S&W 78G and 79G – Part 2
by B.B. Pelletier
Today, we’ll look at velocity and power of the S&W 78G. I’m getting reacquainted with this pistol because I’d completely forgotten how it performs. For starters, I’d sent this gun to Dave Gunter in Oregon to reseal and soup it up. Dave and I decided that I wanted the maximum power I could get from the gun, so that’s what he gave me.
Dave also told me I’d get only a few shots from a CO2 cartridge at this power level. I accepted that because I seldom shoot CO2 guns, anyway, so gas conservation isn’t high on my list, but in this case performance was.
In Part 1, I neglected to tell you about the pistol’s other modifications. At some time in the past, the former owner had the trigger turned into an adjustable one. Though it’s only a single-stage regardless of where the trigger is set, the let-off can be adjusted down into the dangerous range. It was set that way when I bought it through the internet, and I asked Dave to adjust it to a safe level as long as he was working on the gun.
He was shocked at how unsafe this kind of adjustment is, because all it does is reduce the contact area of the sear. For those who are new to shooting, the sear is that part of the trigger that safely holds the action in the cocked position until the shooter intentionally fires the gun through the use of the trigger. That last thing you want is a gun whose sear contact area is so small that it can slip off on its own or even slip when the gun is bumped slightly!
The trigger adjustment just changes the area of sear contact. This is not where the factory adjustment would be. And, yes, that is the first owner’s name scratched into the triggerguard. It’s also on the box.
To get the power from the gun, Dave worked on the valve, both opening and smoothing the ports through which the gas must flow. he also switched the valve return spring to one better balanced to the modifications he’s made. That we cannot see because it’s buried deep inside the gun. But we can see one additional touch he added to the bolt. He thinned the bolt nose and smoothed it to reduce any resistance to gas flow.
The thinned bolt probe is seen on the left, and this photo shows you how the bolt opens straight back. Since it doesn’t cock the mainspring, the bolt is light and easy to move.
Velocity with RWS Hobbys
Okay, time to stop talking and start showing the performance. RWS Hobby pellets are lightweight .22 caliber pellets. At 11.9 grains, they’re just about the lightest all-lead pellets you can find. In my hot-rodded 78G, they average 532 f.p.s. with a spread from 523 to 542. That’s quite a bit faster than the 2240, so I remembered wrong. The average muzzle energy is 7.48 foot-pounds, or a full foot-pound more than the 2240. The 2240 averaged 482 f.p.s., and the Mark I averaged 472 f.p.s.. The 78G is clearly in the lead.
Velocity with RWS Superdomes
With RWS Superdomes the 78G averaged 492 f.p.s. The spread was a tight one, from 484 to 497 f.p.s. The average muzzle energy was 7.8 foot-pounds, so a little more than the Hobbys. For comparison, the 2240 averaged 455 f.p.s. (the Crosman Mark I wasn’t tested with Superdomes).
Velocity with Crosman Premiers
The 78G shot Crosman Premier pellets at an average velocity of 494 f.p.s. The spread went from 486 to 498 f.p.s. That works out to an average muzzle energy of 7.75 foot-pounds. The 2240 averaged 448 f.p.s., and the Crosman Mark I averaged 431 f.p.s.
So, what’s the downside?
You want that kind of power? Then you must pay. You might get that power from a longer barrel, but to get it from the stock 78G barrel means the total number of shots is just 15. There are powerful shots left after No. 15, and a casual shooter might see as many as 25 shots from one cartridge. For tight velocity spreads, 15 shots is all you get.
This is where the 2240 will kick the 78G’s butt. Because for only a few dollars, you can put on a longer barrel that will probably give you the extra oomph you want without disturbing the shot count. This is where the physics of CO2 operations comes into play.
But this 78G is still a cool air pistol. I’m having fun shooting it again after so many months of being dormant. It’s sleek and it’s powerful. We’ll find out next time if it’s also accurate.