Is someone with Quickload able to give me a MV estimate for my 308 shooting 165gn Nosler BTs.
Tikka T3 chopped to 16". Load is 43gns of AR2208. Not sure what other info is needed but let me know if you can help.
Thanks.
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Is someone with Quickload able to give me a MV estimate for my 308 shooting 165gn Nosler BTs.
Tikka T3 chopped to 16". Load is 43gns of AR2208. Not sure what other info is needed but let me know if you can help.
Thanks.
Need your case capacity in grains of water and OAL to be more accurate.
At a stab in the dark I used default case capacity of 56.0Gr and 2.8 OAL and it comes to 2430 fps (would be 2662 in a 24")
OAL is 2.800 inches. Is case capacity a simple matter of filling it with water and weighing the water?
Weigh a fired case with primer in, then fill with water weigh again. take empty weight from full weight should be 56Gr or more.
77gns water.
Thats a bit much for a 308 should be in the high 50'sQuote:
Originally Posted by Shearer
I edited my first post and put a estimated speed on there, but Quickload seems to under estimate speed with 2208 and short barrels in my experience best to chrony it if you can.
Sorry. Typo. 57 gns water (not 77).
Thanks for that. Just wanted a good estimate before I go out and verify it at distance.
Hypothetical question here.
If, when verifying drop of a load, you discover it is different from what is expected (using measured MV and published BC) would you alter the MV or the BC to get the correct trajectory? Or does it matter which you change?
I alter mv
MV, not BC (assuming you've got a realistic one for the pill you're using, some are "exaggerated".) Litz has publised some good data on real world BC's.
But its also likely that your scope may not exactly move in moa (or mils if its metric) as the graduations say. So the error in drop vs dialed might be MV but could also be scope calibration. A lot of "moa" scopes dial "IPHY" (inch per hundred yards) or less, rather than "moa" 1.05 in per hundred yards. You can calibrate your scope dial up by placing a box with inch graduations (10 - 12 inches) at exactly 100 yards (from turret to box) with the rifle held in a fixed, stable position then dial up 10 moa and measure where your POA shifts to. If it shifts down 10 inches exactly then its dialing IPHY. If its moving 10.5 inches then its moving MOA. Some maybe be less than IPHY. Either way you can derive a correction or calibration factor. If your intended shooting range is > 500 yrds then calibration probably not a big factor.
Thanks for that. 500 yards would be an absolute max for me and that rifle. Scope is a VX5 so I assume calibration will be IPHY, not true MOA.
Is Litz's data available on line?
Yip definitely adjust velocity. Bryan Litz has the 165 NBT BC at 0.444 G1 and 0.227 G7.Quote:
Thanks for that. 500 yards would be an absolute max for me and that rifle. Scope is a VX5 so I assume calibration will be IPHY, not true MOA.
Is Litz's data available on line?
Nosler usually have over estimated BC's taken close to the muzzle.
The cheapest way to get access to Litz's data is you by the Applied Ballistics app
If you google Brian Litz BC data there’s quite a bit of info available on line, some of the older data has been updated based on more studies
Thanks, that's excellent info.Quote:
Originally Posted by winaa
Is there a reason to adjust the MV as opposed to BC or is it just the done thing? If the published BCs are wrong anyway would it make a difference to the trajectory outcome adjusting the BC? (not that I care which one I adjust, if I have to, just trying to understand the process).
Interesting. I have always adjusted the bc to get my real world data and app data to match when shooting at distance (600mtrs max)
Can someone please explain why you would adjust mv especially if youve chronyed and its accurate? Bc seems to be the easier one, no?
You can borrow my Magnetospeed to get you true MV if that’s useful to you. Then you can tinker with BC to match your verified drops.Quote:
Originally Posted by Shearer
Short answer:- Because Bryan Litz says so!Quote:
Thanks, that's excellent info.
Is there a reason to adjust the MV as opposed to BC or is it just the done thing? If the published BCs are wrong anyway would it make a difference to the trajectory outcome adjusting the BC? (not that I care which one I adjust, if I have to, just trying to understand the process).
Slightly longer and more informative answer:- The team at applied ballistics found while doing testing with very expensive and "Lab calibrated gear" that you get best results truing the velocity first and then do a second truing of BC past the subsonic range if you intend to shoot that far.
For the average hunter shooting inside 500, you could true either and get good results.
the reason I suggested Muzzle velocity for you is Quickload is only a stab in the dark and the Ltiz BC I gave you will be much more accurate, (True the least known factor)
So if I had a speed form a loading manual and a factory BC I would true Speed
If I had a Chronographed Speed and a BC from bullet manufacturer I would true BC first.
If I had a Chronographed Speed and a tested BC I would true speed.
Remember BC sell bullets, so never trust a manufacturers data
https://www.youtube.com/watch?v=CdDEVYGYs3o&t=0s
Also there is nothing with truing twice if you want to get real accurate. So in your case true your speed at around 300 or so then try shoot another 100-200 past that and see if things still line up, if they don't true the BC.
Awesome. That makes senseQuote:
Originally Posted by winaa
Cheers.
excellent explanation @winaa
Thanks I'm glad it made sense.Quote:
Originally Posted by chainsaw
@Shearer let us know what speed truing gives you, I'm picking in the low 2500fps. I always like to see how close quickload gets, I tends to under estimate speed with 2208 in my 7mm08.
Will do. Not sure how long it will take me to get around to it though.:)Quote:
Originally Posted by winaa