7.5x55 - Where's that accuracy come from?

H Wally

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Alright, I've been contemplating this for a few minutes, here's what I've come up with.

Where does the accuracy come from in the Trifecta of K-31, GP11, and the 7.5x55 round come from?

Is it the super high quality rifle, capable of shooting MOA after 70 years?
Is it the surplus GP11 made at super high specs?
Is it that the 7.5x55 round is ballistically superior?


In the end, I believe that it's the gun, not the ammo that is so accurate about this combination. They're beautifully made and very high quality. They're all acknowledged to shoot well unless thoroughly abused past the point of damage.

I can't claim that GP11 is the reason for accuracy, since many people shoot reloads. GP11 is certainly damn accurate, but I wonder if there were more guns on the market chambered for it, if it would retain its high regard. By this I mean, with two variables, with the GP11 only ever occuring at the same time as the K31 as the other variable, it's impossible to tell which is the more influential. However, since reloads are often shot, it is possible to eliminate GP11, as seen in the next paragraph. It's uniform quality means that there's no variable in the ammo to make a shooter guess at why he's missing, but that comes down to quality control more than a magical bullet/cartridge combo

I also don't believe that the 7.5x55 cartridge itself is in of itself anything special. The .308 diameter bullet is nothing special in accuracy circles. Don't get me wrong, it can be loaded for superb accuracy, but it's not an inherently accurate bullet with high ballistic coefficient and low drop like some cartridge/bullet combos for bench rest of long range shooting out there. It can undoubtedly be tuned for accuracy, but so can just about any cartridge under the sun with suitable effort. (yes I realised many people shoot 308, but it's my firm belief that's because it's common, recognized, and because many militaries use it. Their reasoning likely included capability of accuracy but also was subject to other factors that may have favoured 308 over other calibers) Since the K31 shoots well with many reloads as well as GP11, it could be assumed that while good ammunition certainly isn't hurting its accuracy, it isn't the primary contributor either. In addition, many K31's shoot well with reloads not ideally suited to the gun (IE most available .308 bullets are not the optimal size/shape compared to GP11, in relation to Ogive etc.... I'm getting out of my depth here though, so I'm going to leave this be).
 
Hwally, I have tried some different loads in a K31. I wanted to try some of the Spanish CETME lightweight bullets in .311 diameter in mine to see how well they would shoot, reduce recoil etc. The chambers are so tight, that the brass I have won't chamber when loaded with the .311 round. I pulled a couple of GP11 bullets and replaced them with the CETME bullets and they sat well all the way into the chamber but I will admit a bit snugly. Tight, straight chambers are the secret of well made bench rest rifles. If my K31 is like the rest of them, then that is pretty much the reason for it being accurate.

Not only are their bores tight but their bolt faces are square to the chamber and the headspace is verging on minimum. This could have proven to be a problem for the Swiss if the rifles were ever used under extreme conditions. Just a thought, I'm sure the Swiss tested their rifles under some pretty harsh conditions. I do know that I tried some dirty brass in the chamber and if it were a Lee Enfield, it would have chambered easily but it jammed the bolt, about 2/3 of the way in.
 
Indeed - a return to the gun as the pivotal part of the group contributing to accuracy.

My suspicion with the dirt sensitive guns is that the swiss hoped for a short war that saw them in defensive positions with ample ability to maintain and resupply their troops' needs combined with well trained troops disciplined enough to maintain their equipment and solve issues as they arose. That's the theory at least, how realistic that is we'll never really know.
 
I would say without hesitation that it's the gun.

I have handloaded many different milsurps, and I have said before that the K31 is the hands-down most accurate. What's most notable, is that the K31 sights are mediocre IMO - inferior to several others like the P14/17, LE No 4, and Garand. As for GP11, it is excellent ammo, but the K31 is not dependent on it.
 
I've read about the swedes & swiss having what is refered to as a cult of accuracy.
Apparently hitting an 8 " target at 100 m was not acceptable; 8" at 300,yah.
Limited amount of defenders and limited artillery means you really make your shots count.
 
"...Where does the accuracy come from..." Suspect it has to do with the Swiss, um, obession/fixation with technology.
"...won't chamber when loaded with the .311 round..." Using the wrong bullet diameter will do that.
 
The .308 diameter bullet is nothing special in accuracy circles. Don't get me wrong, it can be loaded for superb accuracy, but it's not an inherently accurate bullet with high ballistic coefficient and low drop like some cartridge/bullet combos for bench rest of long range shooting out there.

That use of .308 bullets made me do a double-take :yingyang: , the first time I learned of it...:redface:
 
311 in 308

Sunray, try a .311 diameter bullet in an M14 or a clone. Try it in any 7.62x51 Nato chambered rifle for that matter. You won't have even a hint of a problem feeding it. To tell the truth, some even prefer them over .308 diameter bullets. I have an Anschuttz in 308Win, a very accurate rifle, it will accept .311 diameter bullets no problem. The rest of the chamber is another story. I need to use small base dies and full length resize every time or the rounds won't chamber. I will accept NATO surplus or factory 308Win and shoot them very well, but the chamber is true and tight. The neck is a bit more generous, which surprises me. I'm not sure why?

The only thing I was pointing out, was how tight the chambers are in Swiss rifles. If it were only one rifle, I would think I was just lucky but both K31s, the 1911 and the 1896 are all the same. Tight, true chambers. IMHO that isn't just a coincidence.
 
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