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Need a Math Whiz to confirm this is a good KZ size for Benchrest Targets 11/7/18

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CampFussell

CampFussell

Member
Apr 1, 2015
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Burgaw NC, United States
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Now I have plenty of the USARB 25 meter BR targets, but most of the time I like to shoot groups.

I think I figured out a good way for a quick visual with five 5 shot groups with my .177 for a 250 score if I can keep them all inside the 3/8" KZ?

For 25 Meter BR at CampFussell...I use 28 yds , it's just 2 ft further



The 10 Ring diameter on a USARB card = 2mm = 0.07874 inches



As we know, the .177 inch pellet hole is scored with a .224 " plug and must touch the 10 ring to score. But I'm making it harder and kicking the plug to the curb and just looking at the hole.



I need a drawing to go with this, but just visualize the 10 ring with two pellets, one on each side of the ten ring. Anytime a .177 pellet hole is completely inside a 3/8 kz it will touch the 10 ring



Note: I'm not taking into account the size of the plug. This is just for a quick visual, and to show you why I use 3/8" for .177 and 1/2" for .22.



Therefore 0.07874 + .177 + .177 = 0.433 inches



I could use a 7/16 KZ but that's cutting it too close for me at 0.438"? Note: would still more than pass with the scoring plug



So I say if a complete .177 pellet hole stays inside a 3/8 inch kz at only 0.375 inches, it will definitely hit the 10 ring with room to spare.



Let's back the math in to prove it. 0.375 - .177 - .177 = 0.021" and we know the 10 ring is definitely bigger than that at 0.07874".



Again I know they use a 0.224 score plug to score with, but this is just a good eyeball reference and maybe a little harder to do.



Now since the .22 cal is just a hair bigger and it's dang hard to keep 5 of those babies in a 3/8" kz

Lets' redo the math for it.



0.07874 + .22+.22 = 0.519 inches



So, we'll use a 1/2" kz for a good eyeball test on the .22 pellets. If the group stays inside that, it is definitely a 10 ring shot with room to spare.



Let's back the math in to prove it. 0.50 - .22 - .22 = 0.060 " and we know the 10 ring is definitely bigger than that at 0.07874 ".





Again , a 0.224 score plug is used on the .22 cal as well, but I just need a good visual.



The two KZ sizes for these two calibers are just a good eyeball feeling for touching the 10 ring every time.



I don't think the 1/2" KZ will be accurate for the .177 pellet which is why I choose the smaller KZ for it.



Let's prove that? 0.50" - .177 -.177 = 0.146 and that is way bigger than the 0.07874 inch 10 ring.

OK let's plug the .177 hole with the 0.224 score plug?

That plug goes over the .177 diameter hole leaving 0.024" on each side of the hole. Which means 0.024" of the plug will be over the 1/2 KZ line. The other .024" will be closer towards the 10 ring.



So we have 0.50"-.177 - .177 - .024 - .024 = 0.098" which is bigger than the 10 ring diameter and means the .177 pellet would not work in a 1/2" KZ to be precise, even with the scoring plug.



How's that for some scientific Fussellized shizzola? LOL



Now 50 yds is a whole new deal.



50 yd Ten Ring = 6.350mm = 0.25 inches



.25 + .177 +.177 = 0.604 inches......5/8 would be too big...would need 9/16" KZ at 0.56 inches



Let's back it in with the score plug and see what we have with the 5/8" anyway?



0.625 - .177 - .177 -.024 -.024 = 0.223 , so in reality 5/8" would work with the scoring plug, but I would rather use 9/16 (0.563")for eyeballing.



Let's do it with .22



.25 + .22 +.22 = 0.69 So 5/8" would definitely work for .22 cal



Trying to keep 5 shots completely hidden inside a 5/8" KZ at 50 yds is pretty tough, especially for 5 groups in a row?



This is five 5 shot groups last night at 28 yds with the Thomas and the 13 gr monsters shooting 820 fps at 3/8" kz's

I think that would be close enough for a 250 score on a BR card?

Group number 4 is the only one questionable and the paper ripped a little, but I have a little to play with even if the hole is just a hair over the line.



1541625150_19150314515be3553e943449.46871773_45662313_2251106291567671_3116273436406579200_o.jpg




Peace and calculator key grease

Fuss




 
I know how to calculate any ballistic calculation for Extreme ranges 1 shot 1 hit , But I dont know what you are asking lol

like

Correct for BAROMETRIC PRESSURE (STD B.P. - MEAS B.P.) x Corr Value = Mils / MOA B.P. high 
Correct for MVV / AMMUNITION TEMPERATURE (STD B.P. - MEAS B.P.) x Corr Value = Mils / MOA B.P. high 
Correct for AMBIENT AIR TEMPERATURE Warm - Mils MOA
(STD AIR TEMP - MEAS AIR TEMP / 10) x Corr Value = Mils / MOA Cool +
Correct for Vertical Coriolis East - Mils MOA Direction of Fire) x Corr Value = Mils / MOA Full cos value: due E or W West +
Correct for Humidity

Correct for Windage Always correct "into" the wind L or R Mils MOA
Ave Windspeed / 10 x cos(Wind Angle) x Corr Value = Mils/MOA Full value from R / L ( - , + )
Correct for Spin Drift RH twist Adj. L (-) Mils MOA
Correction Value = Mils / MOA Always adjust LEFT (-) for R hand twist LH twist Adj. R (+)
Correct for Horizontal Coriolis Independent of DOF Northern Hemisphere Adj. L (-) Mils MOA
Correction Value = Mils / MOA Southern Hemisphere Adj. R (+)
Target Lead Mils MOA
Target speed (ft/sec) x cos(Angle of travel)x Correction Value = Lead Full value L / R
FINAL Mils MOA

Determine FINAL Elevation Setting FINAL Mils MOA


 
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I'm basically finding a comfortable KZ size to use that would mimic the art of shooting the 25 meter Benchrest targets like this one and still hit the 10 ring.

The 9 ring is 8mm ,or .31495 inches , but with the score plug the pellet can be a little over the 9 ring line and still count as a hit. Just hate wasting all my BR targets when practicing.

With a 0.375 kz and all pellets inside it I know it's good enough for a 10 ring score

Like this target below, there are a few shots where it doesn't look like the pellet hole is touching the 10 ring, but with the scoring plug it touches the ten ring for 10 points. With 25 ten rings you have 250 points . This was only the second 250 I've ever shot. Pretty hard to do.

1541642077_10151049955be3975dc45602.12051088_C 11-17-17.jpg


https://www.airgunnation.com/topic/wrabf-erabsf-usarb-25-metertarget-post/

Here's a nice Ed Canoles target you can print out with one hundred 3/8" KZ's inside a 5/8" square

https://www.airrifle.co.za/library/AA_Targets/Target_EdCan_100_Bull_.375.pdf

and another good one

http://www.thagc.com/wp-content/uploads/2015/09/100-38.pdf

And here's a good 1/2" KZ inside 1" squares if ya need it

https://www.airrifle.co.za/library/AA_Targets/Target_Edcan_42_square_25KZ_.50KZ.pdf



25 meters

10 Ring 2mm .07874 inches

9 Ring 8mm .31495 inches

8 Ring 14mm .55118 inches

7 Ring 22mm .86614 inches

6 Ring 30 mm 1.18110 inches

5 Ring 39mm 1.53542 inches





50 yards or meters? not sure

10 X 0.792mm .0312 inches

10 Ring 6.350mm .25 inches

9 Ring 12.700mm .50 inches

8 Ring 19.050mm .75 inches

7 Ring 25.400mm 1.0 inches

6 Ring 31.750mm 1.25 inches

5 Ring 38.100 mm 1.50 inches










 
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Wow!, was looking back at a 25m thread embedded in this topic, anyway I was curious about ”coldking” I don’t think he’s posted in quite sometime?, has anybody heard from him, is he doing well? Probably none of my business! But just thought I’d check
Click to expand...


Yeah, Frank (aka Coldking) is doing well.

He's gotten into benchrest with powder burners now. Probably spends more time on their forums, and shootin' his fancy new .22 Vudoo rimfire?

I'll hit him up and we'll see if he'll talk to us!

Fuss
 
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Thanks Jimmy - my Vudoo came back to me yesterday - had it super tuned by Gene Davis -master gunsmith - he installed a shillin Barrel and a Biggs and Andy super two stage

1.5 ounce trigger . I haven’t scoped it yet but was shooting it at silhouette targets and hitting every one simply by lining up the picitinny rail on the target . I’ve Been shooting my Daystate .303 air rifle -mainly at pests - I had to take out a 30 lb raccoon recently - I didn’t want to but he was really messing with my Rat Terrier Duke .



Thanks for the concern guys - I hope to be more involved herecin the future 

CK 


 
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Yeah Frank, you gotta lot of catching up to do. Wanna see that new Raw up against your Thomas at 25 meters ;-)

I don't blame ya....can't have no critters chewin' on the little Dukester. Rocky raccoon had to go!

I'm gonna have to try some 100 yarders when my Cricket pup comes back from Texas. That is if I can get my lazy butt out there and clear the lane from the hurricane debris?

Peace and air compressor grease

Fuss




 
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LOL - I did feel bad about giving rocky Racoon the dirt nap! And hit him from 40 yards - between the eyes and he dropped like a sack of potato’s ! I love that air rifle ! 

on the .22 rimfire-it’s just like a pellet gun at 25 meters - shooting the .22s at 50 is just as dependent on reading the wind - I’ve had to aim 2” to the left or right to hit the X many times 

and the same thing with air rifles in price/quality is true with benchrest rimfire rifles 

yup I really need to scope The RAW - put it up against the Thomas -hell I need to start shooting all these rifles 

Alfred Of Beaumont is building me A Thor pistol in .224 to shoot the Eley .224 41 grain bullets at 110 ftlb MV 

i think I’ll take it to a silhouette match 😬

cK 
 
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