Part Interchangeability

[RichH]

Hello,
I have a simple question that I hope someone can answer.
What parts are interchangeable between a 20ga and 12ga 870.
Obviously barrels are not but how about shell tube extensions, breech bolts, extractors, etc.
Thinking of upgrading my 20ga Wingmaster Magnum sn xxxx48X to a home defense shotgun.
Not a lot of 20ga parts out there but a friend said a lot of the parts for a 12ga will work on a 20ga.
Any help or opinion will be greatly appreciated.

[kcpanages]

2 different receivers..... I'd be careful as to what I swapped between the two.... And no, the mag tube extensions are two different sizes.... Just b careful


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[Synchronizor]

Hello,Thinking of upgrading my 20ga Wingmaster Magnum sn xxxx48X to a home
defense shotgun.

Is there a letter or letters at the beginning of your serial number?

[RichH]

Hello,Thinking of upgrading my 20ga Wingmaster Magnum sn xxxx48X to a home
defense shotgun.

Is there a letter or letters at the beginning of your serial number?

No Synchronizor, all numbers

[RichH]

2 different receivers..... I'd be careful as to what I swapped between the two.... And no, the mag tube extensions are two different sizes.... Just b careful


Sent from my iPhone using Tapatalk

OK, Thanks kcpanages

[Synchronizor]

Hello,Thinking of upgrading my 20ga Wingmaster Magnum sn xxxx48X to a home
defense shotgun.

Is there a letter or letters at the beginning of your serial number?

No Synchronizor, all numbers

Alright.

An 870 serial number that ends in X and has no other letters indicates a large-frame 20ga model, from 1968 or earlier, that is built for 2.75" or shorter shells. I know you mentioned yours was a magnum, but 20ga magnums from that time period had serial numbers ending in the letter "N". However, non-magnum 870s can be fairly easily converted to handle 3" shells by simply replacing one or two parts in the receiver (just to eject the longer shells reliably), and installing a barrel with a 3" chamber. So if your gun handles magnums reliably, that may have been done to your 870 sometime in the past. If you haven't yet, do double-check and make absolutely sure that your barrel is marked as having a 3" chamber though; not having the magnum ejector parts won't to anything but make ejection iffy, but using 3" shells in a short chamber can cause harmful pressure spikes.

Anyway, the "large-frame" thing I mentioned means that your 20ga is one of the older models that were built on the same-size receivers as 12 & 16ga 870s, rather than the slimmer, lightweight receivers used for modern 20ga 870s. This means that you can install a variety of accessories meant for 12ga guns on yours - most notably, anything that attaches to the receiver. These include things like stocks, saddle-mount optics, rails or shell carriers, rear sling attachment points, and sights. I believe 12ga fore-ends are also compatible with large-frame 20ga models (though it would be nice if someone could confirm this).

Both large- and small-frame 20ga 870s share many trigger plate assembly components and other internal parts with 12ga models, but breech bolts are always different, and there are several other differences. Nothing there should really need upgrading to serve reliably in defensive roles, though in a gun this old, it can be a good idea to replace certain wear parts. If you're concerned, I would just have a good gunsmith look it over, and replace any items that could use replacement or updating.

Regarding barrels, large-frame 20ga barrels are not interchangeable with modern small-frame 20ga barrels. You will need to look for used barrels or old stock if you want to have a short barrel for social work. Remington may have offered a short turkey or slug barrel for those old large-frame 20-gauges, but I'm not aware of any factory riot/combat 20ga models from those early days. You'll likely need to have a hunting barrel cut down if you want something in the 18" range.

As for magazine extensions... I'm not sure. I've only ever handled a large-frame 20ga 870 once, and I didn't take it apart to examine the mag tube in detail. I believe their mag tubes did have the same 1" outer diameter as the 12 & 16ga models (examining the internal diameter of the barrel guide ring is a good way to differentiate small- & large-frame 20ga barrels), and if that's the case, it stands to reason that the magazine cap threads on the end should also be the same. So, 12ga extensions should install just fine, especially single-piece extensions that don't need to be clamped to the barrel (which would have a different OD) in order to stay put under recoil. However, I'm not certain that the internal diameters of the mag tubes were identical; and even if they were, extension kits intended for 12ga shells may well have trouble getting 20ga shells to move smoothly, since the narrower shells would have more freedom to shift around and potentially find ways to snag at internal transition points.

Maybe someone else can step in and confirm that these old 20ga models did use 12ga mag tubes. Or, if you have calipers or some other precision instrument, measure the internal diameter of your mag tube; if it is around .925" at the cap end, and the opening at the receiver end is comfortably larger than 7/8", it will likely be compatible with 12ga extension kits. As mentioned though, that's not a guarantee of reliability. You'll want to do some testing and experimenting before trusting your life to it, and I would recommend buying extensions from brands that have good return policies, just in case things don't work out.

If you have any other questions, feel free to ask.

[RichH]

Synchronizor,
Thank you so much for your very specific information.
It appears you have the knowledge I was looking for.
I will take your advice to heart and be very careful when converting over to home defense.
I have access to a good gunsmith and will continue the process with him, if he ever get's back to me.
Once again, thank you very much!

[s.davis]

Is there a letter or letters at the beginning of your serial number?

No Synchronizor, all numbers

Alright.

An 870 serial number that ends in X and has no other letters indicates a large-frame 20ga model, from 1968 or earlier, that is built for 2.75" or shorter shells.

I believe 12ga fore-ends are also compatible with large-frame 20ga models (though it would be nice if someone could confirm this).

What do the letters before the serial number mean? I have a 1972 20 ga. that ends in X, but begins with S. I would like to know if a 12 ga youth stock and forend will fit it.

[Synchronizor]

For 870s built between 1968 and 2009/2010, the letter or letters at the beginning of the serial number indicated a manufacturing date range. It's not very precise, but it lets you narrow down when a shotgun was made to within a handful of years. That's usually enough to know if a gun probably needs certain updates, whether or not the barrel has been replaced, things like that.

If your gun is a large-frame, it'll take any large-frame furniture. There are some exceptions with fore-ends, but stocks are pretty straightforward.

[s.davis]

Thank you.