STG57

[Bruce_in_Oz]

What bullet were you using?

GP-11 ammo has an "unusual" bullet that has a VERY short parallel section and the ogive is a Secant type. Thus, it starts decreasing in diameter immediately in front of the neck of the case.

When I bought my K-11, the only GP-11 ammo around was "collector" ammo, no bulk shooting ammo around, here in Australia. It is still hard to find in shootable quantities at a realistic price.

So, I loaded up a few cases with Sierra 155gn Palma Match bullets that I used in my .308" Win chambered target rifle. So far, so good.

It got interesting when I passed this information on to a friend who had bought a K-31 from the same collection.

Next thing, he asked if I could come and look at a "problem". He had made up some dummy rounds for testing and now had a bullet stuck in the leade.

The K-11 has a LONG leade to accommodate the older GP-90, round-nosed bullets that were the standard until 1931. So, The K-11 has a long leade, even though it was introduced with the GP-11 with its MUCH more streamlined bullet.

Thus, If you are loading for a K-31 or a PE-57, you need bullets with a SECANT ogive, like some of the Hornady bullets, exotic "VLD" types or, in my part of the world, the Australian -made BJD 155 grain HBC .308" target bullet. These also work fine in the long leade of the K-11 but have a fairly long bullet "jump".

Can you get GP-11 projectiles from Switzerland for reloading?

Information

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[Ovidio]

Hi Bruce, thanks for this very interesting information.
It seems he had the same problem I experienced at the range.
I was using plain and simple Hornady HPBT 168 grs. bullets, and they surely are not with secant ogive.
In the pictures attached you see the Hornady bullet in the middle.
Left is a new monolithic 160 grs. bullet for long range shooting, from a new Italian company (I'll try them in the K31 and M1917), and right there is a classic S&B FMJBT 180 grs.
I also have the 147 grs. S&B. Similar profile, just shorter.
Looking at the shape of the bullets, maybe the monolithic could be ok.
In the K31 I never had trouble with the S&B bullets. I still have to try the Hornady, but I don't think there will be any difference, as they are pretty similar.
Attachment 105422Attachment 105423

[CINDERS]

I gather Ovidio when you resized it was FLS'ing the cases and not just neck the only thing I could think may have happened is you short stroked the press by a phhhhtinth of an inch (Less than a gnats fart) and it has not bumped the shoulder back causing the shoulder to be forced into the chamber but keeping the weapon just out of battery. If all the other cases worked flawlessly then this one well perhaps just missed out and having the projie come out in the lede implies the COAL is to long I would use a dummy round loaded to what you did previously and soot the projie with burning camphor (Mothballs don't do it inside it will soot your nice white walls it arcs the wife up bloke) then very carefully single load it and close the bolt reasonably gently on it then carefully extract it. If it again sticks in the bore then load the projie again put a comparator on it adjust the COAL by 2-4 thou and go again until you get the marking just visible on the ogive I would then give the projie a 30-40 thou jump (Well decrease the OAL by that) and see how that goes. The comparator (Or a Comparator nut if you have one is the way to go to much variation measuring from the meplat.)

You may find the accuracy gets better as all of the rounds may have been slammed into the lede causing mis-aligment of the projie to the bore and a crooked bullet wont fly that straight.
I may be completely off course but thats what I am taking away from this

[Ovidio]

Thanks Cinders. That was on my to-do list. Maybe that rifle just needs slightly shorter boolits...

[CINDERS]

Wow that is a long pill Ovidio that 160 grainer I would be real careful not to get into compressed loads with it

[Ovidio]

That is the reason why I want to try them in very solid rifles.

[Ovidio]

But you got me a bit scared, damn...

[CINDERS]

Its all good Ovidio your not an inexperienced reloader so know the form.

[Ovidio]

Yep. I‘ll measure the oal again and decide what to do.
Worst case scenario, I‘ll cut the loads a bit and see.
The difference in length is not a small thing...
But I‘ll test in very very sturdy rifles. Someday...;-D

[Pierre]

Gentlemen, this is an exercise in logic.
The GP 11 came from the same munitions house in 1898 as the new run GP11 ammunition is being made and currently distributed among shooting clubs in Canada and in Switzerland.
The only change that was ever made and that cartridge was in the early 70s when they changed the coagulent.

The seat depth for the GP 11 cartridge is set approximately two thousands off the lands. When you consider that it worked in the G 11, the Kadet, The K 11, the K 31, the ZFK 55, the PE57 and the MG 51 machine gun, (the only one left in the Swiss Army using this round) why would there be any question whatsoever about powder and seat depth unless you are reloading.

If you are reloading and are unsure about any of these factors, please go here

FAQ | Swissproductsusa and read "What is the process for reloading the 7.5 x 55 cartridge?" This is a specific reloading process dedicated to our cartridge only.

As for brass fired from the PE57, Resizing twice might be okay but as soon as you move on to 3rd time you are rolling the dice. Those striations that you see in the fired brass are the areas that have sunken into the chamber striations that allow the rifle to function on a delayed blowback. They are a substantially weakened area, and please take my word for it. After many hundreds of rounds downrange through a number of different PE 57's In the past 50 years, Second and third round full length brass sizing's left us with plenty of ruptured longitudunal separarions along the striations. You might get away with it once or twice, but it will catch up with you if you're not careful.