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The Purdy Prescription

45K views 271 replies 52 participants last post by  earnest  
#1 ·
Good Evening All

My name is Tony Purdy. A couple of the fine members of this forum suggested I post my idea for tuning rimfire benchrest rifles here on RFC

It has worked well for several shooters.

I look forward to sharing my process with you all

Let me know what I can do.

Thanks
Tony
 
#6 ·
I love it when someone figures out something that works. But figuring out why it works is the challenge. I've had a few discussions with Tony and while I might not agree with the acoustical relationship to accuracy, vibrational formulas do relate to one another. As it turns out, I think I'm seeing the relationship of his method to why it predicts the node position of the structural vibrations - that have been shown to be the root of improving accuracy. Barrel oscillation upon firing resemble structural vibrations of a free ended cantilever beam with one anti-node, 2 nodes and a "remainder". This remainder is very close in length to Tonys 1/9 length - which he converts to 1/8 length by adding the Noodle or Slider extension. On top of this, one can add as much weight as one wants to the node location, without changing the position of that node. So adding length out past the location of the tuner body only reinforces that the node form AT the tuner location. This extension also serves to increase the Moment of Inertia about the node point, thus further smoothing the muzzle motion, making the tuning setting much more stable.
So in my opinion, his method is a big step in the right direction.
 
#12 ·
Suhl Info



Hi John, The Amick Suhl is still where you Tuned it at, it is shooting so well I am not about to screw around with it...

I have my back up BR Suhl tuned with the Purdy Method and have not shot with it yet, with my Harrell's tuner on I have to crank it out to 450-500 to reach the 28 3/4" dimension Purdy calls for ..... the Club has my 50 yd shut down for Sighting in Days (Deer Hunters), I may take a trip down to Gary's place I haven't heard back from him yet though...
are you open to some more tuning at Gary's sometime in the next couple weeks if Gary says "Lets go"...

Chuck
 
#10 ·
I've tried for several days to get registered on the Rimfire Accuracy forum so I could participate in that thread. So far, no luck.

Precise measurement yields more precise results. If you close the bolt and put a cleaning rod down the bore to obtain the length from the breech face to the muzzle, you need to subtract the headspace from the reading.

If I ever get registered there, this caveat will appear there as well. It's in the cue pending my membership request being approved.

Hoot
 
#13 ·
I saw that, as I'm subscribed to that thread as well. Thanks. Another post of mine "in the cue" speaks of dropping down to the next harmonic multiple that lands you in the upper quadrant for folks with very long barrels or really long bloop tube arrangements.

Hoot
 
#17 ·
Thanks Hoot. I knew I could find it over on RA. I was just hoping it would be shared with the members here rather than having to go to another site to learn about it. If the process isn't going to be explained here what's the point of this thread?
 
#21 ·
I think it is not posted because it's hard to follow with a few short sentences. The instructions are three pages long but not that complicated. It seems Tony wants to be sure everybody is successful and does it correctly. Over on the other forum somebody measured their barrel length with the tuner on and did their calculations from that?
 
#22 ·
To All

Please forgive me. My initial post was meant only as an introduction. I fully expect to post anything asked of me.

It was a bit shortsighted of me to not post my email address as well.

You should not have to go to another site to see what I have to offer. I do this for the expectation of nothing in return.

You guys ask, I will answer. I work 6 days a week, 10 hours a day and have very limited time to help all those that have asked, so I ask that you be a bit patient with me.

You send me an e-mail for the worksheet and I will reply within the day

I want all shooters to have the chance to try this, that's why I'm here.

prx2500@outlook.com

Thanks
Tony
 
#23 ·
Thanks for the explantation. Guess I'll do some reading about your method. I'm not much of a BR guy, but like to learn stuff. I assume "RA" is the Rimfire Accuracy website?

This sounds cool, but I got confused with the numbers thrown around. Guess I'll go to the other website to read up on what you're talking about.

Bolero, I don't think PWNolan was out of line. I was wondering exactly what was going on myself. Not everyone is into this stuff like some people. A lot of RFC members don't visit many of the BR type sights. I tried it, but people get a little too cooky for me on those sites sometimes.

Couldn't believe you called Nolan fat:eek:

Pakrat56: Might send you an email in a few days after I digest this and read up on what you're talking about. Sounds neat. Thanks for coming over here. I'm just a mere mortal, but like to learn stuff.

Kenny
 
#24 ·
The best way to digest the entire approach is to actually get Tony to email you his document and read it end to end. A lot of the back and forth on the other forum is comprised of positive testimonials, then questions because some folks may have just skimmed through it. A small percentage want to be spoon fed the result and the other small percentage are folks like me trying to work it back upstream because we are seekers who can't leave things alone.:rolleyes:

Hoot
 
#25 ·
Thanks! Was trying to read the stuff over there but my head started spinning. Think I will take your advice and just send an email.

It's neat to see how this would work. Can't believe someone was smart enough to come up with this. But, I'm not all that sharp anyway....

Thanks again Hoot....

Kenny
 
#34 ·
people on here aren't strangers to the r.a. forum, or brc, or wwa for some.
I am a member of all those sites but I haven't visited RA or BRC for months. I was on WWA recently and I'd only seen brief mention of the Purdy rx. There was not a detailed explanation that I saw. I have not had time to visit RA to pursue this further so when I saw Tony's thread I was hopeful the information would be shared here so it's available to all the members of RFC. I appreciate that Tony's said he'll try to share more info and I've sent him an e-mail for his worksheet. I look forward to learning more about this process.

FWIW, I'm genuinely interested in the Purdy rx and I'm not a naysayer nor am I lazy.
 
#28 ·
Hi All

Its a bit late, getting ready for bed.

I have sent out e-mails with the worksheet for those of you who requested in

Tomorrow (probably late) I'll post the basics of the method with a little back round.

If you want to play around a little bit, try this. Take a barrel if you have one that is not installed, and measure it.

Take that measurement and multiply it by .224. take that length and measure back from either end. Pick up the barrel with your thumb and forefinger at the mark. Tap the barrel with something and listen for a bright clear tone. you are holding a node.

This really doesn't have a lot to do with my process, but shows that math can be used to find a node. There also is one at the mid point. Different tone, but still a clear note.

Have a great note

Tony
 
#29 ·
Okay, look, I have a lot of respect for anyone who has something
to offer regarding anything accuracy related. But what I don't like
is pulling teeth to get the information. PakRat tony, if you have a document
file that you can email to folks who request, surely you would be able to post
said document here on this thread. thanks, douglas
 
#31 ·
Tony, the bottom line is that the Purdy Prescription is YOUR property, and that means you can disseminate it anyway you choose - or keep it totally to yourself. I have absolutely NO right to your property but am deeply appreciative that you're generous enough to share it with me - whether by email, private message, or public posting.

Lesley
 
#32 ·
Lesley: While I agree with you in spirit, in actuality the cat is out of the bag.

Tony has intellectual property that he has freely promulgated. Now that it is out there is nothing to stop anyone from using the information to their advantage or disadvantage.

The gentlemen among us will give Tony credit for his ideas. Those that just want to stir the pot or refute the idea for whatever reason are also free to do so. And it appears there are some who want something handed to them on a silver platter without having to do any work for it.

We have come a long way in the past 2 months with the Purdy Rx. I for one am surprised it has taken this long for the naysayers and lazy folks to show up publicly. bob
 
#33 ·
+1

lesley: While i agree with you in spirit, in actuality the cat is out of the bag.

Tony has intellectual property that he has freely promulgated. Now that it is out there is nothing to stop anyone from using the information to their advantage or disadvantage.

The gentlemen among us will give tony credit for his ideas. Those that just want to stir the pot or refute the idea for whatever reason are also free to do so. And it appears there are some who want something handed to them on a silver platter without having to do any work for it.

We have come a long way in the past 2 months with the purdy rx. I for one am surprised it has taken this long for the naysayers and lazy folks to show up publicly. Bob
+1
 
#36 · (Edited)
.he describes his Theory Ad Ifinitinum many detractors including Calfee.

Chuck
Really Chuck. Tony's not even close to "Ad Infinitum", he's only been posting it for a few months. I should know, been trying to counter Bills counter productive pseudo theory for years. And having Bill as a "detractor" sometimes means you're probably on the right track. Which puts Tony in some VERY good company.
:D
 
#37 ·
Really

It just seemed that way, I changed my wording...

If weight is not a consideration it opens a new door for some sort of calibrated/adjustable tube that can be easily slipped onto the barrel and fastened like a MD is....Pappas should be all over this wouldn't you think...?

Chuck