View Full Version : Mossberg 50660 with 20 inch barrel

Sean Thornton
July 18, 2012, 03:27 PM
I just purchased a Mossberg 590 SP 50660. The specs say it is suppose to hold 8 rounds in the magazine of 2 3/4 inch shells. The down side is that I can only get 7 rounds in the magazine. There does not appear to be any plug in it. Any ideas as to why it does not hold 8. thanks for any information.

the rifleer
July 18, 2012, 03:31 PM
Does it say 8+1 or 7+1? or does it just say 8 rounds total? Usually with shotguns they mean one in the chamber, plus however in the magazine. So in your case it would be 7+1 if you can only get 7 in the magazine tube.

Sean Thornton
July 18, 2012, 03:54 PM
The specs state capacity is 9. 8 plus one in the chamber. It is chambered for 3 inch.

July 18, 2012, 05:47 PM
Are there any roll crimped rounds in the group you are trying to load? Roll crimp rounds are longer before they are fired than fold crimped. Enough roll crimp rounds in the mix can make the difference between 7 or 8 in the tube.

Otherwise, the spring / follower may be binding up due to length.

Sean Thornton
July 18, 2012, 09:38 PM
I was trying to load regular crimped, folded, number 4 Turkey loads into it. the capacity is stated as 9 which I assume menas one in the chamber and 8 in the magazine. it is a 3 inch gun but I can only get the 8th 2 3/4 round in the magazine about half way. there would be no way of getting 7 of the 3 inch shells in as it is suppose to. I will disassembe the mag and see whats up.

the rifleer
July 18, 2012, 10:08 PM
I think you should try some target loads. Different shells are different lengths.

July 18, 2012, 10:20 PM
Sounds like a binding issue to me. I can get that much of an eighth shell in my model 500 and it is only a 7+1 model.

A look see down the mag tube from the front is in order.

Sean Thornton
July 18, 2012, 10:55 PM
With no spring in the magazine it would hold 8 and half of a 9 round of 2 and 3/4 crimped shells in the magazine. With the spring in it only holds 7 and half of the 8th round. When the spring is in the magazine not compressed there is 10 and a half inches of spring sticking our of the top of the magazine. Is that normal or could the spring be too long? I als think with that much spring there is probably binding of the spring in the mag when trying to put the 8th round in. Would a shorter spring work, just a thought.

July 19, 2012, 12:00 AM
That model indeed is billed as a 9 shot by Mossberg which to me translates as 8 in the tube and 1 in the chamber. Your guess about too long a spring is logical, but I would call Mossberg before cutting it. Inspect the inside of the magazine tube for any burrs that may be catching the spring.

Sean Thornton
July 19, 2012, 07:48 AM
The rounds I have tried measure 2 3/8s inch long and only 7 and half of the 8th round will go into the mag. I had some that measured 2.25 and the 8th round almost went in. In order for an 8th round to be loaded into the mag I think rounds would have to measure around 2 and an 1/8 inches long. I guess I will have to settle for only 7 rounds in the mag. I checked the mag for and burrs rough spots etc and all seems to be ok. I might try a wolff spring and see if that makes a difference.

the rifleer
July 19, 2012, 02:22 PM
You might call mossberg and see if they will send you a free spring first.

Sean Thornton
July 19, 2012, 05:09 PM
Great advise, I did just send them an email. It will be interesting to see what they say. I have also found out that several others have had the same problem with only being able to get 7 in an 8 round mag.

Sean Thornton
July 24, 2012, 08:02 AM
I got a new Wolff magazine spring and now it will hold 8 rounds in the magazine with no problems.

the rifleer
July 24, 2012, 01:13 PM
Just out of curiosity, what did Mossberg say?

Sean Thornton
July 24, 2012, 04:42 PM
I have sent them a couple of emails, no responses yet.

Bill from Boomhower,
July 24, 2012, 07:13 PM
That would've been my guess about the spring, maybe just a couple of rungs cut off. The capacity of the guns are always based on two and three quarter inch shells. I remember reading in some other thread where someone had similar problems, and checked the shell length, and one brand(I don't remember which) was slightly longer than other brands. Congrats on your gun, I've been wanting the one with AR-15 front sight, and bayonet, I think it's #50177. Good luck with yours.

Sean Thornton
July 24, 2012, 09:13 PM
Another down side of this shotgun is the 14.5 LOP. I think I am going to put a speedfeed 13 7/8 LOP on that a friend of mine took off of his. I will probably have to get an M9, just because, LOL. My "home defense" load for it is going to be the Federal 8 of the OO buck with the flight control wad low recoil.

July 26, 2012, 08:21 AM
Just call and they will gladly get you on the horn with the guys to hear you...