Help tuning- <12 ft lbs. For those in the know
Hi there,
I know most of you are used to work on much higher power, i wonder if you could give me some advice with regards to setting a consistent power/speed for my needs.
My rifle arrived in uk already set up by Ed, at 11.5 ft lbs.
The hammer spring screw is almost all out, with about 3 threads still in.
I wanted to check its consistence so i chronoed it on several occasions.
My aim was to get 570 fps with jsb exact 15.9 grain, wich translates to 11.5 Ft lbs and thereabouts, which is a safe limit i don’t want to exceed.
Anything above 582fps would be above the limit.
I have found however inconsistence between shots, up to 20fps, so i’m obliged to keep the speed at 550fps, to avoid breaching.
550fps is too slow and it changes the poi a lot beyond 50yds.
The changes in speed occur both during the same refill, and from a fill to another.
I.e, i set it a 570 and i think i got a good consistence, then refill and find out 20ps dofference.
I don’t think temperature influences that much, as such changes can be seen in a matter of minutes.
I fill at 220 bar (my bottle gauge) which is 210 on the gun’s one.
I think the power is higher to start with and then goes down and settles at 170bar, but you appreciate police will fill at 200 and start counting from there!!
Initially i thought the spring was beddin in, and needed to be broken in before settling at its final elasticity, but i’ve shot about 2000 pellets and i guess i should have happened already (or do i need more?)
Im currently trying to make veeery small adjustments at time, rather then moving the screw too much, slowly incresing, let’s see what happens.
However i would muh appreciate your thoughts with regards on how to obtain the best speed consistence.
I hear you unscrew the regulator 1/3 of turn and then decrease the spring tension, i guess i should do the opposite, so that more power needs to be applied from the hammer to discharge the air. This way i can tighten the screw a bit more, as right now i think it is so decompressed that it doesn’t “get” or “keep” the fine adjustments i make to its tension.
I hope you know what i mean.
Anyway i would much prefer to find a solution without having to strip down the gun.
I thought wih a regulated rifle i should have not bother with this shite, but it now seems i can’t enjoy using it as im always there checking the speed.
That’s very disappointing i must say.
Any help appreciated.
Cheers.
All Replies
Fired fresh shots after leaving the gun yesterday night with 190bar in it (was filled at 210).
The speed has gone up.
Again.
Freakin useless piece of machinery!
I reduced the hst and will try again in 12 hours.
It must stop eventually.
Still. Obody can explain why this is happening?
It has happened with reg set at 130, 110 and 70bars.
To me it is not a problem of reg pressure, it’s the reg that is shite.
Hi OG, glad to have you back!
So, first let me tell you that on the first attempts the speed was dropping 20fps or more. I don’t know about your POIs with 980fps guns, but i guarantee you that at 55yds, a difference between 560 and 540fps is 1-2 inches, which equals to failure in terms of hunting (imho).
Let alone competin on HFt contests! (thing that im not doing, but it was worth mentioning).
Anyhow, my greatest disappointment has been so far just the sudden unexpected raise in speed i experienced when leaving the gun overnight.
I can live with a gun that loses 10fps over 60 shots, as 60 is plenty for a session of hunting, BUT i can’t keep a gun that surprises me with FAC shots in the morning.
So, do let me cry! 😉 😛
I have ‘t shot this morning, so i still don’t know if have solved the issue with the last tuning.
Stay tuned i’ll update everyone in the afternoon!
Cheers!
Hi Yoda.
I am certainly learning from you! I am finally starting to catch up from my last/lost weekend. I got covered up with emails, PMs and O ring shipments.
I have been trying to keep up with your trials and tribulations on my Iphone. It is too hard for this oldgoat to reply from it and the overtime at work has been stupid. I really don’t have net access at work, just too busy.
You posted that your speeds kept dropping over your 180 shot string. Your first 60 shots had a 10 fps variation and then you were unhappy that the speeds were dropping!
I really thought, to myself, that you should quit crying and take a look at the first 60 REGULATED shots from a Daystate Airwolf, FX Elite, Air Arms, the new Rapid or any of the other regulated air guns out there. A 60 shot 10 fps variation is equal to the best and a whole lot better than most!
I thought that I would just refill after 60 shots.
If you have your Matador adjusted to give you 260 shots with a flat shot string, I am in awe!
I was going to suggest that you substitute a SAE AS568A-008 Teflon O ring in your transfer port, if you can find them in the UK. The ID of it is smaller that the stock copper O ring or rubber O ring that your Matador has. The smaller ID would restrict the air flow and allow you to increase the HST and get better consistently.
Sounds like you are doing great without it! I will throw a couple of the Teflon O rings in your kit on the 16th, just in case! 😆
Please keep us posted!
i think this is great yoda
as i will be getting my 12ft/lb version soon hopefully, i hope it works ok for you pal
scott
Update, for who is interested.
Decreased the reg pressure to 3/4 of turn clockwise (12:45 or 9, as you prefer).
As you suggested i also cleaned the reg pressurized chamber, and relubed the o-rings. I didn’t touch the chamber that has the valve, just the foremost chamber where the washers are.
1- the hst had to be taken almost all out, but there was still thread available.
The spring is basically completely decompressed but i was surprised that still fine adjustments were still possible and the spring was taking them quite precisely.
2- the speed is much more stable, still went down a little with the shots, but something like 10fps over 200 shots.
3- the shot count went up dramatically, i haven’t counted them but i think a full fill at 210Bar gives 260 shots at the very least.
4- the reg came off at 68-70bar
5- i installed a depinger, Ted Holdover’s style (thanks!)
I refilled and the speed was still there. I adjusted the hst slightly on the second fill as i had initially kept it on a safely low speed during the first tuning.
Tomorrow i’ll shot again, if the speed goes up overnight, fooling me has it has done on the previous attempts, i will just give up, as that would mean the problem would be somewhere else, and playing with the reg as i have been doing will never fix it.
So far looks promising, tomorrow the confirmation
Thanks all for the advice and i hope someone will take some good things from my (long) testing, so that they don’ have to go through (nearly)blind attemps as i did.
Cheers
Yes, it is a gradual decrease.
I.e after a full refill, in 60 shots the situation is the following:
the first 20 shots fired “10min ago” are in their 560’s
The second 20’s, fired “5min ago” are around 555
The last 20’s, fired just 1 min earlier are 550
It is very gradual, but progressing, i.e, to keep the whole 180shots at around 560 i would need to increase the hst 3 times at 60shots intervals
Thanks for your advice, i undeerstand it is a bit awkward to figure out!
But do shots fired with a minute wait show the decreasing speed trend that you have been seeing?
Couldn’t suggest anything at the moment.
Shots fired within mInutes are not different.
This happens just after many hours/overnight..
I’m gonna strip it down again, so the consensus is what:
-going back to stock (12:00)
-Increase the reg pressure (11:45)
-decrease the reg pressure further (12:30)
I’m taking votes here!
Dr Edgun, are you MIA?? Help!
Things happen, could be a small bit of dirt from filling or assembly etc.
So what it might be is that there is a small amount of regulator creep making the first shots of the day a little faster, and maybe the regulator is filling very slowly for some reason.
What might be useful but time consuming would be to wait 1 minute between shots, taking an hour for a 60 shot string and see if they are consistent.
Dave
Dave
How can the reG be dirty or damaged if it’s a new gun?
I see what you mean but a faulty reg doesn’t seem the most plausible explaination..
I don’t know if this is of any help, i have also noticed tha if i don’t shot the rifle for a day and then resume shooting, the first 4 shots are gradually higher in speed, then it flattens back again.
Any insight here?
To be honest, the only reason that I can think of the decreasing speed is that the reg isn’t working properly and the regulated chamber is slowly raising in pressure causing you to get a very small amount of valve lock because you have such a low HST.
I know that this isn’t exactly what you want to hear, might want to strip and clean the reg and possibly replace any seals that are damaged. But perhaps if you don’t feel confident then don’t do it
Dave
I really don’t think the hst is the issue here.
If it was the hst inconsistent, then i would see a shot that is 570, then the next 540, then the one after 560 etc.
That doesn’t happen.
It is more like 20 shots 560, then 20 shots 555 then 20 shots 545 etc.
The freaking hst is the only thing that is working here!
I’m sure the valve is opened pretty regularly, it Is what comes out of it that isn’t!
So, with that in mind, ASSUMING that the hst is doing its job properly, puttin always the same amount of pressure on the valve pin, IF the speed slowly and steadily decreases… What is going on?
The reg is supposed to come off at 110 bar or so, and i can clearly tell when this happens (after 180 shots) as the speed goes quickly up.
I don’t think the reg is coming off any time sooner than that.
My explaination is the reg is set too low.
If i increase the reg pressure, i’ll need more hst tension (i have plenty available) I might lose the overall number of shots, but sice i’ve got 180 right now, i can live with it!
Does this make sense?
Would the speed go down like this if the reg was set too LOW?
I’m trying to understand the physics behind it before playing with it again…
CORRECTION:
I just relized that yours was already a 12ft/lb rifle but was shooting a little higher, i thought yours was a FAC & you wanted to turn it ALL the way down to 12ft/lb.
my advice is not to set the regulator lower in that case if you need slower speed but actually a little higher but not too hgih again where you get of it after a couple of shots as stated already.
One way of finding what my rwegulator is set at is to fill using a tank & keep it connected, then shoot over a chrony until i see the speed changing & then i read the tank gauge.
try that & see whats yours set at.
The problem i see here is that if you set the regulator too high so that the hammer isnt strong enough to open the valve you might get a the power you need but with that options you will quickly get off the regulator since its set high & from there every shot will be stronger.
The regulator is very good on the Edgun, that i can tell you but they do tend to go bad & that might be the case.
If you do set it too high than you will see something similar to what your seeing now, every shot will be slower, thats cause you went off the reg. & from that point onwards the pressure is decresing & therefore the shots are faster until a certain point it starts going back down.
The way i change my regulator is remove the front cap & insert a long tube inside & just turn it & put back the front cap. much easier than opening the full rifle, but it needs some time getting used to it.
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Yoda,
It’s completely normal for speed to change a little if the rifle is kept over night. And the reason ur getting a huge POI with just a 20fps spread is cause ur already shooting slow.
You need to find a little lighter pellet & shoot that at higher FPS.