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SA-20 questions

H

huskers15

.410
Okay, finally a proud new owner of the Mossberg SA-20. Got it home yesterday and I was like a kid at Christmas. Very happy with the quality and it is pretty much spot on with what I personally wanted for a HD shotgun for the house.

In disassembling, cleaning, and re-assembling I learned a lot about my first ever shotgun. First question I have is, the magazine plug that I took out. There is a little "do-hickey" about the size of a dime that held this plug in place. The manual says nothing about putting the "do-hickey back in, so I didn't. Is this correct?

Secondly, one of the features I was looking for in an HD shotgun was the shortest, legal barrel for manuverability in the house. This barrel is 20 inches measured with the bolt closed. I would like to get close to 18 inches w/o breaking the law. The other issue is chokes. I think I would like to have the ability to attach chokes to make it more versatile. And lastly I would like to extend the magazine.

So with all that, when measuring a barrel for legality, is it just the barrel length or barrel length plus a choke?

What are the pro's and con's that you can think of in shortening a barrel? Will the shot shell act differently enough to not be worth it? Will it limit what type of ammo I can use? etc. etc.

Ultimately what I would like is the shortest, most versatile barrel, and a magazine extension that is flush with the barrel for maximum shot's. Choate has two extensions, a 6 inch and a 8 1/8 inch I believe. So based on my questions above I'm trying to decide which way to go with the extension.

After I get to the bottom of barrel length with or without tapping it for a choke, and then figuring out the extension, I plan to add an LED light. That will be my last mod.

Thanks is advance for any info you can provide. :mrgreen:
 
Congrats on the new SA-20!

You do-hickey is simply a plug that keeps the spring from hitting you in the face when you remove the cap. It's not 100% necessary, but can help avoid a face full of spring if you forget it's not there the next time you remove the cap.

huskers15 said:
So with all that, when measuring a barrel for legality, is it just the barrel length or barrel length plus a choke?
Click to expand...

The shortest legal barrel length without going through NFA registration is 18". Most manufacturers produce their barrels at 18.5" to avoid the possibility of any measuring discrepancies that could cause legal issues for the buyer.

The correct barrel length measurement is taken with a rod or other instrument that fits down the barrel and the length is measured from the closed bolt face to the end of the barrel.

The only way a choke would factor into the length would be if it is PERMANENTLY welded into the barrel. Removeable, thread-in chokes will NOT count toward barrel length. Your choice of choke will be a factor that may limit your ammo options. I've got zero experience with chokes, so I'll defer to others here with more experience.

One quantifiable difference in changing barrel length would be a slight loss in muzzle velocity with the shorter barrel. This could possibly effect your ammo selection in that you might have to make up for the loss in muzzle velocity with higher velocity ammo to cycle the action properly. Again, the energy loss would be minor and may cycle fine anyway.

As far as tube extensions, I would first recommend getting in touch with the various manufacturers to see what models they offer that will fit the SA-20. It might narrow your options a bit.

All that being said, the big question is will shortening the barrel by only 1.5" make enough difference in maneuverability to be worth your time and effort?
 
Thanks for the info LES. Through the process of elimination, I guess the choke idea is out as I certainly don't want a longer overall barrel length. I would guess choke's have some amount of length to them and I wouldn't want to limit my ammo choices by having to weld it on to keep it legal.

As far as the mag extension, all I have done is search online, and all I can find is Choate. As I said before they have a 6" and an 8" extension, assuming this thing just threads onto the mag tube, then I'm either an inch short or an inch long of the barrel. I know OCD!! Which makes me wonder if I had a gunsmith make one 7 inches in length, would I even be able to fit 1 more shot shell in it...? I'll have to do the math on it.

As far as the mag plug I pulled out, the "do-hickey" was a dime sized, washer looking thingy. There is still what looks to be another obstruction that keeps the spring from busting my nose. But thanks for being concerned.

Great info much appreciated.
 
The difference between a 18.5 and a 20 inch barrel will be negligible for most shotgun applications.

LES is right about the measuring the barrel.

My HD gun uses a turkey barrel and came tapped for choke tubes. I have security (18.5" barrels for two other guns that are not yet tapped for chokes tubes.)

Chokes are nice for fine tuning your pattern at longer ranges and if you want to use the gun for other things such as clays or small game hunting. They are not required by any means but will offer you more flexibility in the ranges in which you will be able to take game.
 
Yes that is how I measured my barrel, 20 inches on the money. Actually measured LOP as well, ordering from the internet is suspect. People sometimes don't get what they ordered. I was concerned that I might get a 24 inch barrel.

After doing the mathematistic's... A custom made 7" mag extension made to be flush with the barrel I have is still going to leave me 3/4 of an inch short of fitting one more 2 3/4 shot shell in the tube. So that idea is out the window. Gonna go with a Choate 2 round extension and possibly get the barrel cut back another time if my OCD takes over. :)
 
Ordered my mag extension from Choate, as well as a Streamlight LED and an Elzetta mount. Will take pic's when all is said and done. Also, it occured to me that once the mag extension is on and the end cap is screwed back on, it will probably be flush. I'm a nit wit.:/
 
Just bought a SA-20 and 7 shot extension. Thinking about the Streamlight LED + Elzetta mount as well.

Any pics of yours? Do you like the setup?
 
welcome from NY and congrats on you new mossy. you get a chance post a pic. :)
 
Thanks old mossy. I'll post pics soon. Installed the extension; will cut down barrel this weekend hopefully.
 
jdmmd said:
Thanks old mossy. I'll post pics soon. Installed the extension; will cut down barrel this weekend hopefully.
Click to expand...

looking forward to the pics. :)
 
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