CHAIRGUN AND JSB 34 GRAINS MK2

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wajie316

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Aug 10, 2017
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Sindh
I am shooting my Royale 500 at 845fps with 34 grains mk2. The gun is zeroed at 37 yards. I have entered the information in my chairgun and sterlok and both are showing almost identical charts. However, the 34 grains are shooting a bit flatter upto 60-100 yards comapred to the chairgun and sterlok table but at longer distances say 110 and beyond the results are quite accurate with chairgun and sterlok. 

Any help will be appreciated. 
 
My BC for 34gr mkii is .0500 with FPS at 830. I shoot a Bobcat, that should be about the same barrel. Zero at 50y and your first zero will be 19-20y. I use chairgun pro and out to 100y all is dead on. A note to remember concerning different BC calculators is they use different algorithms, my bro shoots same gun set up same way as mine and uses a BC of .0600 with Strelok and he is also spot on to 100y. Nothing like creating confusion. 
 
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Chairgun uses either g1 or ga drag profiles where as sterlok+ uses only G1. GA profile is specifically for diablo pellets. Therefore that explains the difference between the two and why you need to manipulate your bc when changing from chairgun to sterlok+ unless you are using g1 profiles on both. I simply just keep modifying my bc in sterlok+ until I get the same drop at both close distance (25 y) and long distance (100 y) as I would in chairgun and all works out well for me. Good luck.

-Matt
 
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For my Chairgun Program I use the velocity method of shooting over a chronograph at the gun, and then shoot over another chronograph at 50 yards. Then I put these numbers into a ballistic calculator program to determine the true BC of my 34 grain pellets here at sea level. ( http://www.jbmballistics.com/cgi-bin/jbmbcv-5.1.cgi ) Once you determine your true BC and plug this into Chairgun do a preliminary printout showing each yard...these numbers will be in the ballpark but not exact. Then shoot at targets at a half dozen different distances and record the data. Then compare this data to the preliminary table you printed out. Then go back on your computer to Chairgun and tweak the numbers on the table to match the numbers you got in reality while shooting at different distances. I tweak the numbers on the ballistic table to match reality by toggling the "Scope Height" up or down as necessary until the numbers on the table match. 

To let you know how well this works let me tell you guys about a recent trip to the range with my .25 Wildcat. Since I now have a regulator that is totally consistent I did everything I described above and went to the 100 yard rifle range. (My Wildcat is currently set up to shoot the 34 grain JSB pellets at an average velocity of 850 ft/s, and my scope is zeroed at 50 yards.) While waiting for a cold range to put out a target frame, I used my Athlon Midas rangefinder to range a white rock on the hill that was about the size of my fist. I ranged it at 117 yards...my Chairgun Pro ballistics table printout said I needed to holdover 70 clicks...so I dialed in 70 clicks elevation and put the crosshairs on the white rock....when I pulled the trigger the white rock disintegrated right before my eyes! Perfect! 

Then I put out a target frame out at 75 yards...my printout says 21 clicks holdover...I put 21 clicks elevation on my scope and Bingo! dead on point of aim! Same for 100 yards...my little printout called for 48 clicks holdover and Bingo! dead on again! So then I ranged a white piece of styrofoam from a cartridge box up on the top of the hill at 130 yards...the printout says holdover 88 clicks...I put the crosshairs on the styrofoam and hit it eight times in a row!

And that my friends is why I went to all the trouble of convincing Huub Andriessen to make me a regulator for my Wildcat that gives me the same average velocity each and every time I pick up my rifle to shoot it. It used to drive me crazy when my Chairgun Pro ballistics table printout stopped matching reality because my old regulator kept fluctuating up and down all the time. For me personally this was completely unacceptable...I have spent a lot of time and money and work on my Wildcat and Streamline to get both of my rifles to shoot not just accurately, but super consistent so that they both exactly match in reality the wonderful Chairgun Pro ballistic tables. For me it is like winning the Lottery to put the crosshairs on a target using the ballistic table to predict the amount of clicks necessary for holdover, and then when I pull the trigger hit precisely dead on!
Here are a couple pics of the little range card I made using Chairgun Pro: Good luck making your range cards with Chairgun guys! :)


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Thanks Glem.Chally...if you like the ballistics table for my .25 Wildcat you are going to love the one for my .25 Streamline! Now you see one reason why I feel .25 cals. shooting 34 grain pellets are far superior to .22 when you consider that my rifles have more energy left at 100 yards than most .22 cals. have at the muzzle. And my Streamline has a power adjustment wheel to lower the power one to two steps lower if required. Very versatile, lights out accurate, and far less affected by the wind than .22 cal. For me it isn't about buying an expensive rifle and hoping it lives up to expectations...for example I would prefer to buy an inexpensive violin from a pawn shop and tune it and tweak it until it plays like a Stradivarius. For me at least half the fun is getting my two rifles to do what I want them to do. Check out the ballistics table for my Streamline...and remember at this velocity it is giving me 1/2" groups at 75 yards and 1" groups at 100 right now. :) 
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Very impressive. Those range cards look very similar to my .30 Bobcat shooting the 44.75 grain JSB Exacts at 880 fps. My zero is at 50, and my drop at 100 yards is approx. 13 inches also. Good downrange energy, and your ammo costs 1/2 of mine! ;) I think the 50.1 grain shooting at 845 fps has almost the same drop with a 50 yard zero, so its BC is somewhat better than the .30 cal. 44.75 or the .25 cal. 34 grain. I know how much time and effort it takes to get that range card just perfect, very nice work Chuck! Thanks for posting...
Mike
 
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Thanks for the vote of confidence you guys... For the last couple years I have struggled mightily to get my rifles to stay consistent, so that whenever I pick up one all I have to do is range a Target with my range finder, glance at my range card, quickly dial in the clicks of elevation, put the crosshairs on the Target and pull the trigger! And have confidence in the fact that I'm going to hit what I'm aiming at this time and every time in the future! At this point I am golden! But I know there's a whole heck of a lot of guys out there that would like to be golden too, so I hope everything I've described above helps them. I tested everything up one side and down the other before I posted anything about it, for fear of leading someone astray. Right now I am as happy as a lark singing in a tree on a sunny summer day...
All the best, Chuck
 
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If you have adjustable scope rings, it could be the reason for the slight difference. With FX no-limits, they cause the scope to angle down compared to the rail/barrel. I believe that this is an adjustment that could tweak the charts for the same reason high scope mount flatten the pellets fight path at loner distances.
Click to expand...
 
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