5.56mm and 5.45mm ar15 bolts are different?

**kal** · 08-18-10, 22:59

Don't both rounds have the same case head diameter?

What's the difference between the bolts?

**Infidel74** · 08-18-10, 23:40

I don't have my 5.45 bolts to compare,they are different. I can post pics on friday.

**oef24** · 08-18-10, 23:51

I'll be waiting until Friday also to see the difference.

O

**ruf** · 08-19-10, 11:26

Bolts are different and the extractor is different:
https://www.m4carbine.net/showthread...121#post447121

**Infidel74** · 08-20-10, 01:10

Originally Posted by ruf

Bolts are different and the extractor is different:
https://www.m4carbine.net/showthread...121#post447121

I will take some pics when i get to the shop in the morning.

**Infidel74** · 08-20-10, 14:37

Allright I promised pics and here they are. The first 3 shots the bolts are identical looking to the naked eye.

I looked them over with my dad they both looked the same. Knowing that not to be the case, I pulled out the calipers. Upon measurement it was revealed to be bigger on the 5.45x39 rim.

In theory a competent machinist could remove material and make a 5.45x39 bolt face very easy.
I have two 5.45x39 bolts and two barrels. I promised long ago i would get some ammo and build some uppers.
I am still planning on it I just need to get the parts,it will get done just don't know when I could probably build one if I dug in the parts box.
I will put it on a Full-Auto lower and see how well it runs.
With the cost of 5.56 it does not get flipped to the fun button very often.
Enjoy.