Loud 1st shot?

[sir-lamp-alot]

Given my .22lr a dust of as of late and taken it out after the corvids on the cut grass but Ive noticed that the 1st shot is most deffinatly louder than those that follow. Personally I cant make head nor tail as to why it would be happening but it most definatly is and going high too (almost like its gone super sonic). Ammo is just bog standard winchester subs running through a old brno mod 2 and parker hale mod anyone got any ideas?

 

[Liveonce]

old brno mod 2 and parker hale mod

exactly what i have , and sorry no idea as not happening with mine.

 

[calgeo]

Could it be the ammo? When I used Winchester subs there always was the odd round that went supersonic.

 

[jb1]

Seen this loads of times, i would say poor QC but knocking out millions a day it would be a tad difficult to check those numbers.
But have seen/heard loads of what you expect to be subsonic are obviously not, i stick to RWS Subs.

 

[Plitts]

Are you cleaning in between outings and there is oil in the barrel on first shot?

 

[Heym SR20]

22 bullets are lubbed with a waxy greese. This remains in the barrel. After a few days it goes hard.

First bullet this meets more resistance resultant in higher pressures being generated before bullet moves down the barrel clearing the harder wax away. Higher pressures resulting in high velocity and high bang as faster velocity of gases leaving the muzzle.

Subsequent shots the lube left is nice and soft.

After shooting its left a few days and lube hardens up.

 

[Liveonce]

22 bullets are lubbed with a waxy greese. This remains in the barrel. After a few days it goes hard.

First bullet this meets more resistance resultant in higher pressures being generated before bullet moves down the barrel clearing the harder wax away. Higher pressures resulting in high velocity and high bang as faster velocity of gases leaving the muzzle.

Subsequent shots the lube left is nice and soft.

After shooting its left a few days and lube hardens up.

Then why do we not all experience this?

 

[old keeper]

I don't use my .22 LR much now and get the odd loud report. Seldom, if ever, on the first shot. I put it down to the latest ammo, especially Winchester's 42 grain.

 

[Greenmist]

As plitts says, are you cleaning between outings, is it just the first shot, or does it take a few to get back to normal. Is it possible its just you (no offence) if you're not used to it, the first shot may be you getting used to trigger pull and noise.
If you want to be really scientific, you could chrono the shots and even use a sound level app to know for sure

 

[One on top of two]

Attenuation changes after first shot as gasses are left in mod ?

 

[sir-lamp-alot]

Are you cleaning in between outings and there is oil in the barrel on first shot?

cleaning? Well it goes out in the rain every now ad again

 

[sir-lamp-alot]

22 bullets are lubbed with a waxy greese. This remains in the barrel. After a few days it goes hard.

First bullet this meets more resistance resultant in higher pressures being generated before bullet moves down the barrel clearing the harder wax away. Higher pressures resulting in high velocity and high bang as faster velocity of gases leaving the muzzle.

Subsequent shots the lube left is nice and soft.

After shooting its left a few days and lube hardens up.

I reckon you could be onto somthing here as Ive noticed that this batch of ammo the heads are caked in the stuff, more than usual

 

[CookM]

old brno mod 2 and parker hale mod

exactly what i have , and sorry no idea as not happening with mine.

Same here,why buy different.
Never happened once.
CCI,Remi, ELEY,RWS,Winni subs.

 

[paulst]

I recently chronographed some Winchester subs and they were very close to being supersonic with a fair few straying over. Small sample of 50 but I got 8 supersonic.

 

[moeggesit]

Do you oil the moderator and leave oil behind?

 

[Heym SR20]

Then why do we not all experience this?

Because rifles are different, moderators are different, ammo is different, our ears are different etc etc. Some others, judging by this thread have experienced this, others haven’t.

 

[old keeper]

Mention has been made of cleaning, except if the rifle gets wet, my Anschutz .22LR seldom gets cleaned, unlike the centrefires. I've had it over 25 years and when it does get cleaned the barrel is still as new.

 

[Steff]

There's a technical term for this phenomenon. It's First-Round-Pop (FRP). There is still oxygen in the mod which burns on the first shot. Subsequent shots will be more quiet.
And decent test on moderators lists the nominal and FRP attenuation.

 

[Mungo]

There's a technical term for this phenomenon. It's First-Round-Pop (FRP). There is still oxygen in the mod which burns on the first shot. Subsequent shots will be more quiet.
And decent test on moderators lists the nominal and FRP attenuation.

And somehow magically there’s no oxygen on subsequent shots?

I don’t think that can be the explanation for the phenomenon. They’re not sealed chambers!

 

[Steff]

And somehow magically there’s no oxygen on subsequent shots?

I don’t think that can be the explanation for the phenomenon. They’re not sealed chambers!