Loaded Magazine Confusion

**ViperTwoSix** · 07-01-22, 12:46

Originally Posted by razmtaz

Okay, now I'm confused. On these two points I've read many convincing arguments that: 1) 30-round mags are meant to hold 30 rounds and there's no need to under fill them to insure proper function, and: 2) The springs wear out faster by repeated emptying and filling of the mag, as opposed to leaving them loaded. I've lately been reading the US Marine Corps Rifle Marksmanship manual and the following are excerpts pertaining to these two points: 1) "The recommended number of rounds per magazine is no more than 29. Thirty rounds in the magazine can prohibit the magazine from seating properly on a closed bolt." 2) "Ammunition in filled magazines should be rotated frequently if the rounds are not expended. The spring tension on the magazine can weaken if compressed for a long period of time and can cause a malfunction of the magazine." Hard to imagine the Marines have it all wrong...

1. You can fill them with 30 or 29. Whatever you prefer. 30 rounds might make it harder to seat the magazine on a closed bolt, but it’s not impossible. Check your own mags with your own rifle and see what works best for you.

2. It has been proven that spring life is affected by spring compression cycles, not time under tension.

**bobcatdriver** · 07-01-22, 12:49

Originally Posted by Diamondback

Current science has it that it's not time in compression that kills springs, but operating cycles. Look at how long a 1911's mainspring and recoil spring stay under almost permanent compression--their replacement schedule is round-count not "time under load."

With the hammer down and the slide forward, the 1911's main & recoil spring are under some compression but not full compression. The only time they could be near full compression continually, is if it were stored with the slide locked back. Slight compression on an installed captive spring on pretty much anything is normal.

**kerplode** · 07-01-22, 13:21

My "Ready Mags" are aluminum 30-rounders loaded to 28 rounds. I find they seat more easily on a closed bolt with 28rds.

They've been continuously loaded for probably 10 years. I only foresee them being cycled if I eventually decide to change what they're loaded with. Like for instance, if a case of M855A1 fell off a truck, I might cycle a couple of them then.

Otherwise, they'll probably still be loaded when the executor liquidates my estate.

**MegademiC** · 07-01-22, 16:56

I prefer pmags due to the extra room and generally how they handle, but all 30rd mags, even aluminum gi-type get 30. Ive never had a problem.

Practice, figure out what works for you. Remember mags are consumables.

On the subject. Dont do the counter-strike slap. Its slow and unreliable. 90% of the time i watch someone slap the mag, it falls out.

Just push it in till the catch engages.

**17K** · 07-01-22, 17:45

Years of GI mag use has shown me that they WILL occasionally bolt over base when loaded to 30.

Years of GI mags use is also why the only AR mags I own and use are 30 round Gen M3 Pmags. Loaded to 30 every time.

**NYH1** · 07-01-22, 18:01

Originally Posted by razmtaz

Okay, now I'm confused. On these two points I've read many convincing arguments that: 1) 30-round mags are meant to hold 30 rounds and there's no need to under fill them to insure proper function, and: 2) The springs wear out faster by repeated emptying and filling of the mag, as opposed to leaving them loaded. I've lately been reading the US Marine Corps Rifle Marksmanship manual and the following are excerpts pertaining to these two points: 1) "The recommended number of rounds per magazine is no more than 29. Thirty rounds in the magazine can prohibit the magazine from seating properly on a closed bolt." 2) "Ammunition in filled magazines should be rotated frequently if the rounds are not expended. The spring tension on the magazine can weaken if compressed for a long period of time and can cause a malfunction of the magazine." Hard to imagine the Marines have it all wrong...

I've read and been told the same thing.

NYH1.

**Harpoon** · 07-01-22, 18:10

It's Hooke's Law. You can look it up. It basically says that keeping a loaded mag is ok on the springs.

**SteyrAUG** · 07-01-22, 19:44

Originally Posted by 1168

The spring wearing out “problem” is simply bunk. I’ve used mags that I loaded in the previous deployment, on my next deployment. As to trouble seating a full mag on a closed bolt, the Gen 3 PMag was purposely designed to almost hold an extra round for that purpose. USMC issues them….

I'm in this camp, I think Gen3 PMAGS have made this a non issue.