The one that got away

[thomasair]

Wind was awful today...but braved the dust storm to test for a short time. It was actually difficult to maintain my eye relief because the wind was moving my head...lol. I shot this 25 shot group at 50y with my 22 cal 40gr slugs.



This barrel was put on the gun in the wind, so I never got a windage zero. Not sure how much it was blowing. I just clicked over near a bull and started shooting. My range faces south and the wind was mostly from the nw 4:30 direction.

Looks like 24 made it under the spring seat that is .490”. That’s ok in my book given the base wind of 15 with gusts over 20. I’ll call it 1/2 MOA in rough conditions. For some reason the group pics are rotated 90 degrees counterclockwise. Was not able to get them to post correct. Sorry 

Mike 

 

[Keith Rush]

Very nice grouping Mike!!

Keith

 

[davelarson]

That’s fantastic! In the wind at 50 yards and 25 shots?? Wow. Can you say consistency lol! Thanks for sharing your group Mike. 

 

[biohazardman]

Half inch at 50 yards would be MOA. Half inch at 100 would be half MOA?

 

[REFF]

Great shooting! Very good group you got there!!

 

[JohnnyPDX]

Nice shooting and most guys, myself included, would have a few of those 25 NOT ON THE PAPER.

 

[nomojo65]

That’s crazy!, Awesome shooting Mike.

 

[thomasair]

Thanks guys.

Lets do a little math for the folks watching at home.

1 Moa at 100 yards is 1.047”.
For 1 Moa at 50 yards you multiply 1.047 x .50 = .5235”

1/2 Moa at 50 would be .5235 x .50 = .2618”

Since the accepted way to measure groups is center to center....we need to add the bullet (hole) diameter to that to get the outside to outside diameter that is covered by the spring seat.

.2618” + .224” = .4858” outside to outside.

Since the spring seat that is easily covering 24 of the 25 shots is .490”....this means that the center to center dimension of the bullets under the spring seat are 1/2 Moa.

A more accurate way of doing this is to use the measured size of the actual hole made in the paper. My slugs cut a nice .210 hole.

.2618” + .210” = .4718”.

If it would please everyone....I could machine a disc .4718” and place it over the 24 of 25 holes so that I could show that the 24 is 1/2 Moa...but I think I’ll just say something like....I’ll call this 1/2 Moa in rough conditions.

Mike 

 

[biohazardman]

Sorry spaced the CTC thing somehow. A moment of faulty brain function I expect. ;^)

 

[steve123]

That's pretty amazing !!!

If I tried to do the same thing with my 22rf my group would be 3-4 times as wide.

Oh and there you go missing that dot again 

 

[nomojo65]

I’m sure many have shot C.F. Benchrest and my Dad always said they measured outside to outside then subtracted bullet Dia.?

 

[thomasair]

Joe, the trouble with that method is that not everyone’s 22 prints the same size hole. The actual hole is always smaller than the bullet.

Mike 

 

[thomasair]

Steve, the dot is my nemesis.

 

[nomojo65]

Very true Mike, especially with pellets!

 

[Therealld]

I’m sure many have shot C.F. Benchrest and my Dad always said they measured outside to outside then subtracted bullet Dia.?

Yes,

Most use that method, and its pretty good for centerfire shooting, as lots of CF target guns are of such high velocity they cut clean round bore-sized holes. But slower stuff like rimfires and airguns get a bit of advantage, as most holes are smaller than bullet dia. When it comes to airgun pellet holes, we at our club have measured lots of em, and found most to be WAY smaller than caliber size! In fact, most .177 JSB pellets printed holes smaller than .150”, and JSB .22. Pellets printed less than the size of a .177” cal plug!

I have seen a quite a few “250” scores on the International target from .177 airguns, even shot some myself, but have never seen one that would have been “all tens” without the help of the .224” plug! For sure I think true bore size plugs are the largest to score 25M targets, even if it means dis-allowing .22 for the current target design. Frankly, a good case can be made to restore inward scoring targets like we used for the old BR50 game, to penalize oversized holes.