Making a mag extension for Winnie 1300 20 ga


March 10, 2004, 12:54 PM
Hey folks-

I decided to cut down a spare 20 ga duck barrel I had to 20", so that my Black Shadow could be used for HD. Barrel looks great, I'm going to put a bead on it and all that, but I've hit a snag...

I'd really like to put a mag extension on it, but to the best of my knowledge, such an animal doesn't exist for a 20 ga shotgun, the 1300 especially. So, unless I find one in the next month, (slim, been looking already), I'll probably have to end up making one.

Since the threading on the tube seems non-standard, I'm afraid I'll have to make the nut out of a cut up factory tube cap, and then attach the rest of the pieces to it. Home Depot did not have any 7/8" pipe (who would though?), and PVC was either too big on the outside or too small on the inside. I used a friend's 12 ga mag extension as a base for my design, but if I can't get the pipe I need, nor the threading right, I'm SOL.

I've got a couple machine shops (read: "friends' garages") that I can play in, and I'd really like to round her out as a backup home-d shotty. Any advice? ideas?


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March 10, 2004, 01:43 PM
In the BROWNELL CATALOG , TAC STAR has a mag extension that fits WIN 1200/1300 FOR $41.98. Then in the shotgun parts for " WIN 120/1200/1300 ALL S/N Above 382500 " they list "magazine tube -- fits all" and the " magazine CAP -- fits all " no gauge separation like there is for other parts. So it looks like a 12 guage mag extension for a 1200 will fit a 20 guage 1300. I would see if you could find a mag extension for a 12 guage Winchester 1200 at a gun show or discount bin in gun store and try it , if you don't mess up the packaging too much ,if it doesn't fit you can resell it. GOOD LUCK

March 10, 2004, 05:12 PM

Thanks for the leads, but the shotgun my friend has is a 12 ga 1200, and unfortunately, the tube threads do not feed onto my 20/1300. When I talked to TacStar, they said they "didn't have it". Also, the extension tube is much too wide, and I am also told that the inner diameter difference could lead to a stuck round in the tube. Thanks for looking though! I'll double check just to be sure. There just has to be a way...

Also, what really sucks is that I can get the mag spring from Wolff, but so far nothing clear on the extension.

March 10, 2004, 07:08 PM
Why not simply order an extended mag tube from Winchester? Their parts list for the 1300 (see here ( - requires Adobe Acrobat) lists the following magazine components:

6 + U123802400 3800A2400 Magazine Tube, 5 Shot, (Requires Ref #7 1-Piece) $27.95
6 + U123802410 3800A2410 Magazine Tube, 8 Shot, (Requires Ref #7 1-Piece) $27.95
6 + U123802430 3800A2430 Magazine Tube, 5 Shot, Matte,(Requires Ref #7 1-Piece) $27.95
6 + U123802440 3800A2440 Magazine Tube, 8 Shot, Matte,(Requires Ref# 7 1-Piece) $27.95
7 + U123822060 3820A2060 Magazine Throat, 12Ga, Upper (Below S/N L3413900) $2.95
7 + U123822070 3820A2070 Magazine Throat, 20Ga, Upper (Below S/N L3413900) $2.95
7 + U123822300 3820A2300 Magazine Throat, 12 Ga, (1-Piece) $3.95
7 + U123822310 3820A2310 Magazine Throat, 20 Ga, (1-Piece) $3.95
8 + U123822010 3820A2010 Magazine Throat, 12Ga, Lower (Below S/N L3413900) $2.95
8 + U123822050 3820A2050 Magazine Throat, 20Ga, Lower (Below S/N L3413900) $2.95

I'd guess you'll need the 8-shot mag tube, and a 20ga. one-piece throat. With those, you could remove the old mag tube and replace it with the new one.

Good luck!

Badger Arms
March 10, 2004, 08:19 PM
If you get the new mag tube, you'll have to attach a sleeve around the mag tube so that the threaded portion at the front will tighten against the barrel lug halfway down the barrel. Either that, or you could get a new barrel too. Final option is to reattach the barrel lug at the front of the barrel. All three options are compromises and the new barrel and tube might cost as much as a whole new gun on the used market! That assumes, of course, that they make the extended tube in 20ga.

March 10, 2004, 09:00 PM
Badger, looking at their parts list, it appears that they make a standard magazine tube, and then fit it with a "throat" sized according to the appropriate gauge. Makes sense, I guess.

Badger Arms
March 10, 2004, 09:06 PM
ACK! That's bound to make the gun less reliable. Hmmmm, but if that were the case, why would the 12ga not fit on the 20ga tube as mentioned earlier. I think it's a smaller diameter tube. Not entirely sure what the 'throat' is.

March 10, 2004, 09:18 PM
Badger and Preacher-

So, you're saying that I could just get a longer mag tube, and then to use my existing shortened barrel, (barrel lug close to the breach and not the muzzle, like a standard hunting barrel, sawed), just put a sleeve between the barrel lug and the tube cap? As I screw the cap down onto the tube, the sleeve will put the necessary pressure on the barrel lug. Is this correct? I'm looking for the least invasive method, and getting a new home-d barrel from Winchester in 20 ga is like getting a CCW in Los Angeles. Not gonna happen. Sounds like the idea above is about the easiest to do for a non-gunsmith like myself...

Let me confirm, this also would allow me to use my present cap, but should I go hunting, I'd have to put one mean block in there, correct?

March 10, 2004, 09:20 PM
By the way, in my very limited experience, it seemed like the 20 rattled around considerably more in the tube of my friends 12 ga 1200, as opposed to my 20 ga 1300, and I know that the extensions for 1200s work on 1300s. That leads me to believe they are a different size after all, but then possibly not because of the model numbers... Stupid not to have measured the darn things.

Oh, and FYI, from Winchester FAQ page:

The Model 1300 barrels will fit Model 1200 receivers, but 1200 barrels will not fit a Model 1300. Model 1400 barrels will not interchange with Models 1200 or 1300 barrels.

The Model 1300 Defender barrels will not interchange with the 1300 Field models and viceversa.
:( meep Looks like if I want a 2-barrel gun, that this was the way I'd have to go anyway... I wonder if the magazine tubes were like this too, and thats why my friend's wont thread onto mine, (same thread pitch, but peaks are wider...).

Badger Arms
March 11, 2004, 01:14 AM
Barnes, looks like you have my idea down pat on the sleeve. The hardest part is to get suitable material. It won't look pretty, but maybe black PVC pipe? You have to get the inside diameter and outside diameter to work. So, to do this you'll need to make the sleeve, get a new mag tube and a new mag spring. I'm still not certain that they make an extended magazine for the 20ga.

March 11, 2004, 11:17 AM

They do, thankfully, because you can buy the 1300 defender in 20 ga, which uses the same mag tube (I believe) at least, and in longer lengths, although the barrels are different.

As far as the sleeve idea, I can put a notch on one side of it to fit the bead on the barrel lug, and then put a small rise on the opposite side for the cap to click onto. If I make it out of steel I can blue it relatively well, and it'll just look wierd, but not necessarily bad.

:cool:Coolness. I will call Winchester either today or tomorrow and verify parts and availability on the mag tube. Only problem is that they appear to be a @#$#& to replace and mount. I tried to take mine off gently to take measurements and whoo-boy, she really loves that receiver. Just won't come off willingly. Of course, at the time I was not aware of the throat, and imagine that it will cooperate once I remove that. I'd like to save the old mag tube. I don't know what for, but I likes parts.

Thanks you guys!

March 11, 2004, 01:13 PM
Okay, called Winchester.

Preacher was right about them using the same tubes for 12 and 20. They have two kinds of tubes. One, as listed above, is for SNs lower than 3419xxx... and the other for above that number. How much you want to bet that the defenders are below this number, and that my Black Shadow is above it? That would explain why aftermarket stuff works on defenders but not on Shadows...

This would mean that I could just buy the 5 shot version of the defender's mag tube, (and possibly the defender cap, listed above it separately... :)) and buy a regular extension.

Going to call my gun shop, see what I can dig up...

At that point, I will have spent more on this little project than just buying another shotty, but I think its a certainly interesting project...


Badger Arms
March 11, 2004, 01:19 PM
They changed the style? So, is there an internal sleeve or do the shells just rattle around in the magazine? This has got to be the most retarded way of going about things that I have EVER heard! No wonder I own Ithaca's and Remington's. Well, right now I own a few mossbergs and a Winchester Defender for sale... but that's besides the point.

March 11, 2004, 10:11 PM
Problem solved, but not in the way I'd intended. Was about to head to my machine shop when guy at the gun store begged me to bring it in. We went through EVERY 1200/1300 extension in the store. New, used, really old... FINALLY, found one that would thread. It was a Choate 8 shot from what had to be the Reagan years. But it worked, however, I had to make a spacer ring 1/4" thick, because the threads on the extension wouldn't make contact with the lug.

Guess was correct, but backwards. For posterity, I'll include the facts, for those unlucky enough to not have access to an old 1200 extension. The defender tubes are indeed, for the ones ABOVE 3419.... and the Shadow for those under 3419....

How would you fix this? If you didn't want to make any fanagled parts, buy the 5 shot mag tube and 1-piece throat. Then buy a 2 or 3 shot extension tube. Costly, but you will have a set that works without setting foot in your garage. Also, if you wish to use another barrel, (for hunting or whatever) you may want to buy the magazine cap for the Camp Defender, as it is the only one that will thread onto your new mag tube, (but only after you've checked with your old one - as I could be wrong there).

I got blisters galore, and clothes full of ground steel, (wanted the spacer to be purty and shiny). Still, it only cost me $40, for an old mag extension.


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