How to install a S&J Hardware +1 extension on a Mossberg new model 590 shotgun featuring a long, 6 shot magazine tube. You can find the +1 extension here: sjhardware.us/...
Yea, just got mine, and it's giving me fits. I can't quite get 7 shells into the shotgun, close though. S&B 2 3/4" #4 buck. It mentions on the package that some may need to trim the spring, but I wrote them on FB, and will talk to them first. Very nicely made though, and it will be better once I get it to hold 7 shells!
A little update on this issue, I compared some Federal "Flite Control" 00 buck I have to the S&B, and the Federal load is a bit shorter. Times this by 7 shells, and there IS a difference. I went ahead and ordered some Federal Power Shock #4 buck for the home. The kit will take the Federal shells no problem. Maybe it's my shotgun, who knows? Those S&B shells shoot, and pattern great, but they are longer than the Federal shells.
@@davevalerie6708 its just the shells. i have the same problem with S&B. its too bad they didnt make the tube just a hair longer so it would sit flush with the barrel. that little bit of extra length would probably be enough to fit 7 S&B shells in the tube.
@@davevalerie6708 Interesting. This was exactly the answer I was looking for. Was your shotgun made before 2017 by any chance? Apparently, the +1 extension is a little different now compared to those made prior to 2017. At least, I think it is.....they have a +2 tube for pre-2017 guns, which is why I say that.
For anyone that grabs this just make sure you measure the rounds you want to use. The stars and stripes buckshot that I had measured just about 2 3/8 inches and it will not fit 7. Not a huge deal since I have other stuff that is crimped shorter and does work. But ensure you get what you want out of it. Also, If Scoot is still in these forums and at S&J can I get a new spring? I may have trimmed it too short trying to find this out the hard way haha
Think this needs that extra quarter inch to make it flush with the barrel. I can get the 7 snap caps in mine, but those are only 2 5/16". My 2 3/4" ammo won't fit 7--it's close, but the last one needs just a little more room. If you made it, I'd buy the replacement, and I'm sure a lot of people would.
Hi Eric, thanks for the note. I just want to share with you an update on 12 gauge shot shell length. They are crimped at different lengths by different manufacturers. Most are crimped at 2 5/16 same as the snap caps. You will easily be able to reach full capacity. Rio brand shells are the longest I have measured. You will never get full capacity with them. They are a whopping 2 15/16 crimped length. That is almost 2 1/2". Thank you Scott S&J Hardware USA
Facts. Crimped or not its advertised as +1 for 2 3/4 basic shells. Whoever engineered that should have just added a little more length which would have been fine, flush with barrel, and more functional. There should be a huge title on this product saying it only accepts certain 2 3/4 in shells.
I just installed a +1 mag extension on my 590A1 and it sticks out 3/4" past the muzzle. It looks ridiculous. I'm really disappointed. (I didn't get it from S&J Hardware. Probably a different make. Or else my mag tube is a different length.)
They're a 590 pattern so yes. On the model with the 14 inch barrel the extension will protrude past the muzzle a little bit though. The 7 Shot model with the 18.5 inch barrel fits the exact same as the one in the video.
Yes you are correct. It works on 590 and 590A1 Mossberg shotguns primarily. The model that has the bolt goes into the end is the Mossberg 500. Thank You
More extensions are inbound now. Shipping to customers by the end of the week. You can find them here: sjhardware.us/product/mossberg-590-a1-1-mag-extension/
I followed these instructions, in conjunction with the instruction on how to adjust the spring size of the spring provided by S&J. I have a 6+1 590 and a 6+1 590a1. I reduces the spring down to 23 inches, 22 inches, and 21 inches. I cannot get 7, 2 3/4 shells to fit in the magazine with this kit installed. I going to request a refund.
Hi William, I'm here to help you. What type and brand of shells are you using for testing? Exactly how long is one of the unfired shells? A standard unfired shell is the same length as the snap caps. 2 5/16" If you are using Rio's or other imported shot shells they may be too long. Thank you Scott Mueller S&J Hardware.
@@04BlueSmoke I used Remington 2 3/4 STS #8 shot, B's 2 /34 Dry Fire Snap Caps, Estate 2 3/4 00 buckshot, and Sellier and Bellot 2 3/4 #4 buckshot, and I couldn't fit 7 of any of them with the S&J extension.
@@04BlueSmoke Sorry. In my initial reply I typed J&G extension. I meant S&J extension, the one featured in this youtube.com video. But getting back to what I previously expressed, it doesn't work on the Mossberg 590 and 590a1 7 shots I own, with the aforementioned shells I tried. On that note, I have to request a refund, for the extension only serves as a paperweight under these circumstances.
No. That hole is there to let dirt, mud, powder debriefs, and or water out of the mag tube. The sling should be attached at the union between the extension and the factory magazine tube Thanks Scott
On the website, it says that you need to trim the new spring. If so, how much do you trim it by? For reference, I have a new 590A1 with an 18.5" barrel, not here yet but shipping to my FFL as we speak. EDIT: I saw your answer of 23", thank you.
Yes the sling plate does move a bit. It may leave a mark on the barrel. The movement is important for function. You never want a completely tight sling. It makes it too hard to sling the firearm and to get it off your shoulder
Im on the site and it says the spring must be trimmed. I have a Mossberg 590 Tactical 18.5 inch barrel. Same model in the video. Will the spring included fit or do I in fact need to cut it down? I noticed there was no mention of trimming the spring.
Hi Cliff, Thanks for the note. No you do not need to install the sling plate. It is optional. This extension is shipping with a spring that will need to be trimmed to fit. Make the new spring 3" longer than your factory spring. Thank You Scott Mueller
I purchased this +1 extension for my Shockwave. Yes, the installation was easy, and the extension fit perfectly. That said, I CANNOT load the sixth round into the mag (not enough room). Thinking that there wasn't enough space to accommodate the compressed length of the spring, I proceeded to trim the spring incrementally. Eventually, I was able to "force" the sixth round just (barely) past the point where it would fit, but at that point I had trimmed the spring so much that it didn't have sufficient force to ensure that the final round in the tube would load reliably. I haven't given up yet, but am frustrated...the issue just isn't intuitive...
@@texaskid6211 Manufacturing Engineer here: What's going on is that this +1 extension was designed for the standard 5 or newer 6 shot Mossberg magazine, which have oversized mag tubes to handle varying sizes of shotshell. The Shockwave does not have a standard length mag tube, but uses the more compact Short-barrel-shotgun mag tube (Mossberg shaved off a bit of the extra on the more compact tubes to attain a shorter overall length). Solutions? You could try using the original factory follower, which might buy you a few fractions of an inch, or you might try finding a larger gauge spring, which could provide the necessary force with fewer coils. Other than that, I don't know what to tell you, though.
Thanks for the follow-up! Actually, with continued effort, I finally figured out "most" of what you identified above. So, I had already replaced the S&J follower with the original factory follower (not as nice, but--as you suggested--it DID give me a "smidge" more room in the tube). For any others who contact you with the same problem, I also found that when I mounted the sling mount *between* the barrel mount and the S&J tube extension, it also gave me a little more space, so much so that I am now able to insert a sixth round of *most* (but not all) brands/varieties of 2 3/4" shells. So...between your assistance and my persistence, I FINALLY got what I was seeking. Again, thanks SO much for the follow-up response (most companies don't do that these days...).@@adamcard9773
Hello Thanks for your note. The sling holder is not rigid, not fixed. It does pivot and move. I wouldn't say it rattles. It is held in position with a split ring. It is optional. Some choose not to install it. Thank You Scott
Also now the extension has a hole where the original sling mount used to be. Horrible engineering. Allowing all sorts of crap to get into the magazine tube.
Anyone have more detail on how to remove the original spring retainer the OP simply says "gently" but no mention of tools or technique I'm hoping not to damage any original parts just in case thanks
I use a small flat tip screwdriver in the center of the retainer and they I gently work it around 360 degrees until the retainer if free. I do use a cloth over the mechanism so the spring and retainer don't so flying.
Thanks Scott you're right a small flat blade screwdriver works great I was surprised to see there are no dimples etc or any other retaining methods the spring stop is just pressure / tension fit
@@abc123def98 As youve seen like with multiple other people, if you have roll crimped shells which make up a lot 2 3/4 in shells, it wont accept the +1. It only accepts some 2 3/4, so your just guessing with your money.
Slightly extending past the barrel isn't a concern unless it's obnoxiously long, how much past the barrel with it protrude! Thanks a million for the quick response too, I also really appreciate that!
