have, have the detachable mounts, and the bottom of the tube and dot emitter block the iron sights.

Putting the rail on top of the dust cover gets the rail very nearly as low as on an Ultimak Scout Mount.  It is lower than the other Beryl-type rails made by Kreb's ($300!?!?), DPH Arms, UTG, or Red Star Arms.

The TWS rail doesn't add any more weight up front, like a 3 or 4 rail handguard.  Think about it.  Almost all the weight of an AK is forward of the pistol grip.  There's a lot of steel hanging out there already.

Atxjax on the Glocktalk forum weighed everything, and found that the TWS mount only adds 1.04 ounces over the weight of standard steel rear sight and dust cover, 3.46 ounces with an Aimpoint R1.

Cleaning/Clearing Stoppages

The mount/dust cover flips up, hinged off of what used to be the rear sight block, the rear sight now being mounted on the rail on top of the TWS dust cover.  No tools are required to release the cover, and lift it up, although the bullet tip of a cartridge, a pen, or a similar object can be used to push in the button of the recoil spring guide.  If junk gets in behind the bolt carrier, you just push in the take-down button on the guide rod, and flip up the rail.  The mount doesn't hinder cleaning or maintenance as much as a side-mount, except the taller ones.  You can still remove the gas tube for cleaning, and remove the handguard, unlike the Ultimak scout mount, which clamps onto the barrel and blocks the lever that releases the lower handguard.

Live Fire
I got the Tantal out to sight in.  The first trip to the range was mostly uneventful.  I had to move the front sight a bit to the right to align with the TWS peep sight, but that's fine with me, because the front sight had been most of the way to the left, over toward the protecting wing of the front sight base.  Elevation was almost spot on.  The tip of the front sight is nearly at the top of the protective wings of the front sight base for a 100 yard zero, but I was able to get the sights lined up for both 25 and 100 yard zeros (only one at a time, obviously, with just one aperture).

For the 2nd outing, I took my Polish AK-74 up north to indoor range for some rapid fire.  Everything was fine, up until the last round of the last magazine I had with me.  The bolt carrier stayed to the rear, which is weird, because AKs don’t normally have anything to hold them open after the last round.  I didn't really think too much of it at the time.  I tapped the charging handle, the bolt carrier slammed home, I dropped the hammer, and cased the rifle and cleaned up.

When I popped the cover open to clean the rifle at home, I found the “spacer” laying loose in behind the trigger.  Half of the pin that was holding the spacer onto the recoil spring guide was rattling around in the receiver.  I’m not sure where the other half of the pin went.  Fell out, I guess.  The top of the spacer had made some contact with the inside of the dust cover, removing some finish, but I don’t think any structural damage was done.  If you scroll up, and look at the picture of the inside of the dust cover, you'll see two silver marks just forward of the square slot in the rear of the cover.  Those silver marks were made by the tabs at the top of the spacer.

Oops!  That's not supposed to happen.

I tried to get the spacer back onto the recoil spring guide, to show you what it's supposed to look like.  However, the spacer must have been bent out of shape after getting beaten by the bolt carrier, and it no longer fits.  You can see pictures of the assembled spring guide and the Saiga .308 spacer and guide rod on page 63 of the thread, as posted by Rafaga (Nelson of TWS).

I wasn’t crazy about the idea of a metal spacer in there anyway.  I pulled the Blackjack recoil buffer out of my WASR-10, which didn’t need it anyway, and put it on the TWS guide rod.  The buffer is that blue thing you see in the picture with the cover flipped up.  Nelson of TWS is offering to send out solid recoil spring guides without the spacer.  I think I’ll take him up on that offer.  I’m afraid the whole spacer thing is giving him a bit of a headache.

There is another small matter of peening at the rear of the ejection port.  I'm told that it's from ejecting casings hitting the dust cover on the way out, and I guess this must be true.  I don't think it'll be an issue, but it's something I'm going to keep an eye on.  Nelson at TWS says that that part of the dust cover work hardens, and the peening stops after a certain round count.

Sorry, I couldn't get a better picture.  Camera doesn't do close-ups very well.

Heat Transfer
I put 5 magazines through my Tantal with the TWS mount over the course of an hour.  Although there was some heat transfer into the mount through the rear sight block, very little of the heat transferred into the Aimpoint through the rear sight block.  I had a glove on my support hand, afraid of getting burnt by the metal up front, but the red dot sight stayed more or less at room temperature.

I did the same thing with my WASR with the Ultimak Scout mount, and after five magazines, the mount of the Primary Arms red dot was starting to get quite warm.  The Primary Arms sight held up to the heat, but I when I went to clean the rifle, I noticed that the sight was loose on the mount.  I think the heat from the gas tube mount melted the threadlocker I put on the screw that holds it on the rail.
A little too early for me to say yet, but the TWS Gen. II mount definitely shows great promise.  I'm looking forward to putting more rounds though the "new" Tantal, and really shaking down the new TWS mount.  I like my "new" modernized Tantal.

EDIT, 11/19/11:  I e-mailed TWS, and they said to send in the recoil spring guide rod and spacer, and they'd send me the standard no-spacer model.  So that's what I did.  I haven't gotten to shoot with it yet though.

UPDATE, 12/10/11:
  All is well.  I didn't even have to adjust the sights.

Thursday, June 9, 2011

How To Make a Magazine Lip Tool

I wanted a 5.45x39mm AR upper, to shoot some of that inexpensive Russian surplus ammo.  Scored a Spike's mid-length 5.45mm upper from AIM Surplus when they had some in stock.  I've come to find out though, that many of the C Products 5.45mm AR mags are crap.  Most of them work all right, if you load them half way.  However, if I load them with more than 20 rounds, and I got lots of feed failures.

Without getting too deep into the issues with the 5.45mm mags, I'll tell you that the feed lips were part of the problem.  I've been down this road before.

I guess it was back when the only pistol I had was a Ruger Mk.II, that a bullseye shooter told me how to make a mag lip tool from a carriage bolt to keep the Mk.II from jamming bullets into the bottom of the feedramp.

Brownell's sells a tool to adjust AR magazine feedlips for about $13, but a carriage bolt only costs about 60 cents.  It's just a matter of shaping the bolt into a tool.

I'm 90% certain that I made the tool for the Ruger Mk.II tool from a 1/4" bolt.  For the AR magazine tool, I bought a 5/16" bolt.  I could have gone a couple sizes larger, but it gets the job done.  I you have access to key stock, use that, and save yourself a few steps, but the carriage bolts you can pick up at most hardware stores for less than a buck.

5/16" Carriage Bolt, with the head annealed

You've got to cut the flange off the bolt, leaving you with the square. . . lug, at the head of the bolt.  Then you cut a notch in the "lug" to slip over the offending magazine lip and bend into the right shape.  That's about it, really.  If you've got a torch available, annealing and case hardening are optional extra steps.  The annealing helps keep you from chewing up your cutting tools.  Case hardening will help make the tool last longer.

Carriage bolt with the flange hacked off, and the "lug" filed square(ish)
"lug" notched to make the tool
 Large one for AR-15, small one for .22 Pistol
Tool used for bending feedlips into shape