Reloading for 7.55x55mm Swiss question

grisbald · October 31, 2014, 12:09 AM

Recently purchased a K-31 and am having a question about reloading for this cartridge.

I am going to reload some Sierra .308 and Hornady .308 and see which one the gun prefers.

I just loaded a couple rounds using the Sierra bullet. The Sierra manual shows a COL of 3.060" which is also the max. Tried to chamber the round and it won't go into battery, round is too long. So I adjusted the seating die trying different seating depths and the round will chamber with a COL of 2.92". Put that COL into Quickload and it shows I am still way below max pressure. Even going 2.90" still has me about 13k below max with the load I will be trying (42 gr. IMR 4064).

Haven't tried the Hornady bullet yet and book for that is 2.91".

I think I will be fine going with the 2.92", anybody think differently?

Thanks for any input.

Geezerbiker · October 31, 2014, 04:45 AM

If you have backed off 10% from the max load, you should be OK. Find out where that bullet hits the lands and back off .003 to .005" and this will prevent pressure spikes and usually gives the best accuracy or at least it has for me.

I've found over the years that 4064 is a very flexible powder. If you're still worried, you could back off another 5 or so percent and it'll still burn consistently...

I'd like to hear how yours shoots. I bought one back when they were cheap and even though I have 200 pieces of brass and plenty of reloading supplies, I still haven't gotten round to shooting it yet...

Tony

ligonierbill · November 1, 2014, 05:06 AM

Hornady tested in a Model 1896/11. I can't say that model has a longer throat than a K-31, but I have loaded bullets that contacted the lands of mine when loaded to "book". I'd make a dummy round and work the length down in small increments. FWIW, I load Speer 150s (#2023) to 2.85. Those have a fairly "chubby" profile. SMK 175s (#2275) are at 2.933.

hodaka · November 1, 2014, 06:26 AM

K-31's are very sensitive to bullet profile and the relation to COL. I would ignore the book and measure what works best in your rifle. For most of the bullets I shoot, I have to seat them much deeper than one would think, simply to get the bolt to close. Don't have my measurements handy, sorry.

October 31, 2014, 12:09 AM	#1
grisbald Member Join Date: October 23, 2011 Posts: 75	Reloading for 7.55x55mm Swiss question Recently purchased a K-31 and am having a question about reloading for this cartridge. I am going to reload some Sierra .308 and Hornady .308 and see which one the gun prefers. I just loaded a couple rounds using the Sierra bullet. The Sierra manual shows a COL of 3.060" which is also the max. Tried to chamber the round and it won't go into battery, round is too long. So I adjusted the seating die trying different seating depths and the round will chamber with a COL of 2.92". Put that COL into Quickload and it shows I am still way below max pressure. Even going 2.90" still has me about 13k below max with the load I will be trying (42 gr. IMR 4064). Haven't tried the Hornady bullet yet and book for that is 2.91". I think I will be fine going with the 2.92", anybody think differently? Thanks for any input.

October 31, 2014, 04:45 AM	#2
Geezerbiker Senior Member Join Date: March 20, 2011 Location: Willamina, OR Posts: 1,908	If you have backed off 10% from the max load, you should be OK. Find out where that bullet hits the lands and back off .003 to .005" and this will prevent pressure spikes and usually gives the best accuracy or at least it has for me. I've found over the years that 4064 is a very flexible powder. If you're still worried, you could back off another 5 or so percent and it'll still burn consistently... I'd like to hear how yours shoots. I bought one back when they were cheap and even though I have 200 pieces of brass and plenty of reloading supplies, I still haven't gotten round to shooting it yet... Tony

November 1, 2014, 05:06 AM	#3
ligonierbill Senior Member Join Date: May 20, 2007 Posts: 2,458	Hornady tested in a Model 1896/11. I can't say that model has a longer throat than a K-31, but I have loaded bullets that contacted the lands of mine when loaded to "book". I'd make a dummy round and work the length down in small increments. FWIW, I load Speer 150s (#2023) to 2.85. Those have a fairly "chubby" profile. SMK 175s (#2275) are at 2.933.

November 1, 2014, 06:26 AM	#4
hodaka Senior Member Join Date: April 23, 2006 Location: South Texas Posts: 2,010	K-31's are very sensitive to bullet profile and the relation to COL. I would ignore the book and measure what works best in your rifle. For most of the bullets I shoot, I have to seat them much deeper than one would think, simply to get the bolt to close. Don't have my measurements handy, sorry.