If I remembered correctly, the cause of first round pop is from the unburned powder reigniting in the silencer once it meets with more Oxygen.

Once the inert CO2 replaces the Oxygen in the silencer after the first round, there will be no more "pop".

Now, following that logic, if you are doing some midnight backyard murdering but don't want to piss off the neighbors or your wife, is it feasible to prefill the silencer with one of the Dustoff cans to replace the Oxygen in there with inert gas such as R152a.

It's readily available anywhere and only few bucks.  Insert the straw, couple squirts then hunt on.

It is your idea.  Do the research.

If you lower the velocity of the first round to about 800 fps, there is no pop.

So you really need two subsonic loads. A cat-sneeze load and a full-power subsonic load.

Argue all you want about what causes the pop, or how you can circumvent it by weird measures.

12.5 grains Trail Boss with a 200 grain bullet gives me about 1050 fps in a .308 with 16" barrel and Allen Arms big-ass can and a big-ass pop (no crack) on first shot.
Succeeding shots with that load have no pop and no crack.

9.5 grains Trail Boss with same bullet gives me about 800 fps and is no-pop, first-shot, cat-sneeze quiet.
Reasonably accurate out to 100 yards, but has lots of drop after 50 yards.

CAT-SNEEZE LOAD
The rifle is zeroed for a 168 SMK @ 2400 fps.
If I shoot the cat-sneeze 800 fps load in that gun, these are my hold-overs:
50 yards – 7 inches holdover
100 yards – 2 ½ feet (holdover)
150 yards – 5 feet (holdover)

FULL-POWER SUBSONIC
After that first no-pop round is out of the way, I can switch to the "full-power" subsonic (1050 fps), and utilize a more-manageable holdover if you need to shoot past 50 yards.
Most significantly here, notice that the difference in holdover for the cat-sneeze vs. the full-power is only ONE INCH at 50 yards.
50  yards – 6 inches (holdover)
100 yards  – 13 inches (holdover)
150 yards  – 30 inches (holdover)
200 yards  – 55 (4.5 feet) (holdover)

A 200 grain bullet at 800 fps will handle most things you are going to want to engage silently in your back yard.

Yes

Maybe put a piece of tape over the end to help keep it in there if you're not going to shoot right away?

Basically, yes it will help. There was even a company (or two) that came out with adapters that went between your muzzle and suppressor. They had a little valve on them that you hooked up one of those bicycle fillers that uses disposable CO2 canisters. You basically purged your can before the first shot. Of course they didn't sell well

This would work best with a wiped end cap, but it's still fun to play around with. You can use Sprite as an ablative and let the fizz push it all the oxygen too

Would a little water or line pulling gel do the same thing to reduce first round pop?  I have 22 and pistol cans and am waiting in my rifle cans to be approved. But I regularly shoot my rimfire and pistol cans with a little line pulling gel and that does well to reduce FRP.

Some suppressors are worse than others with FRP symptoms.    Monocore designs typically exhibit greater FRP than designs with individual baffles.

I have a 9mm Thompson Machine Isis 2 suppressor which had a monocore.   It was nice and quiet for the second and subsequent shots.   FRP was significantly louder and was quite annoying.   Especially if you were only taking one shot at a back yard Squirrel or Crow.     A little bit of white lithium grease on the blast baffle helped, but it was messy.

I eventually sent the suppressor to Curtis Tactical and he re-cored it with a threaded and shielded baffle stack of his own design.     FRP is totally absent now and the suppressor is much easier to clean.    

To the OP, your duster idea will work but only temporarily unless you seal it inside the can (balloon or condom over the muzzle end).

I played around with using CO2 and Argon for this.  It did help, air duster might help more, since its denser, and presumably won't leak out as fast.

It honestly isn't worth it with a good can, I only played with it on mono-cores.

I would think two problems with this.
1st. If you sprayed the co2 in before hand it would dissipate
Quickly.
2. If you spray that before you shoot the animal will hear that and run.

https://discreetballistics.com/shop/popstop/

Many of those compressed gas duster cans are flammable, you may get a huge fireball instead of first round pop if you used that.

wire pulling, or a KY style, jelly

This.  FRP on a good, baffled rimfire can should be all but indistinguishable from subsequent rounds with no use of ablatives or inert gasses.

chewing fingernails over FRP, completely ignoring the 135ish db spike from a slug impacting in the back yard.

Anything in my yard worth shooting with a centerfire, is worth shooting with or without a can. I.e. skunk.

I'll take the ticket, and I know my neighbors won't bitch. I was ready to light up a skunk with 9mm a while ago if it came in any closer. Ran off before the wife came back with a suppressed gun. I'm NOT dealing with sprayed dogs, I don't give a shit.

A 22lr is so quiet even without a can, nobody is really going to notice. If you use any silencer worth a fuck on a 22 rifle, you ought to be able to shoot it in the next room and nobody would notice. Your neighbors certainly won't when they're all asleep at 2am.

ETA: yeah that air duster is probably flammable. But if you get some inert gas in there, a piece of masking tape or an earplug would hold it in long enough to walk outside and drop a raccoon in your trash. Problem is, you have to fuck around with the business end of a loaded gun to do that sort of stuff. Or maybe, if you can quietly chamber a round real quick, blast co2 in there and lock the action.

They say wire pulling gel works well.

I pulled up to the trailer one night after drinking.

Skunk was in the yard eating a pile of dog shit.

I was way too poor to own one of them sherpreshhers.

So, I grabbed the Glenfield .22 bolt action.

One round of .22 short in the skunk's head.

BIG MISTAKE.

The skunk was DRT for sure.

But he sprayed.

And I'd neglected to close the windows on the trailer.

I was too addled to realize that in the heat of the moment.

I had to cut a length of clothesline from the neighbor's yard, and make a lasso to get rid of the dead skunk.

I lassoed the dead skunk and tied him to the car, and drove until there was no more skunk.

Except when I got back to the trailer.

Skunk's "essence" remained with us (and on all our clothes) for about three weeks.

That's the major issue. If at all possible I'd let it walk. Kill it, and it will likely death-release. Live trap it, and i don't know how you're going to get it out without it spraying proper, or killing it. Kill-trap it, and we're back to square one.

But I'll take a kill release in my yard over sprayed on the dogs release.

Just a couple minutes ago the dogs got into with a coon family, but the coons are much more adept to climb 6' chain link and trees, knowing they're not going to win a proper battle with 85lbs of lab/shepard and 35lbs of elkhound/shepard. Where the big dog has strength, the little girl has speed. I can deal with coons though. They don't stink. They just mind their business and defend themselves. I guess skunks do too... just much more pungently.

My elkhound has made it across the yard, call it 60 feet, in the time it took a cottontail to run cross, about 20 feet. She missed the floofer by a step.

They stopped using Propane as propellant 20 years ago.

Electronics and combustible gas don't mix.

The dusters today are using either CO2 or refrigerant.

That's what I did, and it worked.  I could not tell the FRP from shooter's ear.  

Filled up with gas from the breach, tape over muzzle, chambered a round.

I have two different pistols set up, TX22 with Sig and SR22 with Rugged.

double tap

Interesting science project, totally useless in the real world

Not useless, but fairly niche.

Did you put those rounds on paper OP? It should break the tape before the bullet hits it, but just want to make sure it's still grouping well.

Yes, including difluoroethane which is flammable. I'm literally looking at a can of "Dust Off" right now that has a warning to not use near open flames as contents may ignite.

The Oculus 22 isn't supposed to have very noticeable FRP to begin with, that's a big reason I was thinking about picking one up. Do you get a lot of FRP with it on a pistol?

No, totally useless.  As someone noted, you are staring with a loud sound for the spray.  Then the impact of the round.   What are you gaining here that you don't with shooting wet?  Other than carrying around an aerosol can...

Shooting through tape won't affect a grouping.

https://discreetballistics.com/shop/popstop/

Edit : beat by a mile

I have a dead air mask in jail, it's supposed to have very little frp and that's one thing I'm looking for.
Shot a skunk in the corner my yard a few nights ago, drt,  so I shoveled some dirt and ashes from the fire pit into my wheelbarrow and dumped it on the dead skunk as it started to smell, worked like a charm, no more smell.
.22LR isn't all that loud but at 4am I would like it to be quieter, hence the suppressor, helps with critter control so my chickens don't get ate.

You're basically shooting wet w/ more volume and less stress on the can.  Should be no more sound than squirting in shaving cream.  And if you use tape or a condom, you can insert the CO2 well before you sneak up on the snek.

R134a.

When I'm by myself at our private outdoors range with little ambient noise, yes.  Compare to my other cans, it's less.

I only shoot supersonic rounds, no subs.

Accuracy is not effected at all.

A lot of early silencers were made of wipes, a piece of tape is nothing.

If I gel up a can 4 o'clock in the morning, I'd better shoot it, or have to clean it or dry it.

With the aerosol, no harm no foul, put it up and go back to bed.

I'm thinking you keep your .22 pistol loaded with SV, chamber empty, tape on the silencer, by the back door. When the coons are doing trash panda stuff, you lock your slide open, squirt your gaseous ablative in, and chamber a round. Silently open door/window, and take care of business. Generally pest creatures outside don't care about modest noises inside.

I must admit I've never used any ablatives, but I'm not putting any of that crap in my can and leaving it for hours or days. Some co2 on the other hand, won't do anything bad, and neither will a piece of scotch tape.

What OP is doing isn't the most practical, but it has its merits.

I'm guessing with tape and a chambered round, the gas will stay in there, at least enough to be useful, for quite some time. Possibly for hours.

ETA: yes, impact noise can be rather loud. Easily audible at 50yds when hitting a squirrel in the woods with a pellet gun. A .45acp makes quite a racket going into mud at 100yds. We can't do anything about that. But impact noise is not a gunshot. IME, it's a dull smack, a very low tone, like dropping a rock into water. Much less conspicuous than a high pitch pop associated with a gun.

Hell, I like telling this story. One time during archery season, I was out for squirrel on public land with my bolt action 22 w/ can. The leaves still being up obscured my view of another hunter in his climbing stand. I saw a squirrel in the tree he was in (which at the time, I did not know there was anyone in the area!), it was somewhere around 50yds, decently high up. I picked off the squirrel, with but a tiny ting of the rifle firing (CCI SV). The glorious SCHWACK of said bullet connecting was great, the squirrel tumbled off the tree. I was happy, all was good, for the fraction of a second it took everything to process. Then I heard a scream to the effect of "holy shit", which made me scream something similar. Now thinking by some unholy means I just shot someone, I start moving towards the tree, and see the other hunter, probably sitting in his own intestinal content. He was OK, scanning with his bino/rangefinder, looking around and down at the squirrel. He had no clue where the shot came from, despite me being only 50yds away and after taking two steps, he could probably see my (camouflaged) torso. The shot went about 15ft above his head.

I hadn't the balls to go collect on the bushy tail. Too embarrassed. So i hope dude took the squirrel home, he deserved it in payment for his shorts.

Fatalwishes used to shoot doves off his neighbors' roofs (in suburbia) w/ .22 CBs.