FX When you’ve got (2) 500mm DRS’s but one of them has a larger plenum!

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Michael

Michael

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I wanted to see how much power I could squeeze out of the larger plenum version and still maintain a good shot count of at least 3 full magazines (42 shots).

Here's my baseline
  • Both are .22 caliber
  • Both have a rather small 210cc air capacity
  • My DRS Classic Synthetic has a 32cc plenum
  • My DRS Tactical has a 54cc plenum
  • Both regulators were set at 100b
  • Both of these came perfectly tuned at 880 FPS with 18g pellets
  • As is they yielded 4 full magazines (56 shots). Plus I got 2 more shots within 5 FPS after it dropped off the reg
  • 225b to 100b = 2.2cc's per shot
My goal was to shoot 22g pellets @ 880 FPS. While this was easily achievable, I had to increase the reg to 120b and +30 HST clicks, which was using too much air.

So next I tuned for 22g pellets @ 860 FPS. With the reg at 115b and +21 HST clicks I was able to get 38 shots. Good, but shy of my goal of 3 full magazines. 225b to 115b = 2.9cc's per shot.

Next I tuned for JSB Monster Lite 21g pellets. With the reg at 110b and +12 HST clicks I was able to get 46 shots @ 860 FPS. Goal achieved. 225b to 110b = 2.5cc's per shot. That's as much power as I want to squeeze out of this airgun. With these settings I also tested the velocity of the following pellets: AEA 22g @830 FPS, JSB 25g Hades Monster @800 FPS (I've confirmed that these shoot faster than you'd think for the weight), and 22g FX Hybrid slugs @ 820 FPS.

If you do feel the need to tune it, the adjustments are more accessible in the Classic version as all you need to do is remove the stock to access the HST. But, in order to access the HST on the DRS Tac you need to remove the top rail, trigger guard, and stock adapter. It looks intimidating, but its actually only 11 screws.

IMG_0721.jpg


IMO, the .22 caliber 500mm DRS is a moderately powered (30-35 FPE) pellet shooter. The platform is ultra light weight, yet very rigid. I believe it was designed to simply take it out of the box and shoot, no tuning necessary.

-Michael
 
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MongooseV8 said:
So no noticeable shot count between the two plenum sizes? I imagine both are plenty big enough for efficiency.
Click to expand...
I didn’t take the time to do a full shot string on the Classic. But if my math is correct there’s an extra 22cc in my Tactical plenum. If that air contributes to the useable shot count then 22cc / 2.2cc per shot = 10 extra shots.
 
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Michael said:
I wanted to see how much power I could squeeze out of the larger plenum version and still maintain a good shot count of at least 3 full magazines (42 shots).

Here's my baseline
  • Both are .22 caliber
  • Both have a rather small 210cc air capacity
  • My DRS Classic Synthetic has a 32cc plenum
  • My DRS Tactical has a 54cc plenum
  • Both regulators were set at 100b
  • Both of these came perfectly tuned at 880 FPS with 18g pellets
  • As is they yielded 4 full magazines (56 shots). Plus I got 2 more shots within 5 FPS after it dropped off the reg
  • 225b to 100b = 2.2cc's per shot
My goal was to shoot 22g pellets @ 880 FPS. While this was easily achievable, I had to increase the reg to 120b and +30 HST clicks, which was using too much air.

So next I tuned for 22g pellets @ 860 FPS. With the reg at 115b and +21 HST clicks I was able to get 38 shots. Good, but shy of my goal of 3 full magazines. 225b to 115b = 2.9cc's per shot.

Next I tuned for JSB Monster Lite 21g pellets. With the reg at 110b and +12 HST clicks I was able to get 46 shots @ 860 FPS. Goal achieved. 225b to 110b = 2.5cc's per shot. That's as much power as I want to squeeze out of this airgun. With these settings I also tested the velocity of the following pellets: AEA 22g @830 FPS, JSB 25g Hades Monster @800 FPS (I've confirmed that these shoot faster than you'd think for the weight), and 22g FX Hybrid slugs @ 820 FPS.

If you do feel the need to tune it, the adjustments are more accessible in the Classic version as all you need to do is remove the stock to access the HST. But, in order to access the HST on the DRS Tac you need to remove the top rail, trigger guard, and stock adapter. It looks intimidating, but its actually only 11 screws.

View attachment 554125

IMO, the .22 caliber 500mm DRS is a moderately powered (30-35 FPE) pellet shooter. The platform is ultra light weight, yet very rigid. I believe it was designed to simply take it out of the box and shoot, no tuning necessary.

-Michael
Click to expand...
Michael, Great workup. I could see the DRS tactical being my first FX gun if & when the retirement budget allows it. I like the 600mm barrel. I'm not much into
turning , just shooting!
 
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Michael said:
Does plenum volume count towards overall air capacity?
Click to expand...
I think it depends on if you shoot below the reg, some people do.

I was asking about the difference between the two plenums because I have experienced a little better efficiency with a bigger plenum. Going from like a 10-12cc to a 30-40cc I think you can gain some extra shots at the same power level. But starting at 32cc for a 22Cal is already pretty big, so I was curious if the 54cc was an improvement.
 
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I would really like to see the results if you go up a bit more in pressure to 130b and 140b. Sometimes a quicker puff of stout air is more efficient with a higher reg setting.

IMO you haven't pushed enough power to start showing the difference in the plenums. I also think companies have gone a bit plenum crazy in the past few years. There is a point of diminishing returns on plenum size and even a point where it can be too big if you are pushing small calibers at low power. It's known that if you don't lower the plenum pressure enough to really open up the regulator piston seat for a refill your regulator can appear to be off which would be indicated by a wider ES.
 
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MongooseV8 said:
I think it depends on if you shoot below the reg, some people do.

I was asking about the difference between the two plenums because I have experienced a little better efficiency with a bigger plenum. Going from like a 10-12cc to a 30-40cc I think you can gain some extra shots at the same power level. But starting at 32cc for a 22Cal is already pretty big, so I was curious if the 54cc was an improvement.
Click to expand...
I'll try to shoot a full shot string out of my Classic.
 
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ctshooter said:
I would really like to see the results if you go up a bit more in pressure to 130b and 140b. Sometimes a quicker puff of stout air is more efficient with a higher reg setting.

IMO you haven't pushed enough power to start showing the difference in the plenums. I also think companies have gone a bit plenum crazy in the past few years. There is a point of diminishing returns on plenum size and even a point where it can be too big if you are pushing small calibers at low power. It's known that if you don't lower the plenum pressure enough to really open up the regulator piston seat for a refill your regulator can appear to be off which would be indicated by a wider ES.
Click to expand...
FWIW - I always strive for a short muzzle report & a very small ES.

I understand what you're saying but they have a maximum fill pressure of 230b and a rather small air reservoir at 210cc. I fill to 225b since it's the half way point between the markings.

I'm sure I could get more power out of it by bumping the reg up to 130b or 140b, but that would leave me with only 95b - 85b to work with. Even if the reg pressure was higher, and the valve was closing as quick as possible, I'm not sure that I'd be able to achieve 42 shots at 35 FPE out of 85b (with a 500mm barrel).

But next time I take it apart I just might try that for ya!
 
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FLgunner said:
Isn't the stock plenum on the classic only 12cc? Where did you find a 32cc plenum? Is it a SHP with plugs to reduce the volume? I've been looking for one with a volume of around 24cc, double the stock plenum volume, but still around the same outside dimensions of the stock plenum.
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That’s just what I had written down, there should be some proper specs floating around somewhere.
 
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I tore it apart (again) and tried some higher reg pressure.

I tested reg pressures 125b & 130b. There was no need to go any higher than 130b as I ran out of hammer. With the reg at 130b and the HST at +37 (above OEM tune) I was able to achieve 900 FPS with 22g pellets. That's all she'll do with the current hammer weight/spring.

I really wanted to shoot the 21g & 22g pellets so I went back to work to refine a tune that would work for both of those pellets. The goal was 860 FPS with the 22g, 880 FPS with the 21g, and at least 3 full magazines (42 shots).

I was able to achieve this goal with a reg pressure of 115b and +16 clicks (over OEM tune) of the HST. I got exactly 43 shots on the reg, and then 3 more shots off the reg before the velocity started to drop.

22g AEA pellets, AVE 857, ES 12, SD 2.

I was reluctant to go through the motions again, but I'm happy that I did because I squeezed another 20 FPS out of the 22g pellets. Next I'll put some pellets on target.

If you care to see my journey:

IMG_0767.jpg
IMG_0768.jpg
IMG_0769.jpg
IMG_0771.jpg
 
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Dang, that was great info. I was wondering how much reg I can turn it up to. I’m shooting 18gn AEA’s at 900fps and the reg is at 94 bar. Its shooting lights out.

My daughter plays SB for the University of Akron in OH. I’m up here for about 3 weeks hanging out with her and watching her play. I’m missing shooting in my backyard. 😂
 
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MongooseV8 said:
Id be more than happy with 3 mags at those speeds. Makes me hopeful a 600mm Leopard might be able to replace my beloved M3 I recently sold.
Click to expand...
While the DRS Classic & Tac are meant to be mass appeal pellet shooters, I believe the Leopard will be a slug shooting powerhouse. 👊🏻
 
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ctshooter said:
I would really like to see the results if you go up a bit more in pressure to 130b and 140b. Sometimes a quicker puff of stout air is more efficient with a higher reg setting.

IMO you haven't pushed enough power to start showing the difference in the plenums. I also think companies have gone a bit plenum crazy in the past few years. There is a point of diminishing returns on plenum size and even a point where it can be too big if you are pushing small calibers at low power. It's known that if you don't lower the plenum pressure enough to really open up the regulator piston seat for a refill your regulator can appear to be off which would be indicated by a wider ES.
Click to expand...
Maxed out HST at 130b, see recent discovery.
 
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Michael said:
While the DRS Classic & Tac are meant to be mass appeal pellet shooters, I believe the Leopard will be a slug shooting powerhouse. 👊🏻
Click to expand...
I'm have not make any change on my DRS. It is as arrived from Talon Tunes. I asked Tony to install the super powerful plenum.

Tony send it shooting as a real champ shooting NSA 25.4 grain slugs at 50 fpe (950 fps).

This DRS 600 mm is my must accurate PCP at long range.
 
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