Hmm, I`m definitely leaning towards carrying out the load tests with the Magnetospeed removed based on everyones findings
I do wonder if its worth making an extra round or two purely for chronograph purposes then remove it before firing the string? That way you can have the comfort blanket of knowing the velocity/pressure and no worries that it will affect the test/harmonics
Sniffer, I am not a fan of firing "strings" from light contour hunting weight rifles. IMHO it's counterproductive and wasteful. When you hunt, you don't shoot at your animal with a barrel that's warm or hot from shooting strings. Your first and often only meaningful shot is made from a COLD barrel, which hopefully has been sighted in previously and appropriately fouled in a similar condition.
Heavy barrel match rifles are treated a bit differently but even then, their shooters will try not to get them HOT.
All I'm saying, is to shoot your rifles accordingly.
I cringe when I'm at the range and a nimrod is blasting rounds downrange and adjusting his scope after the obligatory "five shot string." The last fellow I watched do this proudly made the claim "After 20 shots she finally settled down."
I politely asked if he had any more ammo. I noticed he was shooting off the shelf Federal. Surprisingly, he did have more ammo and it was from the same lot. Good.
I kept him talking for about a half hour for two reasons. First, he was a decent fellow with a decent hunting ethic and I really wanted to see how well his Savage 308 Win, bolt action would shoot from a cold barrel.
I likely don't have to tell anyone with experience what happened. 10cm left and 8cm low of point of aim on the first shot from a cold barrel. The shooter was justly surprised. He had no knowledge about temperature causing harmonics changes to the barrel or any of the other issues created in bedding, stock movement etc as the temps rose, then settled back to normal when they cooled.
This fellow was no one's fool. He recognized a problem when he saw it and endeavored to rectify it for the conditions he hunts.
His bore had close to thirty rounds fired since the last cleaning. Out came the can of Wipe Out (another epiphany) and my portable cleaning rest/rod etc. After cleaning, we shot two foulers and waited for 15 minutes to allow things to cool to normal. He used my bags and adjustable rests because they were more stable and convenient than the range provided bags. Two more shots to establish there was a viable group.
Then we adjusted the scope reticles to point of impact from point of aim.
The barrel was allowed to cool to ambient temperature again, then two more quick shots to make sure it was shooting to point of aim. It took one more adjustment for elevation to get it where he wanted it.
We went to lunch at a local restaurant, chatted about shooting/hunting/SXS quads and favorite cartridges. Great morning all around. After lunch we went back to the range, only about a klik away to shoot the rifle one more time.
He shot it ONCE, as should happen with a successful shot on a hunt. His shot was 3cm high and appx 1cm to the right from point of aim. He admitted it was likely his fault. We packed up our stuff and went home.
The next day I could hear shots coming from the range. Not shot strings. Just single shots with 5-10 minutes between them.
It was my new acquaintance. He wanted to make sure what had happened the day before was consistently repeatable with his rifle/scope/ammo combination and find out how many shots could be fired before his point of impact shifted. Like I said, good ethics.
I know this because he dropped by to show me his targets. He had about a dozen of them. All were covered with notes in a folder. He had picked up a can of Wipe Out and cleaned the rifle again, then shot a couple of foulers before putting it away. He was very pleased with his results but when he picked up the Wipe Out, he picked up more ammo. He opted for Federal Premium, which was different from what he had been shooting and 15 grains heavier but twice as expensive. Of course he had to go back and shoot to check point of impact from point of aim and adjust accordingly. Thankfully they were pretty close.
Again, he came back to discuss his targets. That's when I informed him he could have gotten into a very decent hand loading set up for what he paid for five boxes of Federal Premium ammo. He likes to shoot a lot, which is a good thing. We're putting together a single stage press/scale/dies system together for him now. Almost have it all together. Then comes another learning curve.
Back to the magneto speed and other chronies. They use different methods to establish velocities. I was amazed at how close LabRadar and the Magneto Speed were in their readouts. The older Chrony was OK for what it was designed to do and if nothing else was available I wouldn't feel let down.
For me, LabRadar was just to expensive and to specialized for my needs or desires but an excellent product that lived up to everything claimed. The Chrony was to inconsistent and light dependent but OK. The Magneto Speed, comes in a couple of different models. One for those that love gadgets and one for those that want something simple but works well. I have the latter. I like it and I'm willing to work within its parameters.
