22lr Trajectory validation

Evening all, I’m after a bit of advice on 22lr Trajectory validation.

Assuming you’ve got accurate data on MV (ie. Chrono), would you start tweaking the BC or still adjust the MV.

I’ve only had a little play with this so far, zeroed at 50m and then Trajectory validation at 100m. After I input the correction into Chairgun elite app, it was suggesting to drop MV from 1062 to around 1030 (which I was reluctant to do since I have since I have good chrono data) or adjust BC from 0.12 to 0.8 ( which I thought sounded a bit excessive).

I’ve also heard of people running several different rifle profiles for the same gun to get correct data at longer ranges, but wanted to play around with seeing what I can do with just 1 to start with

A lot depends on the number of rounds you are basing your velocity and zero on. Before tweaking BC I'd be wanting at least a 20 shot zero ( analyzed using something like Ballistic X) and a like velocity sample (more if it has a wide ES) 50 rounds would be better for both. Brian Litz recently commented that 50M was probably the optimum zero distance for 22LR (I always thought further would be better).

Hornady Podcast #50 is a game changing analysis of this sort of thing.

For CCI SV Hollow point and solid nose I’m using these values to 250 yards and they are spot on in three different rifles for well over 8,000 rounds

1070fps

40 g projectile

G1 Bc of .150

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Originally Posted by Tentman

A lot depends on the number of rounds you are basing your velocity and zero on. Before tweaking BC I'd be wanting at least a 20 shot zero ( analyzed using something like Ballistic X) and a like velocity sample (more if it has a wide ES) 50 rounds would be better for both. Brian Litz recently commented that 50M was probably the optimum zero distance for 22LR (I always thought further would be better).

Hornady Podcast #50 is a game changing analysis of this sort of thing.

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Thanks mate, I’ll give that a listen.
I’ve put about 200 rounds of CCI Standard over the chrono over 5-6 sessions, all averaging around the same for MV, SD is 12-15, and ES 45-50 (not sure if that’s considered wide or not…)

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Originally Posted by 7mmsaum

For CCI SV Hollow point and solid nose I’m using these values to 250 yards and they are spot on in three different rifles for well over 8,000 rounds

1070fps

40 g projectile

G1 Bc of .150

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Thanks mate, I might run those numbers next time I’m out and see how they go for me

@John P does your app have different BC values for the drop in velocity the further the bullet goes?
As the BC will be dropping.

I've been also testing real world bullet drop now after finding out the hard way.

Quote:

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Originally Posted by 7mmsaum

For CCI SV Hollow point and solid nose I’m using these values to 250 yards and they are spot on in three different rifles for well over 8,000 rounds

1070fps

40 g projectile

G1 Bc of .150

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I put those values into Strelok last time I prepping for rimfire comp. Shot out to 100, 200, 300 metres all correct data. No adjustments necessary.

I would shoot it at 200m as well and see how the drop lines up with the 1030fps mv.
I adjusted the mv of the Norma tac 22 to 1045 to get mine to line up.
Also check your environmental inputs to make sure they line up with actual temperatures and humidity

Dont know if this is any use to you but when shooting silhouettes with subsonic ammo the sight settings are
40m zero (chicken)
60m(pig) 2.5moa
77m (turkey) 4.5 moa
100m (ram) 9.0moa
Thats pretty much spot on for most 22s at those ranges.
Might be of use?

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Originally Posted by dogmatix

@John P does your app have different BC values for the drop in velocity the further the bullet goes?
As the BC will be dropping.

I've been also testing real world bullet drop now after finding out the hard way.

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Yes it does, no option to enter the distance though, just velocity, i assume you would have to true up the data for a given distance, then look at the drop chart to get the velocity for that distance?

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Originally Posted by John P

Yes it does, no option to enter the distance though, just velocity, i assume you would have to true up the data for a given distance, then look at the drop chart to get the velocity for that distance?

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Some ammo makers will have the different BC values for their .22 ammo for the velocity.
Yeah, its a pain without knowing.
Hence I now always do a real world drop check.

Been reading recently that RA4 is the ballistic model to use in apps like Strelok, as it is designed for heeled bullets.

Problem is nobody publishes RA4 BC's so you have to approximate and then true up. In theory should be a bit more accurate once done though.

I like to get real world drop data every 50m out to 250, plus chrono data for the same day. I then tweak BC and or velocity as needed to match up all the points. With Shooter app for example, you can have multiple BC entries for different velocity ranges. Doing this you are essentially creating a custom drag curve through trial and error.