Q:

Questions about Mac1’s "sweet spot" essay in Quick

http://www.network54.com/Forum/419052/message/1230837463/Airforce+Sweet+Spot+101+by+Tim+McMurray+of+Mac-1

I know nothing beats a chrony for proof of the pudding, but doubtful I’ll get my hands on one anytime soon… and Tim states:

“The performance level that seems to give the best accuracy and shot effieciency is a setting on the gun from 0-4 on the wheel and a .100″ gap between valve top hat and the valve face. ”

He also states that a 2500psi fill is optimal.

Has anyone confirmed this through their own testing?

Since I don’t have a chrony, I’m wondering if his suggestions are worth a try. Has he discovered the one-size-fits-all set up for AF guns?

For what it’s worth, my tophat’s at .87, I’ve been filling to about 2900 with PW on 8. The gun’s working great… I’m hitting rolling golf balls at 30-35 yards, but I wonder if his setup provides a superior overall efficiency (better accuracy is cool too)

Any comments?

General Chat

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Viewing 7 replies - 1 through 7 (of 7 total)

quote knifemaker:

Did you mean .097, or is your valve as long as your barrel? 😀

Mike

Oh go play with your pointy-things Mike LOL.

Yea, I missed a zero. .097″ is the standard valve clearance.

I too cant shoot below 10 on my PW, I get the same wierd 100fps velocity variations.

Maybe our valves are twins.

Mine is set at .067 on a condor valve. Any time I have tried to go below 7-8 on the power wheel, I start getting erratic shots. Low-High_low. Like 100fps and more low. Very un-predictable. but that is just my gun.

Did yoyu mean .097, or is your valve as long as your bbl? 😀

Mike

Condor valves come from the factory set to .97″

I didnt mess with it for almost a year. Its now at .78 and shoots the exact same velocity with a lighter hammer.

Weird I know, but this gun always has been.

Good point, PCPs existed before chronographs. IMO when you’re paying attention you can tell when the gun drops off in power and pellets at longer ranges start hitting low. So it should be possible to work out number of shots per fill by the technique Tim suggests (bump up the fill pressure from 2500 (or even lower in some cases) in small steps until the power drops off. This might be harder to judge.

This needs to be done for various spring preloads, Tim suggesting lower numbers.

As I understand it, Tim takes the actual ME out of it by opening the valve up (tophat wide) for the initial testing (to find the fill curve). The tophad can be adjusted down to lower the MV and increase shot count.

Remember, he’s all about consistant shot count at reasonable power. Not raw power, that calls for a different plan.

Good luck.

Doug Owen

Buzz
I bought my talon SS from Tim, tophat is .100 plus.
On PW 4 I get something like 200 shots, shooting paper power is not in question.
When I first got it obviously I had to presure it up to 3000psi and experienced valve lock, thats the time I learned what it is all about.
Later I went down and bought a reg. talon, under his chrony PW had no effect on the velocity, he tuned it right there, cut some bit off the hammer spring to where the PW actually did something.
I believe that every valve is it’s own, as well as the gun itself.
It all depends on what you have.
Tim definitely sets them up for consistency and shot count
Totally happy with the guns I bought from him.

SAW

Thanks Doug, I fully agree with your comments, each rifle has it’s own soul, so to speak…

The price of a chrony isn’t a roadblock, and I might have clarified that I’m just looking for “Pretty Damn Good” and not “Absolute Best”.

In retrospect, I should’ve just set the gun up according to Tim’s advice to see what happens… it’s not like I can’t set it back.

A couple of thoughts, Tim and everyone else I trust has said from the start that each AF gun is a law unto itself. You’ll note it that same post Tim says it’s basically impossible to tune one tank and valve to act the same as another on a given gun.

Knowing that, it’s clear that there is no universal ‘magic formula’. A little logic says this as well, if there was such a can’t miss setup, don’t you think AF would tune that way before the guns left the factory? I mean just because Gaylord used to work there doesn’t mean they’re all incompetent does it?

When folks tell you you really do need a chronograph to properly fine tune your gun they’re not trying to sell chronographs…….

You can buy a perfectly fine chronograph for this for under $50 US shipped to you in a weeks time:

http://www.chronoscopes.com/

My (free) advice is follow all the other advice, get a chronograph and stop guessing.

Doug Owen

Viewing 7 replies - 1 through 7 (of 7 total)

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