Chief II Plus Power Efficiency Thoughts ?

[wll2506]

I have been out testing my Chief II + and at my setting I have gotten a lot of shots from a fill of 2900psi to 2750psi.

I'm shooting 15gr slugs at an average of 775fps that stays very constant for the first 21 shots. I turned the power spring way down when I first got the gun as the gun has LOTS of potential power. The way this is going I'll be able to get 35 to maybe 40 shots at this power range -  and that would be great :- ) Turning this pretty much into an all day hunting gun for up to jackrabbit size game to around the 65 yard range (16fpe at that range, initial fpe is ~20fpe, the slug has a BC of .070 so it doesn't slow down fast at all).

When I shoot the gun it make very, very little noise and the sound I do hear is mostly the sound of the spring, hammer and trigger mechanism working. I'm wondering since I turned the spring so far down that I'm not getting much "Secondary Hammer Bounce" I thought when I first shot the gun a few days ago that I heard a bit of bouncing air "poof-f-f-f" and I got 26 shots from 2900psi to 2000psi ---- now I get 21 shots from 2900psi to 2700psi ---- whats going on ?

I was going to put in a Bstaley "O"Ring in if I got in tear down mode --- I REALLY don't want to tear this gun down right now !!

For those of you that have a Chief II what is the air tube ID ? ----  I wonder if the "C II +" has the same thickness wall as the regular Chief II ?

All help greatly appreciated !

wll

[tracker1955]

If the gun is working well for you as it sits, just shoot it and enjoy it until something occurs that causes you to go inside. Nothing wrong with NOT tinkering.

[nervoustrigger]

Something is wrong with the second set of numbers...the 21 shots from 2900 down to 2700 psi.  The only way for that to be possible is if the velocity has dropped off considerably.  At 775fps, the efficiency would be over 3.7fpe/ci which is beyond anything ever achieved.

Probably what is happening is it is operating at a state of partial valve lock.  Indeed, it would be very quiet but also a much lower velocity with a poor ES. 

[wll2506]

Something is wrong with the second set of numbers...the 21 shots from 2900 down to 2700 psi.  The only way for that to be possible is if the velocity has dropped off considerably.  At 775fps, the efficiency would be over 3.7fpe/ci which is beyond anything ever achieved.

Probably what is happening is it is operating at a state of partial valve lock.  Indeed, it would be very quiet but also a much lower velocity with a poor ES.

Ya, I have to figure something is wrong, maybe the gauge is way off and I'm shooting around the 2200 psi area ? None of my guns has that kind of efficiency ! The velocity is registering on my FX chrono and on line with the velocity I was getting before and changed a bit with every shot, the chrono has fresh batteries also ------ this is crazy.

I may go out today and the gun fires a few shots and then goes poof, what knows ?

wll

[Ribbonstone]

Devil’s Advocate role.


Were people who used the 2k Chief, with better valve retention screws, at higher pressure….and I’m thinking from your measurements of length/diameter, it’s likely the same tube/valve.

Not even sure if it really needed the better screws to bring it from 2K to 3K. 

If the valve sat right on the internal steel ring that takes the big screw from the breech (at the top) and the stock stud (at the bottom), the normal issue valve retention screws have two large sized helpers.

I’ll have to hunt up the stress tests done to see if they included that steel ring.  To be truthful, I added the better valve screws but still keep the Chief (guess that would be Chief I in retro-numbering) to 2K,...it’s a pants and suspenders kind of thing (or for car guys….the seat belts and air bags).

Never saw the hurt in running one at ½ throttle if it got you to where you wanted to go.

When in doubt….and what you have is working for you….I’d leave it alone until I HAD to take it apart for something else.

Do have me wanting to n spend the $180 to find out….but realize (in my situation) that I’d a hard time justifying that (cheap) buy after I had found out.

And yet...still hovering over the buy-button.

-------
Living vicariously….what would help is one good total shot count.

Fill it to 2900psi...chronograph every shot….shoot it down to  where it got “stupid slow”...and let the post-followers take a look at that long string of shots.

MIGHT be that there is room to move “up” and retain most of that shot count…..might b that you are already on the edge of the cliff and moving progressively downward...might be a “see=saw” type of up/down/up/down type of shot count….what ever it is., could point you in a direction of change that might help whatever your goal may be.

EVEN if you do JACKSHIP, don't change any thing....would find the sweetest of the sweet spot for "even" velocity....live inside that short range or pressure, would shoot as well (for fewer shots) as any regulated rifle.

[wll2506]

Devil’s Advocate role.


Were people who used the 2k Chief, with better valve retention screws, at higher pressure….and I’m thinking from your measurements of length/diameter, it’s likely the same tube/valve.

Not even sure if it really needed the better screws to bring it from 2K to 3K. 

If the valve sat right on the internal steel ring that takes the big screw from the breech (at the top) and the stock stud (at the bottom), the normal issue valve retention screws have two large sized helpers.

I’ll have to hunt up the stress tests done to see if they included that steel ring.  To be truthful, I added the better valve screws but still keep the Chief (guess that would be Chief I in retro-numbering) to 2K,...it’s a pants and suspenders kind of thing (or for car guys….the seat belts and air bags).

Never saw the hurt in running one at ½ throttle if it got you to where you wanted to go.

When in doubt….and what you have is working for you….I’d leave it alone until I HAD to take it apart for something else.

Do have me wanting to n spend the $180 to find out….but realize (in my situation) that I’d a hard time justifying that (cheap) buy after I had found out.

And yet...still hovering over the buy-button.

-------
Living vicariously….what would help is one good total shot count.

Fill it to 2900psi...chronograph every shot….shoot it down to  where it got “stupid slow”...and let the post-followers take a look at that long string of shots.

MIGHT be that there is room to move “up” and retain most of that shot count…..might b that you are already on the edge of the cliff and moving progressively downward...might be a “see=saw” type of up/down/up/down type of shot count….what ever it is., could point you in a direction of change that might help whatever your goal may be.

EVEN if you do JACKSHIP, don't change any thing....would find the sweetest of the sweet spot for "even" velocity....live inside that short range or pressure, would shoot as well (for fewer shots) as any regulated rifle.

I'm sort of doing that now, I have 21 shots and I have not touched anything, I chrono every few shots when I'm out to see where she sits. I will shoot another 5-10 shots today as I will go out again. and report back ... once she starts falling in the 750fps area and starts to go down, I will not the shot count when she started to loose her poop and I will take a gauge reading and from there I will have something to go on.

I have some 1.025" dia Butyl washers that are .250" thick, I will have my guy at work laser cut a .750 hole in the middle. This material is designed to absorb shock, vibration and energy and is a keystone to our company. I'm thinking if this washer would fit in the Chief II tube, would it work better than just a couple of "O" rings ?  I don't know ?  ---- BUT -- the gun is working like a dream right now and the very last thing I want to do is take it apart.

Hey Ribbonstone, do you think Beeman is using the same poppet in the plus as they did in your Chief II or do you think they improved it, just wanted your thoughts  - )

I really want to shoot this am but I have to work and I got to tell ya this work thing is getting me down, I have airguns to shoot and work is really in my way !!

wll

[Ribbonstone]

Work/shooting time is always in the way… it’s not a race, ain’t no gold metal for finishing first.  Take as you a day..takes you a week..takes you a month. Takes 4 months....who cares?

Some folks nibble at the edge of the cookie...some folks jam it all in their mouth at once...it’s the same  freaking cookie.


You are already ahead of the game….it’s a useful PCP for you just the way it is.

--------

Honest thoughts:

For the price point, I'd be real surprised if "they" made new parts or a new tube.

They could have...but to meet that price, I'd certainly have used what was already being made that would work for the same diameter/length air tube.  After all, even at a low price, their object is making money.

[Nvreloader]

Hey Will

IMHO,
I would shoot her till SHE decides SHE'S sick and need some help etc.
Get a good total OEM shot string, so you have some info to work with,
then when she dies, tear it down and fix to YOUR liking.

Be sure to note the spec's of the hammer dimensions, spring size dimensions,
total overall work length for a possible SSG etc, PHOTO'S, get GOOD "O" RINGS,
and possible poppet replacement, deburr/polish what needs to be done,
clean up trigger etc.

Then shoot her, till she sings for you............. , I am following along...................

Tia,
Don 

[wll2506]

In a few hours I'll be shooting her again, we will see what happens ;- )

Yes, If I have to do any work on her, I will take pics and measurements of everything ;- )

wll

[mrbulk]

Hey Will you got a highly interesting and successful (for your needs) gun right now, like some have said enjoy her as is and Congratz!
 

[wll2506]

Go out to my spot and it is extremely windy and In the 80's

I start to shoot and start chronographing where I left off yesterday with the remaining 2650 psi left in the tank on my Chief II Plus in 177 cal !

My first 6 shots today are from ~2650 psi to around 2450psi and average ~795 fps

My next 5 shots today are from ~2450 psi to ~2350 psi and average around ~795+ fps.

My next set of 5 shots today go from ~2350 psi to ~2200 psi and average ~800 fps.

My last set of 5 shots are from 2200 psi to 2100 psi and average ~790 fps

I probably could have gotten another 5 shots at the 775 fps mark or above but I didn't !

This string of 21 shots today plus the 22 shots I did yesterday gives me 43 shots from 775fps to 810 (highest shot today, most high shots today were 795 fps+ to 805)

This total two day string of shots I chrono'd gives me a two day average of 791 fps and an average of 20.8 fpe with 15gr Nielsen slugs.
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This gun so far has done more than I could have asked for --- I assume these readings are true and gauges are reasonably accurate, but only time will tell. I bought another one of these in the same caliber, but will leave it in the box as I have WAY to many airguns floating around the house.

So much for my testing today --- again, I'm very, very pleased with these results ---- I have Griffin 177 cal 17gr slugs ordered and we will see how they do when received :-)

Later guys,

wll