screw in chokes

[freekforge]

Does anybody know how thick the walls need to be on a 12ga in order for it to be threaded for tubes? Also about how much would it cost to have this done? I have a 20" H&R that is dying to have a choke.

 

[engineerpower]

There's write-ups for DIY in several places across the net. It's not hard, but you need a reamer, tap, and lathe.

From HomeShopMachinist.net Threading for a Choke:

Pacific Tool and Gauge and Manson Reamers make reamers and taps for modifying your shotgun.

The Rem-Choke reamer and tap will install threads that will accept Rem-Choke and Remington factory tubes. For a 12 gauge, that means a choke with an outside diameter of .814" and 32 TPI.

The Win-Choke reamer will also cut to .814” and with a 32 TPI which allows you to use original equipment tubes from Win-Choke, Mossberg Accu-Choke, Weatherby, Browning Invector. (Note that although the thread pitch is the same, the shape is different between the Remington and the Winchester reamers)

Then there is a Tru-Choke reamer that will cut for .795” diameter choke tubes at 44 TPI and a Tru-Choke Thin Wall reamer that cuts .775” at 44 TPI for thin barrels. The Tru-Choke will accept Tru-Choke choke tubes, while the thin wall will only accept the Tru-Choke Thin Wall Tubes.

The reamers use a pilot bushing to center the reamer in the bore. The pilots come in various sizes to fit your bore.

It is recommended to use a lathe for the best possible results, although the reaming an tapping can be done by hand.

It is also recommended that you use an expanding reamer to remove the choke (the fixed one) prior to reaming the barrel.


Screw in choke installation requirements:

Before machining a barrel to accept screw-in-chokes, you must measure the outside diameter of the barrel to determine if there will be sufficient wall thickness after reaming.

Measure the O.D. of the barrel and then measure the O.D. of the tap. Subtract the O.D of the barrel from the tap and then divide by 2. This will give you the wall thickness after reaming.
For example; .850” barrel O.D. minus .814” tap O.D. equals .036”… Divide that by 2 and you get .018” wall thickness.

It is not recommended to perform this procedure where the wall thickness will result in less than .015”. Also, for a 12GA, you shouldn’t proceed in installing these chokes if the Inside Diameter exceeds .735” (.728” for thin wall chokes) .Exceeding these dimensions WILL cause damage to the chokes and a GREAT POSSIBILITY of barrel BLOWOUT. After installation, make sure the tube does not protrude into the bore. Back-bored or jug-choked barrels are usually not suitable for this installation.

Note: These reamers and taps are not cheap alought it may be possible to rent one. (Yeah, you can, try here: 4D Reamer Rentals, Exclusive Source to Rent Chamber Reamers & for Renting Gunsmithing or Shotgun Tools )

Brownells:
http://www.brownells.com/.aspx/cid=0...=choke_reaming

MidwayUSA:
http://www.midwayusa.com/Find?status...temsPerPage=20

 

[8th SPS USAF]

Not sure ,but I think chokes may be different thickness, per maker?

 

[engineerpower]

Winchokes and Remchokes are the standard.

 

[AllenM]

I have the tooling to do Rem chokes. I would do it for $90.00 send me the barrel if you wanted

 

[JimfromTrafalgar]

Few shotguns warrant the expense of having this done. Fewer still warrant the expense of buying the tooling required. If this is a one time thing for you, have someone who knows what they're about do the job for you. If Allen has a decent rep. for such things around here, that sounds like a good offer.[No offense intended nor implied, Allen.]

 

[drillsgt]

I have the tooling to do Rem chokes. I would do it for $90.00 send me the barrel if you wanted

That would be a good deal! Briley usually charges 125.00 to 140.00. I can't imagine an H&R wouldn't be thick enough but there is always the thin wall choke tube option as well.

 

[Hookeye]

Tru choke (also used on Baikal) is for the thin stuff, are short in length.
Remchoke are longer, like 'em.............but they are Remington only, Browning went to similar style with Invector Plus.
The Mossberg Accumag is of similar style.

Compare a non Remchoke bbl to a Remchoke bbl, factory done, the latter should have some flare nearing the muzzle. This "look" however slight, really p*ssed off a lot of purists back when Big Green brought it out. It seemed way more noticeable then than it does today....and the older bbls do look a little better...........if you're a little older.

On a little 870 Special Field I think the look more obvious.