Bearing Surface, Pressure and Velocity

270 MKV

Well-Known Member
Joined
Aug 21, 2012
Messages
95
so, I was thinking the other day..what effect does bearing surface have on pressure and velocity...

Reason being...I have three bullets I am working with...

the lightest one has the longest bearing surface....hmmmm

so, was wondering....

if a heavy bullet has a shorter bearing surface than a lighter bullet...what would that do to the possible load...could it indeed be loaded to a similar powder charge as the lighter bullet??

Final velocity would of course be lower...but what would peak chamber pressure do???
 

bobnob

New Member
Joined
May 4, 2012
Messages
3
Location
NSW, Australia
so, I was thinking the other day..what effect does bearing surface have on pressure and velocity...

Reason being...I have three bullets I am working with...

the lightest one has the longest bearing surface....hmmmm

so, was wondering....

if a heavy bullet has a shorter bearing surface than a lighter bullet...what would that do to the possible load...could it indeed be loaded to a similar powder charge as the lighter bullet??

Final velocity would of course be lower...but what would peak chamber pressure do???

Good question! I guess all the variables need to be calculated of course. It would depend in part on the differences in the friction bearing area and weight difference.

I can't call on much relevant experience to help except the following; Once when I was working up loads for a 270 I was experimenting with 130, 140 and 150g bullets, and all three weights were of different brands. I used identical charges - 59g - of AR2213/H4831. In the case of all three different bullets the speed was a near identical average of 2970fps with a near identical point of impact.

Not directly relevant to your query but relative somewhere on the periphery.
 
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