Kral Arms A question for you "Unregulated PCP tuners"
- Thread starter Motorhead
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I’ve owned regulated guns in stock form that would have a higher ES than that. Out of curiosity, how much gap/ free flight is this rifle set at?
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I changed it up a bit from Troys typical, the inner spring now sits a tad longer out of the larger by @ 1/4"
This places free flight to the smaller spring @ 1/8" and @ 1/4" to contact the larger primary. Outer is a .500 od .052" wire x 2" and inner the same length tho never measured wire size.
The spring guide post was cut off all but the last 1/4", that allowed making a acetyl nub that i.d. of larger spring firmly slides over and sorta snaps onto. When hammer goes into free flight the primary spring stays attached to adjuster cap staying also centered.
Small inner spring is allowed to float, and it sits on top of this guide nub which sets it the 1/4" forward
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That's a phenomenal set up, but do be aware that your ES is likely closer to 39 than 29 (still great though!) . . .
You can see that it is likely that the peak speed occurs somewhere between 2750 and 2500 (and is probably coming down as it hits that value you show as the peak at 2500 psi). Add in that those are already average values of two shots at each point, and the ES clearly will be a bit higher.
I just point this out as these little things do matter in getting to an actual value. In the end, it won't impact accuracy at normal, ranges hardly at all - and we all know that many people pointlessly chase lower ES values than they really need, as though it is the goal that really matters (and maybe for them it is).
You can see that it is likely that the peak speed occurs somewhere between 2750 and 2500 (and is probably coming down as it hits that value you show as the peak at 2500 psi). Add in that those are already average values of two shots at each point, and the ES clearly will be a bit higher.
I just point this out as these little things do matter in getting to an actual value. In the end, it won't impact accuracy at normal, ranges hardly at all - and we all know that many people pointlessly chase lower ES values than they really need, as though it is the goal that really matters (and maybe for them it is).
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Ran some numbers today .... 70 shots on 400 psi = 5.71 psi per shot.
1200 psi sweet spot divided by 5.71 = 210 shots.
A lot more if one keeps blasting away correcting as it slows down ... slowly
1200 psi sweet spot divided by 5.71 = 210 shots.
A lot more if one keeps blasting away correcting as it slows down ... slowly
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@Bear-of-Grayling , I loved learning how you compensate for pressure with change of pellet weight/type
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Help me understand something. All my 4 guns are .25 cal. I just shoot from bench, 50 yds max (for now). So it seems to me that FPE doesn't matter to me, just accuracy.
The graph above shows a great deal of pressure drop from 875 psi to 775 psi in 30 shots. Is that plenum pressure? Anyway, I would think that that much pressure drop would cause significant POI drop even at 50 yds. Is this right?
The graph above shows a great deal of pressure drop from 875 psi to 775 psi in 30 shots. Is that plenum pressure? Anyway, I would think that that much pressure drop would cause significant POI drop even at 50 yds. Is this right?
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A non-regulated pcp does not have a plenum. I dont see what you are looking at, I think the 875-775 is fps not psi. Most of the time when somebody posts a shot chart it shows the velocity range over a pressure range to show the curve associated with the relationship between the valve and air pressure.
If we assume the value you are referring to is fps, in my experience 100fps drop at 50yds is enough to show up on paper for sure but not really going to affect group size dramatically. Also keep in mind many times the shot chart is to show the whole curve, not necessarily where the user plans to use the pcp at. For a generic example if you have a max fill pressure of 230Bar but only fill to say 215Bar and then refill as soon as fps drops off you will have the best part of the shot curve. From a max fill you will see speeds start to increase with each shot until the air pressure and valve/hammer find an equilibrium and then speeds slowly drop before plummeting.
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