How do you tell a 870 mag reciever

I don't mean to throw RePete under a bus here, :) I just had this info handy and thought to share it in reference to Scooter's question.

The barrel and receiver design combination determines what can be shot from your 870 gauge.

All barrels are clearly marked with the chamber information.
Receivers are marked with letters at the end of the serial number that determine ejection size as follows:

Serial Number Suffix Gauge Ejection

V -- 12 -- 2 3/4" Only
M -- 12 -- 2 3/4" or 3" Only
A -- 12 -- 2 3/4", 3" or 3 1/2"
W -- 16 -- 2 3/4" Only
K, X -- 20 -- 2 3/4" Only
U, N -- 20 -- 2 3/4" or 3" Only
J -- 28 -- 2 3/4" Only
H -- .410 -- 2 1/2" or 3"

Suffix letters in serial numbers represent nothing more than REM manufacturing date codes.
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This is a little of topic, but close enough. Can I modify my 2 3/4 Wingmaster to 3". Will the recvr take the pressure? The bbl is already 3". And if so, anybody know a smith close to Ottawa.
 
ianthomson said:
This is a little of topic, but close enough. Can I modify my 2 3/4 Wingmaster to 3". Will the recvr take the pressure? The bbl is already 3". And if so, anybody know a smith close to Ottawa.
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I could be wrong but from what i understand the only difference between the 2 1/2" only and the 3" 870's is the chamber in the barrel. If you have replaced the barrel with a 3" you should be good to go with 3" . The receiver should be the same.
This does not go for 3 1/2" however.
 
my 2 3/4 wingmaster is currently at the shop getting switched over to a 3". Only thing is you have to make sure your barrell is 3 inch. I have a 3" slug barrel that I can use, but when I put my duck barrel on Ill have to stick with the smaller load. I mainly want 3" for turkey and deer season.

And true, you cant go to 3 1/2
 
Two things are required to convert an 870 from 2.75" to 3":

1. 3" chambered barrel.
2. 3" ejector. Ejected shells may hang up without the new ejector.
 
I concur, with the 3" barrel, the shells will load and fire, no problem. But on the ejection stroke(no smirking) the opened hull fetched on the ejection port. So I am half way there, gotta find a 3" ejector.
 
The easy way to tell is: on a 3" receiver the bump in the ejector is flush with the rear of the ejection port. On the 2 3/4" it is of course 1/4" ahead.

I have changed many 2 3/4" ejectors to 3". The only glitch is that the new rivets will show on the outside of the receiver.

Casey
 
easy said:
I don't mean to throw RePete under a bus here, :) I just had this info handy and thought to share it in reference to Scooter's question.
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Excellent post. I have a turkey bbl, chambered for 3.5", but my receiver is stamped "M". Remington sold the package this way and it confused the helll out out me for a while. Thanks for posting....and a minor hijack:

the two guns we bought in 2006 seem to have an "ejection" issue of stuck shells. We deer hunt, tried 3" shells, but they tend to jam, so now use 2.75" shells after jamming with 3". Seems to have cured it. For turkey, I use 3" (mostly one shot deal).
 
ARWEN ACE said:
The easy way to tell is: on a 3" receiver the bump in the ejector is flush with the rear of the ejection port. On the 2 3/4" it is of course 1/4" ahead.

I have changed many 2 3/4" ejectors to 3". The only glitch is that the new rivets will show on the outside of the receiver.

Casey
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If this is the casey I think it is, M. Ruff... is currently changing mine, cant wait to get it back, he is using my 870 as a test!! I think he is getting the parts from you though.

Steve
 
Another slight hijack here; I have a 3.5" receiver and barrel, but I only shoot 2.75" shells. I have heard that this has a negative impact on the pattern and decreases accuracy with slugs. Can anyone confirm that this is true?

Matthew
 
The barrel can be off a different model than your current receiver. You can have a 3 inch receiver but a 2 3/4 inch barrel! You'll have to measure the depth of the chamber to the point where it tapers in. 3" for a 2 3/4 and 3 1/4 for a 3"(approx). If you're unsure get a new barrel, or i can get my wife to fire some 3 " magnums out of it as we watch from a distance. :D
 
ARWEN ACE said:
The easy way to tell is: on a 3" receiver the bump in the ejector is flush with the rear of the ejection port. On the 2 3/4" it is of course 1/4" ahead.

I have changed many 2 3/4" ejectors to 3". The only glitch is that the new rivets will show on the outside of the receiver.

Casey
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Why is that? Are you drilling completely through the receiver? Not that that would bother me, I like a few scars on my guns.
 
The rivets that retain the ejector pass through the receiver wall. If you look closely at the left side of an 870 receiver, you can see where they are located.
 
depending on how far you want to go with it, you could always get the rivits machined down to match the receiver, although by doing this you may disturb the finish on the one side of the receiver, just get it coated when you are done and its not a problem.
 
also, now that Im getting my receiver switched to 3", I may have to modify the chamber on my duck barrel as its only 2 3/4. I have access to a lathe, (and in my past life I was a machinist) as long as I know the depth and the angle that it tapers at the end I should be o.k.

boy was this ever highjacked good!
 
To lengthen the chamber on a 2 3/4'' BBl simply have it lengthened with a long forcing cone reamer then you can shoot 3'' from it I have done Many times.
 
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