TAC's loading data is too conservative?

[cpatbay]

I am trying to load some test loads for my AR with Sierra 60 gr 223 remington HP and TAC.

While researching load limits, I found (as usual) two sources of data that were not close. The data from TAC recommends 22.1 to 24.6 gr while Sierra's data for AR is from 23.4 to 25.8 gr. Seems like TAC is very conservative or is it? What's puzzling is that TAC's data says muzzle velocity is 3102 f/s at 24.6 gr of TAC while Sierra says 3000 f/s with 25.8 gr of TAC. So who should I believe?

I guess I could just go low but some real world loading recommendations would be very helpful. Thanks.

[XDRoX]

I am trying to load some test loads for my AR with Sierra 60 gr 223 remington HP and TAC.

While researching load limits, I found (as usual) two sources of data that were not close. The data from TAC recommends 22.1 to 24.6 gr while Sierra's data for AR is from 23.4 to 25.8 gr. Seems like TAC is very conservative or is it? What's puzzling is that TAC's data says muzzle velocity is 3102 f/s at 24.6 gr of TAC while Sierra says 3000 f/s with 25.8 gr of TAC. So who should I believe?

I guess I could just go low but some real world loading recommendations would be very helpful. Thanks.

I load 25gr under 55gr FMJ. I have chrono data if you want it I can post it.

[bohoki]

their testing is with a different bullet i suppose

[smalltime]

Ramshot's data was tested with a 24" 1/12 barrel Winchester Small Rifle Primer and Sierra lists 20" 1/7 HBAR AR-15 Remington 7 1/2 Primer. Ramshot's data for that bullet is within 223 pressure (55,000 psi) while Sierra's data is for 5.56 (62,000 psi)

[cpatbay]

Ramshot's data was tested with a 24" 1/12 barrel Winchester Small Rifle Primer and Sierra lists 20" 1/7 HBAR AR-15 Remington 7 1/2 Primer. Ramshot's data for that bullet is within 223 pressure (55,000 psi) while Sierra's data is for 5.56 (62,000 psi)

Good point. Since I am loading for AR, I should be able to use Sierra's AR loading data, right?

[EL_NinO619]

Good point. Since I am loading for AR, I should be able to use Sierra's AR loading data, right?

Yes. But I would start at 25gr, load 10 see if they cycle. They should cycle and stick with that. For accuracy just under max is the best performer.

My load, which is XDRoXs also...

55 Hornady FMJ
24.5gr of TAC
CCI 200
Case length 1.750
COAL 2.230
FPS 3130