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Pete Wass
03-08-2014, 10:01 AM
I haven't been following the CF forums much and am wondering if anyone who uses tuners has tried to use the PRX formula to set their tuner?

Thanks,

Pete

ConRich
03-08-2014, 11:49 AM
I haven't been following the CF forums much and am wondering if anyone who uses tuners has tried to use the PRX formula to set their tuner?

Thanks,

Pete

Hello Pete, Hope that you're enjoying the winter wherever you are, still cold here in ME. What is this PRX formula all about ?

Dick

alinwa
03-08-2014, 12:37 PM
rimfire, rimfire, rimfire :)

You gotta, go over to the Dark Side to find the PRX beliebers.

Wilbur
03-08-2014, 12:40 PM
The PRX formula has to do with tuners. If you have a tuner.....go read up on it. Of course, if that's incorrect, then....I don't know what to tell you!

I think there's some stuff on the rimfire forum 'bout that.....

jwa
03-08-2014, 01:43 PM
I haven't been following the CF forums much and am wondering if anyone who uses tuners has tried to use the PRX formula to set their tuner?

Thanks,

Pete

Although I'm not a CF benchrest shooter it seems to me that most CF tuners don't add length when adjusted. So how can the PRX formula, which depends on total length of barrel plus tuner, work on CF bench rifles? If I'm wrong, I apologize for questioning you Pete.

Jerry

Pete Wass
03-08-2014, 06:08 PM
both CF and RF rifles use the same method of delivering bullets so it might be that the same factors that allow one to tune a RF barrel could work with a CF rifle. Makes some sense to me anyway. I think either kind of rifle can be tuned in a number of ways so the PRX may work for CF rifles as well.

In short, the length of the tuning device is what is critical when using the PRX. It's about harmonics vs weight alone.

Pete

mwezell
06-13-2014, 03:52 PM
both CF and RF rifles use the same method of delivering bullets so it might be that the same factors that allow one to tune a RF barrel could work with a CF rifle. Makes some sense to me anyway. I think either kind of rifle can be tuned in a number of ways so the PRX may work for CF rifles as well.

In short, the length of the tuning device is what is critical when using the PRX. It's about harmonics vs weight alone.

Pete

Acoustics travel at the speed of sound. The PRX is an acoustic tuning method and most match rf ammo is subsonic. Not that it CAN'T apply to centerfire, but the acoustic waves become so close together, that tuning a cf at roughly 3 times this speed isn't feasible...IMHO...and I've tried it. The other thing is that vibrations don't travel through steel like acoustics, but much, much faster.
I feel you can luck into a spot from time to time, but that the acoustic tune won't hold....to many variables in play. More research is being done along these lines by myself and others, including Tony Purdy, who is credited with the PRX tuning method.

Jerry H
06-13-2014, 04:53 PM
I know of 1 case in CF BR that PRX worked. While I certainly believe in using PRX, I doubt that it is actually acoustically tuned. The exiting gases driving a subsonic RF are in fact supersonic themselves but may drop to subsonic very quickly within the tuner . I suspect that the PRX formula is a lucky coincidence that works about 75% of the time. It may be more related to fluid dynamics than sound. If it were a sound related tune, then it would work 100%. I have a duplex tuner that proves weight position is still a considerable factor. It allows independent weight and length adjustment with respect to each other.

SGJennings
06-16-2014, 09:09 AM
Two things:

1. There are two kinds of CF tuners. Those that extend beyond the muzzle and those that do not. The beyond-the-muzzle CF tuners can be viewed as increasing length. Mike's CF is a beyond-the-muzzle tuner.

2. Thank you, Jerry, for your observations about weight and length independence. That's good data.

Best regards,

Greg J.

mks
06-16-2014, 11:39 AM
I suspect that the PRX formula is a lucky coincidence that works about 75% of the time.

Jerry,
I think you hit the nail on the head. The fact that it sometimes works for CF means that the underlying theory is unsound.:D CF bullets travel faster than acoustic waves, so acoustics has nothing to do with tuning.

mwezell
06-16-2014, 01:42 PM
Jerry,
I think you hit the nail on the head. The fact that it sometimes works for CF means that the underlying theory is unsound.:D CF bullets travel faster than acoustic waves, so acoustics has nothing to do with tuning.

Just a 75% coincidence rate I suppose, with rimfires. My tuners use the PRX but are not solely dependent on it. They still tune just like any other tuner that I've seen. The rimfire tuner uses a fixed length tube that is set to the PRX for that individual barrel, and the tuner moves behind it. The cf tuner extends beyond the muzzle and adjusts like a Lambert tuner, but the length changes when turned. I've already stated my view on the PRX and cf's. I won't go so far as to say that it won't work because of it's success with rimfires, but cf velocities present other issues with it being useful, so far.

mks
06-17-2014, 10:06 AM
Mike,
I didn't mean to imply that your tuner or anyone else's don't work. The results are real. As you know, I have been using the Shade Tree for a couple of years now. My quibble is with the explanation of why they work.

Cheers,
Keith

Pete Wass
06-18-2014, 07:28 AM
that not much weight will tame a thick HV barrel; like 3 oz. and it seems to take 8 + with skinny little RF barrels - - - -, even at that, very little movement will affect tune big time. Wonder what 1 oz would do? I would prefer to have to move the tuner more to affect change.

Pete

B.Larson
06-18-2014, 07:56 AM
speaking of tuners.......... has anyone tried the rubber thingy "Limbsaver" markets..... looks like an electrical grommet and you move it 1/2" at a time.........

mks
06-18-2014, 01:37 PM
speaking of tuners.......... has anyone tried the rubber thingy "Limbsaver" markets..... looks like an electrical grommet and you move it 1/2" at a time.........

I tried one on a 30BR that was pretty well tuned before the barrel went south. It made things worse.

Jerry H
06-18-2014, 02:23 PM
It may be that PRX would work better on CF if the higher "harmonics" were tried. Say somewhere around the 21rst.

mwezell
06-18-2014, 03:33 PM
It may be that PRX would work better on CF if the higher "harmonics" were tried. Say somewhere around the 21rst.

Agreed, but they become very close together that high.

alinwa
06-18-2014, 09:28 PM
speaking of tuners.......... has anyone tried the rubber thingy "Limbsaver" markets..... looks like an electrical grommet and you move it 1/2" at a time.........

I've spent quite a bit of time with them, enough to feel strongly that the barrel doesn't even 'see' or feel them before the bullet leaves unless they're 'way back from the muzzle, the movements are simply too small..

I also believe that many steel-on-steel tuners are erratic because they're tightened up in a way that allows 'rattle' or slop in the threads or rings. I believe that for a tuning system to be effective it must be very tightly fitted so as to provide immediate feedback. This can be a challenge when one leaves the butting shoulders small because turning down too far can bell the muzzle....... Some of the best are fitted with clamps.

al

pickles
04-09-2016, 10:07 AM
I just used it on my Shul, and it was very useful. I will use it on my other rifles an expect to have a great outcome.
Thanks Tony.
Pickles.