Spring Gun Modifications?

[NeilMac]

I have been an FT and HFT shooter for more years than I care to admit to. Before that I did a lot of hunting and before that I shot full bore, pistols and rifles.

I have owned a couple of springers over the years, an excellent TX200 back in the late 80's, if only I had realised how good it was. A Whiscombe, which was very enjoyable to shoot and very accurate and which I sold for a quarter of what they are now worth, and now I have an HW77 that has recently had the trigger tweeked and I am considering the prospect of doing some proper FT with a springer.

I have a good mechanical understanding of guns and machines in general, I rebuild regs and triggers and was for a long time an amateur engine builder / tuner working on custom and racing bikes and cars, I also used to set up chassis on racing cars for people.

I see a lot of threads on here about different springers, mainly TX200, HW77's / 97's and more recently Walther LGU's and I wonder what all the various piston / spring etc modifications actually do and what advantage they bring to a rifle.

[cooper_dan]

I don't know all the in's and out's, and have only tried a few things. But this is my basic understanding:

The first thing to consider is that most airguns are now designed for overseas markets, i.e without the 12 ft-lb muzzle energy we have. In this country we get the same basic high powered design, but throttled back in some way to comply with the law. For example soft springs (TX200) or transfer port restrictors (Diana springers).

This means we are generally getting an inefficient design.
The general idea of tuning is to either increase the efficiency of the powerplant, or to make the shot cycle feel how you like it. Which route is best is a very individual thing.

The basic drop in kits will use the standard piston but replace the metal top hat with a plastic one. The metal top hat helps to achieve power on the overseas guns, but we don't need it so the weight comes out. This means less mass is flying around inside the gun and therefore recoil feels less.

Short stroking, will decrease the volume of air available to the piston. As before, high powered guns need a lot of air to make the power. As we can't have access to that power, we are compressing the extra air for no benefit. So reducing the available air to just the right amount, can increase the overall efficiency.

Reducing piston weight again means less weight flying around, but needs more spring load to achieve the power you want unless you can balance the spring/transfer port/pellet selection. At this point you are getting into the realms of tuning the gun for specific pellet (due to pellet start pressure/piston slam/piston bounce)

Then reduced diameter pistons are again trying to increase efficiency and use lighter weight components. Due to the much higher pressures generated, pellet and seal selection seems to be important. Some people have reported more hold sensitivity but I can't say for sure.

But all of this means nothing until you pick the rifle up and try it. I've had a go with most tunes in other peoples rifles, and actually prefer a more basic setup for HFT.
Some people prefer quite harsh shot cycles that feel 'fast'. Other's prefer a softer cycle that feels 'slow and lazy'. I'm somewhere in the middle.
I actually think a HW77 is almost perfect as it is, so you have a good starting point.

And as always, no amount of tuning will buy you points. You still have to put in just as much practice and work as anyone else. But what you can do is make the rifle more enjoyable to shoot. This is where I think the main benefit lies. If it's fun to shoot, you will shoot it more often and be more relaxed doing so. If you don't like how it shoots, you will lose focus and won't want to practice, regardless of how fancy the tune is.


Hopefully someone more informed will be along shortly to correct everything I've said

[NeilMac]

That all makes sense, thanks.

I am really interested in what the various kits do, which then allows me to consider what, if any changes I wish to make to a rifle.

Yes the 77 is very nice to shoot now all the creep has been removed from the second stage, as a regular Anschutz 9015 shooter having got used to a really excellent trigger, creep is just something that I cannot live with.

[cooper_dan]

That all makes sense, thanks.

I am really interested in what the various kits do, which then allows me to consider what, if any changes I wish to make to a rifle.

Yes the 77 is very nice to shoot now all the creep has been removed from the second stage, as a regular Anschutz 9015 shooter having got used to a really excellent trigger, creep is just something that I cannot live with.

I think the best thing to do is try as many differently tuned rifles as possible. See which one you like best and then politely ask what they've had done. For me it's all about how it feels in the shoulder.

None of the weihrauch or air arms triggers I've used have had any creep in them. By creep I mean the trigger is moving but the sears are not. I do have quite a bit of travel in mine. I don't like the 'breaking glass' second stage that most people do. Very personal thing though

The 9015 has an incredible trigger so you've got a very high base line there

[NeilMac]

I'm very much a breaking glass type and have sold good rifles in the past because I could not get the trigger the way I wanted.

I am fortunate to shoot in the same region as John Farbrother, so he worked some magic on my 77 and the trigger is now exactly how I like it.

I'll take your advice and try a few different rifles, but I think I already have a better understanding of what people are trying to achieve.

[Hawkeye20]

i put a spoiler on mine to help with windage

[NeilMac]

I'll try that too

[TonyL]

Excellent and comprehensive post #2 from young Dan

[PhatMan]

NeilMac,

One chappies 'good' tune is another's poison.

Rarely have any efficiency figures been published to show that one tune is more efficient than another, or indeed better than the stock rifle.

A lot of the apparent benefits are based on a very personal 'liking' (or not) of the firing cycle. That is what chappies can experience, and take a view on.

Thus the view of the particular tune is not based on hard data, but empirical user opinion.

My 22 mm Mr. Leach TX200 innards, are for me, the best shooting power-plant I have used in my TX - light cocking effort & virtually no sight disturbance on firing are winners for me.

Wonky Donky's 25 mm extreme short stroke (70 mm) TX innards also shot very nicely (for me) as well.

However, I have no idea of the efficiency of these tunes WRT standard.

Have fun & a good weekend

Best regards

Russ

[NeilMac]

Thanks for that Russ.

I have been at a SWEFTA training session today and was able to speak at length with John Farbrother our local spring gun expert, he said much the same as you.

I now have a much better idea of what tuners are trying to achieve and some of the methods used.

[cooper_dan]

Excellent and comprehensive post #2 from young Dan

Shame I don't listen to my own advice sometimes

It's interesting that efficiency has been mentioned, and I think I agree that we should try and measure this a bit more. Although efficiency is not an indication of accuracy or how nice the shot cycle is, I think it could give an idea of what you are getting when you go down certain tuning routes. Especially if your goal is something like making your springer easier to cock so you can enjoy it more.

If my memory is correct, my standard mk3 TX200's were 33% and 35% efficient (HC and full length). My full length with mk2 internals was up to 39%. And with mk2+ internals its up to 42%. I'm hoping to get it up to 45% and then leave it be for a while. (yea right!)

I like measuring it because it gives me a way of tracking the small changes I've made.