How much does copper fouling affect fps?

[Layton]

Reason for asking is I shot some loads out of my dads rifle yesterday and didn't get near the velocity I thought I should. Around 150fps short of where I expected. I don't think he's ever cleaned the thing so i just did and I musta gotten 2 pennies worth out of it so far.

L

 

[Layton]

Re: How much does copper fouling affect fps?

bump

 

[TonyAngel]

Re: How much does copper fouling affect fps?

I really don't know if severe copper fouling will affect velocity, because most clean their rifle when the fouling starts to affect accuracy.

What caliber is the rifle? Barrel length? Ammunition?

If the numbers you are getting are short of what a loading manual says you should be getting, that's normal. Loading manuals state a specific range of velocity for loads using their specific brands and lots of components being shot out of their test rifle/barrel, which is usually pretty long.