K31 / 7.5x55 Warning

mmattockx

mmattockx

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Spent father's day afternoon loading up my first batch of test loads for my K-31. I was following my Hornady manual, 7th Edition. Bullets were PRVI 150gr FMJ and 168gr Amax's. The 150gr bullets were seated up with no trouble and cycled fine at well over the specified OAL in the manual. I seated them at 2.950" and the manual called for 2.875".

Different story on the Amax's. Specified OAL was 3.025". I couldn't get close to closing the bolt at that length, the bullet engraved on the lands well short of closing. I eventually ended up at an OAL of 2.925" (0.100" less than the manual sepcifies :eek:) and have the bullets very lightly kissing the lands.

The difference between the bullets is the 150gr have a long, tangent ogive and the Amax's have a pronounced secant ogive with a shorter taper on the bullet nose.

So, for those working up loads on their K-31's, be very careful to check how long your throat is or you may find the same problems I did.


Mark
 
Hmmm. Call me dumb, but for almost all rifle and pistol loads, I determine the OAL by first knowing the max length of the magazine and then using a trial and error test seating of a long cartridge until it is either 20 thou off the lands or 50 thou under max mag length, whichever is the shorter.

The only time I look at the book OAL is if I am making hangun ammo to be used in other people's guns. then I make sure that my evloved OAL is not longer than the max in the book.

I also start low and work up to find what groups best in my gun. When I have a load that works well, I might try 10 thou longer and shorter, looking for some more improvement (especially in rifle ammo).

Before posting that the book says I am wrong, please note I have been handloading for 45 years for several hundreds of rifles and handguns.

You note that your OAL is 0.10" different than the book. That is not much. I swear remington throats are about a quarter inch longer than most others. I think they are designed by liability lawyers.

I am just sharing what I do. Your mileage may differ.
 
Ganderite said:
Hmmm. Call me dumb, but for almost all rifle and pistol loads, I determine the OAL by first knowing the max length of the magazine and then using a trial and error test seating of a long cartridge until it is either 20 thou off the lands or 50 thou under max mag length, whichever is the shorter.
Click to expand...

I usually do the same, but this is the first rifle that I have loaded for that had a much shorter throat than SAMMI spec dimensions will work with and I thought I would share that as a warning to those not inclined to check everything, everytime.


Mark
 
I've always thought that a manuals specified OAL(if any) was for the individual gun they used to develope their data. Some manuals don't specify what they used, and your gun will be demanding its own spec., anyways. Ergo .... bullet seating depth is a variable that every handloader should determine for his/herself.

Ganderite's method works well.

FWIW, the Amax's I've used seem to prefer a .020"(or thereabouts) jump. Never had much luck jamming them.
 
vviking said:
I've always thought that a manuals specified OAL(if any) was for the individual gun they used to develope their data. Some manuals don't specify what they used, and your gun will be demanding its own spec., anyways. Ergo .... bullet seating depth is a variable that every handloader should determine for his/herself.

Ganderite's method works well.

FWIW, the Amax's I've used seem to prefer a .020"(or thereabouts) jump. Never had much luck jamming them.
Click to expand...

My understanding of the max OAL is that it would be as specified in SAMMI specs for the cartridge. The OAL they show as used with each bullet is the one they settled on in their test rifle/barrel for that bullet. The max OAL for the 7.5x55 is noted as 3.059" in my manual.

I will see how they work just touching and then try a bit of jump if that doesn't work out.


Mark
 
Seems all North American, and much of the European OAL load data is for the pre-K31 service rifles, all of which have longer throats than the K31
 
diopter said:
Seems all North American, and much of the European OAL load data is for the pre-K31 service rifles, all of which have longer throats than the K31
Click to expand...

That may be true. I did not have any problem with OAL in my 1896/11 with Horn 168 OAL, but I always check first before loading rounds to establish a working max OAL. In the case of repeaters it is lesser of being clear of the lands or the mag length.
 
i just tested my new purchase. the die set said to seat at 3.06( as did the load data at the powder site ). i seated an empty and cycled it though my k31 and it came out as 2.92. i'll try seating at 2.9 and see how that works. interesting. i was just reading up on swissrifles.com . it seems the seating depth of 3.06 is referring to the 1911. the k31 is listed as 2.89!
 
I do what Rick said above with all my milsurps. Seat a dummy to what the book says and then test it in the rifle and mag for a better oal for the rifle I'm using and then adjust slightly from there.

Takes a little longer at the start but once done, I have the data for each rifle in a notebook for future reloads.

Cactus
 
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