Gamo Whisper Cat Ballistics

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jonny75904

Member
Dec 31, 2016
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Texas, United States
Just got done measuring my Gamo Whisper Cat ballistics with the chronograph - it came in way under what I was thinking. It's amazing I've had any success against the squirrels, considering these stats are taken from the muzzle.

10-shot string, Gamo Whisper Cat
Load: Crossman 10.5gr Round Dome, .177cal
Lo: 643fps, 9.63ft-lb
Hi: 680fps, 10.77ft-lb
Av: 656fps, 10.03ft-lbSo I've got about a 10% energy variance (a whole foot pound, sigh) from low to hi. At least it does the job with a well-placed shot by the ear, but it sure doesn't leave much room for error.I had been estimating 16ft-lb, so, I was way off. Goes to show just how fudged the advertised numbers are...
 
10.5 is a little heavy for a mid powered gun. I suggest you try the lighter (around 8 gr.) Crosman domes or JSB domes, H&N Field target trophy, or RWS Superdomes. They will not yield more energy but you'll probably find the shot cycle smoother, making the gun easier to shoot accurately. Numbers don't mean that much compared to accuracy IMO, a well placed shot will get the job done as long as you don't stretch the range too much.
 
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I did chrono lighter pellets, but unfortunately the tins don't have the grains on them. I believe they're gamo, but the tins are unmarked (with clear plastic top, I guess so you can sleep well knowing you still have hundreds left).

I read up some tips on how to get more power out of low-end springers like a whisper cat - the most interesting tip I found was to put a bit of vegetable oil in the pellet tin and shake it up. Vegetable oil is less proned to dieseling than petroleum oil, according to what I read. I haven't chrono'd it yet.

I have a few more interesting pellets coming in, as well as a cold steel blow gun. Looking forward to that thing when it comes in.

I purchased these from amazon last week, I should have them this week:
https://www.amazon.com/gp/product/B001BS3X6I/ref=oh_aui_detailpage_o04_s01?ie=UTF8&psc=1

And these,just out of sheer curiosity about 15gr "sniper" pellets for a .177, though it clearly says "For air pistols / rifles with a minimum muzzle energy of 18.5 ft.lbs," cant help but be curious just by the picture.
https://www.amazon.com/gp/product/B00TZOGVC8/ref=oh_aui_detailpage_o04_s01?ie=UTF8&psc=1



Hollowpoint (presumably gamo)
hi: 826
lo: 784
Av: 804
es: 42
sd: 16

"Red tipped hollowpoints" (presumably gamo)
hi: 784
lo: 755
av: 771
es: 29
sd: 8

I will say this though, the crosman domed pellets are a sure kill-shot every time.
 
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Just chrono'd two new pellets, both .177cal.

15gr H&N Sport Sniper Magnum, 525fps avg
11.37gr Beeman Silver Arrow, pointed. 617fps avg

Both chrono'd for 10fpe, and I'm concluding my whisper cat consistently produces a 10fpe (ish) projectile. Perhaps the cylinder runs out of oomph before the pellet completely leaves the barrel, or perhaps that's all the energy the spring can produce.

Oddly enough, the 15gr fly to the right and higher than my crosman 10.5gr round domes - my go-to pellet for all things accurate.
 
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It's common for heavier pellets to hit higher than lighter ones in springers. If I remember right it has to do with recoil and barrel harmonics. I've often found different brands of pellets shoot left or right of zero.
It kind of sounds like your Gamo is due for a rebuild, good luck finding a replacement spring and seal kit! Five years of heavy use will fatigue most springs. You kind of need to think of springs and seals like tires on a car, they wear out with use.
 
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"jonny75904"I do have to admit that, for the money, it gets the job done well with the same result as high end guns, but the numbers just aren't there. Maybe it's the age of the gun - now 5 years old and a springer.
Click to expand...
You never dieseled it did you? I saw your interest in such things in another thread. Diesling the gun, even one time, could have broken a spring. Dry firing the high powered springers can break a spring. Maybe you have a blown breech seal, consider that as well. It is the first thing you should check because it is very easy to replace that.
 
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I'd be interested in knowing more about recoil and barrel harmonics. I used to teach math and physics before switching careers to software development.

no dieseling here, though it is fascinating to see it in action. Haven't dry fired much, except a month ago I put some gun oil down the barrel and fired it empty a time or two to blow out the excess. It was an attempt to speed up the pellets but I don't think it worked much.

I think it's just getting old. I shot a critter the other day, and it gave me a dirty look before going back to bed.
 
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Yep sounds like the spring and main seal need to be addressed. I have the same rifle for my grandson to use and using the JSB Exact Beast Diablos, it still had speed of 656 fps as an average...this is a 16.2 grain pellet, I would guess your rifle has a problem. By the way this heavy pellet is destroying my gun but I don't care, when it breaks I will rebuild it. It has a noticeable buzz at the end of the shot cycle. I did add a Charlie Tuna Trigger which definitely is an upgrade that you might consider when and if you dig into your rifle, the results are one shot kills and consistency I will take that from my Gamo Whisper any day.
By the way my grandson has put down several dozen squirrels in the woods with this rifle and pellet combination. He loves going in the woods with me but leaves the squirrel cleaning to me.
 
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awesome, thank you so much! this is gonna be fun.

I think the spring has definitely lost its mojo, because it cocks without a whole lot of effort, and I remember when it was new it was a real SOB.

Now it seems like if the gun sits for a week the scope is off. Maybe it isnt tight enough, but ive twisted this allen wrench as tight as I dare (not around the optic, just on the frame... optic is still pretty tight though, with a bit of gap on both sides).
 
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So I broke down my whisper cat today, may it rest in peace...

Two things that got me stuck - the seals. I got the cylinder out, and there is a seal on the end but I have no clue how to get the thing off, and I also dont know how to get the chamber out safely.

The video linked above cuts out the procedure to get the chamber out, and doesnt show how to replace the seals.

I could try a few things, but with my lack of mechanical prowess and experience, I could probably screw this thing up pretty good if i dont reach out.
 
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