+1 mag extension on 14 inch Grizzly

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Just wondering if anyone has put a +1 mag extension on there 14 inch grizzly?
What brand did you use?
How did it measure out/look?
Function properly?
I assume you have to use a longer spring?
If anyone has been down this road and/or has some pics would love to hear from you.
Thanks
 
Timely post; I just recently purchased my first Grizzly, 14” barrel pump, not mag fed. I bought a Scattergun Technologies one shot extension kit. Almost flush with the barrel. It’s now on the EE as I changed it out for an S&J Hardware model, due to the sling setup. I prefer sling plates. The Scattergun model has a sling swivel at the end of the tube. Both have longer springs.

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Does the Grizzly have a dimpled mag tube?

Scattergun practically invented sling plates for shotguns. You can get them both ways.
 
Yeah, mag tube is dimpled. I had to file a groove on 2 sides of the follower in order for it to pass the dimples.
 
I've used TacOrd on a couple 14" and 18" 870 builds. Like above it's close to flush with the muzzle. I upgrade the spring with a +1. The 4 shot spring works but doesn't put very much pressure on the last round in the mag. It functions but doesn't feel confident. I've bought a couple Tacord extensions and they are my go to. I don't like the fluting S&J does on their extensions. It's just not aesthetically pleasing to me compared to the nice knurling on most others. I go to S&J for a spring, follower and jumbo safety. I like both their Rem and Mossberg safeties and use them on all my builds. Their followers are top notch and a great deal. I've also gone to replacing the multi piece factory Rem extension on 18" 870s to a 1 pc Tacord extension and getting rid of the clamp to get rid of the baby rattle sling swivel and requirement to use tools for teardown. I like the ability to quickly and easily field strip my carry guns without tools.
 
Yeah, mag tube is dimpled. I had to file a groove on 2 sides of the follower in order for it to pass the dimples.

Have you ever had the follower rotate and jam on the dimples, I have one with a 14” barrel and was on the fence about adding a +1 extension. I didn’t feel like pressing out the dimples on this one like I did on a different one to add a +2 factory extension.
 
Good question that unfortunately I can’t answer. I haven’t had it long enough for it to present a problem. I read here that some guys just dremel out the dimples. I was lazy and found it quicker to file the grooves into the follower.
 
Good question that unfortunately I can’t answer. I haven’t had it long enough for it to present a problem. I read here that some guys just dremel out the dimples. I was lazy and found it quicker to file the grooves into the follower.

How confident are you that the follower won't rotate and jam when the slots don't line up anymore?
 
Good question that unfortunately I can’t answer. I haven’t had it long enough for it to present a problem. I read here that some guys just dremel out the dimples. I was lazy and found it quicker to file the grooves into the follower.

Fair enough, the last one I did I pressed out the dimples with a deep well socket I tapered on the lathe. It worked well, just had to grease it well before I tapped it in.

Another question for you, how does the S&J or Scattergun tech +1 lock down? Does it need a ball detent on the barrel ring to positively lock tight, or does it use a wave washer?
 
How confident are you that the follower won't rotate and jam when the slots don't line up anymore?

That is a good question and something I didn’t think of, thanks for bringing it up. I am going to try and find a way to mark where the follower stops when loaded fully/spring is at max compression.
 
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Fair enough, the last one I did I pressed out the dimples with a deep well socket I tapered on the lathe. It worked well, just had to grease it well before I tapped it in.

Another question for you, how does the S&J or Scattergun tech +1 lock down? Does it need a ball detent on the barrel ring to positively lock tight, or does it use a wave washer?

I’m going to check when I get home, but I don’t recall seeing either of that makes sense. I’m used to ball detents, I’ve never seen a setup that used a wave washer.
 
Fair enough, the last one I did I pressed out the dimples with a deep well socket I tapered on the lathe. It worked well, just had to grease it well before I tapped it in.

Another question for you, how does the S&J or Scattergun tech +1 lock down? Does it need a ball detent on the barrel ring to positively lock tight, or does it use a wave washer?

The Scattergun Tech has the indents all around the circumference for a ball detent....unfortunately there isn’t one on the Grizzly. The S&J one shot also has the indents to lock into a detent and now I’m more than annoyed as this is the one I’ll be using. I’m not confident in the few amount of threads on the mag tube for it to be secure simply from screwing it down tight. The sling plate goes on after the extension is secured. That is secured with a retaining clip.
 
I have an S&J side sling on my HP9-1. It works fine.

I used to locktite it on but now I just put teflon tape on the threads before screwing it back on and it stays on.

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I've added a detent to the barrel lug by marking, drilling a blind hole, installing a spring and a small ball bearing from my parts bins and then peening the end of the hole with a punch while holding the bearing in. A sling plate will have a bearing held in in a similar fashion but won't lock up completely tight. As in the threads aren't bottomed, the extension is only making contact with the ball. It does work however.
 
Ive done several detents on 8.5”,12.5”,14” Dominion Arms/Norinco barrels with Remington mag cap detents and springs. I bought the staking tool. Easy peasy. Ditching the internal cap retainer often nets you another 2-3/4” in the tube. I even went with the old style mag spring retainers. Although not essential, it is nice not having the cap spring out of your hand and hit you in the face while disassembling it.

Swedging the dimples out is also super easy with a basic socket set and brass punch. Fit in the biggest deep socket possible. I often add a extension to hold it. Smack the dimple from the outside towards the socket with a brass punch and hammer. Rotate mag tube 180 and do it again. Then step up the socket size and repeat. They will flatten right out without making the tube out of round. Then you don’t ever have to worry about a sticking follower.
 
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The Scattergun Tech has the indents all around the circumference for a ball detent....unfortunately there isn’t one on the Grizzly. The S&J one shot also has the indents to lock into a detent and now I’m more than annoyed as this is the one I’ll be using. I’m not confident in the few amount of threads on the mag tube for it to be secure simply from screwing it down tight. The sling plate goes on after the extension is secured. That is secured with a retaining clip.

Thanks for the info, I’ll have to mull it over. Most likely I’ll just leave it be, I swap a 12.5” barrel on this gun now and again so I’m not 100% set on a +1.

If you decide to get rid of the dimples this is the deep socket I tapered on the lathe with a file, grease it and the inside of the tube well. Iirc while I was tapping it into the mag tube I would occasionally tap the outside of the dimple to relieve pressure, making it easy to remove the socket. 17mm is a perfect inner diameter fit for the mag tube, I didn’t want to drill or dremel them out.

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