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7.5 Swiss load data
nemesisenforcer
Member Posts: 10,513 ✭✭✭
I'm looking for some good data to use when reloading my 7.5X55 K31. Most sights want me to pay for their info and reloadersnest.com (which I was referred to by a friend) has some good free info, but not on the bullets or powders I use (lots of norma bullet/powder combos, which I don't use.)
I use Speer, Hornady, and Sierra bullets, (currently the Speer 180 grain for all my 30 caliber needs) and Hodgon powders, mainly Varget and 414, though I have some others and access to lots more.
The Lee manual I have has data for the 7.5 but it seems pretty anemic. It's got a respectable case volume and the factory stuff I have put it in the 308/30-06 range. The reload data however urges loads that reduce factory performance by quite a margin.
any resources or loads that you know of that will help me scratch this itch?
I use Speer, Hornady, and Sierra bullets, (currently the Speer 180 grain for all my 30 caliber needs) and Hodgon powders, mainly Varget and 414, though I have some others and access to lots more.
The Lee manual I have has data for the 7.5 but it seems pretty anemic. It's got a respectable case volume and the factory stuff I have put it in the 308/30-06 range. The reload data however urges loads that reduce factory performance by quite a margin.
any resources or loads that you know of that will help me scratch this itch?
Comments
The following loads have all been found to be quite accurate.
Remington PSPCL 165gr:
N203...................40.5gr
BLC2..................39gr
3031....................36gr
414......................43gr
4064....................37gr
4831....................47gr
2520....................39gr
Military Ball 173gr "pulled":
414.......................43gr
4064.....................39gr
3031.....................35gr
4350.....................38.1gr
4064.....................39gr
BLC2...................40gr
Sierra Match king 168gr:
4064.....................43.9gr
4350.....................46.8gr
4064.....................37gr
Sierra Match king 175gr:
4064......................42gr
4350......................45.8gr
Sierra 165gr HP/BT:
4320......................44gr
4064......................43.5
Berger VLD168gr:
4895......................44gr
Nominal seat depths for the 1911:
3.060"
Nominal seat depths for the k31:
2.890"
Addendum: Here are some recent additions to the list.
1. Bullet: Norma 146gr. FJPBT
Powder: Vit. N140 49grs.
Primer: CCI 200
Case: RWS
2. Bullet: Sierra 165gr. SBT (2145)
Powder: 4350 ACCU 51.6grs.
Primer: CCI 200
Case: Norma
3. Bullet: Hornady 168gr. BTHP (3050)
Powder: 47 grs. ROT R903
Primer: CCI BR2
Case: Norma
4. Bullet: Berger 168gr. HPBT/Moly
Powder: DuPont IMR-4320 47.4grs.
Primer: CCI 200
Case: RWS
5. Bullet: Lapua D-46 185 gr. (.308)
Powder: Vit. N160 50 grs.
Primer: Norma LR
Case: Norma
6. Bullet: Hornady 190gr BTHP(3080)
Powder: Vit. N160 51.5grs.
Primer: CCI 200
Case: Norma
7. Bullet: Hornady 190gr BTHP (3080)
Powder: ROT R907 46grs.
Primer: RWS 5341
Case: Norma
N203......40.5g.........1.69"
BLC2......39g...........1.75"
3031......36g...........1.8"
414.......43g...........1.56"
4064......37g...........1.0"
4831......47g...........1.13
173g
414.......43g...........1.10
4064......39.............97"
BLC2......40g............1.59
4350......38.5g..........1.76
3031......35.............1.97
k31#2 mfg date 1946
165g
3031......36.2g...........1.85"
4064......37g.............1.0"
414.......43.1g...........1.65"
4831......47g.............1.23"
173g
414.......43..............1.15"
BLC2......40g.............1.83"
4064......39..............0.91"
4350......38.1g...........1.94"
3031......35..............1.75
k31#3 mfg date 1955
165g
N203......40g..............1.98"
3031......36g..............1.87
BLC2......39.1g............1.40"
2520......39...............1.55"
4831......47g..............1.30"
414.......42...............1.57
4064......37g..............1.0"
173g
4350......38...............1.99"
3031......35g..............1.85
4064......39g..............0.88"
BLC2......40g..............1.65"
414.......43g..............1.10"
FURTHER testING
All rounds fired from an Accurite Rest, all groups consist of two five rd groups.
Brass, Norma, Projectile- 165g Remington SPLSC & 173g fmjbt, "pulled". Primers, CCI-LR. Brass TTL & champfered inside/outside.
165g
4831SC........45g........1.65"
IMR3031.......35g........1.30"
IMR3031.......36g......... .70"
173g fmjbt
4831SC........48g......... .88"
IMR3031.......34g......... .90" in a perfect vertical string.
IMR3031.......35g......... .44" & 1 flyer .82" out
(second group 3031)....... .71 & 1 flyer .75" out
All BLC2 loads exceeded 2"
What powder do you want to use? The best for that cartridge would be H4350, H4831 or VV N160 and VV N165.
Something the K-31 doesn't like is max loads. If you're shooting anything but a K-31 I would think twice about going to max. The older rifles may have good steel but they don't fully support the case head, I understand.
Behind a 150 gr. Bullet:
51 gr. of H4350(max)... I recommend 48-9 gr. for good accuracy
55 gr. of H4831(max)... I recommend 51 gr. I found this to be very accurate and pushed the bullet out at 2760.
50 gr. of VV N160(near max)...48 gr. was best accuracy load.
53 gr. VV N165(Max) ...50.5 gr was best load.
For the 168's(Nosler Custom Competition):
48 gr. H4350(near max) ...best load was 44.5 gr. -2580
50 gr. H4831(near max) ...best load was 46 gr. -2670
46 gr. of VV N160(near max) best load was 44 gr. -2645
48 gr. of VV N165(max) ...best load was 46.2 gr. This was the most accurate load I shot. 2620
As a reminder, you should get hold of some reloading manuals and compare. My base data came from Sierra. Hope this helps.
You could also try www.reloadersnest.com
Edit:
A little more thought on this. When I shoot the GP-11, standard 174 gr. Spitzers I get about 2600 fps even. These bullets have an incredibly high BC for a .30 cal of it's weight. Take a look at that long ogive. That is just above .308 performance. The same weight(175 gr.) bullet gets loaded to 2550 for M118LR out of an M24 w/ 24" barrel. With the 20" barrel that load goes to 2450 fps. In truth you should be able to squeeze 30-06 performance from this case in a same length barrel. I would only do that in a same style and quality action. The Swiss K-31 actions are good for strength. But as noted above everytime I get too hot with a load the groups spread out.
Again, the reason you are seeing anemic loads is because of the older rifles. If you are shooting one of these maintain using a moderate load.
The case is fully supported. The locking lugs and the way the bolt closes is the reason to stay away from max loads.
Are the K31s really that weak? Really? I just looked at my chronograph data for the 174 gr. match bullets from switzerland that I've been running through mine and the average velocity for that 174 gr. bullet is 2571 fps. That's about .308 ballistics from a factory load in a cartridge made for the K31. Where would be the harm in reloading up to the same velocity with similar bullets?
Nemesisenforcer,
The K-31's are very 're-engineered' from all previous Schmidt-Rubin rifles. They have the strength to load up to 30-06 loads. I wouldn't do this with any other Swiss rifle though. The K-31's are the first actions to use locking lugs directly behind the chamber like the Mauser. Previously the locking lugs were at the rear of the bolt. If there were any concerns about any K-31's it would be about the first ones up to the year 1935. In that year they strengthened the action. read here: http://www.swissrifles.com/sr/index.html
I will tell you I have loaded up the action to high 30-06 loads and found no issues. What I did find is that the action itself doesn't shoot as accurately as it can. It still shoots pretty good but not as good as it did before. I have some Mausers that won't shoot as good as it does with these loads. All I'm saying is if you want a standard military rifle that will shoot holes touching @100 yds./m then load the rifle with 174/175 match loads to around 2550-2600. which, again by the way, is slightly above .308 and not all that far behind 30-06 match loads.
quote:Originally posted by nemesisenforcer
Are the K31s really that weak? Really? I just looked at my chronograph data for the 174 gr. match bullets from switzerland that I've been running through mine and the average velocity for that 174 gr. bullet is 2571 fps. That's about .308 ballistics from a factory load in a cartridge made for the K31. Where would be the harm in reloading up to the same velocity with similar bullets?
Nemesisenforcer,
The K-31's are very 're-engineered' from all previous Schmidt-Rubin rifles. They have the strength to load up to 30-06 loads. I wouldn't do this with any other Swiss rifle though. The K-31's are the first actions to use locking lugs directly behind the chamber like the Mauser. Previously the locking lugs were at the rear of the bolt. If there were any concerns about any K-31's it would be about the first ones up to the year 1935. In that year they strengthened the action. read here: http://www.swissrifles.com/sr/index.html
I will tell you I have loaded up the action to high 30-06 loads and found no issues. What I did find is that the action itself doesn't shoot as accurately as it can. It still shoots pretty good but not as good as it did before. I have some Mausers that won't shoot as good as it does with these loads. All I'm saying is if you want a standard military rifle that will shoot holes touching @100 yds./m then load the rifle with 174/175 match loads to around 2550-2600. which, again by the way, is slightly above .308 and not all that far behind 30-06 match loads.
Good to know.
When you talk about the action not shooting as accurately as it can, does that only apply to the hot loads themselves, or does it mean that the action was weakened by the high power loadings and won't shoot as accurately with anything because it's been permanently weakened?
The accuracy diminishes with high loads then comes back when loads are brought back down. 2-3" with hot loads and 1-1.5" with cooler loads. I've gotten groups under an inch with the cooler loads and as small as .445". I've never gotten close to an inch with the hot loads.
The place you will see the biggest performance factor is the high BC of the GP11 round. Take a look at it and you will see how long and pointed it is compared to the shorter, more abrupt ogive of standard .308/7.62(M80) bullets. There is around a .200 difference in favor of the GP-11 for BC.
nemesisenforcer,
The accuracy diminishes with high loads then comes back when loads are brought back down. 2-3" with hot loads and 1-1.5" with cooler loads. I've gotten groups under an inch with the cooler loads and as small as .445". I've never gotten close to an inch with the hot loads.
The place you will see the biggest performance factor is the high BC of the GP11 round. Take a look at it and you will see how long and pointed it is compared to the shorter, more abrupt ogive of standard .308/7.62(M80) bullets. There is around a .200 difference in favor of the GP-11 for BC.
I've noticed that it's a very prominently pointed projectile, that's for sure. It and any reasonable reloads can probably shoot better than me anyway, so I'm not too worried. As long as the action isn't damaged or weakened in any way with the heavy stuff, I'll just make some hots and some not-so-hots.