velocity of 7.62x39mm in different barrel lengths?

[chickenlittle]

I'm considering getting a 7.62x39mm for my fiance for deer hunting. I'm considering 3 rifles with different barrel lengths. How much a difference will there be in velocity of 125gr and 150gr bullets between a 23.5", 20", and 18.5"?

The 3 rifles are:
CZ 527 Carbine with an 18.5" barrel
Remington 799 with a 20" barrel
Remington SPR18 with a 23.5" barrel

[R.W.Dale]

 Going from one extreme to another 110grn loadhandloads that chronied at 2520fps avg from my CZ's 18.5" bbl were leaving the 26" barrel on my stevens 200 at an average velocity of 2775fps. For a difference of 255fps or an additional 34fps per inch of bbl over 18.5"

 NOW this isn't apples to apples

the CZ has a .310 bore the stevens has a .308
the cz has a 1-9" twist the stevens is a 1-15"

so if anything in barrels with the same twist and bore size this difference mentioned above should be even less

[Val]

You should consider the .243. My buddies 16 year old daughter who doesn't weigh 90 lbs soak and wet shot my .243 with 100 grain Nosler Partitions. She said the recoil was not a problem at all. This load chronographs at 2872 fps. It'd deadly on dear.

[chickenlittle]

The .243 is a typical choice and has more options in rifles and hunting ammunition than the 7.62x39 but also more recoil. Both will be effective on deer. I am satisfied with the rifles available in 7.62x39mm and there is hunting ammo and lots of inexpensive milsurp ammo for practice.

For now, my focus is on helping her to enjoy shooting and hunting. Cutting down on recoil by 10% or 20% with the 7.62x39mm will allow her to enjoy shooting more. The more she enjoys it, the more she will practice with her rifle and hunt with me. I am sure she can handle quite a bit more recoil but I don't see any reason right now to test that. She can decide to step up to a .260 or 7mm-08 someday if she wants.

[John R.]

I chronographed 124 FMJ yesterday out of my SKS, it ran 2515 avg. for 20 shots.

[Mikey]

The standard 7.62x39mm loading, as I understand, runs about 2400+ from the 16.5" bbl of the AK rifle and about 2500+ from the longer barreled (20") SKS.  When you increase the bullet weight in this cartridge to 150 gns you get about the same velocity as you would with the 30-30 and a 150 gn bullet, around 2200+'/sec.

You may also get some variation in both velocity and accuracy depending on the bullets used.  Some shoot the 308 diameter slugs, others go for the .311 diameter slug or .310s if you can find them.  One poster said he used the 150 gn .309 sulg for the 30-30 and got excellent accuracy.  You just have to try and see whichone shoots best in the rifle you get for your fiance. 

That being said I would think the two longer barrels might give you a leg up on both but the increase in velocity might be minimal and not worth the longer barrel, especially if your fiance is hunting in deep brush and the like. 

If she has the opportunity to shoulder both rifles and see which one feels best to her it might make the choice easier.  I think the 7.62x39mm would be good on whitetail to about 150-200 with a well placed shot and either of the longer barrels should do that.  JMTCW.  Mikey.

[chickenlittle]

Thanks to all for your posts. It looks like it there won't be enough of a difference in velocity for that to be a big factor in our choice. I don't know which one we'll ultimately choose. Her .22 is a CZ 452 so the 527 Carbine would be quite familiar for her. It is shorter and nearly a pound lighter than the two Remingtons. The light weight may not be a good thing though.

I'm very tempted by the Remington single shot since it is about $200 less, has the longest barrel, and won't be too long or too heavy. The big concern will be whether the one we buy would function well right out of the box or need a bunch of tuning. I guess you run that risk for any manufacturer but I feel that risk is pretty low with CZ.

[coyotejoe]

No doubt the CZ is a fine rifle, my rimfires in .22LR, .22WMR and .17 HMR are all excellent rifles. I love singleshots but one issue with the Russian made SPR-18 is the very short scope mount rail which really limits scope placement, there just is no room to move the scope fore and aft to adjust eye relief. Some have found an adapter to clamp onto the scope rail and make a longer rail of it but that adds scope height which is already rather high above the stock comb.