View Full Version : AR mags differences in 5.45 @ 5.56

04-04-2010, 4:59 PM
Allright guys looking for info on the difference between a AR mag in 5.45 and one in 5.56? Thanks for responses in advance.

04-04-2010, 5:02 PM
They are basically the same except the follower on them are a little different. I've used my 556 mags on my 545 upper when shooting in cali... and it seems to work okay. I think you need to have a good spring. I had one that worked and then on time when I went to the range I had a lot of feeding problems... I switched mags and it was all good. Just got back from arizona, and was able to use 30 rounders in 545 and they all worked with no issues.

hope that helps.

04-04-2010, 5:11 PM
I never knew these were C&R. :43:

04-04-2010, 5:21 PM
The 5.45 round has a shorter distance from the base of the cartridge to the neck of the case. This means that you should have a magazine that is made for the 5.45 cartridge, and a 5.56 mag will eventually have feeding problems.

The 5.45 follower is the same as the 5.56, except that it is cut on the sides to accommodate the proper grooves in the magazine.

Here's a really crappy quick pic to show you the large grooves that correspond to the cartridge neck, note the setback on the 5.45 mag (below the 5.56 mag):


04-04-2010, 5:26 PM
Start off by looking at the difference in the cartridges. The case on the 5.45 is 1 10/32" to the shoulder where the 5.56 is 1 14/32". The length of the shoulder on the 5.45 is 5/32" where the on the 5.56 its 4/32". The length of the exposed projectile on the 5.45 is 22/32" and on the 5.56 its 14/32". The follower has to support the cartridge to prevent tipping. Sometimes you get lucky and you can use a 5.56 mag with it's follower, most times you don't due to the groves in the sides of the mag body.

04-04-2010, 6:40 PM
Sorry guys, thought I was in the Centerfire forum when I posted. :turned:

04-04-2010, 6:46 PM
Extra question. Any notice feed reliability differences between 20 rd and 30 rd AR mags in 5.56 being used in 5.45 AR? Once again, thanks for the responses.

gun toting monkeyboy
04-04-2010, 6:55 PM
They are not, they are in nevada with my eagle arms ea-15.

Umm... yeah. Please see my signature.

04-04-2010, 7:17 PM
Well, the AR is now just about 50 years old....