Tuning Repairing a 1998 Air Arms Pro Elite

[Bill_S]

The cocking arm was pinned onto the barrel, and secured with a new e-clip.

I lubed the top hat and inserted that inside the piston, then lubed the original spring with Maccari "black tar". Man, that stuff is messy.

The spring and guide were inserted, and it was time to put on the trigger assembly to hold it all in. I noted that there was 1.9" of preload on my old original spring. It definitely requires a spring compressor to get it back together. In the photo below, the spring is butted against the trigger assembly and I still have to align the two holes at the arrows to be able to attach the threaded stud.

In the spring compressor and tightening trigger assembly screws to hold everything together...

And done.

 

[Duckfish]

Awesome, can’t wait to see its performance.

 

[Bill_S]

I put another couple dozen pellets through it and the average velocity is climbing. This morning's last 12 shots averaged 773 fps, with a high of 780 fps and a low of 768 fps. With these pellets, that's a little under 19 foot-pounds.

That's down from when the rifle was new in the late '90s where the average was in the 820-830 fps range. Before the seal went, it had settled into about 780-790 fps after a couple of years of usage, so I suspect that the spring had set a bit. I'm re-using the old spring as outlined previously.

I'm also testing with 20-year old pellets, and they are oxidized. That could impact performance. I need to get some new ones.

 

[Theoben Eli.]

Im now its a old thread, when you have the PE in parts did you measure the piston stroke length ?

 

[Bill_S]

Unfortunately, no, I did not measure the stroke. Sorry!

 

[wijib]

I was wondering why you felt a need to lapp the compression tube. All the springers that I have tuned called for honing the tube in a cross hatch manor. This allows for the piston seal to better seat during the break-in period. Your Pro Elite is a very nice break barrel rifle and it looks like it turned out well. How has it been performing? Accuracy? I was thinking about acquiring one myself.
Bill

 

[A.G.R]

I was wondering why you felt a need to lapp the compression tube. All the springers that I have tuned called for honing the tube in a cross hatch manor. This allows for the piston seal to better seat during the break-in period. Your Pro Elite is a very nice break barrel rifle and it looks like it turned out well. How has it been performing? Accuracy? I was thinking about acquiring one myself.
Bill

He was Trying to true a cylinder , that being said.. the rear section of these guns are tight from their slotted design. The compression tubes,in the piston area rarely were the issue, but rather a poor fitting piston seal design that heated up and swelled from the short stroke over sprung small port design , causing them to melt weld to the face of of the chamber..

The bad rap of tapered tubes is just that big rumors.. I’ll take every one of your tapered tube Pro Elites.. with extensive piston work they are the best break barrel springers made.

 

[wijib]

He was Trying to true a cylinder , that being said.. the rear section of these guns are tight from their slotted design. The compression tubes,in the piston area rarely were the issue, but rather a poor fitting piston seal design that heated up and swelled from the short stroke over sprung small port design , causing them to melt weld to the face of of the chamber..

The bad rap of tapered tubes is just that big rumors.. I’ll take every one of your tapered tube Pro Elites.. with extensive piston work they are the best break barrel springers made.

Many thanks for your remarks. What sort of "extensive piston work". Are you referring to the mods that Paul Watts used to make on them?

 

[Ozwald]

Very well done, Like the way you make your own tools for the job at hand. You have a very nice rifle and even better now you have put some love into it. Steve!

 

[A.G.R]

Many thanks for your remarks. What sort of "extensive piston work". Are you referring to the mods that Paul Watts used to make on them?

The piston needs to be disassembled and remmachined to take a R1/ Hw 80 cup type seal, as well as cocking slot work. . Then the rod needs to be shortened as
well as port work and some bracket work. New spring and guides as well top hat.

This is not for trying to gain huge power but to get a dead blow shot cycle with easier cocking gun. When done right they will shoot much smoother and perform to their potential.. 20 to 22 ft lbs..

These guns are not and never were designed to shoot much more at the stroke and piston set up. I’ve had them at 26 ft lbs and they are seal burners and will not take the heat Generated with a 85 mm stroke

Paul Watts work is top notch , that being said, I’ve taken this gun and a few other as far as they can go and found every weakness and have addressed it.. In stock form it’s not if they will burn up, it’s when. The seal design was done by the janitor when everyone else was on lunch.

 

[JSNZ]

The cocking arm was pinned onto the barrel, and secured with a new e-clip.

View attachment 149531

I lubed the top hat and inserted that inside the piston, then lubed the original spring with Maccari "black tar". Man, that stuff is messy.

View attachment 149537

The spring and guide were inserted, and it was time to put on the trigger assembly to hold it all in. I noted that there was 1.9" of preload on my old original spring. It definitely requires a spring compressor to get it back together. In the photo below, the spring is butted against the trigger assembly and I still have to align the two holes at the arrows to be able to attach the threaded stud.

View attachment 149547

In the spring compressor and tightening trigger assembly screws to hold everything together...

View attachment 149554

And done.

View attachment 149562

Fantastic write-up. Im currently in the process of doing my Pro Elite. Ive just got it from UK (Im in New Zealand), so its sub 12fpe model in .22. Ill try and get it to where it should be - 19+FPE. From the measurements of my piston everything points to only difference being the spring!

Did you measure the transfer port on yours?

Also, the Leupold scope suits it nicely, do you trust it to stand up to the recoil? Out of interest what model is it?

 

[Bill_S]

I'll try to measure an approximate diameter of the transfer port later today.

The Leupold scope is a 3-9x33 EFR. Within the first year of usage it developed an issue and I sent it in for repairs. Since then, I have had zero problems with that scope. Leupold customer service was very good - at least ca. 2000. I haven't needed service since then.

 

[Bill_S]

With the gun assembled, the transfer port is difficult to measure. It appears to be approximately 1/8 inch (~3.18 mm) diameter using a steel rule placed across the opening. It could be smaller than that.

For another data point, I used a small 0.129 inch (~3.28mm) diameter machine screw to use as a go/no-go gauge, and it was slightly too large to slip into the port.

I hope this helps get you in the ballpark!

 

[JSNZ]

With the gun assembled, the transfer port is difficult to measure. It appears to be approximately 1/8 inch (~3.18 mm) diameter using a steel rule placed across the opening. It could be smaller than that.

For another data point, I used a small 0.129 inch (~3.28mm) diameter machine screw to use as a go/no-go gauge, and it was slightly too large to slip into the port.

I hope this helps get you in the ballpark!

Thanks for that, its just a ballpark size to check against mine - in case the TP was reduced on UK models.

Thanks regarding the scope. I have a 6.5-20 EFR "Air Rifle" scope that I may put on, good to hear they hold up ok. Their service / warranty is very good though in the case it doesnt.

On another note I emailed Air Arms and they confirmed within a couple of hours the glue they used was Loctite 480, which seems to match the black glue left on my piston.

 

[JSNZ]

Work has been slow, but the parts from the Countrystore/ Airgun Spares in the UK finally arrived. Most of the delay in shipping was a stop in Chicago where the order sat for weeks.

View attachment 149030

I purchased three OEM seals, two piston rings, one e-clip (that's all they had in stock), a Pro Elite spring, and a Titan spring to fit a Pro Elite.

The Pro Elite spring sent must be UK-spec because the wire is significantly thinner than my U.S.-spec spring. It had a wire diameter of 0.128" with 31 active coils vs. 0.148" diameter/34 active coils of my original spring. The fit was loose over the original spring guide. Estimated spring rate is 31 lb/in vs. 48 lb/in of my original.

Here's a photo of the original Pro Elite spring (top) compared to the replacement from the UK. The difference is obvious.

View attachment 149038

The Titan spring sent is much closer to my original, but still uses a bit thinner wire at 0.141". It has 30 active coils, is nicely made, but is still a bit loose on the existing spring guide. The calculated spring rate is 43 lb/in which is very close to what the original US-spec spring is.

View attachment 149049

My conclusion? - Re-use my old spring and have the Titan for a backup. It would require new spring guides, but I can have those made when/if I need them. The link for Chambers in the UK shows two possible springs for the Pro Elite, so possibly one of them might be US spec. I may try to contact them in the near future to see about that.

The seals shipped looked very nicely made. They snap right onto the piston, but aren't tight without being glued. They can be pulled off again with little effort. They are possibly a urethane material that is more flexible than the Maccari seals that I pictured earlier. Also, they have a parachute lip around the edge. It has a significant outward flare.

View attachment 149055

Im in the process of restoring my UK spec Pro Elite to full power Export / US spec. Does anyone have a lead on original Pro Elite springs? The only thing i can find is the Titan which by your experience seems a little loose on the guide so will likely twang.