Adjust muzzle velocity for powder temperature..

[one shot ST]

The following has been copied from a tip in the ballistic software Precision shooter workbench 4.. "In general, muzzle velocity will increase with increasing powder temperature and decrease as the powder temperature decreases. The "per degree" change of velocity depends upon a number of factors, the calculation of which is beyond the scope of this program and the user is advised to consult an internal ballistics program for this information. (The user is directed to the powder manufacturer for specific powder specifications. Alternatively, QuickLoad (tm), for example, can help the user make these determinations.) Suffice it to say that powders that are relatively temperature insensative may have muzzle velocity increases of only 1 fps per degree or so while other more sensative powders may have muzzle velocity changes of 2 or 3 fps (or more) per degree change. The user may experiment with his powder of choice."

My question is... somebody could you help me how I can find information about the performance of the powders ?

For example if my value is 775 m/s vith Vithavuori N550, 175 grains sierra match with 25 C°...... if I'll shot the same reload with a different temperature how is the change rate to put in the calculation to get the new muzzle velocity ?

thanks

 

[MitchAlsup]

Re: Adjust muzzle velocity for powder temperature..

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: davide</div><div class="ubbcode-body">My question is... somebody could you help me how I can find information about the performance of the powders ?

For example if my value is 775 m/s vith Vithavuori N550, 175 grains sierra match with 25 C°...... if I'll shot the same reload with a different temperature how is the change rate to put in the calculation to get the new muzzle velocity ?</div></div>

That person is YOU.

Start keeping a shooting log. Record the date, time, and atmospheric conditions. On your reloading log you will have already recorded the reloading data. After a number of trips, you will begin to get a handle on the change in performance with respect to temperature and number of the shot. Its sort of like hunting for the Clean Cold Bore PoI difference from the gun-warmed-up PoI.

That data will only really be of value to you and for that exact gun and load. This is due to the myriad of effects that take place between the break of the trigger and the bullet leaving the muzzle a few milliseconds later.

 

[one shot ST]

Re: Adjust muzzle velocity for powder temperature..

thanks for replay, your procedure is what I do daily.. My question was only done to take info about the software request..

thanks

ciao

 

[Lindy]

Re: Adjust muzzle velocity for powder temperature..

The way to find out what the change in muzzle velocity is with respect to temperature is to chronograph your load at different temperatures. I chronographed mine at about 35 degrees, and again at 95 degrees F., as well as at a temperature in between.

It's not only powder performance which matters, but primer performance as well.

 

[one shot ST]

Re: Adjust muzzle velocity for powder temperature..

Thank, I'll do that next step...