250Z Barra 250z - Veiled Camo - .22 Cal - Tuning

[Pumacarl]

The numbers sometimes look more important than they are. Meaning that even with a bigger std dev, one pellet might still group better than another. What happens in flight down range means just as much as the numbers right at the barrel. This is not uncommon actually and this is why everybody has to test everything with their gun. If it was as simple as just doing some math we would all be shooting more and talking less. You need your final data for your ballistic calculations, but for actually figuring out where the accuracy is at, you need to shoot the groups and just accept what you are seeing at the target. 1302 was your proof of this, don't waste your time questioning success, just go with it.

 

[Pumacarl]

@Optics89, as a sidenote, I used to check out British airgun forums too, and a few years ago there was 3 kids from Pakistan who were into airguns and had access to a University oscilloscope. Those kids did some impressive work and used the oscilloscope to track where the pellet was in the barrel when the valve closed, amongst other things. I didn't understand much of it but I got that they figured out a way to tune for ultimate efficiency, and yet their gun was still only as accurate as the other target guns. So in the grand scheme of things you can employ and enjoy the technical aspects of this sport but that is its own reward and not a guarantee of ending up any more accurate.

 

[Optics89]

You're 100% correct puma!

I'm a very analytical person, as some can already tell. Similar to a corporate setting, some plans look perfect on paper but in reality, the outcome is dialing it back a step with slight adjustments to get results as close to the paper as possible. Usually never perfect but close enough to make a consistent impact in a positive way.

The thrill, or reward for me would be the same. Math it out, make adjustments and get as close as possible. What I find is dope consistency falls between realadjustments, and the paper plan due to the variables in weather, rifle, and shooter ability. Once those 3 elements are dialed in, I can be happy with the overall outcome and move on. Definitely easier said than done.

1302 is proof of this concept as you pointed out, and I believe the Apolos have reached the mark on being fully adjusted thus far. Wish manufacturers would list accurate and complete spec sheets of the ammo they market. This would provide at least a baseline to start with. Unfortunately most leave it up to us to perform those calculations.

1 more test on the apolos needs to be done at 100 yards. I'll need to get out and find the space to complete this and report back. Mean time I'll start gathering ballistics on the zans or even try the JSB KO 18.3g heavy pellets just for fun and enjoy this great rifle before then.

 

[Pumacarl]

If you're having fun, you're doing it right!

 

[Cantona256]

I’m new to the PCP world so I totally understand why these numbers look weird to you because it’s just completely counterintuitive to what I’ve read…However my experience has been about the same. The first time I tried to tune it I went hard on the hammer spring and tried to match the psi. It sucked. It wasn’t very fast, shots per fill was trash, it sounded weird and it wasn’t grouping… I have the slug power kit so that probably has a lot to do with it too.

So after I ported the thimble valve I reset the reg and hammer spring. I needed up at around 2550 psi and right now I’m 1/3> but 1/2< a turn on the hammer spring. I haven’t chrono’d yet cuz I’ve been sick but I’m guessing fps is very similar to before since I didn’t have to re-zero the scope. I found that 1/4 a turn on the hammers print was enough to turn a dime sized group at 50 yards into 1.5” at 50 yards. My point being that this gun seems very sensitive on the hammer spring. For the extreme accuracy you’re probably gonna want to hammer tune the gun for whatever pellet/slug you like the best. Also I went from around 10-15 shots per fill to 25-30 and she’s quiet again.

My gun doesn’t seem to prefer any ammo a lot more than the rest. Except pellets, my baby hates them haha. But I’ve tried loads of slugs and it likes them all fine from .249-.251 cal… so far it just seems to like weights in the mid to high 30’s the best. 33gr apolos and 34gr h&n’s…. Have some custom 35,36 and 37 gr slugs on the way but in the meanwhile I’m gonna tune for the 40gr apolos. If you get bogged down finding the “ideal” pellet or slug you’re gonna chase your tail haha… my barra is the type of girl my momma warned me about lol, she ain’t picky and always up for a good time….. make the choice for her and tune for it.

 

[Optics89]

Porting the thimble might be the route in general for this rifle I'm thinking also, but I've never done that before. What did you use for reference when you accomplished that task?

I laughed my *** off when I read "she's the kind of girl my mom warned me about"!!! Great kickoff to an already hectic Monday thank you for the laugh

 

[Cantona256]

Porting the thimble might be the route in general for this rifle I'm thinking also, but I've never done that before. What did you use for reference when you accomplished that task?

I laughed my *** off when I read "she's the kind of girl my mom warned me about"!!! Great kickoff to an already hectic Monday thank you for the laugh

Actually another post on here by pumacarl if I remember correctly. It’s really easy to do. I just went from 4mm to 4.4mm.

 

[Pumacarl]

Porting the thimble might be the route in general for this rifle I'm thinking also, but I've never done that before. What did you use for reference when you accomplished that task?

I laughed my *** off when I read "she's the kind of girl my mom warned me about"!!! Great kickoff to an already hectic Monday thank you for the laugh

If you haven't taken your gun apart yet watch Northeastbeast's video:

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My "Working On It" thread has close up pictures of the thimble too. I just used a simple hand drill, just take your time and be careful. I wouldn't go over 4.4mm either because you are getting really close to the oring grooves then. I only did 4.3mm but I will polish it a little bigger in the future. Good luck.

 

[pan60]

If you haven't taken your gun apart yet watch Northeastbeast's video:

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My "Working On It" thread has close up pictures of the thimble too. I just used a simple hand drill, just take your time and be careful. I wouldn't go over 4.4mm either because you are getting really close to the oring grooves then. I only did 4.3mm but I will polish it a little bigger in the future. Good luck.

there are ways around that
but short of slugs at higher speeds to what end?
same thing I would apply to the plenum at some point the vale isnt going to be efficient enough to dump what you have without some front over dwell.

 

[Pumacarl]

there are ways around that
but short of slugs at higher speeds to what end?
same thing I would apply to the plenum at some point the vale isnt going to be efficient enough to dump what you have without some front over dwell.

Slugs are the point. It is the easiest way on this gun to open its potential. This gun's plenum is tragically undersized and needs this to get more air out faster. I am aware of all the factors and dwell isn't one of them because of the length of the barrel and the tiny plenum volume, doesn't make it an issue. The valve is already quite maxed out and that's why this really helps with performance. You are right though, if you just want to shoot pellets, it's all good. But, I would ask you, who in their right mind would buy a 27" barreled conventional unchoked 1 in 18" twist airgun and shoot pellets out of it? It is made for slug shooting.