10-17-2020, 05:22 PM
I was checking Hodgdons load data to see what some of the lighter 6mm bullets I've accumulated would do in my 6x45 and the velocities struck me as pretty good. Really good, frankly, compared to the ranges Hornady published for 6 ARC. So I decided to do a comparison. I picked 80s since that was what I was looking at and the 3 powders with crossover are H4895, XBR and H335. Hornady data is for an 18" so I adjusted them up 25 fps per inch and added 150 fps to compare with Hodgdon's 24" data. Hornady data is for a GMX; Hodgdon for a Speer Soft Point. For anyone not familiar with it, 6x45 is .223 necked out to 6mm:
6ARC Charge 18". Adj to 24". 6x45 24". Charge
H4895. 27.7gr 2750fps. 2900fps. 2904fps. 27.0gr
8208 XBR. 27.7gr 2750fps. 2900fps. 2867fps. 27.0gr
H335. 27.7gr. 2650fps. 2800fps. 2862fps. 26.0gr
6ARC case holds 34 grains of water; .223 holds 28.8gr
Yes we know the Hornady data is slow, but I'm doing 2990 fps with 70 gr NBTVs and 25.2 grains of Benchmark out of my 24" 6x45; Hodgdon gives 2960 for 27.0 grains. I was up around 3200 at 27.0 and after much mental anguish, decided that was too good to be safe.
All I can do is scratch my head!
243 LBC on the left with 80 grain Speer Soft Point; 6x45 on right with 70 gr NBTV. Caliper to show 243 LBC/6ARC case size difference. 6x45 is loaded at 2.31" and will only work in an ASC mag.
6ARC Charge 18". Adj to 24". 6x45 24". Charge
H4895. 27.7gr 2750fps. 2900fps. 2904fps. 27.0gr
8208 XBR. 27.7gr 2750fps. 2900fps. 2867fps. 27.0gr
H335. 27.7gr. 2650fps. 2800fps. 2862fps. 26.0gr
6ARC case holds 34 grains of water; .223 holds 28.8gr
Yes we know the Hornady data is slow, but I'm doing 2990 fps with 70 gr NBTVs and 25.2 grains of Benchmark out of my 24" 6x45; Hodgdon gives 2960 for 27.0 grains. I was up around 3200 at 27.0 and after much mental anguish, decided that was too good to be safe.
All I can do is scratch my head!
243 LBC on the left with 80 grain Speer Soft Point; 6x45 on right with 70 gr NBTV. Caliper to show 243 LBC/6ARC case size difference. 6x45 is loaded at 2.31" and will only work in an ASC mag.