There's not a lot of information on building a pump gun for competition (Specifically 3 Gun/ Multigun Heavy Divisions). It's really not that hard but I thought I'd share mine with y'all. I was able to put the whole thing together for around $700.

I started off with an old, used Remington 870 Express Super Magnum that I found for $200 at a local gun store.







Bought the following parts pictured in the receipt, as well as a match saver ($30), and used Magpul furniture/ barrel clamp from another arfcom member ($115). (barrel is a 24" Carlson's 870 Replacement barrel)





Gunsmithing total was $155 including all the installations, polishing the chamber, removing magazine tube crimps, and opening the loading port. Shotgun now holds 10 in the tube and is quad load friendly. I may still take a little more material away from the loading port but I want to spend some time running it before I do. I'll update this thread if I do.

Interesting.  I like what you did with this.  There are a few things I need to do to my own shotgun that you did to yours, and I appreciate the good pictures and the dedication to only doing things that improve function.



I don't shoot competition and I want to preserve the 18.5" barrel I have on mine, but the action work and the loading port.....yeah, doing those things when I have a chance to get away from house improvement work.

Thanks, bro. I think I am going to build an exact duplicate of this gun in an 18.5" configuration. I'm a fan so far.

Very nice.

the 870s are not popular in matches for a very specific reason. when you are loading, the gate is down. On a 500/590 the gate is up. Couple of things, one that lets you drop shells in and push rather than need to push them in. Second, you will get your thumb stuck in that gate and rip a chunk out of it. Trust me, I have.

Otherwise it's a good gun and will run, so enjoy it "Nubs"

Yeah I’m aware. I’m used to stabbing the lifter in my auto gun so it doesn’t effect my reloading. I’m going to weld the lifter if it bites me.

The biggest issue I have with the 870  is if you apply too much rearward pressure to the pump, it will hang when you fire a shot. I’m not sure what can be done about that so I may just have to train around it.

Nice work OP.

There is something "off" on your 870 if rearward pressure on the forearm keeps it from releasing.

I was told this would be an issue before I bought it. If you can elaborate, please do so. I might be wrong...always learning.

Thanks brother. The kudos should really go to Brownells and Ortiz Custom Guns (Savannah).

Took a little more material from the loading port. I may take more (if possible). A little at a time.

Nice work. I’m about to start getting into heavy division. I have a 930 jm pro for 4 years now but I’m torn on a benelli nova or getting a 500/590 and modifying it. I like the mossberg safeties being in the tang of the receiver. It’s easier for dumping in the barrel or coming from port arms starting positions.

I opened my 870 up to start shooting 3-Gun and have done very well in Tac-Irons and overall beating a lot of open shooters in local matches. My main issue is be damn sure it's locked forward or you'll get a fun jam when you go to load. I want to win so I've picked up a Franchi Affinity 3 to try and go faster. Overall the 870 is a great platform just make sure you know it's quirks.

I could go deeper with mine but since I'm not shooting heavy I'm going to put it aside for now. I didn't have any problem loading quads like this though.