Glad I took an 870 Armorer’s course today!

[Riomouse911]

I went to an 870 Armorers course today to get my State certification (2 years). Instead of taking one from work to disassemble and work on I took my HD 870. This consists of take-off “Police” stock set, a side-saddle, Choate +2 mag extension and a 1970 20” cyl barrel with factory rifle sights attached to a 1960’s era Wingmaster receiver. I’ve used this gun for years, it’s one smooth-functioning pump for sure.

Well, during the class I did a bit of hearty racking of dummy ammo through the gun when I got a good double feed. I broke it all down and the left side shell stop had somehow come unstaked. It shifted outward I guess and let the shell fall into the carrier jamming it up. I noticed that this earlier gun only had one staking divot on the top and bottom of the shell stop, and it finally gave up.

I also found oil had turned to shellac inside the bolt and on parts of the trigger group, the extractor spring and plunger were a bit rusty and dirty and the trigger/safety system needed a good cleaning as well.

The instructor and I restaked the shell stop with the “C” shaped staking tool, I cleaned everything and lubed all that needed it and put it back together. It’s smoother than ever and genuinely ready for the HD role (I hope I never have to use it in!)



Stay safe.

 

[lemaymiami]

You couldn't have a better tool for close quarters work...

 

[herrwalther]

Better to find out during a course than in an encounter with a 2 way range.

 

[Riomouse911]

Better to find out during a course than in an encounter with a 2 way range.

Amen!

 

[entropy]

Well, during the class I did a bit of hearty racking of dummy ammo through the gun when I got a good double feed. I broke it all down and the left side shell stop had somehow come unstaked. It shifted outward I guess and let the shell fall into the carrier jamming it up. I noticed that this earlier gun only had one staking divot on the top and bottom of the shell stop, and it finally gave up.

That usually results from either many, many rounds through the gun, or putting the forend, bolt carrier, and bolt in and slamming it closed before inserting the trigger gourp pins, with the barrel off. It's more common on the 1100, but can still happen to the 870. Restaking it is the remedy, of course.
Get a tabbed shell lifter on that social gun.

 

[Riomouse911]

Ya, it still has the original “butter knife” shell lifter and not the newer tabbed one. That’ll be next.

I bought it used so I have no idea about the round count or how it was treated before. Having broken it down to tiny parts, the gun is in great shape other than that issue.

Stay safe.

 

[roo_ster]

Never had an armorer course for the 870, but I do like them and like to work on them. When I first buy and every few years thereafter I tear it down, to include ht ebolt. I take out the trigger assy and clean & lube it, but do not dis-assemble it. I have never found varnish on the bolt after the initial cleaning. I use CLP, motor oil, ATF, mineral spirits, remoil on my guns. I think the varnish is a residue of WD40.

FTR, I have never bought a new 870. Always some old wingmaster that I then configure to my needs. GREAT gun.

 

[gralewaj]

While you were in there it would have been wise to add the flex tab conversion pieces to that 1960s 870. Old Wingmasters have the solid carrier and more metal on the bolt. The flex tab allows you to rack through that double feed instead of taking the gun apart. On an HD gun it could save your life. AI&P Tactical has a great video showing how it functions and how to install all four pieces.

Congrats on your certification! I love working on the 870 platform.

 

[lemaymiami]

Thinking about that lube that had turned “varnish” on your bolt...

My first suspect would be old 3 in1 oil since that’s exactly what it does in fishing reels and items I’ve broken down and repaired over the years. For anyone I’d advise them to avoid it like the plague.

 

[roo_ster]

Thinking about that lube that had turned “varnish” on your bolt...

My first suspect would be old 3 in1 oil since that’s exactly what it does in fishing reels and items I’ve broken down and repaired over the years. For anyone I’d advise them to avoid it like the plague.

Do you know what 3in1 ingredient causes this? WD-40 it is supposed to be a wax. I have used 3in1 on occasion when nothing else was available, but then went over it on next cleaning with something else (breakfree, CLP, motor oil, atf, etc.).

 

[lemaymiami]

As long as you have frequent cleaning and maintenance I suppose that 3 in 1 will be just fine... But use that stuff and leave it in place for a few years and it absolutely turns to goo.. then toughens up into varnish... I've done more than one "miracle repair" on a locked up old reel by tearing it down and leaving all the bits and pieces in a mineral spirits bath to loosen the varnish then a thorough scrubbing with a toothbrush to clean the bad parts... Like magic once that stuff was gone - all that was needed was re-assembly with a decent light gun lube (Gunslik, Breakfree) for perfect performance... I doubt it would be much different where moving parts in a firearm were all gummed up....

I have no idea what if any chemical process is involved with the stuff - I always assumed that it simply evaporated over time leaving that nasty residue...

 

[WestKentucky]

Just throwing this out there... carburetor cleaner does wonders on oil-varnish. I have used it before on old oil, but never have I ever had such a quick and effective solution as what I got recently on my Miroku revolver that apparently had never been cleaned of factory assembly lubes that had crusted up. Stripped it and hosed it down a couple times and that varnish was flowing out. I let it sit for about 5 minutes and hit it a third time and it was clean enough to reassemble. I always use gum out, and have never had trouble with bluing. I have not used it on other finishes so I can’t comment on how it reacts to other stuff.