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7.5 Swiss chamber...found answer!
sandwarrior
Member Posts: 5,453 ✭✭✭
I recently purchased a k-31 and ran a few rounds through it that were reloadable.
The problem started when I went to size the cases and noted they did not want to go down easily, even though I had sufficiently lubricated them. I got the micromter out and found that they were .471 at the shoulder instead of the .460 noted in my Sierra reloading manual 1.345" up from the base.
My question is if I bring these rounds to GP11 pressures(the reloadable rounds I bought were way downloaded, 150 gr. @2300fps)and full length resize, is it going to be too much pressure and possibly cause a headspace/rupture problem right away? Is this normal for a K-31 or should I go to a gunsmith for possible barrel setback?
Anyone familiar with these I would appreciate your knowledge on the
subject. -Todd
I found some material on this round. Pierre St. Marie(?) wrote that the k-31's do have a looser tolerance chamber. I continued the reloading process, sizing wasn't easy(I bought Hornady custom dies), using 45.5 gr. of VV N150 behind a Nosler J4 competition and got 2688 avg. velocity.
Accuracy is everything people said it would be with these rifles. I shot 3 groups of 3 shots and a group of 5. the 3 shot groups averaged 1" with one going .410. The 5 shot group went 1.84" I don't normally shoot that well with open blade type sights. With all my Mausers I tend to get more in the 3-4" range. -Thanks anyway to anyone researching this. I would appreciate still if you came up with anything.
We have the second amendment so that all the rest are secure....UNK>
The problem started when I went to size the cases and noted they did not want to go down easily, even though I had sufficiently lubricated them. I got the micromter out and found that they were .471 at the shoulder instead of the .460 noted in my Sierra reloading manual 1.345" up from the base.
My question is if I bring these rounds to GP11 pressures(the reloadable rounds I bought were way downloaded, 150 gr. @2300fps)and full length resize, is it going to be too much pressure and possibly cause a headspace/rupture problem right away? Is this normal for a K-31 or should I go to a gunsmith for possible barrel setback?
Anyone familiar with these I would appreciate your knowledge on the
subject. -Todd
I found some material on this round. Pierre St. Marie(?) wrote that the k-31's do have a looser tolerance chamber. I continued the reloading process, sizing wasn't easy(I bought Hornady custom dies), using 45.5 gr. of VV N150 behind a Nosler J4 competition and got 2688 avg. velocity.
Accuracy is everything people said it would be with these rifles. I shot 3 groups of 3 shots and a group of 5. the 3 shot groups averaged 1" with one going .410. The 5 shot group went 1.84" I don't normally shoot that well with open blade type sights. With all my Mausers I tend to get more in the 3-4" range. -Thanks anyway to anyone researching this. I would appreciate still if you came up with anything.
We have the second amendment so that all the rest are secure....UNK>
Comments
Some guys like a mag full of lead, I still prefer one round to the head.
The J4's I used were 155 Palma's. I did load up some 168's (J4's again) to see how they will shoot. 43 grs. of VV N150 for those.
I also plan to head up to the Gunstop up here today to look into a neck sizing die. Even though the article written by Pierre St. Marie said not to neck size I wouldn't see why that would hurt. The rounds ejected just fine.
They also have Graf 7.5x55 for $31.00 a bag. I thought that is pretty reasonable. Considering the amount of brass to move (.011) at the shoulder my brass won't last long FL sizing. Thanks for the replies. -Todd
We have the second amendment so that all the rest are secure....UNK>
Peary and Tailgunner,
The J4's I used were 155 Palma's. I did load up some 168's (J4's again) to see how they will shoot. 43 grs. of VV N150 for those.
I also plan to head up to the Gunstop up here today to look into a neck sizing die. Even though the article written by Pierre St. Marie said not to neck size I wouldn't see why that would hurt. The rounds ejected just fine.
They also have Graf 7.5x55 for $31.00 a bag. I thought that is pretty reasonable. Considering the amount of brass to move (.011) at the shoulder my brass won't last long FL sizing. Thanks for the replies. -Todd
We have the second amendment so that all the rest are secure....UNK>
I have a K 31 also. Tryed neck sizeing, even with light loads, didn't work. My 2? is that the straight pull action of the Swiss Rifles don't lock up like the turn bolt Mausers. I went back to full length resizeing with Redding dies that are specifically made for the K 31. Thats where your resizeing problem is coming from. The Hornady dies are made to resize brass fired in the earlier Swiss Rifles, ( K 11 ). The chamber dimensions are different and the Hornady full-length die is sizeing the K 31 brass down to much. I don't have that problem at all with the Redding dies made specifically for the K 31 chamber dimensions.
Thanks for that information. I never thought to check up on this before I bought the rifle. I'll look into getting some Redding dies for those. I never made it up to the Gunstop yesterday fortunately, as I was helping to cut Farmington, MN out of a blowdown. I cut about eight trees out of a tangled mess of powerlines and broken poles in the morning. Then spent the afternoon finding out what is wrong with my air conditioning.
So, I will do a little research and find out what I can get that will fit my chamber and see if he will take the Hornady's in on a trade.
Also need to get a stuck case removal system. I did the unthinking thing and "test sized" a cartridge after trimming it down without lubing it properly. Went in fine.....just didn't come out. So, rather than ruin a set of dies I will look into a case extractor there also. Thanks again -Todd
We have the second amendment so that all the rest are secure....UNK>
rufe-snow,
Thanks for that information. I never thought to check up on this before I bought the rifle. I'll look into getting some Redding dies for those. I never made it up to the Gunstop yesterday fortunately, as I was helping to cut Farmington, MN out of a blowdown. I cut about eight trees out of a tangled mess of powerlines and broken poles in the morning. Then spent the afternoon finding out what is wrong with my air conditioning.
So, I will do a little research and find out what I can get that will fit my chamber and see if he will take the Hornady's in on a trade.
Also need to get a stuck case removal system. I did the unthinking thing and "test sized" a cartridge after trimming it down without lubing it properly. Went in fine.....just didn't come out. So, rather than ruin a set of dies I will look into a case extractor there also. Thanks again -Todd
We have the second amendment so that all the rest are secure....UNK>
I had the very same problem, with difficult extracton of neck sized cases in my K 31. Luckily I was able to extract all of them.
The problem with the Redding dies, is whan they changed dimensions of the full length sizer to reflect the K 31 chamber dimension they never revised the previous part/stock number. The only way I was sure that I got the die with the proper dimension is that I ordered it specifically from Graf & Son. Their customer service people are very knowledgeable and were able to get me the new generation dies with the correct full length sizer.
If you could, would you please check the dimensions of your case. I called Hornady yesterday and found out, much to both our chagrin that the K-31 is a different chanber.
For now Hornady is asking K-31 owners to send in brass and get a Sizer die made ($62.00 + $7.50 shipping). If they get enough interest and information they will start the K-31 as a sepatate line than the 1896/1911 dimensions. I didn't get hold of Redding yet.
Thanks, -Todd
We have the second amendment so that all the rest are secure....UNK>
That sure sounds a lot like a normal 7.5x55 Swiss. Do you have the empty case measurements by chance?
We have the second amendment so that all the rest are secure....UNK>
No question about it. It sounds like your chamber is normal for the 7.5 Swiss. I'm beginning to wonder if one of the armorers(the one putting barrels on) wasn't having a little too much Jaegermeister in his coffee in the mornings....? Anyhow, whatever the reason, I and many others have K-31's with big chambers. Which is not entirely all bad. I just need a die that will work so I can reload. Hornady has kindly offered to make me a sizing die but I don't know yet if I need a new insert for the seater die.
We have the second amendment so that all the rest are secure....UNK>