mwezell
Mike Ezell
Reading the thread about ejectors and a few more over time got me thinking about discussions I've had with people over the last several years and how vibration analysis testing applies to some of those discussions.
First, I wanna say that we can't eliminate all vibration and that we should NOT have that as our goal. A test that comes to mind was one where only an inch or so of bbl was left protruding after the bbl was set into concrete. No matter what they tried, that sucker would never shoot well.
Another example that I mention from time to time came from vibration analysis...We had already done lab testing and learned a bit but this was a live fire range test. All was going well and it was time and money well spent. The gun we were shooting was a glued and screwed cf rifle.
I had the bright idea that we should test it unglued vs glued. So, I go get a clothes iron at the local dollar general iirc. I come back and pull everything apart then set the iron on top of the intregral scope base on the Stiller Viper aluminum action until it get warm enough that you can hear it popping and creeking, as well as a little smell from the epoxy used for the glue in. Sure enough, she was ready to come apart, and did...beautifully. If you're familiar with those actions, you may know that the bottom is a fast fly cut finish to give them a good bite into the glue/bedding. Anyway, it came out gorgeous! You couldn't ask for a better bedding finish, shoing all the details from when it was machined when new....just perfectly.
Well, we had already established a great tune and numbers on the o-scope as well as on the tuner on the rifle, prior. So, I waited for it to cool, put everything back together and TORQUED the action screws back to exactly where they were prior to testing...a relatively high 65in/lbs.
Now the fun starts...the gun was pretty significantly out of tune...2 whole marks btw. That's pretty big and is only .002 of tuner travel. So, right out of the gate and based on testing, I moved the tuner IN 2 marks and it immediately starting bugholing just like before. The interesting part though is, it was now vibrating at a totally different frequency of vibration...considerably. So yes, a completely different vibrational node.(technically, anti-node)
Since this is NOT a tuner thread(LOL!), but about vibration, I'll cut to the point. This proved that the joint between perfect bedding vs a glued and screwed bedding MOVES! Later testing confirms that EVERY joint in the system moves, at high enough frequencies!! More torque simply raised the frequency where movement is consistently measurable. That inevitable movement was not amplitude based, but frequency...for all intents and purposes. This proved true as it was still the case on rf and cf bbls. So, what we were able to show is that every joint moves at high enough frequencies and that TUNE REPEATS with that frequency TOO...both rf and cf., but there are small differences beyond just that. Different subject, though.
Bottom line is, every joint moves and that the ultra(ish) high frequencies seen did NOT change accuracy potential!! So yes, stuff moves but that's not NECESSARILY a bad thing. In fact, it's a good one, if they are consistent at the lower frequencies and that the really higher ones did not show on target. At least not to the point where they aren't tunable, repeatedly, within just a few marks on the tuner.
Also, dampening of vibration is much(often) about inevitable movement getting cancelled out by a different movement in the system. So, as long as we have repeatable inevitable movement, we can adjust for it.
This is where the ejector tension and possible vibration changes come into play. First, they are tiny in the big scheme of all the vibration and frequencies going on at once, while the bullet is in the bbl. It doesn't matter, from what I could tell, what happens once the bullet is gone and of course that's at least plausible to most of us, in itself. So yes, I do believe that this tiny, tiny movement of the case upon firing does create a miniscule amount of vibrational change, it gets way....WAYYY lost in the noise.
But...That's not to say that it doesn't matter. In fact, all of what I just said should hopefully make us think about the potential to CONTROL, even those teeny tiny movements to improve upon accuracy even further. Yes, they get lost in the noise but that doesn't mean they are of no value...just that it's very difficult to quantify those changes on the target.
We're already splitting a mighty fine hair with how accurate these rifle are now. This just might be the crumb worth working on further in terms of better managing vibration.. controllably, to move a little step further forward. That's all for now. Just had this rambling thought and am posting it to bounce around on here.
First, I wanna say that we can't eliminate all vibration and that we should NOT have that as our goal. A test that comes to mind was one where only an inch or so of bbl was left protruding after the bbl was set into concrete. No matter what they tried, that sucker would never shoot well.
Another example that I mention from time to time came from vibration analysis...We had already done lab testing and learned a bit but this was a live fire range test. All was going well and it was time and money well spent. The gun we were shooting was a glued and screwed cf rifle.
I had the bright idea that we should test it unglued vs glued. So, I go get a clothes iron at the local dollar general iirc. I come back and pull everything apart then set the iron on top of the intregral scope base on the Stiller Viper aluminum action until it get warm enough that you can hear it popping and creeking, as well as a little smell from the epoxy used for the glue in. Sure enough, she was ready to come apart, and did...beautifully. If you're familiar with those actions, you may know that the bottom is a fast fly cut finish to give them a good bite into the glue/bedding. Anyway, it came out gorgeous! You couldn't ask for a better bedding finish, shoing all the details from when it was machined when new....just perfectly.
Well, we had already established a great tune and numbers on the o-scope as well as on the tuner on the rifle, prior. So, I waited for it to cool, put everything back together and TORQUED the action screws back to exactly where they were prior to testing...a relatively high 65in/lbs.
Now the fun starts...the gun was pretty significantly out of tune...2 whole marks btw. That's pretty big and is only .002 of tuner travel. So, right out of the gate and based on testing, I moved the tuner IN 2 marks and it immediately starting bugholing just like before. The interesting part though is, it was now vibrating at a totally different frequency of vibration...considerably. So yes, a completely different vibrational node.(technically, anti-node)
Since this is NOT a tuner thread(LOL!), but about vibration, I'll cut to the point. This proved that the joint between perfect bedding vs a glued and screwed bedding MOVES! Later testing confirms that EVERY joint in the system moves, at high enough frequencies!! More torque simply raised the frequency where movement is consistently measurable. That inevitable movement was not amplitude based, but frequency...for all intents and purposes. This proved true as it was still the case on rf and cf bbls. So, what we were able to show is that every joint moves at high enough frequencies and that TUNE REPEATS with that frequency TOO...both rf and cf., but there are small differences beyond just that. Different subject, though.
Bottom line is, every joint moves and that the ultra(ish) high frequencies seen did NOT change accuracy potential!! So yes, stuff moves but that's not NECESSARILY a bad thing. In fact, it's a good one, if they are consistent at the lower frequencies and that the really higher ones did not show on target. At least not to the point where they aren't tunable, repeatedly, within just a few marks on the tuner.
Also, dampening of vibration is much(often) about inevitable movement getting cancelled out by a different movement in the system. So, as long as we have repeatable inevitable movement, we can adjust for it.
This is where the ejector tension and possible vibration changes come into play. First, they are tiny in the big scheme of all the vibration and frequencies going on at once, while the bullet is in the bbl. It doesn't matter, from what I could tell, what happens once the bullet is gone and of course that's at least plausible to most of us, in itself. So yes, I do believe that this tiny, tiny movement of the case upon firing does create a miniscule amount of vibrational change, it gets way....WAYYY lost in the noise.
But...That's not to say that it doesn't matter. In fact, all of what I just said should hopefully make us think about the potential to CONTROL, even those teeny tiny movements to improve upon accuracy even further. Yes, they get lost in the noise but that doesn't mean they are of no value...just that it's very difficult to quantify those changes on the target.
We're already splitting a mighty fine hair with how accurate these rifle are now. This just might be the crumb worth working on further in terms of better managing vibration.. controllably, to move a little step further forward. That's all for now. Just had this rambling thought and am posting it to bounce around on here.
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