View Full Version : Shotgun mag spring length

December 5, 2001, 07:21 PM
OK. Well perhaps I have been inhaling too much of the clearcoat that I'm patiently waiting to dry on my refinished 870 stocks or maybe I just have too much time but....
I'm sitting here with some disassembled 870's and noticed some fairly big differences in the mag springs.
I have two 870's that I have put +3 factory extenders on. Both needed longer springs so I used an old factory spring that I had here and a Wilson spring that I ordered.
Here's the rub.
The factory spring is 24.5" long and was made for the +3 extension.
The Wilson spring is 28.5" long and is made for a itty-bitty +2 extension.
The original springs (pre extension) are 15" long.
The extensions are about 8.5" long, FYI.
Both of these guns feed reliably with the only difference being the pressure it takes to load the one with the Wislon spring.
The point? I dunno. I guess mag spring length is not rocket science and I really would have to question the need to ever replace these springs for reliability's sake. I mean, zoinks, a 4" difference is quite a bit and both of these 870's work flawlessly.
Well, back to the varnish!

December 6, 2001, 01:20 AM
This is slightly off-topic, but does deal with magazine springs:

I picked up my 11-87 Police shotgun yesterday, and I decided to break it down and clean it this evening. I'll be shooting it for the first time tomorrow.

Getting the thing apart was easy. The fork-like part that connects with the bolt and pushes the recoil spring is a pain to put back in place, though. It seems that removing the trigger assembly is the only way to line it up correctly. Then, making sure it stays put when the trigger assembly is replaced with its two pins is a chore. Finally, I removed the magazine extension, which means that I needed to install a magazine spring retainer. Boy, what a pain that was to get in. Alas, I got it all together. I think that after a couple more break-downs and cleanings it will become easier.

December 6, 2001, 05:23 AM
I've only put 3 mag extensions on, but they were all on 870's. I like to cut my mag springs.

I assemble the gun with the mag extension on it, leaving the spring out. I lay the gun down on a table, and lay the fully extended mag spring under the gun, flushing it up to where the follower stops in the mag. Then, I cut the spring 5-6" longer than the mag.

I've found that gives you the maximum shell-holding capability with fairly easy loading and reliable feeding. If you don't trust my theory, you can also just clip about 1 1/2-2 inches at a time, and insert it back into the mag and check it everytime you take a clip off it.

Where'd you get the Wilson spring? I need one for an older extension I had lying around. I currently have it installed with 2 stock-spec springs, but I don't like the weaker new springs.

Dave McC
December 6, 2001, 06:40 AM
Mike, IIRC, there was an armorer's SOP which stated that a used spring was to be measured against a new spring, and if the difference was more than 4", not to use the old spring.

I'd go with the practical test. If you can fire off a few full mags down to empty w/o glitching, the spring's OK.

IME, mag springs are not a sensitive part.

December 30, 2001, 11:10 PM
btt for bullmoose