Remember the problem I described in my other thread? Well, when you guys started talking about the 70 gr Nosler RDF needed a long jump, I increased the jump to 0.07" That's about as far as I can go without the case mouth swallowing the ogive.
I shot this target late this afternoon about 6:30 pm.
The groups, all 3 shot groups, at 100 yards, from left to right are: 0.87", 0.6", and 0.44".
For reference, those orange dots are 3/4" diameter.
The SD for the 9 shots was 21.7 fps. This is the first time I've seen both accuracy and a lower SD. Of course I'm not there yet as I need to reduce the SD by about 10 fps or so, but closing in.
If you ask me what I did, it would embarrass me to have to admit I broke a cardinal rule of engineering testing and analysis - I changed two things at once - oh the humility of it all :redface:
I guess patience was wearing thin, so I decided to change rifles, so I went to a Ruger Precision. Then, even though I had done ladders on bullet seating depth, I had not gone far enough. Common thinking was that VLD/ELD bullets like to be jammed into the lands. I backed my last loads out to 0.07" jump. Frankly, I would have gone more, but the case was already close to swallowing the ogive, so I stopped at 0.070"
This morning I ran a barrel profile starting at a minimal load and increasing each successive round by 0.2 gr. That required 13 rounds and produced this:
So I loaded up 12 more rounds in 0.1 grain increments spanning the range of 23.1 to 24.1. That gave me a little leeway on either side of the "flat" spot.
Back to the range which produced this:
Both the 0.2 gr and 0.1 gr show a flat area with a middle value of 23.7 grains. And both sets showed a dip in velocity at 23.5 gr in what would be otherwise a long flat spot for the velocity. That one particular load must land on a touchy point of the barrel harmonics. I loaded 9 rounds in 3 sets of 3 because it was easier to match cases that way.
I took that to the range and got the results seen on the target above. All are sub-MOA and two are well under 1 MOA. So, since I broke the "change one thing at a time" rule, I now have to load the same velocity tests again and see if the MVP LR settles down - it should, but...
The load particulars:
New Hornady cases sorted by weight, trimmed, flash hole uniformed, mouth chamfered inside and out.
Nosler 70 gr RDF bullets
Ramshot TAC powder
Federal GMM primers
Bullet seat depth: 0.070"
RPR rifle - no suppressor
time between shots, about 45 seconds.
cartridge cook time, about 10 seconds.
Clocked with MagnetoSpeed
Tomorrow: MVP LR with bullet seat at 0.070"
I shot this target late this afternoon about 6:30 pm.
The groups, all 3 shot groups, at 100 yards, from left to right are: 0.87", 0.6", and 0.44".
For reference, those orange dots are 3/4" diameter.
The SD for the 9 shots was 21.7 fps. This is the first time I've seen both accuracy and a lower SD. Of course I'm not there yet as I need to reduce the SD by about 10 fps or so, but closing in.
If you ask me what I did, it would embarrass me to have to admit I broke a cardinal rule of engineering testing and analysis - I changed two things at once - oh the humility of it all :redface:
I guess patience was wearing thin, so I decided to change rifles, so I went to a Ruger Precision. Then, even though I had done ladders on bullet seating depth, I had not gone far enough. Common thinking was that VLD/ELD bullets like to be jammed into the lands. I backed my last loads out to 0.07" jump. Frankly, I would have gone more, but the case was already close to swallowing the ogive, so I stopped at 0.070"
This morning I ran a barrel profile starting at a minimal load and increasing each successive round by 0.2 gr. That required 13 rounds and produced this:
So I loaded up 12 more rounds in 0.1 grain increments spanning the range of 23.1 to 24.1. That gave me a little leeway on either side of the "flat" spot.
Back to the range which produced this:
Both the 0.2 gr and 0.1 gr show a flat area with a middle value of 23.7 grains. And both sets showed a dip in velocity at 23.5 gr in what would be otherwise a long flat spot for the velocity. That one particular load must land on a touchy point of the barrel harmonics. I loaded 9 rounds in 3 sets of 3 because it was easier to match cases that way.
I took that to the range and got the results seen on the target above. All are sub-MOA and two are well under 1 MOA. So, since I broke the "change one thing at a time" rule, I now have to load the same velocity tests again and see if the MVP LR settles down - it should, but...
The load particulars:
New Hornady cases sorted by weight, trimmed, flash hole uniformed, mouth chamfered inside and out.
Nosler 70 gr RDF bullets
Ramshot TAC powder
Federal GMM primers
Bullet seat depth: 0.070"
RPR rifle - no suppressor
time between shots, about 45 seconds.
cartridge cook time, about 10 seconds.
Clocked with MagnetoSpeed
Tomorrow: MVP LR with bullet seat at 0.070"
