300 Win 215 Berger Pressure Testing

[treillw]

I want to figure out my gun's max powder charge with H1000 and 215 bergers. Going to shoot a ladder of charges with a magnetospeed attached and monitor velocity and check for pressure signs.

What is the maximum velocity I should expect to get?

What velocity would you anticipate being over pressure?

My barrel is about 24" long.

Thanks in advance!

 

[BadDogPSD]

There really is no way to give you good answers as there are so many variables.
Make & model of rifle?
What barrel?
What reamer was used? How much free bore?
What's your max COAL?
How many rounds through the barrel?
What powder?
What primer?
What elevation?
What temperature?
What humidity?

That said, 2800-2900 fps is achievable in most 300 Win Mags.

 

[treillw]

Answers in your quote

There really is no way to give you good answers as there are so many variables.
Make & model of rifle? Cooper Model 92
What barrel? 70 countour (heavier than standard)
What reamer was used? How much free bore? no clue
What's your max COAL? not sure - new barrel
How many rounds through the barrel? 20
What powder? H1000
What primer? cci 250
What elevation? 5325
What temperature? 80 today
What humidity? 29% now

That said, 2800-2900 fps is achievable in most 300 Win Mags.

 

[Zero333]

You will safely reach 2,825 - 2,850, maybe 2,900 depending on the variables.

Don't rely on primers alone for reading pressure signs.

 

[XTR]

If you are shooting a 300WM there is some good information over on https://www.longrangehunting.com/forums/

Search around for it. The velocities noted above seem to be what most are reporting

The 215 Berger is a long bullet, it takes a freebore >.200 to get it all the way out of the case.

 

[BadDogPSD]

Have you measured your chamber? I always start at .020 off the lands to find my velocity node, then play with seating depth to squeeze out the last little bit of accuracy.

 

[Deton8tor]

I shoot the Berger 215 in my .300WM, ABM brass, 250 or 215 primer (mostly 250) 74.0 H100 and I get 2830 from a 27.5 inch barrel. My numbers for a 300 WM are low too. My shooting partner took his to 79.0 with no pressure; but decided to back up to 74 and leave it. Both shoot very well for use at 74.0. The 215 has a very short bearing surface and does the 200 20X. You won't be disappointed with the 215 or the 200 20X.
I find my lands using Alex Wheeler's method and load from there, typically 10-20 off.

 

[treillw]

I shot some loads over the magnetospeed. All bullets jammed into the lands to create max pressures.

Grain Velocity
75 2675
76 2696
77 2740
78 2799
79 2850
79.5 2857

It seems like the gun will be safe shooting 78 grains as a max load. I don't know a ton about this, but think the 7 fps jump from 79 to 79.5 grains is a sign of overpressure - the bullet can't get out of the way any faster.

All the brass pretty much looked the same. Light extractor marks in the upper charges. Virtually no difference in the primers. Bolt didn't lift hard on any of the shots.

Thoughts?

 

[cheyenne01]

I have a custom 300, stiller action and a brux barrel, my buddy has a Borden action and a brux barrel
both barrels are 26 long, plus the brake.
Chambers were cut with a reamer with enough free bore for the 215. I can check the oal of it if you like.
Both guns we shoot 30 thou off the lands and they are both a touch over 3000 fps.
both of our max charges are a bit under yours ( also using H-1000). Our charges very one grain from gun to gun as I have differnt brass and my brass is a bit lighter.

 

[trailrider121]

My Defiance action with a 28" brux barrel, #4 contour, 1:9 twist, does great with H1000. Gunwerks brass H1000 77.7grs using Berger 215 Hybrids. Avg speed is 3040 fps. When using Winchester brass I get 3020 fps with 77.5grs. No pressure signs. I tried RWS, and ADG brass. Both of those get 2950 fps with chargers around 75-76grs, anything higher in charge, I get pressure signs.

 

[Zero333]

Sometimes a velocity plateau is a sign of a accuracy node.
I'd load some up around 79 gr and see how they shoot.

 

[treillw]

Sometimes a velocity plateau is a sign of a accuracy node.
I'd load some up around 79 gr and see how they shoot.

Isn't 79.5 grains a pretty screaming powder charge?

 

[Zero333]

Isn't 79.5 grains a pretty screaming powder charge?

It can be. But if the freebore supports a COAL of 3.600"+ then 79 gr should be right at a safe max.

 

[treillw]

I had the bullets seated pretty long to make sure I was jamming them. I didn't fuss around with exactly finding the lands too much. It was a little difficult for me to close the bolt.

Do you think by seating them so long I created more space in the brass, allowing a false higher powder charge?