Tuning New to tuning

[jakob8572]

I’m sure this has been discussed many times before. I’m new and can’t find a consistent answer on this, so I’m starting from scratch.

I’m new to tuning and don’t understand whether you tune to FPS or FPE. My use case is target / plinking & small pests. As I was tinkering with the REG Settings and HS, I’ve measured the JSB Hades (.25) on the chrono in a variety of speeds - from mid 800’s to upper 900’s. My reg settings have been 120 (Front) and 80 to 100 (Rear) - overall I’m averaging ~120 shots per cycle.

I don’t see a difference related to accuracy standpoint (other than I need to become a better shooter), but I do realize the difference the pellet hits the target. As I’m shooting 50 to 75 yds currently and have the space to extend that (hoping to get closer to 100 yds before long). Use case is target shooting & pest control.

I don’t ‘want’ to go down the rabbit hole of SD / ES, just want to keep things consistent. What’s the optimal SD / ES ranges y’all target?

Do you typically tune for a specific FPS or Target FPE (to figure out your FPS), considering distance of 50 to 75 yds and/or 75 to 100 yds?

 

[357cal]

1. Set Up Your Chronograph: Place it in a safe shooting area. This device will measure the speed of your pellets.
2. Safety First: Load your air gun with the recommended pellets. Always wear protective gear.
3. Take a Shot: Shoot through the chronograph to get an initial fps reading.
4. Record Your Results: Note the fps for each shot.
5. Adjust and Test Again: Make small adjustments to the hammer spring tension or regulator (if your air gun has one) and take another shot. Record the new fps.
6. Repeat: Continue adjusting and testing until you find the settings that give you consistent fps and accuracy.

You’re aiming for consistent fps readings—this means your air gun is well-tuned. How do you feel about giving it a shot (pun intended)? What do you have for an air gun? Is it capable of what your trying to do?

 

[athlon_oved]

I am only talking pellets here fyi.
The 25-grain going in the neighborhood of 840 to 880 is the best, that I've seen. I tune all my stuff for only one thing stable pellet (no wobbling) from distances from 1 yard all the way out to 100. If it fly's true, all the way out that's when I know I have a winner (speed) for that particular pellet. I find 840 to 880 gives the best results.
However, "I've heard" that 830-940 is a good range to look at, slower even. I've never tested to 940 with stealer and consistent results all the way out to 100. But if I were you, I would try all speeds, you never know what you might find. Plus, it's part of the fun.
As far as FPE. a .25 25-grain pellet going any of those speeds from 1 - 100 yards you can easily get the critters all the way up to Coyote sized. I am not saying I condone this at all mind you. but at those tunes if you pop a dear in the head it would drop like a rock.
People do not realize how deadly these things actually are.

 

[Dr. Kralenstein]

Find which pellet is most accurate in your gun, then tune it for a consistent shot string at the power level and shot count you want, providing it stays accurate.

Generally, as stated, most pellets like to be around 880 fps, but I have guns that will shoot pellets closer to 1000 fps and they stay accurate. Heavier pellets tend to be more accurate at higher velocity.

Now if you plan on shooting slugs, you gotta really find the one your barrel loves AND the speed that slug wants.

Start with pellets lol.

 

[rcarlisle]

If you were planning to shoot field target where there's a cap on FPE, you would tune your gun to shoot its preferred pellet such that the maximum velocity produces just under that FPE specification. Otherwise, you'd pretty much tune the gun for whatever velocity produces the best accuracy with its preferred pellet. This tends to be a little easier with a regulated gun. The farther out you plan to shoot, the tighter your ES and SD should be. I like to keep my ES at or under 2% for shooting out to 50 yards with my .177s, which seem to do best around 900 FPS. My 20 yard tunes can run a little looser at around 4% ES and still produce more than acceptable accuracy. But that 4% really sucks out at 50 yards.

 

[jakob8572]

@357cal - Thank you for the instructions / guide. I think I’ve got most of this figured out. I’m running a FX Maverick Sniper (.25) and so far the hardest part has been figuring out the Hammer Spring.

@athlon_oved / @Dr. Kralenstein - I‘m only shooting pellets at the moment. Since I’m new to the wide world (or dark hole) of PCP , I figured pellets were the best place to start - not to mention the cheapest - as I learned the in’s and out’s. I‘ve got the Hades and the Exact King Heavy’s on hand (I bought used and the Exact King’s were pretty much the only thing the original owner shot). I‘ve been tinkering with the Hades exclusively, but can say the gun really likes the JSB’s (both shoot really well). I found the Hades likes to be in the 880’s to 920’s (~45 to 55 FT/LB - thanks again @357cal for the calculators). I’m eying the RMR SLAPs but wasn’t sure if I needed the Slug Liner or not.

@rcarlisle - I had to look at up how to calculate ES %. I just finished sealing and upgrading a few things on the Maverick. I found I have the ”original“ Maverick - the one without the 20-MOA top rail. Accuracy is alright but could be better - granted I’m not sure if my issues stem from the kinked pellet skirts (I adjusted the spring tension on the ‘wonderful’ FX side-shot magazine, my poor form, or something else.

I only had time for 2 quick sessions (data below) from ~75 yards this afternoon.

Session 1		Session 2
Average Speed:	886.7	Average Speed:	886.2
SD:	1.7	SD:	1.2
ES:	7.3	ES:	5.5
% ES:	0.82%	% ES:	0.62%

I used the entire magazine, 15 shots, in my calculations. Is that too many?

Any tips on how to improve shooting technique? I’m primarily shooting from a bench and can move it around the yard fairly easily to adjust distance to target.

 

[Chukar60]

Trigger control and follow through. Work on the trigger pulll. Do not immediately let off the trigger when the shot breaks. Hold it back and don‘t take your eye off the target until the projectile strikes. It takes an air gun projectile a lot longer to travel the length of the barrel than does a PB so follow through is critical. Any movement by the shooter at the shot breaking is going to show up on the target.
There are of course more tips than that but I found those two the most helpful

 

[rcarlisle]

Your ES is spot on, IMO. However, when tuning, it is best to calculate it over the entire pressure range you will use before refilling. In other words, fill the gun and shoot down to your refill pressure while recording the shot strings and the pressure every 10 shots or so. Calculate your ES over that entire range. You may find a range of pressure that produces exceptionally tight ES, in which case you would want to adjust the max pressure you fill to and when you refill to match. This is critical in unregulated guns, but can be helpful in regulated guns as well when you're chasing extreme accuracy.

 

[jakob8572]

@Chukar60 - Thanks for the tips! I‘m definitely working on my breathing and follow through. I hadn’t thought of trigger pull having as big of an impact, but see where you’re going. I’ll have to dive in a little more there and am hopeful the rear support I made (thanks to older posts) helps address some of the stability issues I have.

@rcarlisle - I typically fill to 285, which results in ~275 when I start shooting (figured the loss of 10 BAR is likely due to the cooling effect after filling from my compressor). Two questions:

1. Is there a target “refill pressure” to aim for? And would, or should, I base that value on the values of my first and / or second regulator?
2. Considering time to reload during a session, do you disregard any shots in the string (i.e. do you disregard the first shot after having to stop & reload magazines)? My time between shots is about the same as the time it takes me to swap mag’s. I can get ~45 shots before having to pause for a bit

 

[Trucker3573]

The hades pellets in my experience are a little more speed sensitive depending on your barrel than the jsb 25.39. I’ve never had a 700 mm fx liner but my 600mm liner didn’t like them above 900. I usually kept them in mid 870-880’s. Basically tuned my Maverick for 900 fps with 25.39 and that put the hades right in that nice velocity. The 700mm may be different. I had an avenger a cpl years ago I couldn’t get to shoot hades very well. Then I saw Steve’s video and slowed them down to 840-850 and it was a massive improvement. Just have to experiment.
As far as the hammer spring on the Maverick I always worked from low to high. Pick a reg pressure. Turn the internal screw all the way in CW and then back it out just a bit. Put the power wheel on 7 and start shorting over the chrono. Slowly work the internal screw CCW until you see no velocity increase for your given reg pressure. Then give it a slight turn back CW when you hit that spot. That spot should give you really tight ES and deviation. If the velocity at that spot isn’t what you are looking for you have to adjust the reg pressure and re tweek that hammer screw in the same manner.

 

[jakob8572]

Thanks @Trucker3573! I had a few groups of the Hades landing (between .5” to .75”) when shooting them around 915 -925. Anything beyond that was very inconsistent. However, I was surprised at how much tighter the groups got after slowing them down to 880’s (measured a few groups yesterday that were between .4“ to .5”). It’s not as consistent as I like, which I realize is more of a “me” problem than it is with the pellets / gun.

I was having an issue with the internal screw (took me a while to realize CCW on that adjustment screw actually increased my tension). I didn’t like the lack of vision on the screw to see how far in / out it was and got my hands on a Quick Tune system (installed over the weekend). For me, having that visual made it much simpler for me to get it to where it was.

I still need a few more sessions to see if yesterday was just a fluke or something that can be repeated.