7.62 x 39 in a 5.5 inch barrel

[Dutch110]

So a buddy of mine and I were having this conversation after seeing a Maxim PDW kit go up for sale on one of the discount sites. After doing some research the only velocity tests I could find stopped at 16 inch. However the spread between a 16 inch and 24 inch barrels for this round was documented at 100 ish fps. 2400 at the top and 2300 at the bottom (approximate numbers.) The next data point I found was "dude on a forum" who said he was getting between 1950 and 2050 fps out of his 7.5 inch barrel. Now on the Maxim web site they say out of their 5.5 inch barrel they average 1675 fps. Only based on the data I found this number seems inside the realm of possibility but I could not find any hard data to support it. Also a wide range of info out there concerning minimum velocity for expansion. I hear anything between 1600 and 1800. Both numbers would effectively mean the 5.5 inch barrel is an expensive flame thrower / range toy with no real world application. Interested to hear the opinions of the masses here. What is the shortest you would go on a 7.62 barrel and why? And to be clear, neither of us are actually considering buying or building a 5.5 inch 7.62. However I may build another 7.62 and am wondering "how short is too short."

[Red*Lion]

I would suggest not to go under 8". I prefer something a little longer, then went with an 11" KAK barrel on my 7.62x39 pistol.

[utahjeepr]

Their stated numbers sound reasonable, it's possibly a little on the high side of what I would expect. Most 122-124 grain ammo other than some hot Uly is gonna be in the low to mid 1900s at 7 to 7.5 inches. 5.5 should be effective, but it's getting toward the bottom end. I would only use it in an AR style system. 7 is as short as you can go in an AK without issues (micro draco be damned). 7 inch is a bloody flamethrower, see my pics in my "other semi" thread.

[Dutch110]

Their stated numbers sound reasonable, it's possibly a little on the high side of what I would expect. Most 122-124 grain ammo other than some hot Uly is gonna be in the low to mid 1900s at 7 to 7.5 inches. 5.5 should be effective, but it's getting toward the bottom end. I would only use it in an AR style system. 7 is as short as you can go in an AK without issues (micro draco be damned). 7 inch is a bloody flamethrower, see my pics in my "other semi" thread.

Yeah this would definitely be in an AR platform. Wonder how short you can go and still put a can on these things without voiding the warranty

[casualreclaimer]

I have one of the KAK value line 11 inch barrels. For the money, they're hard to beat. That said, like most others, KAK uses M4 feed ramps. If you're not scared to work on the feed ramps, it's a good barrel.

[Dutch110]

I have one of the KAK value line 11 inch barrels. For the money, they're hard to beat. That said, like most others, KAK uses M4 feed ramps. If you're not scared to work on the feed ramps, it's a good barrel.

Did yours require blending?

[Dutch110]

I would suggest not to go under 8". I prefer something a little longer, then when with an 11" KAK barrel on my 7.62x39 pistol.

How do you like that KAK barrel? I have been on the "notify when back in stock" list for one of those for months now. I have one of their 300 blk barrels (Mr Blonde) on one of my pistols and its a shooter.

[Red*Lion]

I like the KAK barrel a lot. I bought the accompanying KAK BCG as well. I have gotten around 1.75 moa shooting wolf steel cased. I did blend/enlarge the feed ramps though.

[Arik]

Generally speaking going from 16 to 8 inch barrel has about 300fps loss. There was a video on YT of a guy who tested this on a chronograph using 2 AKs and I think Wolf ammo. I forget who it was, the video was like 10 years old even a few years ago but if you search for 7.62x39 fps I'm sure you'll find something

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