10-13-2012, 07:31 PM
I made my first trip to the range today to begin working on this project. It wasn't a good day to do this as the deer season is just in front of us and everyone wanted to sight in their 30-30 or 30-06 they hadn't shot since last season. On top of that, Savage was holding a demo on the high power range, so I wound up waiting 2.5 hours to get a bench and felt pressured to the point that taking the time to set up my CED chronograph while everyone else waited was just not the right thing to do. So, luckily I had my new Magnetospeed Chrono with me. I had intended to set up both chrono's in series to see how they compared but I aborted that plan and just used the Magnatospeed since I could set it up behind the line.
The thing I've been thinking about most is the requirement to use the 123 A-Max Hornady factory load as the control so I started there, the temperature was 91ยบ F. Using my 14.5" Ultralight upper which has a Satern 1:8 barrel and Grendel chamber on a RRA Carbine lower with a Giessele SSA-E trigger, and Night force 2.5-10 scope from the bags I fired several five shot groups before installing the Chrono which straps to the barrel. The average of these was around .8 MOA at 100 yards. I then installed the chrono and got an average velocity of 2411 fps and a standard deviation of only 5 fps. Wow, this shows me how much variation has been introduced by my CED chronograph I was previously impressed with 12 or 14 fps SD's this chrono is that much more repeatable.
Next I repeated this sequence with my candidate handload using the 123 A-Max seated to 2.250, over a charge of 28.5 grains of IMR8208 in once fired AA cases, sized and trimmed to 1.515" beveled and chamfered and primed by a Wolf Small Rifle Magnum Primer. The groups were slightly smaller, from about .5 MOA to .7 MOA with and average velocity of 2364 fps, a SD of 4 fps, yes 4, the lowest I've ever recorded, max was 2367 and min 2357.
The Magnetospeed Chronograph did indeed shift the point of impact significantly, around 2-3 MOA in the direction opposite the chronograph. It also seemed to affect the group size negatively, not significantly but maybe .2 MOA.
I really like this new chronograph but feel I need to point out the negatives as well. First it won't mount on any gun with a slide over the barrel like my beloved 1911 45 ACP's. It also won't mount on my snubby revolvers or my full length stocked rifles like my M1 garand or Mannlicher carbine, at least not without mounting it in the way of the sights. That coupled with the fact that you really need to shoot groups for accuracy and groups for data separately the cost to run tests is increased. However, in my opinion, the benefits of reduced set up time and reliability in low or inconstant light outweighs the negatives.
Based on these two tests today, I think I have a refined picture of the specific tests I want us to run now. RickOshay and I are meeting for dinner and to finalize the data base we want to construct for all of us to use. We should be able to post the final document and begin collecting data in a week to ten days.
As a side note, I also tried Superformance powder for the Grendel, I used 29.1 grains behind the 123 A-max with dismal results, groups were 3 MOA or more and speeds were in the 1800 fps range, not at all good, and surely rules this powder out as the powder used in the factory load. However with 140 grain bullets it might just be the ticket for subsonic loads
Here is a pic of the Magnetospeed Chronograph strapped to my 6.5 Grendel Ultralight.![[Image: photo344.jpg]](http://www.hunt101.com/data/500/medium/photo344.jpg)
Bob
The thing I've been thinking about most is the requirement to use the 123 A-Max Hornady factory load as the control so I started there, the temperature was 91ยบ F. Using my 14.5" Ultralight upper which has a Satern 1:8 barrel and Grendel chamber on a RRA Carbine lower with a Giessele SSA-E trigger, and Night force 2.5-10 scope from the bags I fired several five shot groups before installing the Chrono which straps to the barrel. The average of these was around .8 MOA at 100 yards. I then installed the chrono and got an average velocity of 2411 fps and a standard deviation of only 5 fps. Wow, this shows me how much variation has been introduced by my CED chronograph I was previously impressed with 12 or 14 fps SD's this chrono is that much more repeatable.
Next I repeated this sequence with my candidate handload using the 123 A-Max seated to 2.250, over a charge of 28.5 grains of IMR8208 in once fired AA cases, sized and trimmed to 1.515" beveled and chamfered and primed by a Wolf Small Rifle Magnum Primer. The groups were slightly smaller, from about .5 MOA to .7 MOA with and average velocity of 2364 fps, a SD of 4 fps, yes 4, the lowest I've ever recorded, max was 2367 and min 2357.
The Magnetospeed Chronograph did indeed shift the point of impact significantly, around 2-3 MOA in the direction opposite the chronograph. It also seemed to affect the group size negatively, not significantly but maybe .2 MOA.
I really like this new chronograph but feel I need to point out the negatives as well. First it won't mount on any gun with a slide over the barrel like my beloved 1911 45 ACP's. It also won't mount on my snubby revolvers or my full length stocked rifles like my M1 garand or Mannlicher carbine, at least not without mounting it in the way of the sights. That coupled with the fact that you really need to shoot groups for accuracy and groups for data separately the cost to run tests is increased. However, in my opinion, the benefits of reduced set up time and reliability in low or inconstant light outweighs the negatives.
Based on these two tests today, I think I have a refined picture of the specific tests I want us to run now. RickOshay and I are meeting for dinner and to finalize the data base we want to construct for all of us to use. We should be able to post the final document and begin collecting data in a week to ten days.
As a side note, I also tried Superformance powder for the Grendel, I used 29.1 grains behind the 123 A-max with dismal results, groups were 3 MOA or more and speeds were in the 1800 fps range, not at all good, and surely rules this powder out as the powder used in the factory load. However with 140 grain bullets it might just be the ticket for subsonic loads
Here is a pic of the Magnetospeed Chronograph strapped to my 6.5 Grendel Ultralight.
Bob