Rifling twist on a Parker Hale 7mmRM

H

hbar2

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Anyone know what the twist rate would be? Buddy is having a hard time getting anything below a 175gr bullet to stabilize. I have tried an internet search but only come oup with the PH musket info. I have enough of my own reloading to do, and will have to work out a load for my own new rifle so I really dont want to have to do it for him too!!!
Any help would be great.
Cheers
 
Measure Twist rate with cleaning rod

Tell your buddy to just measure the twist rate on his rifle himself. A well patched rod turns when it is pulled through the barrel because the patches engage the rifling. Measure the linear distance the rod has to be pulled out to give you one revolution. Use tape on the rod as indicators.

Peter
 
When you say that any bullet weights below 175 gr won't stabilize, what exactly do you mean; that they are key holing on the target or not grouping well?

Has he given the barrel a really good cleaning?

Ted
 
hbar2 said:
hard time getting anything below a 175gr bullet to stabilize. Any help would be great.
Cheers
Click to expand...

I might be completely out of line here but I always understood that the degree of bullet stabilization is directly related to the weight/lenght of the bullet and the twist rate. An increase in bullet weight/lenght usually requires a faster twist rate and not the other way around. You could have over stabilization and this might be what is happening here. In other words, you might be able to stabilize a bullet at 175 gr but not beyond that or not be able to stabilize it at 160 because of over stabilization.

Please see: http://www.gunnersden.com/index.htm.rifle-barrel-twist-rates.html


Duke1
 
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