How to keep zeroed while shooting the CBA score match

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  • Last Post 29 July 2022
John Alexander posted this 27 May 2022

Warning: the whining and question below will probably be of little interest for shooters not interested in CBA benchrest matches -- and maybe not much more of interest to CBA competitors.  But I am hoping some of the latter will have some helpful hints for my problem with score matches.

Just got back from an enjoyable two day match put on by Mel Harris in Roseburg, Oregon where I took both first and last place by virtue of being the only shooter in Hunting Rifle Class. I am still grumbling over a problem I have in shooting the CBA score match.

My rifle and load seemed to working well and although some mirage made the 200 targets dance around, the conditions were generally good. My 5 shot group eggs were 0.75" at 100 and 1.85" at 200. The 10 shot group aggs were naturally bigger at 1.20 and 1.51 moa at the two ranges.  I had my usual trouble with the score match.

The score match requires firing one shot at each of five bulls on the same target card and shooting four cards for a total of 20 shots. Although my groups at 100 yards were clearly smaller than the size of the 1.5" 9 ring of the score target, my score at 100 was 189 out of 200 which isn't terrible for Hunting Rifle Class but three of the shots were 8s and not all out in the same direction. Things were much worse at 200 with shots out in all directions including a miss which requires missing the center by three inches.

I think what is going on is when I move between the five aiming points the position of the rifle on the bags changes enough to change the zero.  I am trying to do most of the moving by adjusting a windage top and a Sinclair "Speed Screw" on my Bald Eagle front rest.

Any comments or suggestions will be appreciated.

John

 

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Ken Campbell Iowa posted this 27 May 2022

you don't have to completely solve the problem ... you only have to solve it better than your shooter buddies ...

*****

in our 22rf ARA shoots, where we shot 25 different bulls ... we wound up making expensive rifle carriages where the rifle never moved in the rest ... we moved the one-piece rest on lead screws..  the idea is to have the vibrations the same at each shot.

we accepted this silliness because it was still a wind ... and pure accuracy  ...  shoot ...  the results were not random ...  

************

so yes, i think progress would entail minimizing all " vibrations " at the shot ...  i became convinced that even where i placed my elbow on the bench changed the vibrations. ...  

*************

an additional concern with shooting at different bulls is that it might change the timing of the shots ...  i found that for 22rf, you need to shoot at least every 30 seconds or risk a " flyer " ...  from uneven barrel condition ...  ( not the same as shooting fast because of trying to beat changing wind conditions ) ...  i tried different lubes on my 22rf, but never found any that changed the effect of varying barrel condition of waiting too long between shots.  i think these " barrel condition " flyers were actually error from a changing " ZERO " , not a random flyer.  all of my 22rf rifles did this, with all brands and lubes.

*********

just some thoughts.

ken

 

 

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Paul Pollard posted this 28 May 2022

John,

Borrow Ken’s rest. That should verify your suspicions.

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GWarden posted this 29 May 2022

John

Just finished up shooting at Iowa's NMLRA territorial matches. Shooting BP cartridge matches at 100 yd. Moving slightly on a target with more than one bull, has always been one of the mysteries how POI can change moving from one to another bull. Been trying to get on top of this for years. 

bobv

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Lucky1 posted this 29 May 2022

This is something I have struggled with since I went to the first Nationals 5 years ago. Asking for expert advice and they told me how to setup and move my rest better and that it comes with experience. So if John is still having issues like this, it kind of lowers my expectations that time will cure it. The one thing that has helped is the discovery of our 308 rifles having alot of sensitivity to cheek pressure on the comb. Now we barely touch the rifle (if at all) and the consistency seems to be better as we change elevations. Plus we have probably learned to set up the rest better with practice. This is certainly a game of nuances.

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Wineman posted this 30 May 2022

When you shoot 10 M air rifle at a target with multiple bulls it's challenging. The natural tendency is to "muscle" the rifle since they are all so close together. What needs to occur is a new NPOA for each and every bull. Just shifting the position is not enough. You need to make every bull it's own target. You have to confirm that with the eyes closed and opened that you are really "on" the bull and you didn't just think you were. On target; close eyes and breathe a couple of times while relaxing; Open eyes and check the NPOA, If it is not perfect, readjust and repeat. Where is the front sight after the shot? Probably where the shot landed. I have found recently that trying to make the best trigger pull is not good. The bullet time in the barrel is so much longer that if I "mash" the trigger, I have less time to move the rifle as the shot is going down range. Again your mileage may vary.

Dave

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Lucky1 posted this 31 May 2022

Thanks Dave. That makes alot of sense technique wise and we were working our way there, but not knowing if it was right or not. Maybe cheek pressure for us was also just enough to knock us out of the the NPOA. As a beginner I was definitely trying to muscle the rifle in more with the subsequent bad results. Back to the range this weekend to put theory into practice.

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Wm Cook posted this 03 June 2022

John,

Since you’re using a Sinclair speed screw I’m guessing you’re dialing horizontal with the lil knob that pushes / pulls the top rest. Are you bag squeezing and if I could ask one more question, what rear bag are you using? Bill Cook.

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Tom Acheson posted this 03 June 2022

John, we both have similar experiences. I always do better in the group events. 

I really can’t comment on “a changing” zero. Only a supposition but as we move the “bench set-up” for each progressive shot on the score target, our control of the gun during recoil changes. If we think we have a good zero, and the wind is minimal, why does the first shot for group end up 2” @ 10:00, we go back to the sighter, good hit inside the 10-ring and then back up to record target and we pause….aim at the center or chase the first errant shot. That’s when the mental fun starts…..and confidence in my “zero” gets questioned.

As a point of interest, when at home after the match, I trace over the hits on the score target and develop a “group”. Never has that group been close to the match groups. Things happen during score….and if I ever discover the solution, I’ll let you know.

Tom

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4060may posted this 03 June 2022

John

I have been shooting the local Groundhog matches at my club.

6 Bull target, 5 score 1 sighter

32-40 BS No.1 Ruger 36X Leupold scope, 200 gr cast,  joystick front rest , heavy bag rear rest

the POI\is driving me bonkers, on the sighter two center hits go for score, every center hold the bullet goes somewhere else, just a test, I shot the target as I would in a match, but did 5 shots per bull, but in order of the match, one shot per bull 5 times around, more times than not I would get 5 groups under 3/4 MOA at 100yds, pretty consistently, but in 5 different locations on the bull

Th 200 yd target is somewhat easier, on sighter, one record bull, figuring the POI and Mirage, on one bull without moving the gun around works better

So my conclusion is, flat bottom front , parallel butt stock, learn what the gun wants as far as hold

and then forget it all at the next match

 

 

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John Alexander posted this 03 June 2022

Bill,

Yes, i am using the horizontal movement knob to move to a new aiming point. I limit bag squeezing to only the final minute adjustment, After recoil, I push the rifle back to the same aim point and then move to the next one by the Speed Screw and horizontal adjustment knob and try to get very close to the next aim point before bag squeezing.  Today I tried making the vertical adjustment with the front rest's vertical adjustment instead of with the Speed Screw.  That seemed to reduce butt movement on rear bag and the results were a bit better -- maybe.  Will shoot more this way and see.

Rear bag is a Protektor with leather rabbit ears and filled to less than rock hard.

John

 

 

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Wm Cook posted this 04 June 2022

You may be right about using the vertical stem for elevation adjustments instead of using the speed screw. It'll be interesting to hear how things workout.

How about this excuse thought.  In group shooting we usually hammer the rig pretty firm into the front and rear bag.  I keep the side plates for the front bag (the plates that can be screwed in tilted into the ears to pinch the stock) as tight as I can get them and still allow a smooth free recoil. 

Even with the ears tight you can get a smooth recoil with Cordura bags or for those with a leather front bag, baby powder.  The purpose for the firm side to side control keeps horizontal or wobbling movement from happening.  This way you have the rifle firmly held so it tracks straight back allowing us to shoulder push the rig back until it makes contact with the front forearm stop for shot 2, 3, etc..  A couple shots after getting the rig bedded allows things to get settled in and we're normally good to go for the first match.  That works for group shooting.

For score shooting that might not be the ticket.  My SWAG is that if the front bag is filled hard with heavy sand and if the ears are pinching the front bag as tight as I would normally want for shooting groups it may cause the forearm to tilt, cock, bind or crawl up the front bag ears whenever large horizontal and vertical adjustments are made. You're disturbing that safe nest your stock had with the bags that otherwise is taken for granted when shooting groups.

Moving a MOA or two for shooting groups you might not notice it.  But when you're adjusting horizontal 6.5" and elevation 14.5" the front bag might not allow you to hold your zero.  You may be right about the stem adjustment versus the speed screw but the next time I'm out I think I'll give the front stem versus speed screw and maybe try giving the front rest a little freedom. 

Did you ever notice how your return to battery is less precise in match 1 compared to later matches?  Probably just me. 

Thanks for starting the thread.  Its a good one.  Bill C. 

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Ken Campbell Iowa posted this 04 June 2022

wm cook :::  you might be on to something.

for multi target competition ... maybe the compromise favors a system where the rifle slides freely (  in our carriage rest systems we allowed the rifle to freely recoil on slick plastic  balls.. then pushed the rifle back against the front stock stop ) ....... rather than a snuggly wuggly captured-in-a-bag system.

consider a pretty good bench system for handguns is a bipod front sliding its feet on a slick plate coated in baby powder ... several 22rf ara shooters used handguns with this system shooting the 50 or 25 bull targets.  recently, Joeb reported here some good testing with his pistol with a similar rest system.

so maybe a sliding rifle would hold zero better resulting in higher multi-target scores but not shoot as good groups .. 

wonder who will be the test rabbit ?? ...  and report his results here ? ...

oh, also consider the surprisingly good results from shooting prone on the 10 bull target ... ...the rifle sees little variance in the shooter's grip .

ken

 

 

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John Alexander posted this 22 June 2022

This morning I went to the range to continue my effort to get my score shooting ability from terrible up to fair. This match requires moving the rifle to shoot one shot at five bulls, and has often been my undoing.

I shot three matches (15 shots) on same CBA target card. I first shot a group on the sighter bull to confirm zero. I then used the speed screw and windage adjustment to move sight to next bull but only after pushing and bag squeezing the rifle back to aim at the bull just fired on.

No mysterious wide eights, no eight eights at all.  Scores were 50, 48, and 49.  This is equivalent a 196 -- good enough to win most aggregates in CBA Production or Hunting Rifle class. 

This is way too few shots to start celebrating that my problem is solved, but at least it is encouraging and will get me back to the range soon to see If I can keep it up. If I had tried to methodically solve this problem forty years ago, I might have some hair left.

John

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Wm Cook posted this 22 June 2022

John just so I understand and can learn from this.

1) After shooting your 5 (guessing 5) shot group on the sighter you were not POA on the sighter bull when you returned to battery after the fifth shot?

2) To adjust POA to the sighter bull after the 5 shot group you pushed and squeezed the rear bag? Not sure what “pushed” means.

3) Once your rear bag was manipulated back so POA was center target bull you then adjusted vertical (speed screw), horizontal (windage adjustment screw) to POA on each of the 5 score bulls?

One pertinent question and one odd one if you’re indulge me.

1) What sequence do you shoot your 5 score bulls.

2) Assuming you were shooting your .223 what was the +/- in .1 grains in bullet weight. Thanks, Bill C.

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John Alexander posted this 23 June 2022

Bill asked: 

" 1) After shooting your 5 (guessing 5) shot group on the sighter you were not POA on the sighter bull when you returned to battery after the fifth shot?

 

2) To adjust POA to the sighter bull after the 5 shot group you pushed and squeezed the rear bag? Not sure what “pushed” means.

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Return to battery would be an overstatement for a six pound rifle with a skinny round stock. I seem to get best results when gripping the rifle hard. So after the shot things are out of whack even for a 223.

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3) Once your rear bag was manipulated back so POA was center target bull you then adjusted vertical (speed screw), horizontal (windage adjustment screw) to POA on each of the 5 score bulls?

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Yes.

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One pertinent question and one odd one if you’re indulge me.

1) What sequence do you shoot your 5 score bulls.

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5, 4, 3, 2, 1, -- One less horizontal  movement, but I doubt that it makes much difference.

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2) Assuming you were shooting your .223 what was the +/- in .1 grains in bullet weight. Thanks, Bill

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I don't know because I never weigh sort bullets except when doing some test or other to see once again that it doesn't improve groups. My last article on this tested Berger 68 grain bullets that varied from light to heavy 1.4% and still shot well. CB shooters that sort bullets 200 grain bullets to 0.1grain are achieving weight variation less than 1/20th of the Bergers. Any decent caster can achieve weight uniformity much better than that box of Burgers -- without sorting by weight.

 

John

 

 

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Wm Cook posted this 27 July 2022

John, it’s been a couple months and I was wondering if you had an update on holding a consistent zero when shooting for score? Thanks, Bill Cook.

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John Alexander posted this 28 July 2022

Bill,

I have tried several more targets but I am still shooting those 8s. So I don't have anything useful to offer, but I haven't given up.

John

 

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RicinYakima posted this 28 July 2022

Ok, been thinking about writing this for awhile, but didn't do it, so here goes. Five shot groups don't mean anything. One target at your home range, shoot a 25 shot group and no called flyers. Calculate your point of impact. Adjust your scope and do another one. That is your real zero, as any five shot groups are just random noise.

When I shot the Nationals at Raton, I listened to the shooters talking about zeroing at that elevation and humidity. So I followed along and changed my scope settings. The CBA Past President shooting next to me never touched his scope settings. He won the Production rifle class. I should have followed his example.

FWIW, Ric

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Bud Hyett posted this 28 July 2022

Like Ric, I reset scope turrets to zero for elevation a decade ago. I had found this to be a constant. The variance was in the seasons, cooler temperatures in Spring and Fall caused a half-minute adjustment. This was with a standard load that was thoroughly tested. 

I also agree that five-shot groups are just random noise. The American Rifleman once used five-consecutive five-shot groups at 100 yards; then reported the smalled, largest and average. I felt this was a good representation. Now, you have to read the fine print in the caption to see number of groups and yardage. 

Farm boy from Illinois, living in the magical Pacific Northwest

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John Alexander posted this 28 July 2022

Good advice, but it isn't the number of shots in the group that matters. For purposes of a solid zero, a string of five shot groups can easily be put together to form a 25 shot group or a 50 shot group, for that matter, by plotting the distances of group centers from aim point.

I have been preaching for a long time that SINGLE  five, three, or even ten shot groups don't mean much.  iIt's shooting enough total shots and using the information correctly. If you do that it doesn't matter how many shots are in each group.

John

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RicinYakima posted this 28 July 2022

I agree, but have never seen anyone at a match bring back targets to calculated centers, they just look through the scope and crank the knobs. 

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John Alexander posted this 29 July 2022

I agree, but I wasn't commenting on what shooters do but what they should do.  I don't think many shoot 25 shot groups to find a zero either but they did they would have a better zero. A shooter should do one or the other if they want a solid zero.

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shootcast posted this 29 July 2022

I don’t have the answer but must lie at the bench approach. The reason I say this we frequently talk about between relays. Some clubs shoot two shots per target before changing them. Very often a miss in one relay will end up with a miss in same location as shot in relay before. No one has figured this out but happens often enough that many have noticed.

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