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It makes no difference in terms of safety or harm to the gun or magazine. It WILL slow down your reloads, and it MAY cause a magazine to not seat properly.

^^^^^^^^^^^

There's your nice straight, short answer.

In addendum to that, when inserting a magazine...always give it a tug (down) to check that is has fully seated.

After charging your weapon, no 'press check' is necessary. The 'normal' arrangement in your magazine for traditional AR cartridges is 'staggered'. If you need to verify a round has chambered, simply note (before inserting the mag) which side the top cartridge was located.

Drop the mag and note where the current cartridge is. IF opposite the first, then a cartridge was stripped from the mag. and you are 'hot'. Reinsert mag, tug....you are good to go.


Disclaimer:

IF a magazine has been modified to use a center feed follower (usually a Big Bore or wildcat cartridge) this would not work for you.

Abraham wrote:Actually, most of the responses don't address what I am seeking to know.
Here's my original question: Is there any long term problem associated with inserting a loaded magazine on a closed bolt on an AR or is it preferable to do so on an open bolt?
Or, does it make no difference whatsoever?
The responses, while providing useful information, don't really address my questions.
My questions came about due to the difficulty of getting a magazine to easily insert on a closed bolt, so I thought over time inserting on a closed bolt might create some sort of wear and tear that could be avoided if I always inserted on an open bolt...

I do not believe wear is a factor. Under normal conditions, an AR bolt locks to the rear after the last round in the magazine has been fired. The idea is to leave the bolt locked back, remove the empty magazine, insert a fresh magazine, and press the bolt release.

As an instructor, I tell people to remove the magazine and leave the bolt locked back to begin with and between strings of fire for safety reasons. That way after inserting a fresh magazine, one only has to press the bolt release to be ready to shoot.

Either way will work, but I have to wonder why would one want to start off with the bolt closed under everyday practice conditions?

However, if one finds oneself in a situation, needing to execute a tactical reload, then leave the bolt closed on the loaded chamber, remove the partially depleted magazine, insert a fresh magazine, and tap it to ensure it is locked in place.

ever think why an AK platform has a rotate cam system for inserting magazines ? same thing

txtaxman wrote:

Abraham wrote: My questions came about due to the difficulty of getting a magazine to easily insert on a closed bolt, so I thought over time inserting on a closed bolt might create some sort of wear and tear that could be avoided if I always inserted on an open bolt...

I do not believe wear is a factor.

I think OP is over-thinking this.

The BCG travels 30 times back and forth at very high speed over the rounds in a standard magazine. Whether or not is is closed or open for the 1 out of 30 times you load the magazine is inconsequential in the overall scope of things with regards to any wear and tear.

My 1st AR a Colt 1 model SP1 came with green furniture and chrome bolt carrier & 3 prong flash hider it is so old, at 1 time I got free ammo and took advantage of that, it had the 3rd barrel on it all the rest is as good as new, shoot yours till you wear it out !

PSA: Do not chamber the same round more than once in an AR-15.

In other words, don't eject the round in the chamber, put it back in the magazine, then load it again.

AR-15's have a free floating firing pin, and the pin can make contact with the primer when the bolt is slammed closed. Doing this too many times could either cause an accidental discharge or it could cause a dent in the primer that prevents the firing pin from discharging the round when intended.

We carried our duty weapons like this in the USAF - open bolt (ensure empty chamber) close bolt - insert magazine - place weapon on safe - we would only charge our weapons on orders or if someone entered the close in security area without authorization or improperly.

Once again, lots of good information.

Thanks all!

There should be no problems inserting a mag on a closed bolt. That's what you'd be doing during a tactical/pro-active reload. At my last job the shotguns and ARs had loaded mags (in the magwell), empty chambers and safety on. This was referred to as "cruiser ready." From what I remember Magpul says they made the PMags with a little extra room so you can put a full mag in on a closed bolt.

Some of my builds mags are 'tighter' in this situation than others. If you think about it, like previously stated, the top round in the mag is more likely to move than the BCG in the upper receiver.

I press the mag in and do the 'pull check'. Over time you may actually loosen the mag spring and break it in enough where this may not even occur.

Either way, tight is nice! That spring will push those rounds up, making them available every time the gun goes pop.

FA, sometimes. If I have time, I always push it. In a defensive posture, sending rounds down range, simply drop the mag, insert, and pop the bolt catch. The gun is already 'heated' and unless you've fired hundreds of rounds, should be GTG!