H4350 vs IMR4350 for .243 with 85 gr HPBT GK's

[mac805]

I have been loading Sierra 85gr HPBT Gamekings for some time now over H4350 for my .243. My most accurate load has been at 42.2 gr, which is the sierra listed max for IMR4350 (H4350 is not listed in Sierra data). I have not had any signs of overpressure even shooting in very warm weather, but have not moved past the listed max.

I know many consider the two powders interchangeable, but I have noticed that some manuals do list both (Speer for example). In most cases with 85-95 gr bullets, the loads listed for H4350 are as much as 2-3 grains more than IMR4350.

I would like to try working up a little higher with H4350 to see if my groups continue to tighten up.

Any advice or experience would be much appreciated.

 

[venatic]

The hodgdon manual I have shows a max of 45.0 gr of H4350 so get to working.

 

[DieByTheBow]

looks like your at the starting load. IMR has a different burn rate. You still have a couple grains to play with.

 

[muskrat30]

I would not consider those 2 powders interchangable. The are very close & in the same ballpark H-4350 is usually listed slower on the burn rate comparison charts. The true interchangable powders are the likes of win 296/ H-110, where they are the same powder.

I would work with data you see listed for H-4350. Of course with a slower powder you usually end up with higher charges weights compared to a faster powder. That jives with what you see comparing IMR & H 4350 max charges. I like H-4350 & am loading up some 180grn 30-06 ammo now with it. I glance at the IMR charges but I find H-4350 data to base my loading on.