Ballistics calculators and MV

[BP72]

I'm working up a load with 2208 and 69gr nosler CC's for my 22-250 with 1-8 twist barrel 28" long. I found 32.2gr is very consistent it's over max but no pressure signs so all good. My question relates to validating MV in both strelok+ and shooter in the ipad. The rifle is zeroed at 200 yards and shots 16.5 inches or 43cm low at 400 yards, both distances are measured with GPS so they should be ok . My quandary is strelok gives me 3366fps ( on android phone) and shooter says 3260 fps which one do I use as I don't have a chrony?

[Dave001]

Just chucked all that info into QuickLOAD, and it gives 3300fps.

If you put all the data into PointBlank it will get you closer to the actual figure.

I can do it for you if you'd like, but I'd need the sight height, altitude and temp.

[BP72]

Thanks for that dave001 , altitude 328 ft, sight 1.9" , temp 20 deg C

[Dave001]

200 yard zero, with a 16.5 inch drop at 400 yards, gives a muzzle velocity of 3405fps.

[BP72]

Thanks for that dave001 , that's cranking ! Can't wait to splat a few foxes with them

[jeffk]

Thanks for that dave001 , that's cranking ! Can't wait to splat a few foxes with them

In all honesty, without the actual MV (and even if you had it) check where it shoots compared to the ballistic calc at a few intermediate ranges before you go after foxes! The calculated 500m drop from a 100m zero on my Fly gun is sufficiently different to the real one for it to easily be a miss on a live animal.

[Brad Y]

Thats the best way, set up targets at 100, 200 and 300. Zero 200 and know holds for the other two. You will be about an inch high at 100m and around the 4 inches low at 300m depending on scope height.

[mick_762]

Thats the best way, set up targets at 100, 200 and 300. Zero 200 and know holds for the other two.

Defintely the best way to do this. I have done it with all of my hunting rifles.

Zero at a known range, and test your loads

[andrewk]

the most accurate drop card I've ever done is shoot a 500m target and zero then count clicks back to 100m and record MOA. Fudge figures in JBM ballistics calculator until the drop matches and its been super accurate out to 1000yds. chrony and calculated MV don't come close to each other.

[Brad Y]

I reckon that also is because alot of the time we only have G1 BC figures to work with. And I dont think many G1 figures are that accurate. A combination of different BC and different muzzle velocity from chronies to actual works against you alot of the time

[jeffk]

I reckon that also is because alot of the time we only have G1 BC figures to work with. And I dont think many G1 figures are that accurate. A combination of different BC and different muzzle velocity from chronies to actual works against you alot of the time

Brian Litz's book gives measured G1 & G7 BC's...IF he's tested the bullets you want to use. The Dyer was in there though, which was great!

Either way, you're best shooting it once and truing your ballistic app to the real world results for future use.

[Brad Y]

Yes but the dyer HBC has changed a bit since the lot I gave you. They are now a bit shorter and different measurements overall as he broke his dies and had to get new ones done. Consistency isnt great with their bullets at the moment from what I hear- mind you havent shot any 308 for ages.

[jeffk]

Yes but the dyer HBC has changed a bit since the lot I gave you. They are now a bit shorter and different measurements overall as he broke his dies and had to get new ones done. Consistency isnt great with their bullets at the moment from what I hear- mind you havent shot any 308 for ages.

I'm on a new batch since then, bought a while back, and they seem OK. However, I'm only shooting at 500m with that gun, so just zero and adjust for conditions against the splash plate when needed. Don't need a ballistic app.

My point was more that unless you have a measured BC (For the velocity you're shooting at) and known MV, you're going to be truing up against actual results if you're shooting at any kind of distance.

[MISSED]

Yes but the dyer HBC has changed a bit since the lot I gave you. They are now a bit shorter and different measurements overall as he broke his dies and had to get new ones done. Consistency isnt great with their bullets at the moment from what I hear- mind you havent shot any 308 for ages.

I'm on a new batch since then, bought a while back, and they seem OK. However, I'm only shooting at 500m with that gun, so just zero and adjust for conditions against the splash plate when needed. Don't need a ballistic app.

My point was more that unless you have a measured BC (For the velocity you're shooting at) and known MV, you're going to be truing up against actual results if you're shooting at any kind of distance.

That makes a lot of sense Jeff as BC changes with the launch velocity.

[BP72]

They seem to work pretty well, six from six was the score last night, from around 100-300 yards