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Tuning Custom Spring Guides

They can be different (esp. true "custom") would your spring be needed, yes or exact measurements but unless you are planning on making your own (lathe) if available for your rig you might be better of buying a kit. JM is well known https://www.airrifleheadquarters.com/page/page/251488.htm

Whatca tuning? How much wear to date & such would make a difference - spring sag... -. Depending on what you own some might well have both factory and custom measurements so you could DIY.

Some have been known to do a "shrink tune" (maybe not the hot ticket for top end springers?) as in shim yours with shrink tube/other. 

Personally always used full kit's from JM. Vortek & others may be worth looking at.



John
 
You're probably not going to get a custom guide for your existing spring unless you have a tuner make it or you make your own using a metal lathe.People who manufacture a lot of parts (like Jim McCarri) don't have time to work on "one-off" parts. Least expensive option is a shrink-tube tune. You just get some heat shrink tubing and shrink a layer onto your existing guide. Cost is a few bucks for the heat shrink tube. The next least expensive option is if JM or another parts supplier sells a spring to fit the factory guide for your gun. Then you're cost will be around $20 or so for the new spring. Fit will probably be better than the factory spring but there's enough variation in parts size that fit can be anything from great to just so-so. Next option would be to buy a kit with all parts (guide, spring, top hat) already fitted together. A kit will run you $60 or $80. By the way, the spring guide needs to fit both the spring and the latch rod (center of piston) if your gun has one. Length of a guide cannot be longer than approximately the length inside the piston. I say approx because sometimes there's a little bit of extra space available. Some factory guides are full length and some are shorter than they need to be.
 
Its something I have been testing for years, drawn from maybe 100 tunes.

The main conclusion I drew (My own conclusion personal to me and not everyones experience) Is that the Top hat makes all the difference.

The fit of the rear guide does not seem to effect accuracy. It can effect velocity and noise, depending on the material but running the numbers, it does not appear to effect consistency shot to shot. However, I found the Top hat to be much more critical. 

The Top hat serves to centralise the flailing spring end at the distal end of the piston. If made correctly, centralising it about the latch rod, or centralising it inside the piston. This does impact shot to shot consistency, and depending on its weight, can play a critical part in balancing the cycle. It also can remove torque given up to the distal end of the piston.

The Guide Rod, in almost every gun I have ever tuned, is usually well centred enough. This is because the latch rod has to pass through it....which sort of enforces a no choice but to have it pretty well central at manufacture, or the gun will not cock. This being reasonable, limits improvement. From here, we can then argue all day long as regard its material. Steel giving a slightly faster spring release versus slightly more damped sound from one of Delrin. I have never detected better shot to shot consistency regardless of which i used, except for better feel and nicer sound. Also any spring resonance occurring here will start milli seconds after the pellet has gone.

The real key is get on and learn your gun and find the best pellet for it....




 
I have two guns a Beeman 97K and an HW50s. I recently ordered a kit for each from ARH, so I guess I'll see what comes with that. I'm new to all this but I got up the courage to open up my 97 since it was making a grinding sound on cocking. It was a used gun, but from a well respected member on gta. I found the minor problem and corrected that and cleaned and relubed everything. It now cocks and shoots even better. I just ordered a kit to have for down the road.

The 50 is a new gun from aoa. It shoots great but really has a twang/buzz. After a while I will get brave again and put the kit in it. I've only got about a tin of pellets through it so far so I'm just going to shoot it some more.

I was just curious about the custom spring guide. Thanks for the replies.
 
Top hat reduces vibration at front of spring and spring guide reduces vibration at back end of spring. The spring guide also keeps the spring straight so it doesn't "kink". Combined length of top hat and spring guide has to be short enough to fit inside the piston (approx). You might not be able to use a top hat with factory guide. With a kit, everything will be matched up and properly fitted.