Dynamic .25 cal PCP - First Impressions and Observtions

[nervoustrigger]

Jason, pack it up and send it to me....  …. I like a challenge.... 

Haha, I know you do 

Already replaced the O-rings.  Easy as pie.  I just wanted to see how the originals would fail...sure enough, classic extrusion failure.  The high side O-ring on the reg squeezed through to the cavity where the bleeder hole is located, tearing it.  The original O-rings are soft.  Feels like 50 durometer.  They didn't stand a chance.

[nervoustrigger]

Oh, and my wife found the shroud end cap in the yard.

After dark. 

With a flashlight.

In an area I scanned at least 10 times when visibility was good.

[ACHiPo]

Oh, and my wife found the shroud end cap in the yard.

After dark. 

With a flashlight.

In an area I scanned at least 10 times when visibility was good.

That’s hilarious.   Congratulations!

[Gertrude]

Well, with the barrel all fixed up, I was excited to get it back together to see how it groups now.

On shot #2...



...the shroud ejected its guts all over the yard.  I spent an hour hunting the parts and found the baffles and even the small retaining ring but the end cap is nowhere to be found.

Ok, so now we have another point of concern regarding the QC.
 I will be going to Aim Sports on Friday morning to speak with them.
I will certainly be adding this to the list of items to be discussed.

 Jason, Thank you for sharing this.
 I will let you know what I find out.

I had the opportunity to spend some time with all 5 of the rifles Ron had brought to our group shoot. My first impression of the rifle was wow, nice and short, lightweight and looked good. I shot the rifle and was impressed with the accuracy although yes the trigger was very heavy. For me the trigger was not as much of an issue as the slop in the sidelever. Ron disassembled "his" rifle in front of me at the table and saw some good things about the design. The QC is obviously very poor, oring grooves shallowed by teflon tape, sharp burrs on machined parts. The regulator looked well made, the valve poppet is wrong material and spring is ridiculously stiff. I think for the price point the gun could be a great tinker project if one does not go overboard on improvements. In my opinion the gun may be best left to lower power levels with the focus on the valve, sidelever and some smoothness to the trigger. The design really is good, has all the components to make a great field gun, just executed very poorly and with horrid quality control. I'm willing to bet these guns will be hit of miss as they have signs of tooling that is worn. Parts are run and run with nobody to adjust for tooling wear.     

Dana, It was great sharing some trigger time with You, Terry, and "The Gang" again. That BBQ was FANTASTIC Too ! ! !
 I will make sure to include all of the above discrepancies we are seeing, when I speak with Aim Sports this Friday.

[Rat Sniper (AKA: PaulT58)]

Oh, and my wife found the shroud end cap in the yard.

After dark. 

With a flashlight.

In an area I scanned at least 10 times when visibility was good.

And???  Any signs of damage or anything that would give an indication as to why it blew?  I wonder is the thread depth is not enough to securely hold it together?

Ron, Looking forward to what you find out from Aim Sports.  I corresponded with Ed yesterday via e-mail about the 2 stripped set screw holes on the shroud retainer on my new .25, and asked about getting a cone shaped spring for the valve.  Apparently they are expecting a shipment of parts tomorrow.  Let them know I'm very happy with the service I received from Ryan and the parts he sent has my .177 working perfectly!

[Lastdog]

Shipped my 25 back to Aim yesterday (22 still working great). They should get by 9/6. Hope they get on it fast and fix with the new and correct parts. Still think the 25 will make a great coon and coyot gun.

[nervoustrigger]

Paul, I put calipers to the parts last night to see if I could tell anything about what happened.  Of course this was after the parts separated so I don’t know how well they fit originally…although clearly something wasn’t right for it to blow out like that.  With that said, the end cap (thread OD) had a consistent measurement at several places around its circumference and visually the threads seemed well formed so I don’t think it was damaged.
 
However the tube (thread ID) measurements varied quite a bit around the circumference.  There was more than 0.010” variation and the threads did not appear to be as well formed but that’s harder for me to ascertain than external threads.  Granted, part of this variation may be because the thin wall tubing was “ovaling” as I attempted to work the calipers.  I tried to keep the pressure to a minimum and measured multiple times so even if my measurements were not precise, I think I was at least getting a clue that something was amiss with the threads.
 
Then it occurred to me that I should compare the threads on the other end…those that secure the tube to the collar at the receiver.  Those had never blown apart so they should be undamaged.  And indeed there were similar indications on that end, just not as severe.  Since those threads looked a bit better, I turned the tube around and reassembled everything, using a liberal amount of threadlocker on the retaining ring and end cap.  Also based on your comment, I added an O-ring between the barrel shoulder and the square sleeve, figuring that would help alleviate any stress that might arise from differing thermal expansion rates.
 
Anyway, after the threadlocker had cured for a few hours, I dry fired a few times and it held.  I’m skeptical that it is a sufficient long term fix but I’m back in business for now.  Hopefully I can put a few groups on paper this evening to see if the barrel work has improved things.

[Rohmpm]

Received DAR 25 yesterday
nicely packaged, no damage.
White scuff under forearm
crappy magazine, had to dissasemble, grind the pi
aired up and fired ten JSB 25.4's
first shot 880. Progressively dimished to
860 for the last three.
No problems yet but am going to replace orings before progressing any further.

[Rat Sniper (AKA: PaulT58)]

Jason,  Maybe that's why there was so must thread lock on there to begin with!  Also, be careful dry firing it, Wayne said he damaged the brass sleeve the poppet slide in when he dry fired his.  He was able to fix it, but he said it had damaged it initially. 

Good to hear you are back in business.  Had you changed the setting of the regulator prior to the end cap blowing off?  Just curious as what was the initial cause?  These things are still pretty much a mystery, but experiences of all those on GTA who have one sure sheds some light on the various things to be looking out for!

[Rat Sniper (AKA: PaulT58)]

Received DAR 25 yesterday
nicely packaged, no damage.
White scuff under forearm
crappy magazine, had to dissasemble, grind the pi
aired up and fired ten JSB 25.4's
first shot 880. Progressively dimished to
860 for the last three.
No problems yet but am going to replace orings before progressing any further.

The steady drop is probably your regulator o-ring fixing to blow out!  LOL! JK... Mine does the same thing, I'm sure the regulator has to settle in a bit before we start to see more consistency.

[Wayne52]

The shroud on mine didn't have any thread locker on it to begin with but it was very tight on there from the factory, I've never had any clipping from either gun at all.  I haven't taken the shroud apart on my .177 yet but I'm sure I will eventually.  My .22 will be here tomorrow and to me it only makes sense to replace the airtube and regulator o rings before I air it up.

[nervoustrigger]

Hi Paul, I had not changed the regulator.  Had not even accessed it yet.  However last night after the high side regulator o-ring extruded out and evacuated the cylinder, I pulled it.  It was marked “14.6” and the jam nut was nice and tight so there was no sign that its setpoint would have shifted.

Oh regarding the dry firing I mentioned, it was with the cylinder pressurized so as not to overdrive the poppet.  I don’t think there was any risk of it getting damaged.

[nervoustrigger]

Wayne, yeah I think it’s sage advice to just go ahead and swap the regulator O-rings straight away.  I chose not to just so I could confirm the failure was by way of extrusion.  That soft factory O-ring didn’t stand a chance at 3000psi.  It looked like black silly putty squeezed out of the groove over into the vent chamber. 

[nervoustrigger]

Rohm, the slightly higher velocity on shot 1 matches mine.  It’s probably due to regulator creep.  As some regs do, it may break in and stop doing it. 

[Gertrude]

I'm looking forward to a positive and productive day at Aim Sports tomorrow. I have a good feeling about it.
 I spent today taking my gun completely apart, and taking notes (2 pages worth), for each individual piece regarding functional discrepancies that mine and everyone else here has been experiencing.
Sure hope they've got some good strong coffee in the machine !   

Not too sure how long I'll be there, and I MAY head to my permission straight from there.
 Dove season opener is Saturday, so I may not be around here till Sunday or Monday. We'll see how it goes.

[Wayne52]

Hi Paul, I had not changed the regulator.  Had not even accessed it yet.  However last night after the high side regulator o-ring extruded out and evacuated the cylinder, I pulled it.  It was marked “14.6” and the jam nut was nice and tight so there was no sign that its setpoint would have shifted.

Oh regarding the dry firing I mentioned, it was with the cylinder pressurized so as not to overdrive the poppet.  I don’t think there was any risk of it getting damaged.

Another thing I'll do with mine before I air it up is open up the regulator 1 turn probably and see where it is, I'd like to get about 40fpe from it for shooting the 217-30-FN boat tails.
If you dry fire these guns it mushrooms the brass bush that the stem goes through, you can try it but that's what happened with my .25, I used a jeweler's rat tail file to clean mine up and all is good.

I'm looking forward to a positive and productive day at Aim Sports tomorrow. I have a good feeling about it.
 I spent today taking my gun completely apart, and taking notes (2 pages worth), for each individual piece regarding functional discrepancies that mine and everyone else here has been experiencing.
Sure hope they've got some good strong coffee in the machine !   

Not too sure how long I'll be there, and I MAY head to my permission straight from there.
 Dove season opener is Saturday, so I may not be around here till Sunday or Monday. We'll see how it goes.

Ron I wasn't aware that you personally purchased one, which caliber did you choose ?

[Gertrude]

Wayne, We have five of the .25 cal in my group of shooters.

[nervoustrigger]

Wayne, oh, so on yours the hammer smacked the brass bushing despite pressure in the cylinder?  Any chance the pressure had fallen substantially below the setpoint?  I know mine is an air hog so it wouldn’t take many dry fires before that happened.
 
I had dry fired about 10 times so I completely stripped mine down last night and inspected the brass bushing and it looked fine and the valve stem moves smoothly in it.  I also could not make out any signs on the end of the hammer that they might have contacted at some point.
 
There are several other things that come to mind that could explain why ours behaved differently:
1.       My regulator setpoint may be higher.  It’s marked 14.6.  Presumably that means 146 bar (approx. 2100psi) although it seems weird that they put a decimal in it.  But mine is making less energy than yours so that is unlikely.
2.       My hammer spring might be at less preload.  The end cap behind mine was flush with the outside edge of the receiver (i.e. the least possible preload).  Was yours perhaps dialed in a bit?
3.       My brass bushing was threaded in fully.  I recall someone saying theirs was backed out which moves it closer to the hammer and puts it at higher risk of being hit.  Ron also found one where it would thread in so far that it begins obstructing the exhaust port…so presumably others may not be threaded deep enough.  Mine stops right at the edge of the exhaust port.
 
There are a few other fringe possibilities that also come to mind, like maybe our valve stems are different lengths.  I didn’t measure it but I want to say my stem protruded about 3/16” beyond the brass bushing.  It’s unusual to get more than about 1/8” of lift (unless the system is not pressurized) so that should be plenty.
 
Well, that was a longer reply than I intended…just trying to build an understanding of what all issues folks are running into so we will know how to prevent them.

[Lastdog]

Well guys not only the DARs are having o ring problems. Bought a refurb synrod 25 to play with while I am waiting for my DAR 25 to go through AIMs warranty repair prosse. Got it yesterday. Zeroing the scope and poofff. Blew an o-ring.
Earlier shot and adjusted with some great advise from the Maurader forum and could only get 30 FPS with JSB 34s . Man I sure am missing my powerful 25 Dynamic

[Wayne52]

Jason it was my own fault I dry fired it without air.