First round pop

[Pappabear]

I have a shit load of cans and have never noticed any significant FRP.

Explain the engineering of how it happens, and what cans are most notorious for it?

PB

[BigWaylon]

Monocore cans seem to be the most likely to have FRP, and usually it's more noticeable on shorter barrels (pistols vs rifles). The Sparrow and Osprey are two good examples. The Liberty Regulator is advertised to have eliminated it for the most part.

Has to do with oxygen in the blast chamber.

[czgunner]

With my sparrow on my 3" buckmark, the pop is noticeable but it's never been loud enough to bother my ears.

[Benito]

Monocore cans seem to be the most likely to have FRP, and usually it's more noticeable on shorter barrels (pistols vs rifles). The Sparrow and Osprey are two good examples. The Liberty Regulator is advertised to have eliminated it for the most part.

Has to do with oxygen in the blast chamber.

If it's just the size of the blast chamber, why would monocore or not mae a difference? Just curious.

[darr3239]

First I've heard of FRP. What the heck does it sound like?

[P2000]

I have a form 1 (semi-home made) 22lr can on a pistol. It has formed freeze plug baffles and tubing spacers of different lengths.

Originally it had the largest spacer at the rear of the can, creating a large blast chamber, and it had noticeable FRP. Later the spacers were rearranged with a much smaller spacer at the rear, and the biggest spacer at the front. FRP went away and it also seems a touch quieter.

FRP is just louder than the subsequent shots.

[BigWaylon]

If it's just the size of the blast chamber, why would monocore or not mae a difference? Just curious.
Absolutely no idea.

[BigWaylon]

First I've heard of FRP. What the heck does it sound like?

I checked some of the simple videos and had and found two that you can hear it. Neither are a huge difference. There are 5 round unsuppressed in each, then suppressed fire for the rest of the mag. The first shot with each can is louder than the rest. Sometimes it's really noticeable, sometimes it's not.


https://youtu.be/IsYxm7renAU

[BigWaylon]

And since it's one video per post, here's the second one:


https://youtu.be/ccT3yv3VCuw

[MegademiC]

Fireman has a vid of shooting indoors you can hear it distinclty.

There is O2 in the silencer so the powder burns inside making it louder. After the first shot, enough O2 is consumed that the subsequent shots are a bit quieter. It's noticable on my rev 9, but it's only slight, especially when running wet.

I'm not sure if it's really louder or just a different tone.

[ggammell]

Fireman has a vid of shooting indoors you can hear it distinclty.

There is O2 in the silencer so the powder burns inside making it louder. After the first shot, enough O2 is consumed that the subsequent shots are a bit quieter. It's noticable on my rev 9, but it's only slight, especially when running wet.

I'm not sure if it's really louder or just a different tone.

Is this the reason why sometimes you see some flash from a suppressor on the first round?

[Pappabear]

And since it's one video per post, here's the second one:


BigWaylon, thanks for the vids. I'll see if I can hear on my 10.3 this weekend. And might try with my MPX with Ti rant 45 can. Interesting.

PB

[steyrman13]

Has anyone tried blowing through their can before mounting it to see if it depletes or increases the amount of frp?

Again, BEFORE mounting it.....

[BigWaylon]

Is this the reason why sometimes you see some flash from a suppressor on the first round?

That was always my thought. You can see it in my 15-22 video above. First suppressed shot definitely flashes.

[MistWolf]

When smokeless powder burns, it produces a quantity of superheated flammable gas. When it mixes hot and fast with oxygen, it ignites and rapidly burns. That's what causes muzzle flash. Flash hiders work by cooling the gasses and slowing down how fast they mix with oxygen.

First round pop occurs when those gasses mix with oxygen in the suppressor. It takes awhile for the burnt gasses to ventilate and oxygen to seep back in, so the immediate following shots are quieter

[MegademiC]

Has anyone tried blowing through their can before mounting it to see if it depletes or increases the amount of frp?

Again, BEFORE mounting it.....

Might slightly reduce it, but your breath still has significant o2.

Purging with inert gas like n2 and sealing the end would eliminate it.

[Pappabear]

Good info guys, I appreciate it.

PB

[hypno02]

I've found FRP much easier to notice on rimfires cans vs centerfire. This is where "wet" rated cans can help you to eliminate FRP.