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All Springer/NP/PCP Air Gun Discussion General > Machine Shop Talk & AG Parts Machining

How does tophat weight effect performance?

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Toolmaker:
 I'm about to do my first springer tune. I understand how the guides need to fit the spring but what does the weight of the tophat do for performance? Does more weight = more FPS?

airgunandy:
From what I've seen, yes. But it comes at a price I think. All that extra mass flying about can make the gun more "jumpy."

Tim40189:
I posted a similar question on the old forum and Bob and Gene both advised me there to keep the top hat weight on a Gamo around 45 to 48 grams.  I went a little less than advised at the time and have had great results in several different makes of guns and they said it would not effect the gun overall as long as the results were what I was seeking of the gun and tune combination.  The reccomended weight from Bob is less than the stock weight and I went even less as I wanted to really smooth out the shot cycle and get the most accuracy I could from the gun.  Weigh your stock top hat and then start at appx. 80% of that weight with your new one and check your results, then you can work down from there if you want to tame the shot cycle a little more.  Reduce it by appx. 10% at a step by drilling out the center of the hat or machining off a small portion of the inside the spring end of it.  Good luck with the tune and let us know how it turns out.

Tim

One of the most important things I learned from Bob and Gene I forgot to mention earlier is: velocity is not the reason for a tune on a rifle, it is the ability to acheive accuracy with each shot.  Doesn't matter how fast the pellet gets to the target if it doesn't hit the intended point of impact everytime.  A gun that shoots at 1200 fps is useless if you don't know where it's going to hit, give me the same gun at 800fps with a smooth cycle and a 3/8" group at 25 yards and let's go hunting, or target shooting and you can watch the smile on my face all day long.

tjk:
TM, while Tim gave an excellent reply, there is another use for the top-hat,....spring spacing!!! The TH weight can and usually contributes to higher fps and added 'jump' in the recoil as well, but proper spring spacing can achieve the same initial goal of more velocity without the added re-coil. The trick is to space the spring for its maximum power and efficiancy,...and no two springs are the same either. That's why Maccarri custom fits the components in the tune kits he offers. An example: a delrin or other light weight material used instead or ss or brass. Just something to think about. tjk

Toolmaker:
 Thanks for the info guys. This will be a learning experience. I believe I'll make the tophat from delrin. I want good power but not at the cost of accuracy.

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