7.5 Swiss for K31

.Ben

.Ben

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I am working up some loads for my K31, with 168 grain hornady BTHP, Prvi brass, and IMR 4350

I have 2 questions for anyone else loading for a K31.

how short can the COAL be? at 2.950 the bolt requires a hard push to get it closed and even more force to extract, at 2.920 it chambers and extracts with ease. is this too short however for pressure and such? it seems there is a lot of boolit in the case.

also does anyone have any load data for 7.5 swiss and IMR 4350 I cant find any, all I can find is H4350 which is similar but not exact, I started at the bottom of the h4350 data and worked up half grain at a time from there, does this sound reasonable?

thanks guys.
 
I use Reloader 17. The K31's chamber is short for a milsurp. The OAL will change with each bullet you try. I make a dummy round, seat the bullet and back it off until you can close the bolt without the bullet jamming into the lands, seems like you've found the sweet spot. As you know, the ogive of the Hornady match HPBT is different than the GP11. You want a short jump to the lands. I use 50gr of R-17, works very well.

Note : burn rate chart indicates that your powder burn rate is essentially the same as what I am using. If no data exists, use data for that bullet using 308 Winchester data to start. The GP11 is a higher pressure round so I suggest starting to work your load near max 308 data, as long as you're seating the bullet at correct OAL.
 
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Your COAL is fine. Working up your loads a half grain at a time does sound very reasonable. I've been doing some reloading for my K31s but haven't done any real formal testing or spent enough time at the range to come to any conclusions regarding a specific load. I'm using Varget for powder and a couple different bullets in the 150gn range. Excited to get out and do some real testing now.
 
Jongun is right at OAL of 2.92 you should be fine. I went back and checked my notes. In fact, I'm loading the same bullet at 2.95OAL. I doubt you have to back it off much more.
 
I pretty well follow the same steps as Ben to achieve my OAL, easy chambering, easy extracting and stop there. I've loads of 3" that chamber fine using FMJBTs and down to 2.65 with my cast projectiles.
 
here are some load tables I found on the swiss rifle forums

h ttp://theswissriflesdotcommessageboard.yuku.com/topic/9041/7-5x55-Load-Tables#.Uz67GkBOVet
 
Not to sidetrack, but what do you guys figure it is costing you to reload for the k31? I'm hoping to pick one up in the near future and get started in reloading. BTW I mean the cost to reload not including equipment, just bullet, case and primers.
 
woobie said:
Not to sidetrack, but what do you guys figure it is costing you to reload for the k31? I'm hoping to pick one up in the near future and get started in reloading. BTW I mean the cost to reload not including equipment, just bullet, case and primers.
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You can look online at cost estimators, all you have to do is plug in the variables, ie component costs. Brass will definitely be the most expensive component...currently, with taxes and shipping, will be close to 1$ apiece for brass alone. So I opted to buy Prvi Swiss ammo and have been reloading the cases since they are boxer primed. If you buy components in bulk, this obviously helps to bring the costs down.
 
My favorite round for my K31 is, 150 grain pushed by 42.5 grains of IMR4895, Winchester large rifle primer, any case, COL is 2.920. Extremely light recoil, extremely accurate. I also tried IMR4350 with the same bullet and COL but it was pushed by 49.0 grains with slightly more recoil and flying much higher than the IMR4895 load. But to date I have not pursued both rounds any farther.
 
.Ben said:
I am working up some loads for my K31, with 168 grain hornady BTHP, Prvi brass, and IMR 4350

I have 2 questions for anyone else loading for a K31.

how short can the COAL be? at 2.950 the bolt requires a hard push to get it closed and even more force to extract, at 2.920 it chambers and extracts with ease. is this too short however for pressure and such? it seems there is a lot of boolit in the case.

also does anyone have any load data for 7.5 swiss and IMR 4350 I cant find any, all I can find is H4350 which is similar but not exact, I started at the bottom of the h4350 data and worked up half grain at a time from there, does this sound reasonable?

thanks guys.
Click to expand...

The K31 has a short throat, so you may need to go shorter than is typical to keep the bullets out of the lands. My Hornady manual has load data with that bullet and IMR4350, PM me your email and I will send a scan of those pages to you. The OAL given in the Hornady data is way too long for the K31 throat, though. I just kept seating deeper until the bullet was off the lands.


woobie said:
Not to sidetrack, but what do you guys figure it is costing you to reload for the k31? I'm hoping to pick one up in the near future and get started in reloading. BTW I mean the cost to reload not including equipment, just bullet, case and primers.
Click to expand...

It costs the same as .308 except for the brass. Cases will run close to $1 each bought new, but you can get a lot of loads out of them with a bit of care. Pressures are not super high, so primer pockets don't open up very fast and you can neck size to keep the stretching to a minimum.


Mark
 
Alright, thanks for all the replies guys, I have loads worked up from 45 grains to 47.5 grains in half grain increments. Imr 4350

As far as costs go this batch 100 rounds is about 38 bucks for boolits, 4 bucks primers, 18 dollars of powder so about 60 cents per round not including the brass which is Prvi $80/100 brass

I also have a case of GP11 I want to try to remove the primers with water and a punch and reprime with berdan primers, just to see how it works, would save a lot of brass cost.

As of right now you are better off to buy the GP11. Cost wise
 
.Ben said:
Alright, thanks for all the replies guys, I have loads worked up from 45 grains to 47.5 grains in half grain increments. Imr 4350

As far as costs go this batch 100 rounds is about 38 bucks for boolits, 4 bucks primers, 18 dollars of powder so about 60 cents per round not including the brass which is Prvi $80/100 brass

I also have a case of GP11 I want to try to remove the primers with water and a punch and reprime with berdan primers, just to see how it works, would save a lot of brass cost.

As of right now you are better off to buy the GP11. Cost wise
Click to expand...

No need to punch out the primers. You can buy Large Rifle or 762N Berdan primers from Budget Shooter Supply.

http://www.budgetshootersupply.ca/frame.cfm?ItemID=545&CategoryID=97
 
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