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7.62x39: Advantage of bolt-action over semiauto?

Posted: March 15th, 2018, 1:27 pm
by gman68w
I'm looking at a Ruger American Ranch in 7.62x39. Couldn't tell you why, don't think you could talk me out of it. However, if you still feel the need to talk me down from this ledge, then maybe you can help me whittle down my expectations.

See, I've never really fully understood the advantage of a bolt action over semiautomatic operation. I've heard that it's something to do with getting more 'oomph' out of the cartridge, because there's not bleeding out the back when the chamber cycles, that it's all driven forwards. It makes sense, but there's something about it that sounds like amateur physicists talking out of their collective ass. I would have thought that the less gas following the bullet out the muzzle, the less chance there is to cause the bullet to tumble when one little piff (that's a technical term, look it up!) of the gas comes out unevenly.

On the other hand, since a cycling chamber is not part of the firing action, that's less parts moving around while you're trying to keep your sights on point.

Personally, I'd have thought all these forces were too small to affect anything too much, but there was this guy I knew that wished he was in Vietnam, used to tell me stories about how all it took was one blade of grass to throw his shot off course. I wouldn't have believed him, if not for the tone of authority in his voice.

Re: 7.62x39: Advantage of bolt-action over semiauto?

Posted: March 16th, 2018, 12:59 pm
by Curly1
More velocity leads to more distance, stability, accuracy and damage on the other end.

Re: 7.62x39: Advantage of bolt-action over semiauto?

Posted: March 17th, 2018, 9:42 am
by gman68w
And you really get that much more of a gain from an AK round? It's not something that works better with a larger bullet like 30-06 or .308?

Re: 7.62x39: Advantage of bolt-action over semiauto?

Posted: March 18th, 2018, 12:07 pm
by Ketchman
In theory, yes the bleeding off of propellant gas to function the action of the semi auto does indeed reduce downrange energy and momentum of the bullet. However, this is the same physics that governs the gap between the cylinder and forcing cone of a revolver. It is true but the amount of gas lost and resulting energy difference is so small as to make zero practical difference at the moment of impact of the bullet downrange.
That being said though, the larger number of moving parts and tolerances of those moving parts in a semi auto versus a bolt action usually results in the bolt returning to battery in a minutely different way after each shot, affecting accuracy. This is where the "a bolt is more accurate than a semi auto" came from. Early semi auto's had loose tolerances to facilitate reliable function as powder fouling and dirt built up in the action. However, modern CAD CAM machining methods have reduced the differences between shots to a minimum, resulting in fine accuracy from most modern semi auto's. The Ruger Ranch rifle is an update of the old Mini Thirty and the action has been redesigned to improve the accuracy of the Mini Thirty which had serious issues with accuracy because of the design and tolerances in machining of the components. Your biggest problems with accuracy and "ooommph" ( that too is a technical term :lol: ) downrange will now come from your choice in ammunition.
Good luck with your new rifle and give us a range report.

Re: 7.62x39: Advantage of bolt-action over semiauto?

Posted: March 18th, 2018, 4:39 pm
by gman68w
This isn't the Mini-14 Ranch Rifle, I've already got one of those. It's one of these. https://ruger.com/products/americanRifl ... 16976.html

Unless you mean the bolt action is an update of a semi-auto?

Re: 7.62x39: Advantage of bolt-action over semiauto?

Posted: March 18th, 2018, 5:22 pm
by Ketchman
I thought that you were talking about the redesigned mini 30 as I interpreted your question to be from the semi auto viewpoint, I stand corrected and embarassed sir. :oops:

Re: 7.62x39: Advantage of bolt-action over semiauto?

Posted: March 18th, 2018, 6:28 pm
by gman68w
To be fair, the 7.62x39 American Ranch does accept Mini-30 magazines.