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2/13/2012 5:49:49 AM EDT
zzz
2/13/2012 8:02:19 AM EDT
[#1]
I don't have the bore dimensions for the AK74 on hand but I DO have the official bullet diameter of the 7N6 listed as .2146     the CIP specs which is the European equivilent of SAMMI in the USA lists the bullet diameter of the 5.45 Russian as .2236 (or 5.68) the bores on most AK74's do vary some according to manufacturer (Russinan or Ukranian or Bulgarian)? and time of manufacture. My S&W AR in 5.45 is the most accurate and perfect 5.45 shooter I have ever seen and it has a unique US bbl design that slugs to .217 on the bore and .228 in the groove 4 groove 1/8 right hand twist. QC is very uneven on surplus ammo and dimensions can vary even within the same can. Theoretically a 5.56 bbl should work for 5.45...but in practise it doesn't work real well for a host of reasons. the "touchiness" of the 5.45 round is one of the reasons why the Finns  rejected it, although for all practical purposes it works very well for combat, it is considered obsolete by everyone, even the Russians.Of course this is always a controversial topic, but in my honest humble opinion, a bore on the tight side that is chrome lined is perfect. I have never seen a 74 with a chrome lined bore keyhole. If you want to know anything about AK's ask the Finns, they did more research on them and the ammo than anyone else. The Finns ultimately rejected the 5.45 because of their local terrain, a battlefield where you have close ranges and rocks and thick tiaga forests, the 7.62 out performed the 5.45 in this terrain and at these ranges.
2/13/2012 8:50:41 AM EDT
[#2]
zzz
2/13/2012 10:02:54 AM EDT
[#3]



Quoted:



Quoted:

I don't have the bore dimensions for the AK74 on hand but I DO have the official bullet diameter of the 7N6 listed as .2146  




That has to be a misquote.



Bullet diameter is not .2146.  No way, none of it.  That is land diameter.





Just measured one at that is pretty close to what in got.

 
2/13/2012 10:33:23 AM EDT
[#4]
I know that the E.G. barrels are .214.
2/13/2012 10:54:11 AM EDT
[#5]
zzz
2/13/2012 10:55:49 AM EDT
[#6]
zzz
2/13/2012 10:59:35 AM EDT
[#7]
Just measured a wolf black box 5.45 round and got 0.219in.  Measured it right where the steel case started.
2/13/2012 11:01:57 AM EDT
[#8]
zzz



2/13/2012 12:35:50 PM EDT
[#9]
Tx-Zen has the numbers for his Bulgy, SGL31, and Krink.

I want to say .214 sounds awfully familiar.
2/13/2012 1:10:43 PM EDT
[#10]
zzz
2/13/2012 1:21:37 PM EDT
[#11]



Quoted:



Quoted:

Just measured a wolf black box 5.45 round and got 0.219in.  Measured it right where the steel case started.




Sounds about right for that location.



Now, pull the bullet and re-mike it closer to the base.



Diameter is wider behind the case mouth on the bearing surface of the bullet.



For what it's worth, the math on the subject is 5.45 millimeters = 0.214566929 inches.  The nomenclature cites, as is common in European tradition, the bore diameter.  Bullet diameter for 5.45x39mm is 5.62mm (.221") and bullets in production may vary somewhat from that, but not .214.


About .221 in that area with my more accurate digital micrometer.



 
2/15/2012 11:45:10 AM EDT
[#12]
zzz

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