FX FX DRS with low velocity first shot! What should I check?

[FLgunner]

My DRS is experiencing a low velocity first shot after it sits awhile. Any idea what could be causing this? I have already replaced the AMP Regulator because it was much worse, the first 3-4 shots were considerably lower than the rest after sitting awhile. It's just the first shot now, but for testing this is unacceptable because I don't always have the luxury of blowing off one shot and then go for a kill shot. Here is the result of a 5 shot string after it sat overnight:

FX Hybrid .22 22.0gr

Shot count: 5

Low: 761 FPS
Hi: 830 FPS
Avg: 815 FPS
Spread: 69 FPS
STD Dev: 26.8 FPS

1 - 761,FPS,28.3,FT Lbs,
2 - 828,FPS,33.5,FT Lbs,
3 - 826,FPS,33.3,FT Lbs,
4 - 830,FPS,33.7,FT Lbs,
5 - 828,FPS,33.5,FT Lbs,

Since only the first shot is 67 FPS less than the rest, I'm wondering if it might be the valve leaking off a small amount of air after it sits a while. Any thoughts on what I should be checking?

 

[Ta-Ta Toothie]

Normal for these guns. Copied from a reply by Weevil when I had the same concern. Your pressure has increased in your plenum.

When the pressure creeps up, the valve releases less air from the same hammer strike, so the projectile speed is lower. What you’re observing is the reg creeping up overnight. If it’s new, it can take a few hundred cycles (shots) to settle in. You can dry fire rather than waste ammo. Some never settle to a satisfactory level and my sense of the Panthera regs is that they’re not very comfortable operating at <125bar. In that case, you can get a Huma replacement that is optimized for lower pressure use

 

[Ta-Ta Toothie]

Just an increase in temperature will cause this. Taking the gun inside etc.

 

[Motorhead]

Would also say REG CREEP and for a hunting rifle not ideal

 

[FLgunner]

Thank you for the replies. The gun stays inside, I shoot out the back window of the house from air conditioned comfort, so I don't feel it's got to do with temperature. I guess it's time to bring out all my old, unused and/or cheap ammo and give that new regulator a really good work out and see if it settles it down!

 

[Ries]

Try increasing the hammer spring a bit? So more hammer can overcome the creep.

I remember the FX Impact has that aswell, but thats due o ring stiction on the valve rod.

 

[Ranchibi]

Paul, if it's reg creep the reg might just need more time to settle in. You could also add just a hair more HS tension and see it that helps as the plenum pressure has increased and that's why the low FPS overnight because the valve needs a smidge more strike pressure to open like Ries said above.

 

[frankie]

Try increasing the hammer spring a bit? So more hammer can overcome the creep.

I remember the FX Impact has that aswell, but thats due o ring stiction on the valve rod.

Has anyone found "THE" solution for Impact first low shots velocity. Mine is horrible 15+ shots before it gets to where it should be. I finally got the accuracy that I was after, I just can't depend on it for hunting because of the velocity drop.

 

[FLgunner]

Paul, if it's reg creep the reg might just need more time to settle in. You could also add just a hair more HS tension and see it that helps as the plenum pressure has increased and that's why the low FPS overnight because the valve needs a smidge more strike pressure to open like Ries said above.

Yep, I'll have to give that a try. I kinda took the DRS out of commission today. I got the SHP Plenum for it and thought I had bleed both the air tank and plenum, but the plenum still had pressure in it and when I loosened the screws holding it in place, it blew out the o-ring! I have some coming from The O-Ring Store, but they won't be here till next week. I also have the angled gauge mount, so I will be able to attached a gauge on the plenum and see if it's creeping up as it sits.

 

[FLgunner]

Has anyone found "THE" solution for Impact first low shots velocity. Mine is horrible 15+ shots before it gets to where it should be. I finally got the accuracy that I was after, I just can't depend on it for hunting because of the velocity drop.

When I first got my DRS it took 4-5 shots before it hit full velocity. I was sent a new regulator and since installing it, only the first shot is low and not by as much as they were before. You may need to replace your regulator. I have had good luck with the Huma Air regulators, I have them in my Dreamline Classic, Crown and my Huben K1. I will probably eventually get one for the DRS as well!

 

[Justaguy]

Yep, I'll have to give that a try. I kinda took the DRS out of commission today. I got the SHP Plenum for it and thought I had bleed both the air tank and plenum, but the plenum still had pressure in it and when I loosened the screws holding it in place, it blew out the o-ring! I have some coming from The O-Ring Store, but they won't be here till next week. I also have the angled gauge mount, so I will be able to attached a gauge on the plenum and see if it's creeping up as it sits.

Where did you get the angled gauge mount?

 

[Motorhead]

Purchasing upgraded non OEM parts to make an AG shoot / operate correctly .... Priceless

 

[FLgunner]

Where did you get the angled gauge mount?

Utah Airguns

 

[Justaguy]

Utah Airguns

The one for the impact? Does it fit/work?

 

[FLgunner]

The one for the impact? Does it fit/work?

They say yes, I guess I'll see when I get the replacement o-ring for the plenum!

 

[Ranchibi]

Yep, I'll have to give that a try. I kinda took the DRS out of commission today. I got the SHP Plenum for it and thought I had bleed both the air tank and plenum, but the plenum still had pressure in it and when I loosened the screws holding it in place, it blew out the o-ring! I have some coming from The O-Ring Store, but they won't be here till next week. I also have the angled gauge mount, so I will be able to attached a gauge on the plenum and see if it's creeping up as it sits.

Sorry about the air in the plenum ordereal! But, you will be up and running soon with nicer gauges and more POWER !

 

[Vetmx]

My walnut DRS should be here tomorrow. If I become a member of the first slow shot club and can’t remedy it, the gun will join the classifieds club. I plan to hunt with it. I have a bunch of guns that don’t have the first slow shot blues. Some of them seven years old or older. Absolutely no excuse for it.

 

[Dairyboy]

Don't these guns have balanced valves? Could be valve stiction.

 

[Ries]

Has anyone found "THE" solution for Impact first low shots velocity. Mine is horrible 15+ shots before it gets to where it should be. I finally got the accuracy that I was after, I just can't depend on it for hunting because of the velocity drop.

Yes. @mubhaur sells a modified part fo the impact. I have bought one, first shot is only 10 fps lower and from there dead on.

 

[Trucker3573]

If only FX had sold it with a reg pressure gauge it would be much easier to figure out. I mean they have moved beyond the streamline, royale etc .