M96 6.5x55 problem with 160 grain loads

[fourfive8]

Yes, that is not good! Looks like either really high pressure or excessive headspace. A headspace comparator gauge that compares the headspace length between a “suspect” unfired round and a fired round that has conformed to the chamber will tell that story. A .001” or so difference in bullet diameter with a conventional cup and core bullet wouldn’t likely cause that much pressure increase with an otherwise reasonable load.

Also be sure to trim case length— a long case will crimp the case mouth into the bullet at the end of the chamber which can really cause high pressure. A long case can usually be felt as stiffness right at end of bolt turn during chambering.

I think all the possibilities as others have posted have been brought up in this thread. Probably worth a check off process for each possible variable to eliminate the most likely. Failing IDing the culprit, definitely time for visit to gunsmith.

A basic headspace comparator gauge is very simple and can easily be made. Find some thick wall tubing or bushing (aluminum is easy to work with). Needs an ID a few thousands larger than the cartridge neck diameter and slightly longer than neck. Ends need to be square cut (important). Slip the gauge over neck until it contacts shoulder... should be just outside neck junction (approximate location of datum ring). Measure length from end of gauge to base of cartridge. Compare a cartridge fully fireformed in chamber to resized cartridges.

 

[James Adamson]

What was the outcome of this problem, I would be interested to know?

This came up in a google search as I was looking up 6.5 bullet diameter. I have a box of RWS 6.5 160gr bullets that I was going to work up a load for in my 6.5x55 but when it came to seating the bullet it fell into the case. Turns out they are 3 thou under sized.

 

[JanP]

Hi James, the 6,5mm comes in different sizes. Some calibers, like 6,5x52R, use .257.
Other calibers. use 264. The Swede is a .264.

 

[James Adamson]

Hi James, the 6,5mm comes in different sizes. Some calibers, like 6,5x52R, use .257.
Other calibers. use 264. The Swede is a .264.

I am aware that the swede is .264 I was just trying to figure out what these .261 bullets were for but I have just seen online that RWS made 159gr .261 bullets for the mannlicher- schoenauer. I got a box of them in with a mixed batch of various 6.5 loading gear from someone that was giving it up.

 

[Shootist43]

James Adamson, thanks for posting this article. I learned something new from it. I had no idea that various bullet and rifle manufacturers used diameters other than .264". I will certainly keep my eye out when shopping at estate and garage sales from now on.

 

[Frederik]

Ben, I shoot the dame exact model with a 23" barrel and over the last year developed a load for the 160gr Hornady Interlock running at 2400fps

Cartridge length 75.90mm
Norma cases
Powder Somchem S365 similiar to Vita N550
Load 40.9gr
CCI 200 Primers

Get MOA groups all day long as long as I don't shoot more than 3 before the rifle cools down.

Playing on QL I have to use 41gr 2209 to get the same speed so you are in well under max pressure.

Have you measured any of your loads on speed as speed will easily tell you if your over max.
But I think something is going wrong when you resize Case you easily feed like factory loads?
I only necksize the 6.5 and anneal the cases every 3-4 cycles.

The 160gr bullets is superb when hunting recently hunted again with this load and still have to retrieve a bullet.

With 140gr S&B bullets I have switched over to Vita N560, 49.2gr case filling is 99.4% and speed at 2740fps with my 23" barrel accuracy supberd out of the old rifle. Pressure is almost max but I don't shoot more than 100 rounds a year with this paper load or longer range hunting.

 

[bruce moulds]

cases need trimming?
bullets jammed into rifling?
bruce.