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Author Topic: Adventures in home gunsmithing, the tale of my new 3-gun shotgun.  (Read 7100 times)

Offline bkoenig

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I’ve posted a couple of times about my new 3 gun shotgun.  I thought I would write up something about it so those who are considering buying a gun for this purpose can decide if it would work for them.

Last year was my first time trying my hand at 3 gun shooting.  I used the “run what ya brung” philosophy.  I didn’t already have an AR-15, so I did my research and was able to build one that was very suitable for this style of shooting.  I also had an M&P 9L, which worked well.  My shotgun was my tried and true Remington 870.  I just stuck an extended magazine on it and headed to the match.

I actually did better than I thought running a pump gun.  What I found was that it’s more important to knock over the steel with a good hit on your first shot and to be able to reload quickly (still working on that one) than to be able to yank the trigger really fast.  Still, by the end of the year I decided I needed to transition to an autoloader.  Mainly because I have an incurable problem; I’m addicted to buying guns.

I did a lot of research into what people were using.  I found that pretty much every autoloader out there is going to need some modifications to make them suitable for 3 gun.  The shell lifter typically needs welded up to keep it from catching your finger while loading quickly, and you’ll need to add an extended magazine.  The Benelli M1 and M2 are considered by a lot of people to be the top of the line, but you’re looking at $700 or so for a base M1 and at least a Grand for an M2.  The Winchester SX3 / FN SLP is fast becoming a favorite with competitive shooters, but it was also out of my price range.  A lot of people use the Remington 1100, but it has a reputation for not being as reliable as others under heavy use.  Still, you can pick up a used 1100 for a very reasonable price, so I figured I would go that route. 

I had briefly considered the Mossberg 930, but when they first came out I heard a lot of complaints that they didn’t want to run with light target loads like are typically used in 3 gun, so I dismissed it.  However, when I ran across a new in box 930 on Gunbroker for $380 I decided to take a second look.  I found the reliability problems were found to mostly be due to the heavy grease Mossberg coated the action with from the factory.  The rest of the problems typically went away after a couple hundred rounds of break in.

So I decided to give the Mossberg a shot.  My particular gun was very cheap because it had a big scratch on the forend.  Some elbow grease and sandpaper fixed that up in an afternoon.  While I was at it I stripped the ugly factory tinted varnish off the stock and forend to reveal some nice black walnut wood.  A few coats of oil had it looking good.  It’s already picked up a couple of dings without that hard varnish coating, but a banged up gun is a well loved gun, right?

Offline bkoenig

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Re: Adventures in home gunsmithing, the tale of my new 3-gun shotgun.
« Reply #1 on: March 27, 2011, 08:31:23 PM »
The biggest problem with the 930 is that it comes with a ported barrel.  I have no idea why Mossberg doesn’t offer the gun unported, because in 3 gun running a ported shotgun puts you into Open class.  I didn’t want that, so I had the barrel cut down right behind the ports and rethreaded for the factory chokes.  This gave me a barrel length of 22”.  I then added a Choate +4 extension to give me a total capacity of 8+1.  This is where my cheapskate tendencies bit me, though.  I’d heard a lot of people recommend paying the extra $25 to buy a Nordic Components tube, but I figured a tube is a tube.  I was wrong.  I had all kinds of feeding problems with the Choate.  I know they run fine for a lot of guys, but I couldn’t get it to work for me.  Shells kept hanging up in the tube, or not feeding into the action when the bolt racked back.  I switched to the Nordic tube and my problems were fixed.  I think this was because the Nordic has a bevel where it meets the factory tube, while the Choate doesn’t.  The spring and follower kept hanging up in the mag tube with the Choate.

One of the other problems with the 930 is that it’s very hard to load quickly in its factory configuration.  The shell lifter has a big notch that catches your thumb, and there’s a huge overhang at the front of the loading port where the mag tube mates to the receiver.  Combine the two and loading this gun was like playing with Chinese fingercuffs.  So, I welded up the lifter and took a file to the loading port.  I got rid of that huge overhang, and while I was at it I opened up the sides too, so my clumsy fingers would have a better chance of hitting the port while I’m stuffing shells in.  I refinished it with Aluminum Black, but after the first use it started scratching off right away.  I also shortened up the back of the forend, since it normally runs right up to the edge of the port and can get in the way while loading.

One of the mods I’m pretty proud of is the sights.  I can’t hit anything with slugs and a regular bead sight.  I’ve tried it, and it just doesn’t work for me.  We’re talking not even on the paper at 25 yards.  Clamp on rifle sights are readily available, but I like to tinker with things so I decided to add a set of Hi-Viz 10/22 sights.  The base of the sight’s dovetail is a little deeper than I wanted to go into the rib, so I filed both of them down to about half their original size.  I then filed dovetails into the front and rear of the barrel for the sights to slide into.  They’re nice and solid, and I can drift them to adjust for windage with slugs.  The rear sight flips down for shotshells, and when I shoot slugs I can flip it up.  The fiber optic tubes make it easy to pick the sights up quickly.  This was my first time cutting a dovetail with a file, so I practiced on a leftover cut off barrel piece until I was comfortable doing it on this gun.  It was easier than I thought, but you do need to make “safe” square and triangular files by grinding the teeth off one side (on the triangle) or opposite sides (on the square).  This allows you to cut only one surface at a time without worrying about enlarging the dovetail in the wrong direction.  You first start your cut with a hacksaw to define the inner dimension of the dovetail (the part that will be the top).  You then take the square file and file straight down until you’ve reached the desired depth.  The smooth sides of the safe file keep you from making the cut wider than your initial hacksaw cuts.  Then you use the triangle file with the smooth side down to cut sideways and define the angled part of the dovetail.  Go slowly and keep trying your sight until it fits snugly.  Remember, a file is a handheld precision milling tool, not something to saw back and forth and remove a ton of metal.

The trigger was pretty good from the factory so I just polished everything up.  It has just a hint of creep, very little overtravel, and I would guess it breaks at about 3 or 4lbs.  I wouldn’t want it any lighter.  I also added an extended charging handle and safety.  These weren’t at all necessary, but they make it look more tacticool.

So far I’m very happy with this gun.  I’ve run less than a hundred rounds through it, so it’s not broken in yet.  In my first outing I had one minor malfunction – one empty shell stovepiped sideways in the ejection port.  I just pulled it loose and kept shooting.  I’m hoping once it’s broken in that won’t happen any more.  I found that I could transition from target to target much faster than with my 870.  Reloading was very fast, at least for someone who doesn’t have much practice stuffing in shells.  Recoil is so light with target loads that I don’t notice it at all while shooting a stage.  This is a piston operated gun, with a long recoil spring in the stock, so the action soaks up a lot of recoil.  It also has a very thick, soft recoil pad.  I’ve found that even with 3” magnum slugs it’s manageable.  It rocks me back pretty hard, but it’s not unpleasant. 

There are a few minuses to the gun.  Like all Mossbergs, it has an aluminum receiver, which has always felt cheap to me.  The gas system also seems a little cheesy.  It has some plastic parts, and although they’re pretty beefy I would prefer to see all steel here.  The length of pull on the stock is very long, something like 14 ½”.  Looking at the recoil assembly in the stock I think it could be shortened by maybe ½”, but that could still be too long for people with shorter arms.  I think most women would have a problem using this gun even though it’s pretty light.  It just wouldn’t fit them well.  I have long arms so it doesn’t bother me.  I’ve also heard that the stock angle and drop are uncomfortable for some people.  The gun comes with spacers to adjust the drop.  I thought it felt fine right from the factory, which is good because I promptly lost the spacers after opening the box.  My particular gun was the field model, and I’m not crazy about the chrome bolt and gold trigger.  I might try to refinish them at some point.

Overall, I would highly recommend this shotgun to anyone who’s looking to put together a 3 gun rig without spending a ton of money.  A couple of big time shooters have started shooting these on the national circuit, and Mossberg is rumored to be working on a competition-ready model.  I have less than $600 into mine, and I doubt if the factory competition gun will be that cheap.  I was able to do all the work myself except cutting and threading the barrel, so that helped.  If you would like to give it a try and you shoot at Eastern Nebraska Gun Club’s matches let me know and I’d be happy to let you use it.  I think Mossberg has a real winner here, and if they would just offer it with an unported barrel they would dominate the entry level 3 gun market. 
« Last Edit: March 27, 2011, 08:41:43 PM by bkoenig »

Offline bkoenig

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Re: Adventures in home gunsmithing, the tale of my new 3-gun shotgun.
« Reply #2 on: March 27, 2011, 08:33:23 PM »
And now, pics!  Notice the sandpaper under the crappy Choate mag clamp.  It won't hold in place under recoil, so that was an attempt at giving it something to bite onto.  I need to get a new clamp.  The lifter is a little rough looking.  I wanted to make sure it would work OK before I put a lot of effort into making it pretty.  Eventually I would like to Duracoat the entire gun.







« Last Edit: November 26, 2011, 07:33:47 AM by bkoenig »

Offline Ghost

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Re: Adventures in home gunsmithing, the tale of my new 3-gun shotgun.
« Reply #3 on: March 27, 2011, 09:45:37 PM »
bkoenig - I've paid money for gun magazines that didn't have stories this good.  Good write-up and pix!  Thanks!

Ghost
A well-regulated militia, composed of the body of the people, trained to arms, is the proper, natural, and safe defense of a free State......George Mason