.22 LR barrel porting.

[Brian Ski]

I want to port a .22 LR barrel to keep high velocity .22LR rounds subsonic. I understand the "it will ruin your gun" "don't do it". Just looking for some good advice. I do not have access to an EDM but I do have access to milling machines.

Has anyone here tried porting before? How many ports and what diameter? I have about a 10"? barrel. (I need to double check length) Subsonic should be around 4-5" IIRC. I guess pull out the Chrony and give it a try a little at a time.

[BWS Arms]

Porting will not ruin your gun. Look at the mp5sd.

[Brian Ski]

Porting will not ruin your gun. Look at the mp5sd.

I meant for the ones that will mention "drilling holes" will damage a barrel. I know porting is fine.

Just trying to see what other have done. Barrel length, port diameter, how many holes and how far from the muzzle, etc Thanks

[BWS Arms]

It’s going to be trial and error to get the correct amount and diameter. You can search the old threads here and probably find a starting point. You could also tap the ports and use allen headed set screws to block them off when not needed.

[BWS Arms]

I would start porting close to the chamber. Again, use the mp5sd as an example.

[Brian Ski]

I would start porting close to the chamber. Again, use the mp5sd as an example.

Wow, Never got to look at one before. Must be 30 holes in that barrel. I will start off slow. Thanks for the help. It may be a while. Will try to post a follow up.

[alordnapa]

What is your overall barrel length? Too long a barrel and ports to close to the chamber can give you squibs ( Which you will probably survive if your gun explodes) Putting ports in four inch barrels is not going to buy you much. There are many interrelated factors to consider.

[Brian Ski]

What is your overall barrel length? Too long a barrel and ports to close to the chamber can give you squibs ( Which you will probably survive if your gun explodes) Putting ports in four inch barrels is not going to buy you much. There are many interrelated factors to consider.

I think my barrel is about 9" (or 10?) I don't have it here right now. Looking to drop the cheaper high velocity down to a subsonic level. I thought High velocity was subsonic around 4" or so.

[Capt. Link.]

I want to port a .22 LR barrel to keep high velocity .22LR rounds subsonic. I understand the "it will ruin your gun" "don't do it". Just looking for some good advice. I do not have access to an EDM but I do have access to milling machines.

Has anyone here tried porting before? How many ports and what diameter? I have about a 10"? barrel. (I need to double check length) Subsonic should be around 4-5" IIRC. I guess pull out the Chrony and give it a try a little at a time.

A pair in the throat for 900-950fps in rimfire using HV ammo.

[Brian Ski]

I want to port a .22 LR barrel to keep high velocity .22LR rounds subsonic. I understand the "it will ruin your gun" "don't do it". Just looking for some good advice. I do not have access to an EDM but I do have access to milling machines.

Has anyone here tried porting before? How many ports and what diameter? I have about a 10"? barrel. (I need to double check length) Subsonic should be around 4-5" IIRC. I guess pull out the Chrony and give it a try a little at a time.

A pair in the throat for 900-950fps in rimfire using HV ammo.

Do you have an idea on what diameter?

[Capt. Link.]

I would start with the smallest size until you reach your desired speed. Nobody can give you an exact size as chambers very as do barrels. The old saying of the devil is in the details apply. Make sure you do not cut into the chamber or the lands center it in the throat.

[Brian Ski]

I know, You cannot undrill it.

[sub-sonic]

Freebore the barrel back to 3.75” and it will make all ammo subsonic then drill ports as you like in the freebored section to let out gas

[collinis]

Freebore the barrel back to 3.75” and it will make all ammo subsonic then drill ports as you like in the freebored section to let out gas

How do most people go about doing this? What diameter would you bore out to for a .22 ? How would you insure a good crown on the inside of the barrel? Thanks for the advice?

[SILENCERENGINEER]

Be careful when porting. This isn't usually a home hobby job. Best practice would be to cut and crown you barrel to desired length (3.75" if you desire) then thread that to 1/2-28. Then add a barrel extension to legal rifle length and pin and weld. The barrel extension will have a bore diameter I'd recommend of .250" and port that extension all you want. Don't bore your barrel directly because you will negatively affect accuracy. Also don't port directly into the rifling because you will leave burrs that will affect accuracy and/or you can destabilize the bullet. depending how many holes you machine and their location along the length.
Hope this helps

[Capt. Link.]

Be careful when porting. This isn't usually a home hobby job. Best practice would be to cut and crown you barrel to desired length (3.75" if you desire) then thread that to 1/2-28. Then add a barrel extension to legal rifle length and pin and weld. The barrel extension will have a bore diameter I'd recommend of .250" and port that extension all you want. Don't bore your barrel directly because you will negatively affect accuracy. Also don't port directly into the rifling because you will leave burrs that will affect accuracy and/or you can destabilize the bullet. depending how many holes you machine and their location along the length.
Hope this helps

Porting is well within the ability of most amateur hobby shops. A long barrel extension as described would affect accuracy in the negative as contact would most likely occur plus the gases passing the bullet would cause instability. Boring a barrel directly can be done if the recessed barrel muzzle is crowned. Porting into the rifling will not affect accuracy if de-burring is done ,it not difficult.
Simply cutting a barrel short dose not add to the suppression of super sonic gases or allow powder to burn off decreasing fouling and gas pressure on the base of the bullet. A longer barrel that is properly ported will do all these things plus increase accuracy if the barrel is put under tension.
You should read the AMF tech book done on porting plus the latter work done by H&K for the MP5SD.
Sorry to be stick in the mud on your post but its nothing but disinformation.
CL

[Historian]

The size of the barrel determines the velocity out of the barrel.

Please detail the weapon and barrel length you have.

For example 5.5" barrel keeps even HV subsonic.

And while on the subject do others find it annoying when
YouTube presentation of a suppressor shoot with a subsonic
around and then a HV round but not a SV round? And even more
noisome is hitting the steel plates.

Standard for a presentation is set for a can on a 5.5 barrel on youtube is the
excellent and always enjoyable :
<< https://www.youtube.com/watch?v=fyBNJ_31uQc >>

[SILENCERENGINEER]

Be careful when porting. This isn't usually a home hobby job. Best practice would be to cut and crown you barrel to desired length (3.75" if you desire) then thread that to 1/2-28. Then add a barrel extension to legal rifle length and pin and weld. The barrel extension will have a bore diameter I'd recommend of .250" and port that extension all you want. Don't bore your barrel directly because you will negatively affect accuracy. Also don't port directly into the rifling because you will leave burrs that will affect accuracy and/or you can destabilize the bullet. depending how many holes you machine and their location along the length.
Hope this helps

Porting is well within the ability of most amateur hobby shops. A long barrel extension as described would affect accuracy in the negative as contact would most likely occur plus the gases passing the bullet would cause instability. Boring a barrel directly can be done if the recessed barrel muzzle is crowned. Porting into the rifling will not affect accuracy if de-burring is done ,it not difficult.
Simply cutting a barrel short dose not add to the suppression of super sonic gases or allow powder to burn off decreasing fouling and gas pressure on the base of the bullet. A longer barrel that is properly ported will do all these things plus increase accuracy if the barrel is put under tension.
You should read the AMF tech book done on porting plus the latter work done by H&K for the MP5SD.
Sorry to be stick in the mud on your post but its nothing but disinformation.
CL

I'm an engineer specifically in Silencers and I do this for a living, daily. I'm 100% certain of my answer. I literally have tested bullet destabilization, tested porting barrels and their effect, tested velocity changes with barrel length, phantom high speed camera testing, etc. Zero disinformation.
Almost everything you said is bad advice except yes, hobby shops that are proficient in machining and GD&T are capable. I'll let the people decide who's answer they trust.

[Capt. Link.]

I'm an engineer specifically in Silencers and I do this for a living, daily. I'm 100% certain of my answer. I literally have tested bullet destabilization, tested porting barrels and their effect, tested velocity changes with barrel length, phantom high speed camera testing, etc. Zero disinformation.
Almost everything you said is bad advice except yes, hobby shops that are proficient in machining and GD&T are capable. I'll let the people decide who's answer they trust.

Not a engineer never taken a photo of a bullet nor did I sleep in a holiday inn. I'm also not seeking validation.
CL

[BWS Arms]

I am not an engineer but I do build suppressors and firearms as a 07/02. I have ported barrels in only the groves and ported them into the lands and groves. I saw no significant difference between the two. Both worked well and I have no problem with porting either way.