Magazine springs too strong.

[AFJuvat]

I picked up a few USGI spec 3 Round M1 Carbine magazines.

They are marked 'UU', which means they came from Korea, The body and dimensions are exactly to the original USGI spec.

That said, the magazine spring is too strong - Pop a round out of the magazine and 2 - 4 rounds pop out. Last time I took it out, the bottom of the bolt was gold colored from rubbing on the brass.

Anyone know a reliable way to make a magazine spring weaker?

Thanks

[sdmc530]

if the spring is too hot you could just cut off one coil at a time, then try it. this should alleviate the issue if the spring is the issue.

[Riverpigusmc]

cutting a spring can make it stiffer sometimes...have you tried stretching it? And are you sure the feed lips aren't stretched open?

[wxl]

Originally Posted by AFJuvat

I picked up a few USGI spec 3 Round M1 Carbine magazines.

They are marked 'UU', which means they came from Korea, The body and dimensions are exactly to the original USGI spec.


Thanks

Could be Korean but original USGI mags from Underwood can also be marked with "UU".

[AFJuvat]

Originally Posted by wxl

Could be Korean but original USGI mags from Underwood can also be marked with "UU".

Too new to be original Underwoods.

I ordered 2 original surplus SEY hardbacks. Will give them a try.

[Caleb]

I'd try stretching them before snipping.

[AFJuvat]

Update.

Received the 2 SEY magazines and compared them to the 'UU' marked Korean magazines.

The SEY magazines are 'hardbacks', which were the first 30 round magazines produced, whereas the Korean magazines are the later 'splitback' type.

Body thickness and weight are actually pretty close to each other - within 5 grams. USGIO magazines are blued, whereas the Korean magazines appear to be painted.

The SEY spring is actually thicker and longer than the UU springs, which since I was operating on the presumption that the Korean springs were too strong.

Breaking out the calipers, I found the issue - it was the feed lips.

Though they are profiled exactly the same as the USGI feed lips, the lips on the Korean magazines were 0.002" higher on each side, thus making the opening on the magazine 0.004" wider than the USGI magazines.

Loaded the magazines and with a small brass hammer, tapped the lips profile to match the USGI magazine. No double or triple feeds after.

What is interesting is comparing my USGI 15 round magazines to the Korean ones, the Korean magazine feed lips are also about 0.002" higher, but don't double or triple feed rounds. I suspect that is due to the 30 round spring having to be significantly stronger.