FX Trajectory turmoil

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TC724

TC724

Member
Nov 26, 2021
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New Castle PA, United States
Video is having issues so I’ll explain here I hope.

-Shooting JSB 18s out of my Crown.
-I shot shot strings and confirmed my average fps at 870.
-Put my chrono at 50y and got my own BC.
-Went to check my dope (in Chairgun) and it was telling me a 1mil drop at 50y at 12X with my AMX reticle.
Here is where it gets confusing…
-I shot a 5 shot group at 50y and they all landed at “Half” mil dot at 50y.
I assumed my BC was off so I retried it 3 times, and triple checked my velocity as well.
-Once I confirmed all my data was correct, I did a trajectory validation on Chairgun. This told me for me to have a “half” mil drop at 50y my muzzle velocity needed to be 933fps.
-At this point I figured screw it let’s try it at 933 for the app and I’ll see what it says to hold for 75y.
- So it told me to hold 2.5mil at 75y and it was dead on…

So I’m perplexed other then maybe double checking my scope height on how I would come up with this data. I have to be missing something I’m sure someone will point out…

PS: I did double check my distances were accurate as well
UPDATE: Scope height is accurate.
-Now looking to assume my distances may be off?
 
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Hey TC, with us field target guys, using chairgun for example, we zero the gun at whatever range, and since we shoot as close as 10 yards and as far away as 55, we shoot at 10 yards yards and see how many clicks it takes of the elevation wheel to hit the 10 yard zero. We then go back to the main page of chairgun and in the scope height, we raise and lower it to match the number of clicks it took for 10 yards. We then shoot 55 yards and see how many clicks it takes to match the 55 yard shots. We then change the BC to match the 55 yards numbers, but you have to go back and forth because when you change the BC alot it will change the number of clicks for 10 yards in their algorhythm. We have to go back and forth until the numbers match or are close enough, that the distances for 10 and 55 are good, then hope the in between numbers work. Even then when checking the in between distances sometimes are close and sometimes not. I also shoot hold over with UKHFT and 12x with my Hawke AMX, and what chair gun said, it was close on some but not even close on the longer distances. For example CG said 8 yards was 4 MD and was actually 3, MD and 40 yds was 1/2 MD and 45 was 1 MD. However it actually shoots 40 at ,75 MD and 45 at 1.25 MD. So in cases where CG just isnt right, I just shoot it and go with my numbers. Welcome to the world of chasing your tail...haha
 
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elh0102 said:
I guess I don't get the whole Chairgun thing. If you practice to know your holds at the relevant distances, why bother with it? Just shoot your rifle.
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Well thats the issue, I rely on Chairgun for my holds because I do a lot of shots at varying angles which greatly affects the POI, especially further out. I can get my dope for the basic stuff the old fashion way but it still leaves me with partial data.
 
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BC said:
Hey TC, with us field target guys, using chairgun for example, we zero the gun at whatever range, and since we shoot as close as 10 yards and as far away as 55, we shoot at 10 yards yards and see how many clicks it takes of the elevation wheel to hit the 10 yard zero. We then go back to the main page of chairgun and in the scope height, we raise and lower it to match the number of clicks it took for 10 yards. We then shoot 55 yards and see how many clicks it takes to match the 55 yard shots. We then change the BC to match the 55 yards numbers, but you have to go back and forth because when you change the BC alot it will change the number of clicks for 10 yards in their algorhythm. We have to go back and forth until the numbers match or are close enough, that the distances for 10 and 55 are good, then hope the in between numbers work. Even then when checking the in between distances sometimes are close and sometimes not. I also shoot hold over with UKHFT and 12x with my Hawke AMX, and what chair gun said, it was close on some but not even close on the longer distances. For example CG said 8 yards was 4 MD and was actually 3, MD and 40 yds was 1/2 MD and 45 was 1 MD. However it actually shoots 40 at ,75 MD and 45 at 1.25 MD. So in cases where CG just isnt right, I just shoot it and go with my numbers. Welcome to the world of chasing your tail...haha
Click to expand...
Lol! I guess when I used to have the Strelok Pro app, I never had this issue and it seemed to be very accurate...I can't imagine the math or formulas could be wrong because then the app itself would be useless, especially for guys shooting powder burners at great distances, but I get your point. I am going to double check my scope height and be sure its accurate, I think thats the next best logical step.
 
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elh0102 said:
I guess I don't get the whole Chairgun thing. If you practice to know your holds at the relevant distances, why bother with it? Just shoot your rifle.
Click to expand...


chairgun is a wonderful tool,
hawke should bring back support for it.

i use it every day,
and every time i go pesting or to the range.

once setup properly i can range my target animal/target,
slide the slider to that yardage,
and it shows me exactly where i need to hold.

or,when setting up a new gun,
ill chrono it and put the numbers into chairgun.

and since i only have 12 yards in my yard,
i can tell chairgun im going to zero at 50yds,
and it will show me where the pellet should be hitting at my 12yds,
i can then sight in till the pellets hits where chairgun says it should at 12yds,
then im very close to zero when i actually go sight in at 50yds.

IMO invaluable!


4k+ dead pigeons dont lie lol
 
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I can't say that your experience is the exception, but neither does it seem to be universal. Best I can tell, experience varies a great deal with such products. I suppose, as with most things, it's a matter of understanding it and using it correctly. My shooting is mostly under 50 yards, and with a little practice at interim distances, I'm comfortable with my hold points, and it has always worked well for me. The technology-based tools are interesting, and I think they appeal to folks who have a greater appreciation for such things. I can honestly say, I don't believe I've ever missed, or badly hit a squirrel due to a trajectory miscalculation. The challenge for me is ranging, since knowing trajectory doesn't help if you assume the wrong distance!
 
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elh0102 said:
I can't say that your experience is the exception, but neither does it seem to be universal. Best I can tell, experience varies a great deal with such products. I suppose, as with most things, it's a matter of understanding it and using it correctly. My shooting is mostly under 50 yards, and with a little practice at interim distances, I'm comfortable with my hold points, and it has always worked well for me. The technology-based tools are interesting, and I think they appeal to folks who have a greater appreciation for such things. I can honestly say, I don't believe I've ever missed, or badly hit a squirrel due to a trajectory miscalculation. The challenge for me is ranging, since knowing trajectory doesn't help if you assume the wrong distance!
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agreed, ranging by eye takes lots of practice,

i used to be very good at eyeballing ranges when i was heavy into 3d archery.

but when pesting or hunting,or even just sighting in, a rangefinder is invaluable
 
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starlingassn said:
agreed, ranging by eye takes lots of practice,

i used to be very good at eyeballing ranges when i was heavy into 3d archery.

but when pesting or hunting,or even just sighting in, a rangefinder is invaluable
Click to expand...
Yep, when I'm hunting I always have both binoculars and a rangefinder. I usually stay in one place at least 30 minutes, sometimes much longer, so I can range a few benchmark trees or rocks, and then I'm reasonably confident of my holds. Of course, a squirrel in the top of a tree needs some additional assessment.
 
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Update: I have now double checked everything including scope height, bullet profile, muzzle velocity….everything.

At 10 yards it’s telling me to hold 2.5mils, in reality I hit 1mil low at 10 yards.

* I am asking for someone to input my data (I will send in message) to their strelok or whatever they use to see if it gives them the proper solution. I can’t think of any other way to figure this out
 
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