Hello, I am new to reloading and don't have a chronograph. I was wondering if there was some way of estimating muzzle velocity based on powder, barrel length, twist, bullet, etc. I know it's probably a long shot, but I don't feel like spending the money on a chrony, mostly because velocity isn't a huge deal to me (reloading for varminting, nothing crazy either like 800 yard shots). I just thought it would be cool to compare published data to my own, even if it isn't 100% accurate.
Finding muzzle velocity without chronograph?
- Thread starter KyleWoods
- Start date
You can use Quicklaod for a SWAG but that will be as much as a chronograph if you buy it. Really $100.00 isn't much in the scheme of things when you can use it for a lifetime.
Or go shoot your load at various ranges say 50, 100 and 200 and them reverse engineer the speed based on bullet drop assuming., big assume, you have a true BC on the bullet you are shooting.
Greg
Or go shoot your load at various ranges say 50, 100 and 200 and them reverse engineer the speed based on bullet drop assuming., big assume, you have a true BC on the bullet you are shooting.
Greg
ninehorses
New member
It is not that hard. Get a good dead nuts zero at 100, then move out to 200. Measure the drop, play with the velocity numbers on a ballistic app until it fits. You will need the BC of the bullet, and a no wind day. Would be better to stretch out to longer distances and repeat.
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Hornady has a 4dof ballistic program that may be a tad more accurate, 4DOF, for reverse-eng approach.
Down side is they only have limited data on projectiles, heavy long range types.
They use empirical drag curves in place of BC, based on each bullet from several barrel types.
Good instruction info too.
Down side is they only have limited data on projectiles, heavy long range types.
They use empirical drag curves in place of BC, based on each bullet from several barrel types.
Good instruction info too.
Varminterror
New member
Just buy the chronograph. If you're an engineer, you make enough to buy one, because you should also be smart enough to not have over extended your way of living beyond your means, and dropping $100-200 on a chrony isn't $hit in the scheme of things.
I'm an engineer too, used to work in munitions development even. First - velocity doesn't mean $hit. Go shoot at range in different conditions, that is all you need. Second, even with velocity, as mentioned above, the published BC's are generally bogus, so you still can't rely upon published data to make shots at range without DOPE. If you shoot without a chrony, you have an undefined system - the velocity AND BC are unknown. Can't solve it without making some BS assumption for one or the other.
I'm an engineer too, used to work in munitions development even. First - velocity doesn't mean $hit. Go shoot at range in different conditions, that is all you need. Second, even with velocity, as mentioned above, the published BC's are generally bogus, so you still can't rely upon published data to make shots at range without DOPE. If you shoot without a chrony, you have an undefined system - the velocity AND BC are unknown. Can't solve it without making some BS assumption for one or the other.
Originally Posted By: KyleWoods...some way of estimating muzzle velocity based on powder,.(etc)..
Eng-2-Eng,, TMI,,, here's how I take a swag at a new load, given powder, projectile, barrel length:
Green #s are simple arbitrary inputs of intermediate trial powder loads.
The red# (-120,) is an input taken from Berger manual 1st ed.
the red#s (46.6, 49.0) are inputs, taken from Hodgdon www.
The red#s (2542, 2708) are results of fps plus barrel length adjustment, fps inputs taken from same www site.
Slope is calculated from line 45 and line 39.
FPS #s in black are linear interpolation using Slope.
Certainly not a true linear relation, but easy and useful anyway.
www site didn't have the 168 amax so chose 168 SIE HPBT as a substitute.
These intermediate FPS are based on www site data, which has been amazingly close on a few earlier examples.
Have a chronograph and use it to confirm FPS, but do a lot of testing using method above and looking for accuracy nodes, w/o chrony.
Normal caution applies about working up toward a max load.
Eng-2-Eng,, TMI,,, here's how I take a swag at a new load, given powder, projectile, barrel length:
Green #s are simple arbitrary inputs of intermediate trial powder loads.
The red# (-120,) is an input taken from Berger manual 1st ed.
the red#s (46.6, 49.0) are inputs, taken from Hodgdon www.
The red#s (2542, 2708) are results of fps plus barrel length adjustment, fps inputs taken from same www site.
Slope is calculated from line 45 and line 39.
FPS #s in black are linear interpolation using Slope.
Certainly not a true linear relation, but easy and useful anyway.
www site didn't have the 168 amax so chose 168 SIE HPBT as a substitute.
These intermediate FPS are based on www site data, which has been amazingly close on a few earlier examples.
Have a chronograph and use it to confirm FPS, but do a lot of testing using method above and looking for accuracy nodes, w/o chrony.
Normal caution applies about working up toward a max load.
DannoBoone
Active member
Originally Posted By: newmexkidI would just buy the MangetoSpeed Sporter and be done with it.
^^^^^^^^
THIS!! Simple, even for engineers who like to over-complicate
everything!
^^^^^^^^
THIS!! Simple, even for engineers who like to over-complicate
everything!
Originally Posted By: VarminterrorJust buy the chronograph. If you're an engineer, you make enough to buy one, because you should also be smart enough to not have over extended your way of living beyond your means, and dropping $100-200 on a chrony isn't $hit in the scheme of things.
I'm an engineer too, used to work in munitions development even. First - velocity doesn't mean $hit. Go shoot at range in different conditions, that is all you need. Second, even with velocity, as mentioned above, the published BC's are generally bogus, so you still can't rely upon published data to make shots at range without DOPE. If you shoot without a chrony, you have an undefined system - the velocity AND BC are unknown. Can't solve it without making some BS assumption for one or the other.
Amen to that! (I'm also an engineer, and I wouldn't dream of trying to reverse engineer a velocity. Too imprecise.)
I'm an engineer too, used to work in munitions development even. First - velocity doesn't mean $hit. Go shoot at range in different conditions, that is all you need. Second, even with velocity, as mentioned above, the published BC's are generally bogus, so you still can't rely upon published data to make shots at range without DOPE. If you shoot without a chrony, you have an undefined system - the velocity AND BC are unknown. Can't solve it without making some BS assumption for one or the other.
Amen to that! (I'm also an engineer, and I wouldn't dream of trying to reverse engineer a velocity. Too imprecise.)