Big Cat with Pyramyd Air Venturi Gas Spring Report

[hdrider]

I just got my Big Cat back from Pyramyd Air with the Gas Spring Installed.  I decided to Chrony some pellet speeds to see how they compare with the stock Big Cat.  With the stock spring it was getting an average speed of 914fps and SD of 9.59 with CPL's (7.9gr).  Now with less than 200 pellets through the new gas spring it's getting an average of 936fps and SD of 8.6 with CPL's.  I had a bunch of other pellets available so I went ahead and chony'd them too -- the results (of 10 pellets each) are:

7.9gr CPL 936fps Avg, 8.60 SD
7.9 gr CPHP 966fps Avg, 6.70 SD
7.9gr Cross. pointed 976fps Avg, 5.09 SD
7.9gr Cross Destroyer 950fps Avg, 8.24 SD
10.5gr CPUM 795fps Avg, 14.31 SD
8.3gr RWS Superdome 917fps Avg, 8.18 SD
8gr Predator Polymag 938fps Avg, 4.79 SD
8.8gr Beeman Field Target 893fps Avg, 28.56 SD
8.8gr Beeman Crow Magnum 909fps Avg, 7.81 SD
10.6gr Beeman Kodiak 810fps Avg, 6.48 SD
8.4gr JSB Exact 927fps Avg, 4.00 SD
10.2gr JSB Exact 830fps Avg, 6.40 SD
7.2gr Daisy Precision Max 1003fps Avg, 13.96 SD
9.6gr Gamo Rocket 837fps Avg, 15.26 SD
5gr Gamo Raptor 1160fps Avg, 33.66 SD

I plan to do 15yd accuracy testing with most of these pellets and the new gas spring in a few days and will post the results here.  All I've done so far is to sight the scope in (Centerpoint 4x16 40mm AO), but the first impressions of the Gas Spring are that it really transforms the gun.  It's much smoother now, somewhat harder to cock, and the accuracy seems less sensitive to hold.

Has anyone else put a Pryamid Air in their Big Cat that would like to share their impressions?

[larspawn]

I know this is subjective but do you think the gas ram has more recoil than stock?  And what about sound?  Is the gas ram quieter?

Sorry to contribute to the hijack of your last thread.  Curious as to your perceptions and if overall you think the gas ram was worth the price?

Thanks.

Andy Wong aka larspawn

[airiscool]

"..............It's much smoother now, somewhat harder to cock, and the accuracy seems less sensitive to hold. ..........."

Found the same happened after installing an Air Venturi gas spring in  my 22 Whisper.

" I know this is subjective but do you think the gas ram has more recoil than stock? And what about sound? Is the gas ram quieter? "

I think it has a bit more recoil, but, it may be just that the recoil is differant, not increased ?? Either way, I don't see that in this case it's a negative.

No more power plant clatter, just a solid "thunk".

Not sure about "quieter" as in a true reduction of decibles, but it is a shorter duration noise.

"Curious as to your perceptions and if overall you think the gas ram was worth the price?"

Was for me.

However, something to keep in mind for anyone thinking about doing the same. Buying the Whisper with the Air Venturi already converted from Pyramyd would have been about $25.00 less than what I put into the gun total. And, I understand that getting the conversion done by Pyramyd, the warrentee wouldn't be voided.

But then,  I wouldn't have had an excuse to tinker with the gun as much....... and I DO love to tinker with guns !!!!!    

Paul

[hdrider]

I agree with everything Airiscool said about his experience with the Air Venturi Gas Spring.  It "seems" quieter perhaps because it doesn't "twang" anymore -- just a nice solid thunk.  The recoil might be about the same, but the duration is shorter -- it doesn't move around a lot when fired like it used to -- just quicker and smoother.  Feels more like a real firearm now that it doesn't have all the vibration from a mechanical spring.  From what I've read about "Tunes", if I could only afford a tune or a Gas Spring, I'd go with the Gas Spring for sure -- it gives all the smoothness of a tune with the reliability of no spring to break.  I also have the GRT III trigger which makes it a dream to shoot.

I'll give an update after I do my 15yd accuracy testing (in my basement) in a few days -- I expect great accuracy, but that will really be the deal maker or breaker on this conversion.  At least I have a wide selection of pellets to try.

[pindog2000]

plan on getting a whisperer with a gas ram

[Bullfrog31581]

I bought my Whisper .22 with the gas ram and regret it. The ram kept breaking my scopes. Even after being tuned and filling my stock to make it heavier, the ram's recoil was totally unmanagable. It also kept blowing my seals and causing accuracy and power to vary. I've now sent my gun to Gene to have the air-ram removed and replaced with a custom spring.

I understand not everyone has had this problem with their gas rams. Maybe I had a bad unit or a different unit than others. But regardless, I can't recommend the air-ram based on my personal experiences. My .177 has a turbo-tune with a custom spring and I recommend that route over the air ram for an improvement in accuracy, power, and quietness.

[hdrider]

I guess there's always another side to every story.  So far looks like one for and one against the gas ram -- I don't think my initial impressions can be counted because I just got my gas ram gun.  I have heard other stories about breaking scopes though -- so far, so good for mine (Centerpoint), but only time will tell.

I have had a chance to do some preliminary accuracy testing with the Gas Ram in the Big Cat and found that accuracy really suffers with any of the light pellets (including CPL's and CPHP's at 7.9gr).  So far the most accurate pellets seem to be the JSB Exact Heavies (10.2gr -- I can seem to keep consistent groups of 1/4" to 1/2" at 15yds with that.  The next closest is the Beeman Kodiak (10.6gr) with 1/2" to 1" groups at 15yd and then (surprisingly) the Beeman Crow Magnum (8.8gr) with roughly 1" groups at 15yds.  The others I tested (see Chrony report in my first post) either had some decent groupings with some bad flyers (CPL and CPHP) to very bad groups that looked like the scatter from a shotgun.

So far, my experience with the gas ram is that it really changes which pellet your gun likes -- perhaps it's the higher velocity, or the way the pellet velocity is delivered by the gas ram -- whatever it is, it looks like it takes a pretty heavy pellet to tame it.

[hdrider]

I've done some more pellet/accuracy testing with the Gas Spring.  The preliminary results indicate that the accuracy with lighter pellets (anything above 900fps muzzle velocity) has been pretty much destroyed.  Groups in this velocity range are way larger than 1" at 15yds (with the exception of the Beeman Crow Magnum which is about 1") -- some look more like a shotgun pattern than a grouping.

All those with an average muzzle velocity below 900fps (with the exception of the GAMO Rocket) grouped about the same as before the Gas Ram conversion.  The groupings for the 4 best Pellets (with the Gas Ram Big Cat) were:

NOTE:  Average and Std Dev of Six 10 Shot Groups:
JSB Exact Heavy (10.2gr)
0.541" Avg, 0.119" Std Dev.
Beeman Kodiak Match 10.6gr
0.721" Avg, 0.170" Std Dev
CP Ultra Magnum 10.5gr
0.643" Avg, 0.142 std dev.
Beeman Crow Magnum 8.8gr
1.002" Avg, 0.174" Std Dev

I have heard that the Gas Ram air pulse is so much faster and intense than a Spring that it can actually deform/flatten the skirts of lighter pellets against the gun bore and kill accuracy.  Perhaps that's what's happening here -- the gun doesn't shake or vibrate like it did with the spring, but instead emits a strong single intense pulse.  Also, I should note that this gun has fewer than 500 pellets shot through it to date and is still supposedly in a break-in period.  I would expect the accuracy to improve somewhat as the action and barrel gets smoother with use, but I'm not sure how much the effect will be.  I wouldn't expect the Gas Ram pulse to change much at all with use.

I'll reconfirm the accuracy results after I get about 1,000 round through it to see if the overall accuracy and the accuracy with lighter/faster pellets has improved at all.

So far my scope (Centerpoint 4x16 40mm AO) is holding up well to the harder recoil.

[hdrider]

Just to verify that light pellet accuracy had been destroyed by the Gas Ram installation I did accuracy tests today on 3 popular light pellets and a repeat of the Heavy JSB exact.  The following is the Average and Standard Deviation of 6 ten shot groups at 15yards.

Crossman Premier Light (7.9gr)
1.220" Avg, 0.252 Std Dev
Crossman Premier Hollow Point (7.9gr)
1.694" Avg, 0.304 Std Dev
JSB Exact (8.4gr)
1.003" Avg, 0.349 Std Dev
JSB Exact (10.2gr)
0.599" Avg, 0.108 Std Dev

So....just as I had visually observed, accuracy with light pellets (over 900fps) is really terrible.  Accuracy with Heavy Pellets is acceptable, with the best being the JSB Exact Heavy (10.2gr) that are consistently grouping around 1/2" or less (10 shot groups) at 15yds.

I'll probably do a repeat of some of the chrony pellet velocity numbers after I shoot a few hundred more pellets to see if the gas spring has settled in to some nominal higher or lower velocity numbers after breaking in.

[airiscool]

Same here.

Before the gas ram, the Whisper shot light pellets (Raptors) moderatly well. After the swap, very poorly.

However, now it's shooting the slightly heavier pellets MUCH better. Since those are what I prefer to use anyway, I'm very happy with the gas ram swap.

Paul

[hdrider]

I'm surprised that the light pellet accuracy issue with the Gas Spring hasn't been addressed before in the forums.  I've seen some mention of it in early Pyramyd Air Blog reviews when I did a search -- back then it was call the Air Venturi Gas Ram conversion.  Now it looks like it's called the Crossman Nitro Gas Spring conversion.  With Crossman now selling the Nitro series commercially with the gas spring standard it will be interesting to hear reports and reviews of this gun from others concerning the type of pellets this guns likes and what type of accuracy it's getting.

I do agree that the gun seems less hold sensitive in getting accurate groups with the heavy pellets (which I like), but it doesn't look like there's any hold that will make the light pellets accurate.  Since other guns with similar velocities (with Springs) don't seem to have this issue so it must be something in the way the Gas Spring delivers the air pulse versus the Mechanical spring and how that affects the pellets interaction with the barrel/rifling.

[mackeralboy]

Earlier this year I converted my .177 Gamo whisper to a gas spring. I did not notice much change in accuracy but then again I had been using Beeman Kodiak Match's prior to the conversion and continue too after. What I did notice is that my Whisper is no longer quiet. This isn't due to the pellets beaking the sound barrier, but due to the solid "THUNK" that the piston makes slaming home.

For what it is worth, I recently bought a .22cal Crosman Nitro and I am very impressed with it's, noise level and accuracy. There isn't a pellet that I have shot through it that it dosen't group well with. To put this in perspective the only other gun that I have that groups like this is my Air Arms Prosport.

[hdrider]

I've got over 500 shots through the gun now so thought I'd repeat a couple of Pellet Velocity Data Points.  I checked the JSB Exact Lights and Heavies ss well as the Kodiaks and found some very interesting changes from the previous numbers.

The JSB Exact Lights (8.4gr) avg speed decreased from 927fps to 918fps but the extreme Spread increased from 15fps to about 30fps.

The JSB Exact Heavies (10.2gr) Avg speed increased slightly from 830fps to 838fps, but the Extreme Spread increased from 22fps to 30fps.  I had also noticed in shooting this pellet that I would occasional get a diesel (sounded like a 22LR gun shot).

The real surprise was the Kodiak Match (10.6gr).  The Avg speed of those increased from 810fps to 850fps and the extrme spread was about the same at 20fps.  Looking at this I decided to retest the accuracy of the Kodiak and fired 6 ten shot groups at 15yd.  The average group size was 0.565" with a standard deviation of 0.125".  This compares with the previous group average of 0.721" with a standard deviation of 0.170.  It appears that the accuracy of the Kodiaks has improved to the point that it's now more accurate (and faster) than the 10.2gr JSB Exact pellets.

I plan to do a side by side accuracy comparison of the JSB (10.2gr) and Kodiak (10.6gr) at 25 yards to see if these results hold up.

I notice that the JSB's are a lot looser in the barrel than the Kodiak's -- perhaps this has something to do with the change after breakin?