Max load 308, 175 SMK and Varget?

Niko-PG

Niko-PG

CGN Regular
Rating - 100%
154   0   0
Location
Kamloops/Africa
Depending on the book/source, I found 43 grains vs 45 :eek:

I know I should load up to pressure signs then back down but I'm not too sure about my skills at reading pressure signs. Plus, I'd like to find my load in one trip, meaning loading samples up to the max published (minus 1 because of LC brass).
I have a nice load at 42.8 (speed unknown) and wonder if I should keep going up: depending on the max, it is a slow round or a borderline safe one...
 
Niko-PG said:
Depending on the book/source, I found 43 grains vs 45 :eek:

I know I should load up to pressure signs then back down but I'm not too sure about my skills at reading pressure signs. Plus, I'd like to find my load in one trip, meaning loading samples up to the max published (minus 1 because of LC brass).
I have a nice load at 42.8 (speed unknown) and wonder if I should keep going up: depending on the max, it is a slow round or a borderline safe one...
Click to expand...

According to Sierra 41.7 gr of Varget is maximum load.
I used 41.7gr of Varget over 180gr SMK's which is also max load and I was starting to get a slightly sticky bolt.

http://www.6mmbr.citymaker.com/f/Sierra308Win.pdf
 
Lyman recommends 1 or 2 grains less than maximum charge for millitary brass.
This means that 43gr is very close to a maximum load.

As for pressure signs, the most reliable pressure sign is case head expansion.
Simply put, it should never expand under normal conditions.

Other signs, such as primer deformation, difficulty in extraction are very misleading and often appear after maximum load has been reached.

Another excellent indicator is velocity: it's almost impossible to get high velocities without high pressure!

Alex
 
Niko-PG said:
That's where I'm confused: Hodgon book says 45C for 175 SMK :eek:
Quite a difference!
I'm at 42.8 with LC, so about 43.8-44 grains equivalent and no sign I can see
Click to expand...

Both Hodgdon and Sierra are very serious companies but it's possible that differences in their test setup and procedure justify the difference in maximum load.
Take a look at SAAMI specs and you'll understand why you might get such differences.
http://www.saami.org/specifications_and_information/publications/download/206.pdf

Also Sierra might have been sued and lost in court while Hodgdon has not...
Finally, remember that 3gr is only 6% of difference in maximum charge and that you should always starting with the "starting load".

This summer, because of a faulty electronic scale, I have badly overloaded 243 Win ammo (almost 7gr of Varget too much) and the rifle is still intact but the bolt was really sticky and primer had vaporized.

Alex
 
I loaded new lapua brass with cci br2 primers and 175smk today. It was pouring too hard so I was unable to crono. I took three loads 43gr 44gr and 44.6gr. I got no pressure signs with any of them but the 43 gr was most accurate and the 44.6gr was the least.
This was out of my 20" Remington LTR with a 1 in 12 twist
 
Today I shot some of the 175gr SMK with 42.5gr of Varget, Win LR mag primer and Lake City brass. Sub 1" group at 100yds. No signs of pressure. I got my data from Reloaders Nest and cross referenced with Hogdon.
 
You must log in or register to reply here.
Back
Top Bottom