This started in the Hunting forum, but I figured I'd post it here and link to it from there.
Hornady has just started selling lead-free ammo (GMX) to compete with offerings from Barnes and Winchester (also relatively new). It's supposed to be "compatible with standard load data." It is also supposed to be relatively interchangeable with Hornady SST.
I tried this out for myself, and here are the results. First, I did find that the load my rifle "likes" best with regular Hornady BTSP bullets, 56.5 grains of IMR 4350, works best with the SST and GMX bullets also.
The GMX, while it is a good deal longer and sits deeper in the case, is compatible with standard load data. Score 1 for Hornady. Works as advertised.
Rifle: Weatherby Vanguard Sporter .30-06, 24" barrel, factory-stock. Burris Fullfield II 3-9x40mm scope, set to 9X.
Load: 165 Hornady SST and GMX bullets over 56.5 grains IMR 4350, WLR primers, Winchester cases. Cartridge OAL 3.238" to 3.240".
Conditions: High desert BLM open land, my folding shooting bench, short Harris bipod on the front sling swivel, shooting bag as a rudimentary rear support. Initial weather was upper 70s with a light breeze.
I used a Nikon Laser 440 to measure 100 yards to my target, which was taped to a cardboard box weighted with rocks I found.
As I shot more, I got a bit tired, and it got hot with some thermals, and pretty gusty. My groups weren't as good.
Pictures (gridlines are 1 inch):
1. SST-first-string: These were the first three shots I fired when I set up, with SST bullets and a cold barrel.
2. GMX-second-string: I walked over to check the target from the first string, then walked back and fired these three with GMX bullets. I jerked the gun to the left when I pulled the trigger on the third shot; the flyer that's low and left was my fault. The group should have been sub-MOA, with that shot still a bit low, but not so far left.
3. GMX-hot: I shot this string after I was a bit fatigued, the wind and thermals had come up, and the barrel was dirty and hotter. I'd done a bit of sighting in with the SSTs, but not the GMX. Note that the gun appears to be sighted in for the GMX, so they're REALLY close to each other.
4. SST-hot: I shot this string right after GMX-hot, without changing the scope settings. Again, the barrel was pretty dirty, I was fighting fatigue, heat, wind and thermals, so the group isn't as good as the earlier ones.
5. GMX-SST-bullets: This is so you can see the similarities and differences between the two bullets. Note that cartridge OAL is the same for both, so the GMX does sit a lot deeper in the case. Still, the same charge worked for both.
Conclusion:
SSTs seem to have great accuracy potential. The longer GMX might not stabilize quite as well in my barrel, but they shoot almost as well. Both are good for 3/4" groups with a cold, relatively clean barrel, without any special work on the rifle or the cases.
The GMX and SST shoot to within <1 MOA of the same POI without scope adjustment, using the same powder charge. They both "like" the same powder charge. Score another two for Hornady.
It appears that one could keep the gun sighted in so that either bullet could be used interchangeably, zeroed close enough for hunting, field practice, etc. The groups overlap. Or, it would be easy to just go two clicks on each knob if you can get it down that close.
This is a good thing, since the GMX bullets retail for about 65 cents apiece, whereas the SST bullets retail for about 28 cents apiece. I'd rather practice with the SSTs!
Any related questions, comments, or experiences? Please post 'em!
Hornady has just started selling lead-free ammo (GMX) to compete with offerings from Barnes and Winchester (also relatively new). It's supposed to be "compatible with standard load data." It is also supposed to be relatively interchangeable with Hornady SST.
I tried this out for myself, and here are the results. First, I did find that the load my rifle "likes" best with regular Hornady BTSP bullets, 56.5 grains of IMR 4350, works best with the SST and GMX bullets also.
The GMX, while it is a good deal longer and sits deeper in the case, is compatible with standard load data. Score 1 for Hornady. Works as advertised.
Rifle: Weatherby Vanguard Sporter .30-06, 24" barrel, factory-stock. Burris Fullfield II 3-9x40mm scope, set to 9X.
Load: 165 Hornady SST and GMX bullets over 56.5 grains IMR 4350, WLR primers, Winchester cases. Cartridge OAL 3.238" to 3.240".
Conditions: High desert BLM open land, my folding shooting bench, short Harris bipod on the front sling swivel, shooting bag as a rudimentary rear support. Initial weather was upper 70s with a light breeze.
I used a Nikon Laser 440 to measure 100 yards to my target, which was taped to a cardboard box weighted with rocks I found.
As I shot more, I got a bit tired, and it got hot with some thermals, and pretty gusty. My groups weren't as good.
Pictures (gridlines are 1 inch):
1. SST-first-string: These were the first three shots I fired when I set up, with SST bullets and a cold barrel.
2. GMX-second-string: I walked over to check the target from the first string, then walked back and fired these three with GMX bullets. I jerked the gun to the left when I pulled the trigger on the third shot; the flyer that's low and left was my fault. The group should have been sub-MOA, with that shot still a bit low, but not so far left.
3. GMX-hot: I shot this string after I was a bit fatigued, the wind and thermals had come up, and the barrel was dirty and hotter. I'd done a bit of sighting in with the SSTs, but not the GMX. Note that the gun appears to be sighted in for the GMX, so they're REALLY close to each other.
4. SST-hot: I shot this string right after GMX-hot, without changing the scope settings. Again, the barrel was pretty dirty, I was fighting fatigue, heat, wind and thermals, so the group isn't as good as the earlier ones.
5. GMX-SST-bullets: This is so you can see the similarities and differences between the two bullets. Note that cartridge OAL is the same for both, so the GMX does sit a lot deeper in the case. Still, the same charge worked for both.
Conclusion:
SSTs seem to have great accuracy potential. The longer GMX might not stabilize quite as well in my barrel, but they shoot almost as well. Both are good for 3/4" groups with a cold, relatively clean barrel, without any special work on the rifle or the cases.
The GMX and SST shoot to within <1 MOA of the same POI without scope adjustment, using the same powder charge. They both "like" the same powder charge. Score another two for Hornady.
It appears that one could keep the gun sighted in so that either bullet could be used interchangeably, zeroed close enough for hunting, field practice, etc. The groups overlap. Or, it would be easy to just go two clicks on each knob if you can get it down that close.
This is a good thing, since the GMX bullets retail for about 65 cents apiece, whereas the SST bullets retail for about 28 cents apiece. I'd rather practice with the SSTs!
Any related questions, comments, or experiences? Please post 'em!
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