by Tom Gaylord
Writing as B.B. Pelletier

Sig M17 pellet pistol
Sig Sauer P320 M17 pellet pistol.

Part 1
Part 2

This report covers:

  • Correction
  • Sig wonders why we want to disassemble the gun
  • The test
  • Sig Match Ballistic Alloy
  • Rifled barrel
  • Magazine gas loss
  • Air Arms Falcon pellets
  • Crux Ballistic Alloy
  • Blowback
  • Trigger pull
  • BBs
  • Daisy BBs
  • Smart Shot a no go
  • Beeman Perfect Rounds
  • Shot count
  • Discussion
  • Summary

Today we look at the velocity of the Sig P320 M17 pellet pistol. But there will be more to this test than just three pellets. Because readers wondered if it could also shoot BBs and I learned that it can, I will test them, as well. As long as I’m testing BBs, I will test lead balls of differing sizes, because when we get to the accuracy test I’ll want to test them as well.

Correction

I told you in the last part that the magazine cap has to be removed to insert a CO2 cartridge. That was incorrect. Just remove the mag from the gun and insert the cartridge by following the directions in the manual. Leave the cap alone.

Sig wonders why we want to disassemble the gun

Sig asked me why anyone would want to disassemble the gun for any reason other than clearing a jam. I explained that, like airsoft, these lookalike pellet and BB guns are attractive to shooters who cannot own the firearms they represent. For shooters in places like California, New Jersey, Illinois and New York, the gun laws are very restrictive. It might be impossible to own an M17 firearm in those states because it has a magazine that holds more than 10 rounds. A pellet gun might be as close as they can come. I think this view is one that a company gets as they continue in the lookalike field. I remember when I asked Wulff Pflaumer, the owner of Umarex, to make a single action revolver that looked like it had been well-used — he was amazed that anyone would want such a thing. But twenty  years later Umarex can’t keep up with the demand for guns that have the “battlefield finish.”

The test

Okay, let’s start testing. I will shoot 10 shots with each type of projectile and record the results. Because this pistol if powered by CO2 I will wait at least 10 seconds between shots, unless I say otherwise. That keeps the gun from getting too chilled and affecting the velocity.

Sig Match Ballistic Alloy

First up were Sig Match Ballistic Alloy target pellets. They averaged 368 f.p.s. over the chronograph. The spread went from a low of 359 f.p.s. to a high of 387 f.p.s. That’s a spread of 28 f.p.s.

Rifled barrel

A couple readers asked whether the M17 has a rifled barrel. Yes, it does. Dani Navickas of Sig sent us a great photo of that.

M17 barrel
Yes, the M17 barrel is rifled.

M17 pellet
The rifling only touched the pellet lightly at both the head and the skirt.

Magazine gas loss

Each time the magazines is removed from the pistol there is some loss of gas. The magazine pops out of the gun because of its internal gas pressure and you can hear a small pop, which is the gas escaping. Because of that, I loaded 20 pellets or BBs into the magazine each time it was out of the gun to minimize the number of times the magazines had to be removed.

It was easy to index the magazine belt so there were 10 of the same projectile to be tested. When you look at the back of the mag the belt climbs on the right side, so just set it so the last pellet that you don’t want to chrono is in the window at the top and when you pull the trigger the next pellet, which is the first one of your string of 10, will move into position. After those, of course, the next 10 will be the next pellets or BBs to test. And after that it’s time to remove the mag and reload.

Air Arms Falcon pellets

Next to be tested were 10 Air Arms Falcon pellets. These are lightweight lead domes. They averaged 319 f.p.s. with a 37 f.p.s. spread, from 295 to 332 f.p.s.

Crux Ballistic Alloy

Next up were some Sig Crux Ballistic Alloy domes that are made from pure tin, like the Match Ballistic Alloy pellets. This is a pellet I haven’t tested yet. This is the first time I have tried them.

They averaged 359 f.p.s. in the M17, with a 31 f.p.s. spread that went from 347 to 378 f.p.s. If you look at the specs you will see that the Crux weighs a little more than the Match pellet, so a slight velocity drop is to be expected, I guess.

Blowback

The M17 has full slide blowback, so the feeling of recoil is realistic. And the gun doesn’t use the slide to cock the hammer or to advance the pellet in the magazine, so it isn’t using as much gas as some guns do.

Trigger pull

I measured the double action only trigger pull at 6 lbs. 4 oz., which is very light for a double action pull. The trigger stacks (increases in pull weight) at the end of the pull, so you can control the pistol quite well.

BBs

Now let’s test some different projectiles — starting with a steel BB. I chose Daisy BBs for this test. They load into the magazine well and do not fall out when the mag is turned over, so there must be magnets in the plastic chambers of the belt.

Sig M17 mag
Looking at the back of the magazine with the loading door open, the belt moves counter-clockwise.

Daisy BBs

Daisy BBs averaged 331 f.p.s. for 10 shots. The range was 36 f.p.s., going from 321 to 357 f.p.s. I think these BBs are so small for the bore than gas passes them and they lose velocity. Let’s try something else.

Smart Shot a no go

I tried H&N Smart Shot next but they were not retained by the magazine. When I tipped it over they fell out and I didn’t want to jam the gun, so I didn’t shoot them . However, there might be a solution.

Beeman Perfect Rounds

Beeman Perfect Rounds are a true .177 caliber and they fit snugly into the chambers in the belt. Nothing fell out when I turned the magazine over. They averaged 252 f.p.s. in the M17. That’s slow, but these balls weigh more than 8 grains.

Perfect Rounds are no longer offered, but Gamo Round Lead Balls should be essentially the same. I don’t know why anyone would want to shoot them in this pistol unless they are incredibly accurate, but they do work.

Shot count

At this point in the test the gun has been fired 51 times on the same CO2 cartridge. So I loaded a magazine of Sig Ballistic Match pellets to see what the remaining velocity might be. Instead of an average, I will show the entire string.

Once I saw what the first round did, I decided to shoot as fast as I could and still record the numbers. That put 5-8 seconds between each shot.

Shot……….Velocity
1……………..404
2……………..392
3……………..365
4……………..376
5……………..363
6……………..377
7……………..378
8……………..364
9……………..DNR
10……………347
11……………323
12……………341
13……………322
14……………320
15……………308
16……………303
17……………296
18……………294
19……………288
20……………262

Discussion

Looking at these numbers I feel the gas ran out somewhere around shot number 12 on this string. That would be a total of 63 shots on a cartridge. But I continued to shoot, just to see if that was right. I was certain the gas was gone, so I loaded 5 more of the same Match Ballistic Alloy pellet and recorded the velocity. This time I allowed a minute to pass between each shot, to give the gas every chance.

Shot……….Velocity
1……………..251
2……………..241 gun got very quiet from here on
3……………..227
4……………..238
5……………..215

As you can see, the gas has run out. But because of how the gun is designed the slide is still blowing back with every shot.

Summary

Okay, now we have a good idea of how various projectiles perform in this pistol. I guess all that’s left is the test it for accuracy. Yippie!