I got out today to do a little more testing with the 300 PRC. Today's goal was to shoot groups with the 3 different powders and see which ones are worth spending more time with. I also loaded up a pressure ladder using the 153gr Apex Afterburner bullets to see how those do. All shooting was done at 335 yards. Today's conditions were pretty typical of the weather in western WA in March; 45°, raining, and windy. All groups were shot from a bench with a bipod and rear bag. Just a reminder, my specific rifle runs higher than normal powder charges to reach the same velocity as most other rifles chambered in 300 PRC. I wouldn't suggest anyone use these charges in their personal rifles.
RL-26
-Lapua Brass
-Fed 215 primer
-208gr ELDm
-OAL 3.720"
-79.5gr RL-26
I loaded 9 rounds with the charge listed above and fired 3 separate 3 shot groups at 335 yards. These are the group sizes (center to center):
- 2.3"
- 2.2"
- 2.6"
There was about 1" of vertical in all 3 groups and the rest was horizontal spread. The 2.6" group had one shot that was a pretty clear flyer because of a bad wind call. The wind was very hard to read today and that showed in my groups.
H-1000
-Lapua Brass
-Fed 215 primer
-208gr ELDm
-OAL 3.720"
-82.0gr H-1000
Same as with the RL-26 load, I fired 3 groups with 3 shots each at 335 yards. These are the group sizes (center to center):
- 2.8"
- 2.7"
- 2.4"
These groups showed more vertical spread than the RL-26 loads. The groups were slightly larger overall than the RL-26 loads.
RL-33
-Lapua Brass
-Fed 215 primer
-208gr ELDm
-OAL 3.720"
-95.0gr RL-33
I had 9 rounds loaded with RL-33, but only fired 6. The groups were poor enough that I didn't bother shooting the other 3 shot group.
- 3.6"
- 3.5"
This load still isn't showing any pressure signs, despite the high velocity (roughly 3100fps), but the accuracy just isn't good enough to be worth pursuing.
I'll try adjusting the seating depth on the RL-26 and H-1000 load for the next trip out and see if the groups tighten up. I'm not too unhappy with the accuracy so far considering it's a factory rifle. I'd like to get it down to around .5 MOA with a good quality hunting bullet.
The other goal on this trip out was to shoot a pressure ladder with the new (not released quite yet) 153gr Apex Afterburner. I have a handful of pre-production samples left that I was given to play with a while back. It sounds like Apex Outdoors is very close to officially releasing these. Mark at Apex Outdoors shoots them out of his 300 Win Mag and gets a little over 3300 fps, so my goal was to land in the 3350-3400 fps range. For comparison, I get 3520fps with this same bullet in a 24" 300 RUM using RL-26.
The Afterburner is designed to be crimped into the groove machined into the bullet, so there is going to be a fixed COAL for each chambering. I seated them to 3.330" in the 300 PRC and crimped the bullets using a Lee factory crimp die adjusted to just touch the shell holder, then 1/2 additional turn.
153 Apex Afterburner
-Lapua Brass
-Fed 215 primer
-COAL 3.330"
-H4350 powder
73.5gr- 3140 fps
74.0gr- 3135 fps
74.5gr- 3173 fps
75.0gr- 3209 fps
75.5gr- 3240 fps
76.0gr- 3276 fps
76.5gr- 3315 fps
All 7 shots landed in a 4" group at 335 yards. My rifle has shown pretty poor accuracy with the Magneto chronograph attached to the barrel, so the group size means very little to me at this point. There was no sign of pressure, bolt lift remained unchanged from the lowest to the highest charge weight, and all the primers look good with no flattening or cratering. I'll probably load a few more going as high as 78.0gr of H4350 and see how they perform.
The most satisfying groups of the day came from the other project gun that I brought out. I have a 7mm SAUM that's been very picky about loads. It shot the 168gr Matrix VLD sub .25 MOA (I have multiple 100 yard groups that would make BR shooters jealous!) with H4350 at a leisurely 2930 fps. No other bullet has shot well in that rifle and the 168 Matrix is no longer available. I happened to come across some 180gr SMKs to try and they're shooting almost as well as the old Matrix VLDs did. What's interesting is that this gun shoots best at relatively low velocities. The 180 SMK is shooting sub .3 MOA at 335 yards at 2845 fps. It's interesting to note that the 183 SMK shot 3" groups at 100 yards!