Resources Tuning the Piatt/Thomas

[Troy Bakel]

She’s a real nice lady. I was lucky to buy 2 of Wills rifles after he passed from her.

That’s cool about the name engraving

I have only talked to Mrs. Piatt on the phone and she is very pleasant to talk with.

Mr. Piatt has such a good reputation, I wish I had the chance to shoot with him.

 

[Troy Bakel]

those are great procedure write ups......thanks alot.....BC
and thanks for reconfirming my recollection of the procedures......

I had time tonight to compare the tapered #6-32 with a non tapered #6-32 of nearly equal length (~2 threads longer) and the FPE dropped to 10.9 - 11.3 over 50 shots. Backed out the jet screw just until 1 thread was visible and the FPE jumped to 12.9 - 13.7 over 4 shots.

So l am leaving the rifle tuned with the original jet screw at just less than 12 FPE.

Unintentionally, I now own a USFT, a Thomas, and an FX M3 all tuned to <12 FPE.

 

[thomasair]

Be mindful that the taper has nothing to do with the guns performance. Fiat or tapered are functionally the same.

Mike

 

[igolfat8]

Be mindful that the taper has nothing to do with the guns performance. Fiat or tapered are functionally the same.

Mike

Out of curiosity Mike, how do you drive a "Fiat" into a Thomas jet hole? Perhaps its one of those jet powered Fiats?

Sorry, I couldn't resist

 

[thomasair]

You gotta get a good run at it.

 

[Troy Bakel]

Be mindful that the taper has nothing to do with the guns performance. Fiat or tapered are functionally the same.

Mike

I agree. I just re-tested the full length #6-32 by backing it out from seated ~1/4 turn at a time and achieved 11.2 to 11.9 FPE over 6 shots.

Last night's test was way off because the jet screw seems to face off the cap and not the shaft (leaving a bit of open air space) and the length of the cap is about what? 3 to 5 threads. So backing out the screw to expose 1 thread above the cap pocket opened the airway a fare bit.

Why is the original jet screw somewhat shorter and tapered?

 

[thomasair]

I put a taper on mine because it makes the transition from fully into the transfer port bore to just beginning to leave the bore less sensitive. With a flat ended screw....a tiny bit shorter can make a big difference if you happen to be just emerging from the bottom bore in the port.

Mike

 

[cavedweller]

@cavedweller, Hello Rudy! We shot together when you stopped buy PSA to visit Rod!

I was shooting my Rod tuned and setup USFT off of my Rod customized Targetshooters.com one piece rest.

I forgot you sold this rifle to Rod. The serial number is 0314 (my wife's birthday!!!!)

What do you know about this rifle? When I ran a dry patch through the barrel it came out spotless, a second patch with WD40 was also spotless. So unless you shot it and cleaned it I don't think you or the person you bought it from shot it.

I contacted Mrs. Piatt and she is going to research her husband's gunsmithing paperwork to find any related info on this rifle and pass it along.

I bought this as the third owner- guessing Piatts wife sold it to the guy I bought it from. I wanted to make an FT stock for it but……
Definitely didn’t see much wear or tear well cared for tool!

 

[edgard]

interesting!

 

[Troy Bakel]

interesting!

I combined the setup procedures listed above. I executed the hammer spring adjustment optimization process as part of the procedure and when finished all settings - jet screw length, jet screw taper, hammer spring adjustment knob position - were the same.

The greatest effect on accuracy was changing to a one piece pendulum rest with a mechanical top ( no sand bag).

From: 

To:

 

[igolfat8]

What is a “pendulum rest”? Are you using a bungee on the new rest?

 

[Troy Bakel]

What is a “pendulum rest”? Are you using a bungee on the new rest?

I found bungee cord is a bit too springy.

I use two strands of 40 mil Spectra as the core of a 23.015 meter cobra braided parachute cord that is knotted into a 9 foot diameter monkey's foot with a 1.6 ton pure cobalt 60 ball bearing core having a 75.0173 micron thick Zirconium surface layer.

The Cherenkov radiation burns like a bitch but once you get the gun duc taped tightly to the monkey's foot, your POA will never shift.

At least while you are still breathing.

 

[igolfat8]

Your words paint a vivid picture. Thanks for the detailed explanation.