Brl/mag tube clamp replac for pump S&W 3000?

[rodregier]

Can some kind folks tell me the dimensions of the barrel / extended magazine tube clamp on a Rem 870 and a Mossberg 500?

I'm trying to replace an out-of-production Choate barrel/magazine tube clamp for a S&W 3000 pump-action shotgun that was launched into "places unknown" during a 3-gun match, lost forever.

I'm hoping that the dimensions for a Rem 870 or a Mossberg 500 clamp will permit using it for my application.

My S&W 3000 barrel diameter is 0.810", magazine tube diameter is 0.987" and the center to center spacing is 1.25" at the clamp location.

I believe the inter-tube dimension is the most critical, the other dimensions can be fudged a bit.

Already tried an 11/87 clamp, inter-tube dimension is too far off.

Thanks

 

[dfariswheel]

I believe that Choate still has new clamps to fit your gun.
An email to them will get you a fast answer.

As I recall, Choate only makes one design clamp, a two-piece design that is a "one size fits all" type.

http://www.riflestock.com/

 

[rodregier]

Choate has new clamps for in-production firearms. No current listing for the S&W 3000, which has been out of production for several years.

Choate has one clamp design, but the dimensions are adjusted for the specific product. Since I launched the prior Choate clamp, I'm also looking for a better design. The stamped steel design they use doesn't generate a lot of friction between the clamped tubes and the clamp. Tighten too much, crush the barrel or mag tube - bad news!

"Plan C" is to settle for a Choate clamp.

 

[Big Az Al]

Numrich Gunparts

Lists A clampfor the S&W 3000/ Rem 870

7.90

 

[rodregier]

Good sleuthing, Big Al. Appreciate the effort.

The fact that the 870P and S&W 3000 part numbers are different gives me deeper confidence in the dimensional accuracy.

Band & Swivel Assembly For Extended Magazine Tubes

Model: SMITH & WESSON 3000
Item No. 252170B


Model: REMINGTON 870P
Item No. 252170A

Guess I'll try acquiring the "B" model.

Skateboard tape under the magazine tube clamp may be the ticket to keep it from launching under recoil.

 

[dfariswheel]

I suspect that the Gun Parts clamp is a copy of the Choate.

Take a close look at the clamp made by Uncle Mike's. It's a near-exact copy of the Remington factory clamp, except it doesn't interlock with a groove in the tube like the factory unit.

http://www.unclemikes.com/
Their site seems to be inoperable right now, but they make a one-piece clamp almost exactly like the Remington factory clamp. Other than the Remington, it's the best clamp there is unless you have deep pockets for a Clark unit:

http://www.brownells.com/aspx/NS/store/ProductDetail.aspx?p=5022&title=SHOTGUN+MAGAZINE+BAND

 

[rodregier]

The Gun Parts clamp is a indeed a dead-ringer for the Choate.

The 11/87 clamp I purchased and tried was the Clark (liked the design).

Wrong inter-tube dimension :-(

Still waiting for someone to volunteer the 870P inter-tube dimensions...

 

[rodregier]

Finally acquired the Gun Parts S&W 3000 clamp assembly with some logistics help. Correct tube/barrel spacing.

Current plan is still to use skateboard tape under the clamp on the magazine tube to keep the clamp from slipping off under recoil like the last one I launched/lost.

I'm open to better suggestions. Just keep in mind that the setup has to be capable of simple disassembly since the magazine tube extension is also what clamps the barrel to the receiver. So, it has to be removable to permit field stripping the shotgun.

 

[dfariswheel]

Since most of these use a standard thread screw and nut, go down to the hardware store and buy a screw with a larger head and slot it with a wider slot that will allow using a coin or even the rim of a shot shell.

Choate clamps come with a extra screw with an attached sling swivel.
The swivel can be used as a lever to unscrew the screw.

 

[rodregier]

I'll be upgrading to a proper Uncle Mikes sling swivel.

I just checked, the thread is the same as the ones used by Uncle Mike's - thank goodness.

My removability comment was more focused on avoiding suggestions involving "permanent" adhesives to avoid launching/losing this clamp in recoil too.

 

[rodregier]

Got a chance to test-fire S&W 3000 with replacement barrel/magazine tube clamp and traction tape on magazine tube. Fired around around 12 rounds rapid-fire, found clamp lying on deck :-( Fortunately it was an indoor range with concrete floor, so the clamp wasn't lost this time.

I had the tension screw fairly tight, any opinions on how tight it can be before damaging the tube or barrel? Should I be using loctite on the threads?

 

[dfariswheel]

The limiting factor is the clamp screw. Tighten it enough, and the screw or threads strip.
Tighten fairly tight and use just a dab of Loctite Blue on the threads.
Another option is to use a "Nyloc" nut instead of the usual flat nut.

Moving clamps is one reason the Remington factory clamp is the best made.
The factory extension tube has a groove that the clamp screw interlocks with.
The clamp CAN'T move because of the interlock.

My best suggestion now, is to cut up a bicycle inner tube or other thin rubber and glue some small patches on the clamp.
This will give a good grip on the smooth barrel and extension, and should prevent shifting.

Yet another option: Use a good epoxy, or possibly even better, some Loctite Black MAX adhesive to bond a small piece of steel to the extension tube to act as a positive stop for the clamp.
With a positive stop, the clamp will not be able to slide forward.
You could soft solder a stop on, but this might damage the extensions finish if you get messy with the flux.

You can buy Loctite Black MAX from Brownell's.

 

[rodregier]

Tks dfariswheel.

The metal stop idea sounds like the best, since it doesn't need to replaced as the surfaces wear (unlike anti-skid tape or rubber).

 

[rodregier]

(Earlier testing using adhesive-backed grit tape on the magazine tube under the clamp demonstrated clamp slippage. It had almost fallen off during testing with just 24 rounds of light shot loads.)

Fabricated a clamp stop collar for attachment to the end of the magazine tube. Used a 3" length of 0.75" wide x 0.125" thick aluminum stock, formed into a circular collar/sleeve shape to fit the magazine tube. Painted the collar flat black using model paint, glued to the magazine tube using 1 hr epoxy. Epoxy was selected because there were moderate gaps between the magazine tube and the fabricated collar. Black Loctite MAX 380 is specified as a thin gap adhesive, so it would have been a poorer choice for the parts configuration I had created. Oriented the collar gap towards the barrel to maximize the cosmetics of the installation. Replaced original clamp machine screw with Uncle Mikes threaded sling stud plus Uncle Mikes plastic washer. Installed clamp just behind the stop collar and on the barrel, tightened half a rotation beyond "finger tight".

Tested with 24 rds of light shot loads, stop collar and clamp stayed put.
Looks promising.