what are the needed spare parts?

[Rtodacheene]

I have a 870P. What specific spare parts should I keep? Springs, latches, .....pins???

What I have is magazine spring, firing pin, firing pin spring, barrel and a screw driver.

[Synchronizor]

The 870 doesn't really need parts replaced all that frequently. I don't usually bother stocking spare parts unless I know something's getting near the end of its life, or I need them for a video or experiment. Most of the time, I just order replacement parts when I need them. But seeing as you live in a state that doesn't want you to bear arms (funny, considering that there're some bear arms right on the flag...), I can understand the desire to get some spares on hand while you still know you can.

For wear parts, I'd say springs first. The magazine spring and trigger plate pin detent springs can weaken and start causing problems with heavy use or frequent disassembly.

Carrier dog follower springs, extractor springs, & sear springs seem to stand up pretty well, but if you're really tearing through the shells, they should also be changed eventually. These springs are also probably the most likely to fly away and get lost when you're working on your TPA, so it'd probably be worth keeping an extra one of each for that reason alone. You can also get different sear springs, and swap them out to change your trigger pull weight for different activities. I really like the yellow light-weight sear spring for slug shooting.

The safety spring, firing pin retractor spring (new-style ones), magazine cap detent spring, hammer spring, action bar lock spring, and ejector spring rarely need replacing. The latter four also require special tools to get to and change - they're generally gunsmith jobs. If you are buying those tools to do it yourself though, I would add a spare hammer pin & some ejector rivets to the list, as they may need to be replaced along with the corresponding springs.


As for small internal parts, I'd put a spare firing pin high on the list. The improved new-style ones aren't really prone to breakage (especially if paired with a new-style retractor spring), but it's a pretty critical part. An 870 can limp along without many parts, but a broken firing pin means a broken gun. You'll want an 1/8" dowel punch to change firing pins properly, though other items can work in a pinch.

I would also suggest a replacement receiver stud, and an extra of whatever fastener your stock uses. Though generally easy to avoid if you're paying attention, cross-threading your stock bolt in the receiver stud can FUBAR the fine threads in pretty short order. If this happens, replace both parts.

Extractors rarely wear out and break, but it can happen. I've also heard of folks breaking extractors when they drop their breech bolt assembly on hard floors while taking their guns apart.

In extreme cases, carrier dogs can chip a tooth, or carriers can bend, so a replacement carrier assembly might be something to consider.

I've never actually seen a broken factory plastic magazine follower, despite many internet claims. They can get scraped- & dinged-up with heavy use, though, especially if you use a stiffer magazine spring (as many Police models do) or shoot a lot of rounds without cleaning your gun.

The ejector may break if you're too rough on it when re-assembling your gun or changing barrels, though it's quite unlikely so long as you take the extra second to seat the barrel properly. If you're stocking a spare ejector, you'll probably also want replacement rivets. The old ones can often be re-used, but not always.


By the way, a lot of the internal springs & small parts come in Marine Magnum versions. They're mechanically identical & generally cost the same, but are supposed to be more corrosion-resistant.


For major components, maybe a replacement fore-end tube assembly. The action bars are softer than the shell latches they actuate, so they're the thing that tends to accumulate wear - albeit very slowly. But with enough cycles, you may start seeing feed problems, and at that point, a new fore-end tube assembly is what you need to fix it. The action bars can also get bent or tweaked due to amateurish re-assembly, or twisted when folks run vertical fore-end grips. User-induced damage seems to be a much more common problem than honest wearing-out (that pretty well applies to the 870 as a whole, actually).

Also, if your 870P has a magazine extension, a replacement extension tube (not the whole kit, just the tube) is a good thing to have on hand if you're running it rough through a lot of classes or drills. The factory extensions are a military design, and they're tough, but drop the gun just right on a rock or a hard surface, and your gun may become a single-shot.


Really, it all depends on how far you want to take it. You could order just a couple critical spares so you don't have to cancel a range trip; or flip to the exploded diagram in your owner's manual, call Remington, and say "I want one of everything". 870s are tough, and I guarantee that there are 50 - & 60-year-old specimens out there that see regular use, and are still running flawlessly on 100% original parts. If you want a pretty good stash of spares on-hand, I would say order a replacement set of trigger plate pin detent springs; and an extra sear spring, carrier dog follower spring, magazine spring, magazine follower, receiver stud, stock bolt, and firing pin. From there, you can add on whatever else lets you sleep at night.

[Rtodacheene]

Awesome, I did think of getting spare 'marine' springs, it probably be best if I were in need to replace.

Last question, I probably should ask on a forum format. Ive heard -youtube- that people buy long ribbed barrels and cut to 18.5 for home defense; also mossburg barrels are thicker, due to the fact a person might drop and significantly dent a barrel that may effect/disrupt shooting. I havent bought into this (both my barrels are fixed chokes) that a berrel will dent or be from a drop or a bang from an accedent. If someone was to drive over or clamp in some way- sure, but id think in a military application it may be necessary but thoes people are pushing to the extreme.
Robert Todacheene

[Synchronizor]

Last question, I probably should ask on a forum format. Ive heard -youtube- that people buy long ribbed barrels and cut to 18.5 for home defense

It's common to do this for 870s for which there aren't widely-available riot/combat barrels, like SuperMags (which can take 3" or 2.75"-chambered 12ga barrels, but then the ability to shoot 3.5" shells is lost), or 870s in the less-common gauges. Even for more common 12ga & lightweight 20gs 870s, where riot barrels are easy to get, some folks just prefer vent ribs on a fighting shotgun, or they have the vent-rib barrel, and want to make use of it rather than buying another one.

Vent-rib barrels are great for this, because you can cut them to any length, and still have a sighting system without having to do any additional work. Vent-ribs are pretty effective on their own, but they can also be used to mount a variety of other sights without having to mess with epoxy or solder.

also mossburg barrels are thicker, due to the fact a person might drop and significantly dent a barrel that may effect/disrupt shooting. I havent bought into this (both my barrels are fixed chokes) that a berrel will dent or be from a drop or a bang from an accedent. If someone was to drive over or clamp in some way- sure, but id think in a military application it may be necessary but thoes people are pushing to the extreme.

I think it's just certain 590 variants that have the extra-heavy barrels. I don't exactly remember if it was requested by the military, or Mossberg's idea, but from all accounts, it makes those 590's pretty nose-heavy (and they don't exactly balance great to begin with). I agree that it's probably overkill. Just standard-profile 870 barrels are pretty darn tough; I read one article talking about how they were apparently tested to something like 50,000 or 55,000 psi (well over the 11,500 psi peak pressure limit for standard 12ga shells) without failure. Comparing my 870 barrels to the one on the Ithaca 37 that I'm holding onto for my brother, the 870 barrels make the Ithaca's look paper-thin - and the Ithaca 37 was the go-to hard-use fighting pump for LE & military before the 870 took over.