The Swiss 7.5 x 55 Build

[RC20]

First there are no pictures, I don't think there is anything interesting enough to go to the effort to make the account to do it. Its just a gun, the interest is the cartridge.

This has no serious goal other than fun and its just an interesting one that got my attention and is doable without a huge cost.

The goal is to build a modern version of that I can shoot full power loads with.

As this is a low cost effort, I have looked through the barrel makers and Lother Walther offers that chamber, they also offer a Varmint Profile pre fit Savage. As that is 308 and that's what bullets we have for it that works perfectly. Still trying to narrow down the price, $524 last quote but I think I can get it around $400 or so using the Savage Pre fit and just a different chamber.

As they do not offer a Bull profile the price escalates to get one. The shooting is low level so the Varmint contour works and the stock is not a Bull channel (says it is but not). I could open it up but it works the way it is so that is fine.

Working on getting a K31 to go with it, that would be limited to appropriate 7.5 Swiss loads.
Just for fun I got a K31 Bayonet with an SN to go with it.

The Brass is PPU. I had hoped enough variation to allow fit in a 30-6 family bolt head but that does not work.

As I have two long action bolts I can open one up and see how that goes. With the brass I have the template.

If I can open it up enough to extract the 7.5 Swiss and still do the 30-06 bolt cartridge family I am good. If not I can get another 30-06 family bolt head or just use the 30-06 family bolt between two guns and keep the modified one for the 7.5.

The chassis for what I call my play gun. Its the one I will switch the 3 barrels around on.

The basis for that is a 116 that is now a Single Load (it has the open bottom but its in a boxed in stock).
It not intended for anything but a bench rest gun. So the long action does not matter (I currently have an original Savage Varmint contour 308 barrel on it). It also has been adopted to top bolt release.

Die is on the way, the 308 Seater will work for that purposes, primers are the same, powders are shared with 308, bullets re the same and I have 3 different ones to choose from.

Resize die is on the way.

[stoky]

Is this a long action?

[RC20]

Yes it is. Deliberately so, I have a 270 barrel I am going to play with on that action as well.

It could be run off a short action for the 7.5 but as this is my play gun its long action so I can go any way I want.

I filled in the mag well with wooden block and spacers. It feeds fine for 270 or 308 I am shooting out of it right now.

The 7.5 will be on it most of the time.

[Akajung]

Sounds interesting. I do like the cartridge. The first time I took out the K-31 I was very impressed.


Sent from my iPhone using Tapatalk

[RC20]

Thank you.

I have the brass now and its most interesting. I would call it a 308 Improved, but it was there far before the 308.

Shape may be more due to the straight pull design, but the case is only a bit longer than 308, but it has the shoulder much further forward and more square. Maybe wound up with a more efficient cartridge for other reasons? 308 WUM?

At this point its about to come together. Dies on the way.

I just have to order the barrel. Prices is as stated, that will hurt a bit, I though I could get it 450 or so, but so it goes.

If I start a trend it may come down for the those following!

[RC20]

With the Brass in I did some comparing to the 308. Holds about 7 grains more power per case than the 308.

Barrel order still in process of finalizing the order

I may have a couple of K31s to get on the way if the pictures pan out.

If they are a go then they will get here before the barrel does.

I am going to put the 12FV 26 inch up for sale, with the XC on 308 and the 7.5, I don't need the second 308.


I have worked with R17 powder, put two and two together and realized as it its from Switzerland unlike most of Aliant's powders that are from Sweden, its was probably developed with the 7.5 in mind.


Reports are that it is so that works out nicely.

When the barrel gets in I will set the headspace to match the K31 and should be able to use the brass between the two.

[RC20]

I got the bolt face opened up to accept the 7.5 case. Used a dremel tool and did just fine. A bit at a time, tested 4 times before I had it.

Fun taking the bolt apart, its the newer system, hard bugger but a long handled Allen and pop the top with the rubber hammer on the bench borke the glue.

Firing pin is different from the old one, nothing difficult, just different.

The ejector pin was the hardest part to removed, It was in pretty tight. I had to make a mini punch out of a drill bit.

It ejects 308 brass just fine, will see how it does with fired brass. Worst case I have a long action bolt from the 06 I can use but it won't be often, most of the time it will have the 7.5 barrel on it.

[Swissfan]

I also like the cartridge and have done exactly what you are doing just for the "different" factor. I purchased a used LW barrel in 308 and had it reamed to 7.5x55 and put it on a long action. Had the bolt face opened up and had to do nothing else to get the brass to extract and eject. I haven't taken the time to do much load development for it yet, but is shoots the 185 Juggernaut fairly well. Don't remember what powder I used, but intend on trying other bullets and powders to find something that shoots better. I have some R17, I'll have to see about finding some loads for it. I'm interested in how yours works out and what loads shoot well for you.

What barrel length and twist are you going to use? Mine is 24" with a 1:10 twist. I know the K-31 has a twist somewhere between 10 and 11.

[RC20]

Funny its a LW barrel. My choice was due to the fact I didn't have to get one chambered separately.

Mine is also 254 inch and 1-10 twist. Original I think is 10.75 or some such. Probably tells you how viable that was/is for the 30 cal bullets.

I kept coming across the K31 reference and followed up on it and realized I could do one in the Savage.

Opening up the bolt face worked nicely, I do that kind of fiddly fine fitting from time to time, still was not sure if I cold do it well enough by hand.

It all works in well with power for 308 and 30-06. The R-17 seems to like the heavier bullets, I think 175 is the lowest, good but not fully consistent results with 168 (odd flyer form time to time). I would think the 185s would be right in its sweet spot.

Also ironic is that I got in touch with a guy who wants to move his K31 onto a good owner, all at the same time, I was expecting to be a longer search. I started some loads in R-17 at 44 grains and working up by 1/2 gran increments. The K31 should be good for full power but will look for a lower load for that. Keep the high power stuff for the Savage barrel.

I am using PPU brass. I have that in 308 and its about equal to the RP to me at least. Oddly its more consistent neck tension wise to start with (new) than the Lapua in 308/30-06. I could not find any Lapua. I am not keen on converting brass and happy with the PPU.

I found I could get a cutter for my brothers Gerard trimmer in the 7.5 Swiss, so that takes care of the trim end.

I have gotten hooked on the trim on the shoulder. The WTF is good but does not chamber and de-burr. The Gerard does (he has the self contained motorized one, I am using my drill). Gerard makes one called the Tri Trimmer for drills but its limited calibers and it has to have the right setup for the shoulder to work.

It also chambers and deburrs which takes care of two more steps you don't have to do for case prep.

The 7.5 is indeed an odd shoulder. Looks more like a Mauser type shoulder. Makes sense as it would extract in machine guns in particularly better but also easier in rifle extraction in fouled chambers. Not sure why the 30-06 went with the longer shoulder. The claim is its a Mauser copy but its more like the Mauser idea done to their own ideas of what was best.

Sorry, rattling one, pretty cool to be going into summer and getting the setup going in time for more

[Swissfan]

Yeah, I got the barrel used for a decent price, that's the only reason I went with the LW. Originally I was going to try to do the rechamber by hand and figured it would be a smaller loss if I screwed it up. I ended up having a gunsmith do the rechamber with the reamer I bought. I also had the gunsmith open up the bolt face.

I have the go and no-go headspace gauges if you want to borrow them. Let me know and I'll mail them to you and you can return when you get the barrel on.

I started getting the 7.5 brass/bullets/powder out last night after I saw this post. I used 44.4gr of IMR4350 with the 185gr Bergers.

I have a few different brands of boxer brass that I've picked up the last couple of years. I was thing I would shoot some of the factory PPU I have just to have more brass. I also have some of the berdan GP-11 brass that I have reloaded. I found some berdan primers at a gun show a couple years ago.

I have some 150gr and 175gr Sierra's and 180gr Nosler and Swift I am going to load up. Are you using 308 Win load data?

I haven't been reloading very long and am not comfortable in using the 308 data for the 7.5.

There are several 7.5 loads in the manuals, I will start with those and go from there.

[243LPR]

I



When the barrel gets in I will set the headspace to match the K31 and should be able to use the brass between the two.[/QUOTE]

If you are full length sizing the brass what does it matter what the headspace is?

[RC20]

thank you very much for the offer of the gauges. I will get it in and see how it goes. The K31 should be here first so I can get a fire formed case to try setup. If that does not feel right or work out then I will take you up on it.

I did some sleuthing for the load data. 44 gr was my start point, I found some reference on the Schmidt Rubin site that seemed to match up with the 308 data though I am starting low.

Lowest I saw was 41 gr, I went with 44 as the K31 should be fine with it, the LW can use that as a start.


I may have a 1898 in the works and the low load should be good but will Chrono those others first and see where they sit.

Agreed is by far the best to be cauttious. I know you can't use burn rate as a solid, but R-17 supposedly is a close match and low loads should be ok.

My Honrady book and Sierra both have loads for IMR4350 and I am sort of scaling to those as well as other data.

I had not expected the K31 or the 1898 so have put another gun up for sale (WWI 1917 and not an interest item for this group so not litsed)


I am going just with PPU and looks like I will need to pick up more as more shooters for it . Maybe Lapua if anyone gets it back in stock. I was impressed with how consistent ant the neck tension was on the PPU. Typically Lapua is more erratic tension and by a lot on the first load though the Lyman M die smooth's that out.




Yeah, I got the barrel used for a decent price, that's the only reason I went with the LW. Originally I was going to try to do the rechamber by hand and figured it would be a smaller loss if I screwed it up. I ended up having a gunsmith do the rechamber with the reamer I bought. I also had the gunsmith open up the bolt face.

I have the go and no-go headspace gauges if you want to borrow them. Let me know and I'll mail them to you and you can return when you get the barrel on.

I started getting the 7.5 brass/bullets/powder out last night after I saw this post. I used 44.4gr of IMR4350 with the 185gr Bergers.

I have a few different brands of boxer brass that I've picked up the last couple of years. I was thing I would shoot some of the factory PPU I have just to have more brass. I also have some of the berdan GP-11 brass that I have reloaded. I found some berdan primers at a gun show a couple years ago.

I have some 150gr and 175gr Sierra's and 180gr Nosler and Swift I am going to load up. Are you using 308 Win load data?

I haven't been reloading very long and am not comfortable in using the 308 data for the 7.5.

There are several 7.5 loads in the manuals, I will start with those and go from there.

[RC20]

I

When the barrel gets in I will set the headspace to match the K31 and should be able to use the brass between the two.

If you are full length sizing the brass what does it matter what the headspace is?[/QUOTE]

I hope this comes across as intended. Back in the 70s when I was doing my own reloading (worked with my dad when I was 8 or so) I did not know what I know now. I don't know if unknown or it was advanced and just not listed.

What I have found is that there is what I think poor information from RCBS and the die makers on re-size, where they say touch the ram to the shell holder and then 1/8 or 1/4 turn past that.

I got back into this the same time my brother did and we wound up with breaks in cases at the base. Had not seen that before, but I only did a bit of rifle and for hunting and not a lot of that.

So there is re-sizing of the case and the shoulder bump back. Going 1/4 turn and a cam over on the dies pushes it way back, that puts stress on the base where it transitions from thick to normal and they break down there (or fortunately crack in our case) after 6 or 8 reloading's.

The way to avoid that is to do a minimum shoulder bump back and still do a full size case (that's my preference, there are others that go with neck, but you eventually have to resize FL, call it a appeals to me approach as to any right or wrong.

Hornady makes a device that screw onto the blade of a micrometer.

http://ads.midwayusa.com/product/709931/hornady-lock-n-load-bullet-comparator-body?cm_mmc=pf_ci_google-_-Reloading+-+Metallic+Reloading+Equipment+(Not+Presses)-_-Hornady-_-709931&gclid=CJuumsmV3NICFUlNfgod_ecH9w

There are two types of adaptors, Bullet Ogive and the Cartridge Shoulder ones.

You measure a fired case, then slowly work the sizer dies down until you get a .002 or .003 bump back on the shoulder.

That gets the size right but does not stress the base.

the 7.5 will be interesting as I don't think there is an adaptor for that, but I can make my own.

The Hornady ones are fine, but you can take a smaller one, drill it out so that it hits about mid shoulder and you are good.

As I have new brass, I can fire it in a K31 chamber, then use that fired one to set the head space (really the shoulder intersection in the chamber) to the Savage LW barrel.

Its possible the chamber size will be big and will be too much stretch.

If that's true then you just separate out the cases and use dedicated ones in each gun.

I have used common cases in the mil surplus rifles and the Savage though I am now segregating those out. the 1917 is pretty non conforming to SAMMI as it was a combat chambering that had a very long head space (almost field reject). I pick up enough 30-06 I have different mfg to keep separate.

Ok, phew, send this off and see if it makes sense.

[RC20]

The K31 came in and I got the next step going in that I created my NO Go gauges.

The gun is in wonderful condition, no troop tag but the stock is in far better shape than they usually are per my FFL who has 3.

Bore is clean, the MW gauge won't even start to fit in so its a tight 7.5. Metal is in perfect condition. Its just late enough its a birch stock but it looks good as its darkened up.

The straight pull is very impressive and I finally realized what it reminds me of is a AK 47 type long stroke piston bolt shape and function. Works very well, no issue knowing its I in the full close position and that is easily seen on the SN on the bolt and the back of the bolt to the receiver.

All top quality as expected, the clip is very good. As I don't have or plan on using strippers, it works well for removing and loading up and its solid latch system.

It has a bit of that solid AK Clip feel.

I don't have GP11 so not sure how well my loads did, as expected, the Iron Sight are hard to see, not as bad as a 1903A3 as the front sight is very close to a Model of 1917 with a large, flat and square face and top, none of that thing blade stuff.


Still had not issues with the loads including some hotter ones so I have well blown out cases for the chamber.

I do have a non intrusive rail clamp for a scope on the way.


The questions came up if it was closer to 30-06 or 308. Length wise 308, but I did a powder measure between the 7.5 and a 30-06 case, filled to top its 4 gains different and to the bottom of the neck 3 grains.

Its amazingly 30-06 like in a shorter but fatter case (7.5 Ultra Mag as it were)

[RC20]

The project is close to complete, still a bit of futzing to do.

The Lother Walther barrel came in, its a work of art. Mirror gleaming. There were a few odd pits in it, more stand out as the rest is so well lapped.
I put it a bit above Shilen normal class, not sure if the Shilen Super Match is more polished.

The Barrel checks to be 1/2 on a Muzzle Wear gauges, tight without being too tight. 1 would be fine so the 1/2 is good without going too far.

Threads were excellent and the nut spun on nicely without being loose.

Assembly per normal, I got the head space just a shade tight per the cases shot in the K31, its close, I will adjust a bit before the next shooting session.

First test load got a 5/8 group x 5 shots. I only had 15 of those and shot the others up in the K31 to see how it liked it. The next two increments got worse so the first load is going to be the focus. R17 and the Sierra 175M are the general choice there and that looks to work fine.

The barrel is a standard 30 caliber 1-10 twist, not the K31 1-9.75 (or close) twist). Not enough difference to be work more custom work.

COAL came out a bit longer than the K31 has and that's not an issue, they are close and bullet seating easily adjusted between the two.

So far the K31 has not really liked anything so I am going to change bullets up in it. With the scope on I think it should get around 1.5 inches.

Cases flip out is erratic, rims on the PPU vary a bit and I except its related. As its a filled in stock with a wooden block and single shot that's not an issue.

I had noted some comments on someone who had done the gun a while back. While the rim is rebatred, the whole case is larger so you have to open up a bolt head or try a magnum and see if that works. I opened it up and that is working fine.

Now to fine tune it on the higher load and find a lower load as well.

K31 gets tested with the Hornady 168 ZMX and the 168 M to see if it likes one of those.

[Swissfan]

Everything I have seen about the K31 and handloading is that it is hard to find something better than GP-11. I have loaded some of the 150gr and 175 gr Sierras and 180gr Swifts, just need to get the range and see how they do. If you still don't have any GP-11, I'll send you a couple/three 10rd boxes to try, pm me your address.

[RC20]

Thank you for the offer. I reload and have more rabbits to pull out of the hat both for powder and bullets.

Shipping to AK is hugely expensive for that kind of haz. It has to go ground and no one wants to deal with Canada that is not an operation setup to deal with the regs.


Regardless of the K31, the Savage shot very good for a first attempt so I can refine that one.


K31 is still fun to shoot, something about that straight pull just tickles me.

I was a bit surprised on the K31, I was in the area that matches the GP11, no joy. My first loads were better and they were way low.

If I can find a low load that its happy with that's the better way to go to keep barrel wear down.

[RC20]

If you are full length sizing the brass what does it matter what the headspace is?

Sorry I missed that one.

The K31 is setout per a typical military rifle with a lot of head space. Keeping in mind the military is not interested in SAAMI or European equivalent .

If I shot the cartridge in that gun first then minimum bump back, it will chamber and shoot in both rifles.

If I do a full bump back, then the base will work hard and crack in 5-10 firings. I prefer not to buy cases if I can avoid it. Ergo they will also get annealed.

[RC20]

I also like the cartridge and have done exactly what you are doing just for the "different" factor. I purchased a used LW barrel in 308 and had it reamed to 7.5x55 and put it on a long action. Had the bolt face opened up and had to do nothing else to get the brass to extract and eject. I haven't taken the time to do much load development for it yet, but is shoots the 185 Juggernaut fairly well. Don't remember what powder I used, but intend on trying other bullets and powders to find something that shoots better. I have some R17, I'll have to see about finding some loads for it. I'm interested in how yours works out and what loads shoot well for you.

What barrel length and twist are you going to use? Mine is 24" with a 1:10 twist. I know the K-31 has a twist somewhere between 10 and 11.

So far the LW likes R17 and the Sierra 175 Gr match bullets. First load up was 48.5 gr and it shot that to 5/8 at 110 yards.

It did not like anything higher, I am going to try 39.5 and range up to 48.2 and see if it likes anything a bit lower.

1-10 twist on the LW as I did not see any need to go exotic there with such a small twist difference.

The K31 does not like any of it very much, so I am going to start with IMR 4895 of which I have a lot (precaution purchase) and try the Hornady 168 ZMX to start with.

[RC20]

Well I got all 3 down and did some shooting with the G11/K31 and the Savage 7.5.

I continue to be impressed with the LW barrel. It shoots a variety pretty good in the 3/4 to 5/8 range.

I have not hit a tack driver yet but you have to love a barrel that is honest up and down the range.

These were pretty low level loads, G11 (which I found I can't see the sights very well) and the K31 I want to be easy on.

I have an backup 8 lb jug of I4895 so went with that, down in the 2200 to 2400 range with a Cabella only H168ZMX (yellow tip, the Zombie thing) Low cost bullet that does pretty well, its technically a varmint so its a combo match/varmint with more match to it as Varmints hit with anything are toast.

I have to assess the results and see where it looks promising, I finally was getting some groups from the K31 that are in the 1 inch range.