That @#!&@ Mossberg 500 mag tube spring

[Midtown Gunner]

I've been cleaning and reassembling an old Mossberg 500A (with one action arm). It needed a new magazine spring, which I ordered (6-shot spring ordered from Mossberg). I cannot get the magazine screwed back in without the spring bursting out of the 1 inch gap between the forearm tube and where the tube screws in!! I've watched several YT videos on it, which have not been helpful (nobody there seems to have a problem, naturally).

What do I need to do to put it together without buggering the spring? Alternately, how much would a gunsmith charge me for this? (I'm in Sacramento)

[Boarhuntor]

Never had such a problem, done it many, many times.
Why did it need a new spring?
Make sure the spring is the correct length. 500A has 5 shells in the mag as I remember, but my memory betrays me often.

Per instructions the spring must be 12 to 18 inches longer than the magazine tube, I prefer 8-12" on pump guns. Just measured mine, it is 26" total. The mag tube is 15" so my spring is 11" longer than the tube.
Some people make it only 4"-5" longer. But I think it is extreme.


After you made sure the spring is the correct length, push the spring inside the tube, You can use a dowel of the correct size as a guide,
Hold the spring with your thumb, push in the follower, hold it with your thumb, press it to the receiver simultaneously removing the thumb, screw it in.

And one more advice, never blame a tool or machinery, blame the operator.
Mos 500 is one of the simplest and easiest tools to manipulate, hence the most popular.

..

[Spyder]

I'm not sure what you mean. I swap between short mag tube and long mag tube on mine ALL the time and have never had a problem. Perhaps you're trying to stuff a big mag tube spring in a short mag tube and it just doesn't fit?

[Boarhuntor]

I'm sure he uses the size they sell which is usually 40".
For 5 shell mag it should be no more than 28-30"

[Midtown Gunner]

Why did it need a new spring?

It wasn't ejecting very well, and it was rusty when it came out.

'm sure he uses the size they sell which is usually 40".
For 5 shell mag it should be no more than 28-30"

The spring is 30 inches long. The magazine tube is 14.5 inches. It holds 6 shells without the spring, and everything I've read says it holds 5 (+1 in the chamber). The spring I bought doesn't list its length, but reviews of it at Brownells say 30".

Should I start trimming one coil at a time?

[Boarhuntor]

First, make sure when you insert the spring you top it with the follower instead of dropping it into the receiver.
Start from 28" total and then see how it goes.
Te mag, including the spring, should hold 5.5 she's, meaning, when you load 5 shells and try to load 6th, it should go at least 1/2 of its length..

You can check it by inserting the spring, the follower, and them using a dowel with marked 5 shells length on it push everything in.
This way you can figure it out if it is the arrow or the Indian.