I'm presenting my thoughts, along with some data and images to back them up, about what I've found to work when 'making' your own mags for the 450. There has been discussion on this forum and others but I have not seen any on this specific aspect. Forgive me if this is old news!
Based on recomendation from someone on this forum I picked up 3 of the single round inserts for the mags:
http://fulton-armory.com/magazinefollow ... astic.aspx
Three shipped cost $39.85
I had also read somewhere that the stainless 20 round mags would work great for the 450 so I picked up 3 of:
http://www.midwayusa.com/viewproduct/?p ... ber=132999
Three shipped cost $38.92
So for just shy of $80 I've got 3 new 450 mags... Wrong - and here's why!
After messing around with the mags and cycling rounds through the gun (not shooting just with swift pulls to the charging handle) it was obvious that the mags were not created equal. The opening (specifically where the round is held by the top of the mag) was narrower on the factory 450 mag from bushmaster I have as compared to the new AR Stoner mags. I checked three of the 30 round Brownells mags I've got and found them to be much closer to the factory bushmaster mag.
Here's the data (in inches) - I measured the back, middle, and front of the opening (that holds the case) and here's the results (in that order of measurement for each mag).
Factory mag .442, .456, .461
Brownells 1 .438, .447, .450
Brownells 2 .443, .447, .455
Brownells 3 .449, .453, .459
AS Stoner 1 .467, .491, .505
AR Stoner 2 .460, .485, .501
AR Stoner 3 .463, .492, .500
The round is .500 at base and .476 at 'neck' (image attached)
The difference is obvious. And reflect how the rounds feed. The AR Stoner mags with the wider opening don’t hold the round in place well enough and they feed horribly, and I scratched and dented the rounds constantly with this exercise. All three of the 30 round Brownells mags with the narrower opening fed great, and held 10 to 11 rounds easily.
I’ve attached a photo. From left to right you are looking at:
LEFT: factory mag MIDDLE: AR Stoner mag RIGHT: Brownells
In the middle photo you can see the blue follower piece in the AR Stoner mag. The first question that came to my mind was what the follower looked like? I tried putting the follower from the factory mag in the AR Stoner mag and it made no difference.
Now for your thoughts…
Bill