Choices choices…
Ok, my valve seems to be doing pretty good but the fps deviation is a tad more than I’d like (14fps). I’m getting similar upper-numbers from both of the following:
10mm of spacer with a 100g hammer.
17mm of spacers with a 50g hammer.
Which config would offer better long-term consistency do you think?
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31gr Kodiaks. 🙂
Next string was all over the place. Left it for a couple of hours, then fired one more which came in at 550. WTF? Turned out the hammer was dragging on the barrel (there was a slight imperfection in it’s delrin sleeve). Cleaned that up and got the following:
2600psi
17.5mm spacer
80gr hammer
5.5mm aperture
1007
1029
1033
1034
1034
1034
1029
1028
1020
1016
Max deviation of 27.
Looks like the hammer was retarding every one of the last ten-shot string.
I’ve got a bit of air blowing out on the valve, I think I ran the delrin a bit hot when I cut the last aperture-plug and it took a few thou more off than I wanted. Easily fixed.
That is really good I don’t think i’d change a thing, maybe alittle more tweeking what pellets are you shooting it is probably on here so if it is forget me.
Cheers Mam. Yes, it’s looking more hopeful now. 😀
Well now that is smoothing out nice…..
Finally getting somewhere. It was definitely the 6mm aperture…
2600psi
15mm spacer
80gr hammer
6mm aperture
1077
1081 +4
1084 +3
1086 +2
956 -130
963 +7
827 -136
944 +117
938 -6
934 -4
I tried various fills with various spacer combos, nothing worked, the FPS was wildly inconsistent.
2600psi
17.5mm spacer
80gr hammer
5.5mm aperture
988
994 +6
983 -11
985 +2
985
972 -13
974 +2
973 -1
973
969 -4
I’ll try 16mm spacer tomorrow and see if I can start a little less hot and get a more even spread (and more useable shots). Might try upping the fill a bit too on the current spacers.
I should add here that Pablo’s getting similar numbers but using only 25psi per shot, comnpared to my 35psi per shot. I reckon this is down to Blod’s valve having a 5mm bore in the stem compared to my 6mm. My design is less efficient if that’s the case. I’ll get around to cutting a new stem at some point with a 5mm bore.
Looks like you’re headed in the right direction Lang….
Pellets came today. 🙂
Made a 15mm spacer, started off at 2900psi and climbed from 830fps to 944fps. Then there was a sudden transition to 1018fps. Took a bottle-reading, it was at 2650psi.
So, from 2700psi:
1018
1028
1059
bad
bad (turned on the overhead light and closed the door, too much sunlight)
1045
1030
1033
1012
1005 Took reading, 2300psi.
There’s the bell-curve, but it’s far too sharp for my liking. And this valve, at least with this particular aperture (6mm) seems to have a taste for sudden transition. Like it goes from not opening nicely to suddenly opening full chat (944 to 1018 on this run).
I think I’ve exhausted the spacer options, I’m going to reduce the weight of my 150gr hammer and have a play with that now.
Sorry Mam, I had the reply-window open for the last few minutes and missed your post. Are those pellets .25?
Yes they are .25cal…
In that case yes, I’d very much appreciate them. Thanks Mam. 😀
Re your earlier point, yes, if the reg works out I’ll definitely get a bigger bottle.
Sorry Mam, I had the reply-window open for the last few minutes and missed your post. Are those pellets .25?
Yes they are .25cal…
2100psi to 2000psi 10mm spacer 60gr hammer:
1004
989
978
3000psi to 2900psi 10mm spacer 60gr hammer:
479
499
488
498
502
I guess this is a perfect setup for the 2000psi regulator, IF it has the volume.
Sorry Mam, I had the reply-window open for the last few minutes and missed your post. Are those pellets .25?
I’m down to eleven pellets and the shop just rang to say the order I put in on wed night for three tins is down to two (all they have) and is going out today. Hopefully I’ll have them tomorrow.
Pablo’s a fan of starting with a lower initial fill in the bottle. I tried that last night, starting at 2600psi and using 7mm spacer with the 100gr hammer. I got the following 10-shot string:
947
1004
1058
1038
1048
1032
1032
1030
1025
1018
It’s weird how the first shot is always low. 2600psi in the middle of previous strings gives well over 1000fps every time. Maybe it’s the nylon-on-delrin seal right after a fill is causing some kind of stickyness…? Odd. Apart from that though it’s a reasonably decent spread of fps. Question…would you guys say ten good shots at .25 is what I should expect, or would you expect more? If they were all in the 950fps range would twenty be expecting too much?
Edit: Damn, my question’s answered by my own numbers above with the 20-shot string with 5.5mm aperture. A high of 1021 to a low of 959 gives a max deviation of 62, and all sub-sonic.
That’s today’s work sorted then, I shall be mostly cutting a new 5.5mm insert and pumping that bottle again.
Yea the consistancy looks good. There still seems to be a lot of air going
somwhere but I have never dealt with .25 so I am not familiar with how
much air it takes to get one up to speed. I don’t remember if you are
using a stock size bottle but as we are aware, a larger bottle would
surely help….The difference in shot count between my Airhog valve and
the US Blodnob is probably triple but the US Blodnob valve doesn’t flow
as much air as the Airhog hence about a 100 lower range of FPS. I am
just rambling.
Oh, on a final note….I have about 100 Diana Magnum Rastatt pellets
that I
can’t use. They resemble a JSB Exact Diabolo…I got them in a pellet
trade deal…You want me to pack them in with
the Airhog stuff when I send it?
*JaboOody Dubs Billy Mays voice* “Mmm, BURNT CHEESE!”
Ahem. Turns out my 50gr hammer is actually 60gr and my 100gr hammer is actually at least 150gr. 😳
Thanks for the encouragement and suggestions guys, it’s all appreciated. 😀
I’m down to eleven pellets and the shop just rang to say the order I put in on wed night for three tins is down to two (all they have) and is going out today. Hopefully I’ll have them tomorrow.
Pablo’s a fan of starting with a lower initial fill in the bottle. I tried that last night, starting at 2600psi and using 7mm spacer with the 100gr hammer. I got the following 10-shot string:
947
1004
1058
1038
1048
1032
1032
1030
1025
1018
It’s weird how the first shot is always low. 2600psi in the middle of previous strings gives well over 1000fps every time. Maybe it’s the nylon-on-delrin seal right after a fill is causing some kind of stickyness…? Odd. Apart from that though it’s a reasonably decent spread of fps. Question…would you guys say ten good shots at .25 is what I should expect, or would you expect more? If they were all in the 950fps range would twenty be expecting too much?
Edit: Damn, my question’s answered by my own numbers above with the 20-shot string with 5.5mm aperture. A high of 1021 to a low of 959 gives a max deviation of 62, and all sub-sonic. 17mm of spacer though…
I think I would lower hammer weight slightly along with the tophat.
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I think you’re on to something Lang…
I want to see that stinkin valve and apeture plug…lol