1981-2001 760 Pumpmaster bad BB accuracy

This is the place to talk about everything airgun related including air rifles, air pistols, pellet guns, pcp airguns and more.
Post Reply
Message
Author
Ausername
Posts: 171
Joined: Thu Apr 27, 2017 5:38 pm

1981-2001 760 Pumpmaster bad BB accuracy

#1 Post by Ausername »

Anybody else have the old 1981 to 2001 pumpmaster and get like 11" group with BB's yet get 1/4" groups with pellets at 15 yards? is it because it has a rifled barrel, if mine does, i don't know if it does, just a thought.
Chevota
Posts: 1287
Joined: Sat Jan 25, 2014 9:16 pm
Location: United States

Re: 1981-2001 760 Pumpmaster bad BB accuracy

#2 Post by Chevota »

The BB's tend to roll out the barrel and do this: http://tinyurl.com/oz22l4q
See the 20 sec mark.
You can watch the BB's do this. If you can't see them try shooting at clouds, or better yet near sundown with the sun at your back so you can see the bright reflection. Works really well for firearms.

Only a few 760's were rifled, and if you do have a rifled barrel I'd stop shooting BB's b/c they can damage it. Best to keep a rare barrel intact but up to you.
Daryl
Posts: 11981
Joined: Wed Jan 05, 2011 12:35 pm
Location: P.G. B.C.

Re: 1981-2001 760 Pumpmaster bad BB accuracy

#3 Post by Daryl »

YUP!
Best Wishes
Daryl
Ausername
Posts: 171
Joined: Thu Apr 27, 2017 5:38 pm

Re: 1981-2001 760 Pumpmaster bad BB accuracy

#4 Post by Ausername »

Chevota wrote:The BB's tend to roll out the barrel and do this: http://tinyurl.com/oz22l4q
See the 20 sec mark.
You can watch the BB's do this. If you can't see them try shooting at clouds, or better yet near sundown with the sun at your back so you can see the bright reflection. Works really well for firearms.

Only a few 760's were rifled, and if you do have a rifled barrel I'd stop shooting BB's b/c they can damage it. Best to keep a rare barrel intact but up to you.
I thought it may have a rifled barrel, but i checked but it's smooth bore... any ideas why it's bad with BB's?
Daryl
Posts: 11981
Joined: Wed Jan 05, 2011 12:35 pm
Location: P.G. B.C.

Re: 1981-2001 760 Pumpmaster bad BB accuracy

#5 Post by Daryl »

BB's are smaller than the bore. The BB cannot spin around it's point of balance as a bullet does when fired from a rifled barrel, thus the BB is unstable. While in the barrel, it takes on a spin like a base-ball thrown as a curve, hook, slider or even a knuckle-ball if there is no spin at all - or a combination of any of these. All of these 'traits' cause the ball or BB to not hit where it is pointed. Only a properly spin stabilized ball or bullet will hit where it is pointed.

I would like to witness those 1/4" 15 yard groups fired with pellets from a smooth bored air gun.
Best Wishes
Daryl
Post Reply