Air Gun Home :: View topic - Custom Air Rifle Build (I hope this works!)

TheAznInvazn · Member

Very interesting...
I may have to play around with both rams that I have then

I currently have a lightweight polymer ram, and I have on order a brass ram
We shall see what happens!

shawnhu · Member

rsterne · Moderator

It has been my experience that a lighter hammer, when compensated for with slightly increased spring preload.... produces slightly more consistent shot-to-shot velocities.... YMMV....

Bob

TheAznInvazn · Member

Since I will have both the light polymer and the heavy brass ram on hand, I'll try both of them out

Bob, I've boon looking into some of your other threads, and I think that I saw that some of your poppet stems are quite long, and I assume that's to increase the time the valve is open (mechanically controlling dwell). Did you find that the longer time the valves were open hurt your efficiency?

rsterne · Moderator

Generally speaking, the shorter the dwell and the higher the pressure, the higher the efficiency.... You can actually see that during the shot string on a non-regulated PCP.... The gun gets less efficient as the pressure drops....

The valve stem length has little to do with the actual lift.... I recently measured the valve lift and it was ony 0.060" at 3000 psi and 0.120" at 1600 psi in the gun I checked....

Bob

TheAznInvazn · Member

Very interesting...
This gives me more ideas to tinker with!!!

I can't wait to get the parts in and start this project!

TheAznInvazn · Member

First round of parts came in!

Solenoid and valve for the project!

Getting excited!

TheAznInvazn · Member

Scrounged around m parts bin, and found a regulator that I will use to control the ram pressure (how hard the ram hits the valve)

Have the stock in transit to me, should be getting here Thursday, and all the misc. pneumatic parts for theoretical testing has been ordered from McMaster-Carr

Once my preliminary testing is completed with the .22 cal barrel I have, if it's successful, I'll step it up and order a .25 cal barrel, either a Lothar Walther or an FX Smooth Twist

Can't wait to get cracking on this!

SMP · Silver Status Member

If you want an absolute proven performer go with the Lothar. The Smooth twists seem cool but there is a lot of spray that they just don't work as intended....enough to have some doubts

TheAznInvazn · Member

I have heard and read quite a few threads across the various forums about the smooth twist barrels, and some people swear by them, while others won't touch it with a 10ft pole.

I also saw the YouTube reviews by Ted/EdgunUSA and the performance he is getting is remarkable
Perhaps before ordering a barrel, I'll talk to Airguns of Arizona and see if I can get some kind of agreement that lets me swap barrels if I get a lemon

SMP · Silver Status Member

I don't think you need to worry about getting a lemon as they are very high quality barrels.

But the smooth twist idea has been around for quite awhile now ( maybe 15yrs) and it's never taken off...gotta be a reason for that.

Beyond that the most accurate rifles in the world air in fact air rifles. And a good many of them use LW barrels. None use a smooth twist design. So the guys who are after gold medals usually know shite from shineola

TheAznInvazn · Member

To be honest, the big factor that's making me lean towards the smooth twist is the barrels ability to shoot hundreds of pellets before needing to be cleaned.

I know that's probably a pretty lame reason to want one barrel over another, but low maintenance is very appealing to me

Even if traditionally rifled barrels do prove to be more accurate, I can live with trading off a bit of accuracy for super low maintenance.
I will also say that current barrel quality is such that up to a certain point, it's the shooter that is the limiting factor for accuracy, and not so much the barrel itself

SMP · Silver Status Member

I wouldn't worry about the cleaning factor. Match barrels are hand lapped to a very high surface finish which means they don't have a problem with lead streaking

After the initial seasoning most would say don't even think about running even a felt through them for several thousand rds.

Just an example. During practice I would probably shoot 200 rds a day. Coming into an open match you wouldn't even think about cleaning your barrel because it could disturb the seasoning. A match day is ish 300 to 500 shots with sighters, ranking, qualifiers and finals. Times two days.

So
Thursday 200
Friday 200
Saturday 500
Sunday 300

During this time you wouldn't dream of cleaning. See what I'm getting at

TheAznInvazn · Member

I see said the blind man!
Though I hear that some people with LW barrels say they need cleaning every 200 or so rounds, or accuracy begins to suffer?

If what you're saying is really the majority of LW barrels, and those who clean after a couple hundred is the minority, than I'll absolutely get a LW barrel, they're much cheaper than the FX barrels to boot!

SMP · Silver Status Member

That's absolutely what I'm say.

After initial seasoning there is no way an LW needs or should be clean that much.