So I picked up a 1984 870 special field yesterday in great condition. Only thing is it has a Hastings 18 inch barrel, and a magazine extension. I found an original 21 inch barrel for it and bought it today. What size magazine spring and magazine cap do I need to restore it back to stock?

The whole barrel thing was very confusing since it's a factory 18" with choke tubes, I'm not sure the purpose of an 18" barrel with choke tubes is but someone might of special ordered it from Hastings.

What is the size of the magazine extension? I would start by just using the same spring and see if it works.

The 18" barrel with tubes allows more versatility to tune buckshot or birdshot while keeping a barrel that can be used for hd, turkey, deer, etc.

I paid a lot to get an 18" barrel threaded a short time ago.

MikeD wrote:What is the size of the magazine extension? I would start by just using the same spring and see if it works.

The 18" barrel with tubes allows more versatility to tune buckshot or birdshot while keeping a barrel that can be used for hd, turkey, deer, etc.

I paid a lot to get an 18" barrel threaded a short time ago.

I believe it's a +2, I ordered the original 21 inch since I wanted to have an original piece but I do like that I have a special 18 inch barrel for it, I have never seen or heard of another special field with one since the lug on the barrel is specific to this model.

With a +2 the spring is not that much longer, I would try it and see if all the rounds fit. If not just order tbe std length spring, i do not recall offhand what the exact measurement is.

ill give it a try ill try and post pictures soon. Might just put her up in the safe since the wood is rare and is beautiful.

Hope to see it soon kpla51. I recall Rem made em at first with a 21 inch and later with a 23 inch barrel. Another I should have grabbed before they quit making them.

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I believe Remington just used the standard magazine spring since it was only one round less capacity in the magazine. The magazine cap was the same as a standard.

Like others have said, caps and magazine extensions from standard 870s of the same gauge should all be interchangeable. If you're taking the extension off and going back to a magazine cap, you may want to also use a spring retainer. It's an optional part, but if you decide you want one, I'm going to recommend a Benelli spring retainer over the factory Remington part, as it's much better.

As for the spring, you'll probably be just fine using springs intended for standard 4-round 870s; there isn't all that much difference in tube space. But if you are seeing shell rims being beaten up, crimps getting deformed, or loading is just stiffer than you like, you can always simply snip off a few coils at a time until you get the level of force you want. Cut coils from only one end, and put the cut end against the magazine cap or spring retainer, so that the follower still gets even pressure from the finished end of the spring.