Increased pressure, but a decrease in velocity

[GettinJiggy88]

I’m new to PCP rifles and new to this community. I’ve always wanted to get into PCP rifles but they were cost prohibitive. I recently found a Gauntlet Gen 1 .25 on sale for $200 and couldn't resist.

I decided to tinker with this, and upgraded the bottle to a 0.38L and a 2200 psi reg (was 1900psi reg). When I put the new reg on, I lost an average of 56 FPS (Shooting 850’s with the 2200psi reg and 900’s with the 1900psi reg). I checked the pressure on both regulators, and they’re both surprising spot on (1900psi reg putting out 1900psi, and 2200psi reg putting out 2200psi).

Does anyone know why I’m increasing pressure and loosing FPS?

 

[weevil]

Completely normal. When you increase the pressure behind it, the valve is both harder to smack open and it closes faster, releasing less air to push the projectile. You need to compensate by increasing hammer preload tension and/or weight of the hammer. Not sure which option(s) are available for that gun.

 

[EPG]

Hi,

You have too much reg pressure for the amount of hammer spring preload that you are using.

On the Gauntlet G1 (I have one) the hammer spring preload is not adjustable, but you can fix this with a kit from Hajimoto (he lurks these forums and has a website). His hammer spring adjuster will require you to drill a small hole in the stock.

Or you can simply swap the hammer spring for a stiffer spring. Or take yours out, put a spacer behind it (will increase pre-load) and reinstall.

You learned that increasing velocity is not simply a matter of increasing regulator pressure. You have to be able to hit the valve hard enough to release the pressure - your hammer spring and hammer weight must be up to the task.

Enjoy the Gauntlet G1 - it was my first PCP and the thing still shoots really well with no issues.

-Ed

 

[2L8]

Classic problem that needs the solution you have all mentioned.

Patrick

 

[Motorhead]

 

[aroundlocks]

I’m new to PCP rifles and new to this community. I’ve always wanted to get into PCP rifles but they were cost prohibitive. I recently found a Gauntlet Gen 1 .25 on sale for $200 and couldn't resist.

I decided to tinker with this, and upgraded the bottle to a 0.38L and a 2200 psi reg (was 1900psi reg). When I put the new reg on, I lost an average of 56 FPS (Shooting 850’s with the 2200psi reg and 900’s with the 1900psi reg). I checked the pressure on both regulators, and they’re both surprising spot on (1900psi reg putting out 1900psi, and 2200psi reg putting out 2200psi).

Does anyone know why I’m increasing pressure and loosing FPS?

View attachment 357376

View attachment 357377

Hi jiggy 88
You've created more air pressure on the valve poppet by raising regulated pressure.
If you've upped reg pressure I presume your after more power" so your not just looking to get back the fps you have lost.
You should get it back by just adjusting hammer spring but the more power you are trying to get the more involved the modifications on your gun will become.
It would be helpful if we knew what you are trying to achieve.

 

[HogKiller]

In the case of airguns, more isn't always better, it's a fine balancing act, try lowing your reg pressure, IF you CAN, and see if the speeds climb, simply adding more dwell time on the valve will most likely wind up wasting air. If that doesn't do it then slowly start increasing your spring tension, there is a happy medium in there somewhere.

 

[GettinJiggy88]

Thank you all for the wealth of info here! I’ve learned more from your answers than I did from hours of scouring the internet!
I love target shooting with this PCP, but it’s main purpose is to hunt squirrels, rabbits and raccoons. I want something powerful and accurate enough to make clean ethical kills. I also like the idea of long range shooting. In both scenarios, it seems slugs are superior (based off of what I found online and very little experience with slugs). I found a couple YouTube videos of people shooting slugs out of the gauntlet Gen 1. All of them were using increase reg power, so that’s one of the reasons I decided to up the power.

Seems like I have 2 options; Slowly add shims to increase the reg pressure on my Ninja 1900 psi reg until I start to loose fps, or use the 2200 psi reg and increase the tension on hammer spring and know there might be some inefficiencies. I’m leaning towards increasing the hammer spring tension. I’m still using a pump, so filling a bottle every time I want to test the reg pressure sounds painful. Im going to play around with shimming the hammer spring first, but I have my eye on the hajimoto super tune kit which includes the power adjuster. I just have to talk myself into dropping another $100 into this gun.

Thanks again everyone for all the info! If you have anymore advice for me I would love to hear from you!

 

[aroundlocks]

Thank you all for the wealth of info here! I’ve learned more from your answers than I did from hours of scouring the internet!
I love target shooting with this PCP, but it’s main purpose is to hunt squirrels, rabbits and raccoons. I want something powerful and accurate enough to make clean ethical kills. I also like the idea of long range shooting. In both scenarios, it seems slugs are superior (based off of what I found online and very little experience with slugs). I found a couple YouTube videos of people shooting slugs out of the gauntlet Gen 1. All of them were using increase reg power, so that’s one of the reasons I decided to up the power.

Seems like I have 2 options; Slowly add shims to increase the reg pressure on my Ninja 1900 psi reg until I start to loose fps, or use the 2200 psi reg and increase the tension on hammer spring and know there might be some inefficiencies. I’m leaning towards increasing the hammer spring tension. I’m still using a pump, so filling a bottle every time I want to test the reg pressure sounds painful. Im going to play around with shimming the hammer spring first, but I have my eye on the hajimoto super tune kit which includes the power adjuster. I just have to talk myself into dropping another $100 into this gun.

Thanks again everyone for all the info! If you have anymore advice for me I would love to hear from you!

Your best bet is too look what other people have done with theirs that works
See if the hajimoto adjuster is going to work for you.
Shim hammer spring first should cost nothing and see what you get power wise" if your happy buy the adjuster.
I've not owned a gauntlet but heard good things of them.
The power its putting out is not shabby
Slug wise is not one size fits all" you will have to try various slugs in different grain and diameter ect " but again see if people shooting the gauntlet have shot them and put you in the ball park and go from there.
To put another $100 into it doesn't seem outrageous to me.
Wind your spring up see what you get first" it cost you nothing and try both regs when you do it.

 

[GettinJiggy88]

I added 2 shims between the spacer and the rear air tube plug. WOW! 980fps with a 26.54 grain JSB Hades! It is definitely louder. If I keep it this powerful I might need a moderator to keep this thing back yard friendly.

I did try both regulators, and got a 45fps increase with the 1900psi reg. compared to 80fps with the 2200psi reg.

Can’t wait to do some more tweaking and accuracy testing this weekend!

 

[EPG]

I added 2 shims between the spacer and the rear air tube plug. WOW! 980fps with a 26.54 grain JSB Hades! It is definitely louder. If I keep it this powerful I might need a moderator to keep this thing back yard friendly.

I did try both regulators, and got a 45fps increase with the 1900psi reg. compared to 80fps with the 2200psi reg.

Can’t wait to do some more tweaking and accuracy testing this weekend!

Pull one shim out, run the 2200psi reg and you’ll likely be close to what your looking for with The 26g Hades.

Good luck - have fun!

 

[aroundlocks]

I added 2 shims between the spacer and the rear air tube plug. WOW! 980fps with a 26.54 grain JSB Hades! It is definitely louder. If I keep it this powerful I might need a moderator to keep this thing back yard friendly.

I did try both regulators, and got a 45fps increase with the 1900psi reg. compared to 80fps with the 2200psi reg.

Can’t wait to do some more tweaking and accuracy testing this weekend!

Hi jiggy
Might pay to get the adjuster then so you can power up and down if you need to
Throw a moderator on it you wont scare everything off within a mile lol
Glad your happy.
Now to find a slug that you're barrel likes and your there.
I feel sorry for the critters in your back yard lol.

 

[GettinJiggy88]

I had a chance to do some shooting this weekend. I tested several pellets and 1 slug. The JSB Hades performed well! My last group could fit within a quarter at 40 yards. I tried the buck-rail moderator but it seemed to open my groups up… it’s got me second guessing purchasing a higher end moderator.

I tried H&N Grizzly’s .25 31 grain slugs. My groups looked like a shotgun blast… they were everywhere! Planning on pushing a slug though the barrel and measuring the slug to figure out the correct diameter. Also planning on polishing the chamber port and barrel.

Having a lot of fun trying to get the most out of this gun… this is addicting.

 

[aroundlocks]

I had a chance to do some shooting this weekend. I tested several pellets and 1 slug. The JSB Hades performed well! My last group could fit within a quarter at 40 yards. I tried the buck-rail moderator but it seemed to open my groups up… it’s got me second guessing purchasing a higher end moderator.

I tried H&N Grizzly’s .25 31 grain slugs. My groups looked like a shotgun blast… they were everywhere! Planning on pushing a slug though the barrel and measuring the slug to figure out the correct diameter. Also planning on polishing the chamber port and barrel.

Having a lot of fun trying to get the most out of this gun… this is addicting.

View attachment 358428

Hi jiggy
Reading up about slugs for your gun and it seems the barrel on the gauntlet has a sharp leade where the pellet enters the barrel and for you to shoot slugs you need too round it slightly to allow slug to enter without damage hence the shotgun groups.
There is a video out there showing how it's done.
Spend your money on a good tried and tested moderator donny fl or alike.
Try the crosman hollow points some on here are shooting them at high velocity with very good groups and no where near as expensive as hades.
And yes its addictive bud but also great fun seeing what you can achieve with something you have personally put your effort into.
Great shooting by the way

 

[GettinJiggy88]

Hi jiggy
Reading up about slugs for your gun and it seems the barrel on the gauntlet has a sharp leade where the pellet enters the barrel and for you to shoot slugs you need too round it slightly to allow slug to enter without damage hence the shotgun groups.
There is a video out there showing how it's done.
Spend your money on a good tried and tested moderator donny fl or alike.
Try the crosman hollow points some on here are shooting them at high velocity with very good groups and no where near as expensive as hades.
And yes its addictive bud but also great fun seeing what you can achieve with something you have personally put your effort into.
Great shooting by the way

Thanks aroundlocks! I was reading the same thing. I got some ultra fine sanding papers I’m planning on using the polish the barrel. Hoping that will do the job. If not, I might have to break out the dremel and a little buffing compound. I’ll give the crosmans a try!