TAC & Temp Sensitivity (Input Needed)

Posted by: Tonester

TAC & Temp Sensitivity (Input Needed) - 07/13/21 09:15 AM

I have a question for those of you who use TAC.

I figured out that TAC is temp sensitive through testing, shooting, and hunting over the last two years.

Here is my .223/556 load:

Below 60 degrees: 24.1 gr TAC + 68bthp.

Above 60 degrees: 23.5gr TAC + 68bthp.

The hotter it gets, the more the 23.5 gr load tightens up.

Now, I just found a .223 load for a 55gr Vmax that is 23.8 gr. I tested it at 79 degrees. It will be months before I can find myself in less than 60 degree weather.

Based on the data above, is 6/10ths of a grain the rule of thumb for adjusting my winter/summer loads?

Any sound input is appreciated.

Posted by: reb8600

Re: TAC & Temp Sensitivity (Input Needed) - 07/13/21 12:52 PM

With reloading there is no rule of thumb. You change any component including the gun and everything changes. Even a different lot number on your components. Only way to know is to test it. One persons results probably will be different for you.
Posted by: muskrat30

Re: TAC & Temp Sensitivity (Input Needed) - 07/13/21 09:50 PM

I like TAC, went through a fair amount. I never tried to test temp sensitivity to the levels you mentioned. There should be some net reviews on how it does.

Two powders I bought somewhat after TAC are Exterminator and 8208, similar speeds, Exterminator has the faster burn rate. Iím often loading lighter bullets in the 223, though there are other uses.
Posted by: Coyote-conquest

Re: TAC & Temp Sensitivity (Input Needed) - 07/16/21 10:58 AM

Ive always been a big fan of TAC. I had a good hot load at almost Western Powders max @27 gr. It shot really well last spring or maybe the spring before. I shot it again a month or so ago when it was in the 90s. The group went to crap. Ill have to experiment a little more in different temps but I'm fairly confident the temps were the reason.
Posted by: Kino M

Re: TAC & Temp Sensitivity (Input Needed) - 07/19/21 06:41 PM

As Reb stated, there is no rule of thumb but what I can say is .5 or.6 of a grain in a 223 is quite a bit when you are close to max. I have shot and loaded TAC extensively and for a ball powder it is one of the best for temp stability but its still a ball powder. If you think its fluctuates bad try BLC 2!!

TAC performs best at or close to max with any bullet weight I've tried and thats from 50-77gr in 223.

So question, why are you adjusting your loads??? Is it a pressure issue, group issue or are you chasing a certain velocity??

The best advice I can give you or any new loader is WORK UP YOUR LOAD IN THE HOTTEST WEATHER and check your ACCURACY in cold/normal hunting temperatures. If it still shoots then rock on and don't sweat the velocity loss. To back this up try taking your summer time load and running it through a ballistic program and then deduct 50fps, you will then realize that your DOPE in real world hunting ranges is either exactly the same or its so close its not worth worrying about.....