by Tom Gaylord
Writing as B.B. Pelletier
This report covers:
- Trigger pull
- On to velocity
- Gamo Match pellets
- Qiang Yuan Training pellets
- H&N Finale Match Pistol pellets
- RWS Hobby pellets
- On to the other velocity tests
- Warming the pump head
Today is velocity day for the Gamo Compact target pistol, and you readers have given me several additional things you want tested. Let’s begin with a look at the trigger.
I mentioned in Part 1 that the trigger on the test pistol feels heavier than mine did 19 years ago. It’s advertised to break at 3 lbs. and the one on the test pistol breaks at 3 lbs. 4 oz. out of the box. There is also some light creep (discernible movement and stopping in the second-stage pull). I told you I would see what I could do about this, so I removed the grips and looked at the trigger unit.
The Compact has a plastic cover on the right side of the grip frame over the trigger parts that are housed inside. This cover is translucent, not transparent, so you’ll need good light to see what’s happening underneath. As long as this cover remains on the gun, the gun can be cocked and the trigger will work. But pay attention to the 2 pins you see through the cover. They are axles for the trigger parts and they need the cover to hold them in place so the trigger will function. So the cover is a functional part that must be in place to use the gun.
The trigger parts are retained in the grip frame under a translucent cover. The pins indicated are crucial to the trigger’s operation, and the cover keeps them in place. I have already removed one screw at the lower right of the cover.
Here you see the trigger parts exposed. The part indicated by the arrow rotates up when the gun is cocked, aligning the step on its bottom with the step indicated on the other long part. The two steps with arrows pointing at them form the sear.
I put moly grease on the two mating sear steps shown in the photo. Both those parts are made from several stacked sheet metal plates rivited together, which is the same way airguns triggers were made in the 1950s. It’s inexpensive and it works well.
I did try cocking the trigger with the cover off, but the pin for the moving sear part was not held by the cover and the part started rotating out of place. So I stopped and put the cover back on. That pin tried fo fall out of the gun on the left side of the grip frame as I did this, by the way. So if you do what I did, please be careful. I don’t want to hear about parts flying everywhere!
The trigger now breaks at 2 lbs. 6 oz. — a reduction of 14 oz. from before. There is no difference in the trigger pull between dry-firing and fully pumping the gun. Best of all there is absolutely no creep in stage 2 anymore! The trigger now breaks cleanly, like a target trigger should.
On to velocity
Now let’s take a look at the pistol’s velocity. There are several things to be tested, so let’s get to it.
Gamo Match pellets
The pistol came with a tin of 250 Gamo Match pellets, so I shot them first. I found they fit the breech either very loose or vary tight and nothing in-between. Ten of them averaged 380 f.p.s. The velocity spread went from 373 to 387 f.p.s., so 14 f.p.s. That was the largest velocity spread of the 4 pellets tested.
Qiang Yuan Training pellets
Next I tried Qiang Yuan Training pellets. They averaged 379 f.p.s. with a velocity spread from 378 to 381 f.p.s. They were the most consistent pellets, with a total velocity spread of just 3 f.p.s. They also fit the Compact’s breech very loosely.
H&N Finale Match Pistol pellets
H&N Finale Match Pistol pellets were next. They averaged 383 f.p.s. in the compact and were also very consistent. The spread went from 380 to 386 f.p.s., so just 6 f.p.s. These pellets fit the Compact’s breech snugly, but not tight.
RWS Hobby pellets
The last pellets I tried were RWS Hobby pellets. At an average 386 f.p.s., they were also the fastest in the test pistol. The spread went from 380 to 391 f.p.s., so the total spread was 11 f.p.s. Hobbys also fit the breech snug but not tight.
On to the other velocity tests
Now that we know the baseline velocity of the Compact I’m testing, it’s time to look at those other questions. The first was — if you pump the gun slowly will the velocity be less than if you pump it very fast? I used the Qiang Yuan pellets for these tests since they are the most consistent.
First I shot 2 shots at the normal pumping speed — just to see where the gun was before I tested it. I got 379 and 378 f.p.s., which is exactly on spec. Then I pumped it very slowly for 2 shots. I took about 4 seconds to complete the pump stroke. I shot twice and got 379 and 376 f.p.s.
Then I pumped the gun very rapidly — taking 1/4 second to complete the pump stroke. I then recorded 379 and 381 f.p.s. It looks like there might be a subtle trend to slow down or speed up with fast and slow pumping, but it’s so close to the normal velocity that I can’t really say for sure. I would say that you can pump the Compact at whatever speed feels comfortable for you, because there isn’t a significant difference that’s based on the pumping speed. Just be sure to pump it consistently every time.
Warming the pump head
The last test I did was one that reader Siraniko asked about. I have a method of exercising the pump lever of a single stroke pneumatic to heat up the pump head by partially compressing it many times before completing a pump stroke. I call it heating, but flexing is probably a more accurate term. Heating or flexing makes the head more pliable, giving better sealing and greater velocity. I did it with the Compact and the Qiang Yuan pellets and recorded velocities of 403 and 409 f.p.s. So, this procedure does work with the Compact. And, yes, the Compact is a 400 f.p.s. gun.
From today’s tests we have lightened the trigger and made it crisper. We have also tested the average velocity with several target pellets and found the Compact to be on spec. And finally we have discovered how to get a little more velocity from the pistol, if we really need it.
The current Compact pistol seems to be very similar to the one I owned many years ago. I can’t wait to see what it can do on paper!