Factory barrel & PRX

L

linekin

Active member
I am wondering about the math for factory barrels (without a tuner) & PRX. Using the regular formula for them no matter which harmonic leaves the barrel short every time. I am just curios if it can be done with them as well.
Keith
 
Recessed Crown

These were used in the past by some damned good smiths, No make that Great Smiths. It can be done, you just have to find the smith that will do it.
 
Prx

You could play with a factory that had a heavy barrel & counter bore but you are probable "pissing in the wind" with anything less!
However, Tony's Formula can tell you how much to counter bore any barrel for a given harmonic.

Make Sense??
 
Doug said:
You could play with a factory that had a heavy barrel & counter bore but you are probable "pissing in the wind" with anything less!
However, Tony's Formula can tell you how much to counter bore any barrel for a given harmonic.

Make Sense??
Click to expand...

Doug, it doesn't make sense. I have Tony's worksheet & unless I'm missing something the AL is always longer than the barrel itself.
For instance, a 20 in barrel in the 9th harmonic.
20/8=2.5x9=22.5 AL
See... it comes out 2.5 in longer .
I am just pissing in the wind. I'm just curious is all & probably missing something.
I have seen a few heavy barreld gun with their barrels shorten that shot really well & was wondering if the were in better tune is all.
Keith
 
Hi Keith

If I'm not too tired after bowling tonite, I'll post how to figure for a counter bore.

It is slightly different than normal, but really just as easy

Have a great nite

Tony
 
Keith,
Hopefully Tony will correct me if I am wrong:

Tony stated The PRX works best for barrels that are between 22” & 25” long.
The formula was built around the concept that the Physical Length is always longer than the Barrel Length (bolt to crown).
Next it assumes that the ID from the crown to the physical end is larger than to rifle bore.
Make Sense??

For a rifle where the PL & the BL are the same you could use his formula to solve for BL rather than PL. Then the difference could be used to Counter Bore the barrel.

For Example:

PL: 20”
Counter Bore ID: .5”
Harmonic: 9th

Would give you a Counter Bore depth of 2.1” and thus a BL of 17.9”
 
Last edited by a moderator:
Great explanation on figuring for the counter bore tune.

I have shyed away from posting about this, since it does require the barrel to be altered. All the other PRX tunes, if they don't work, you just go back to your original tune. No harm no foul

If I figure wrong on a counter bore tune, I've trashed a $400 barrel.. DOn't think I'm prepared for that.

I you are interested, I would suggest that you do the initial tune to the 9th harmonic. That way you can still trim the counter bore back to the higher harmonics, rather than try to counter bore again. Much bigger chance of something going wrong

Have a great nite

Tony
 
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