k31

[aloreman]

does anybody have any load data or reloading tips for the 7.5 swiss in a k 31

 

[DukeDuke]

http://theswissriflesdotcommessageboard.yuku.com/topic/9041/75x55-Load-Tables

 

[Laurie]

7.5X55mm case capacity falls between those of .308 Win and .30-06 Springfield, actually closer to .30-06. Although nominally 7.5mm (0.307" groove dia.), it's a 308 in all but name, at worst a marginally tight-bore one.

Anything that works in 308 and .30-06 works well here too. Since the original bullet was a 174gn FMJBT, 175gn match bullets like the Sierra MK, 178gn A-Max, 175gn Berger LRBT are all good choices as are the 168gn HPBT match models. You can use any 308 cal bullet you fancy of course, but the further you move from the original weight and MV, the more likely the sight settings won't correspond.

Any powder that works well in 308W/.30-06 will also do so in the 7.5, so you've got a huge choice with 168-175s. They're usually pretty long-throated - or that may be wear and tear in surplus rifles - but don't worry about that with the likes of the 168gn or 175gn SMK. Load to standard COAL and look for what works. There's lots of data around as most powder / bullet manufacturers cover the cartridge, but little if any for recently introduced powders.

FL size the brass unless you use very light loads. My 1911 and K31 had rather slack chambers at the rear end. If you go a bit warm on your loads, but almost certainly still within CIP MAP limits, you'll likely find they're devils to resize even when really well lubricated needing a lot of press handle effort. I got 100 Norma 180gn PSP factory cartridges with a long IG11 years back and could hardly resize the brass after firing some, so ended up pulling the remainder and dropping loads by ~10-15%, I can't remember what exactly.

I used mild loads of Viht N140, N150, even N160 with good results with 168-180gn bullets years back. Viht now lists loads for the GP31 for its three .308" Scenar match bullets - 155, 167 and 185gn with loads data for N140 and N150 giving similar MVs and N540 running a bit faster for the 155 but no different for 185. If loading the cartridge again today, I'd likely start with Viht N150. Viht's max N150 loads are 49.7gn, 47.5gn, 45.2gn for the 155, 167, and 185 respectively. In north American powders, I'd most likely have a go with H4350, although Hodgdon's data gives higher MVs with H4831. IMR-4007SSC would likely work well from my experience with it in 7.62X54R, but Hodgdon doesn't give any data for that one. Going a bit faster burning, I'm sure VarGet / Re15 and similar will work well too.

 

[Steve Blair]

I bought a bunch of surplus 173 grain M118 FMJ bullets for a very reasonable price. They are pretty close to the Swiss GP11 bullet, at least ballistically. I load with 44.0 grains AA 2495, which duplicates GP11 velocity in my K31. At 80°F, they are ~2596. The sights seem to be pretty close. We should note that loads mentioned for K31 can also be fired in the M1911 rifle. I have a 1911 and use the same load for it. Rifles earlier than the 1911 should not be fired with anything approaching GP11 pressure. As with any old military rifle, use an abundance of caution. With a 1911 or K31, start low and work up. With earlier Swiss rifles, have the bore slugged, chamber cast and inspected by a qualified gunsmith familiar with the series.

 

[2506]

Many loading manuals have load data for the 7.5X55 but the suggested COAL is wrong for the K-31. It has a very short throat. Take you a case and size it. Then take a cutting tool of some sort and cut you a line from the mouth down to where the neck meets the shoulder. Just start a bullet into the case by hand. Place it in the chamber and close the bolt. Ease the bolt open and carefully remove the round. measure the COAL. This is the too the lands measurement. I would seat the bullets 10 thousands deeper. You can remove the bullet form that case with your fingers and pinch the neck tighter and use other bullets to find your COAL.
For bullets 168 gr and lighter IMR 4064 really works great and with the heaver bullets IMR 4350 is great.
My match load is the suggested accuracy load out of the Sierra manual as far as the powder goes.
45.0 grs IMR 4064. Graf/Prvi case, Fed. 210M primer, 155 Nosler custom competition HPBT, COAL 2.880 and I use a Lee Factory Crimp Die because it makes it more accurate.
I have also found that if you will place a thin shim between the handguard and forearm up at the muzzle end under the band on both sides it free floats the barrel some and helps accuracy. I use the large end of a flat tooth pick.

 

[letronshootit]

I have had a lot of fun with Swiss 96/11, 1911, and K31 rifles. Well made, nice trigger pull, and well balanced. Oh yeah they shoot nice too. I use a black 7 1/2" bull at 100yds. for load work. My favorite accuracy load for all my Swiss rifles is 46gr. Reloder 17, PRVI brass, 168gr. PRVI HPBT, CCI BR2 primer. Keeping the bullets well off the rifling produced the best results, 100yd 3 shot best ever group was 7/16" with the 96/11 may never happen again but that day...man.