Porting

[WeinerDog]

Have a question. Does porting in a pistol affect the velocity of the rounds to any great extent ?

[Bruenor]

Go to the source..

http://www.magnaport.com/company.html" onclick="window.open(this.href);return false;

It should be noted that Mag-na-porting a firearm:
does NOT reduce velocity
does NOT affect inherent accuracy
does NOT raise noise level

Mag-na-porting:
DOES reduce muzzle lift
DOES reduce perceived recoil
DOES increase the value of a firearm

[Mr. Glock]

Although, it should be pointed out, that porting does make close retention pistol firing unpleasant (to say the least). For example, a close quarters encounter where you don't extend the firing hand or you tuck it into your chest (side hold or front turret-style). Doesn't apply to a range toy or competition gun, obviously.

[glocksmith]

Although, it should be pointed out, that porting does make close retention pistol firing unpleasant (to say the least). For example, a close quarters encounter where you don't extend the firing hand or you tuck it into your chest (side hold or front turret-style). Doesn't apply to a range toy or competition gun, obviously.

It probably makes it even more unpleasant for the person right next to you on the firing line .

[Brian D.]

Go to the source..

http://www.magnaport.com/company.html" onclick="window.open(this.href);return false;

It should be noted that Mag-na-porting a firearm:
does NOT reduce velocity
does NOT affect inherent accuracy
does NOT raise noise level

Mag-na-porting:
DOES reduce muzzle lift
DOES reduce perceived recoil
DOES increase the value of a firearm

From many years of wasting time in gun stores and shows, I definitely take issue with Mag-na-Port's long-held assertion that their work increases the "value" of a firearm. It does increase the amount of money the owner who sprung for the porting has in the gun. Maybe that's not how Mag-na-Port defines the word 'value' though.

[sodbuster95]

From many years of wasting time in gun stores and shows, I definitely take issue with Mag-na-Port's long-held assertion that their work increases the "value" of a firearm. It does increase the amount of money the owner who sprung for the porting has in the gun. Maybe that's not how Mag-na-Port defines the word 'value' though.

I'd also take exception with this. I have to assume I'm not the only person who does not care for (read: won't purchase) firearms that have been modified with these types of "customizations". No offense to those who do it and/or like it, but "stippling" is one of the things that will almost instantly turn me off to any firearm.

Back on topic - I'm no expert on the topic (to be fair, I've never even thought about it before right this second), but it seems to me that allowing the combustion to escape the barrel prior to the projectile leaving the muzzle would reduce the impact of the expansion on the projectile (I.E., reduce velocity). If that's not the case, I'd be interested in a (layman's) explanation as to why.

[DontTreadOnMe]

There's no question a ported barrel will reduce velocity, the question is by how much and is it "significant". That depends on the size and location of the ports, barrel length, and the ammunition being used.

From my own experience the most effective muzzle flip reduction I ever experienced was with a friend's revolver that had porting very close to the chamber. I've fired the S&W PC Shield and some other guns with the porting out towards the muzzle and the effect on barrel flip, to me, was negligible.

The PC Shield is the one I've shot most recently, earlier this year. Comparing it to a standard shield with an Apex trigger kit, they felt pretty much identical to me. The most obvious difference was in muzzle flash. It went from barely noticeable to "whoa!" (Hornady CD, IIRC). I wouldn't want to fire that one from a retention position.

[Sevens]

I will also agree that adding in the bit about adding to the value being pure "salesmanship." However...! It's a little hard to blame M-N-P for doing that. When you consider that they are indeed selling their work AND they are likely the premier outfit for such work AND their work is extremely clean AND their reputation is very, very good, then one might argue if someone is going to put a HOLE or series of them at the muzzle end of your barrel, Mag-Na-Port is likely who you want doing the work.

To the subject, I would like to pit my buddy's 7.5" Redhawk .44 Mag up against my 7.5" Redhawk .44 Mag as mine has the 4-port M-N-P work done to it. The problem with this of course is that even though I have the chrono and access to both revolvers and access to an array of fine handloads... it's never going to be a fair comparison because they are not the same revolver. The absolute best method would be (high round count) testing before and after on the SAME revolver. Dead honest truth is that two 7.5" Redhawks made on the same day can show different chrono results even when you manage to strip all the variables away. Likely more variance than the porting can/will do, but test on your own before calling me a liar, please.

Best I can do here would be to show off some chrono numbers from my Redhawk on loads that I have crafted and you can decide if I gave up much with a 4-port M-N-P job. The Redhawk is a mass-produced workhorse that couldn't win a beauty contest even with a huge Trump campaign donation, so I don't care if four EDM cuts look "a little ugly", it absolutely makes this revolver more enjoyable to shoot.

19.2gr Accurate#9 under a 240gr cast LSWC -- 1,362fps average
20.2gr is the max published load in the Accurate 3.5 printed guide. YMMV. Please be careful.

[JimE]

A lot of the issue depends where the ports are, and how large they are.
Compare the size of the ports on a Shield ,(or a Performance Center M&P) to the ones that Magna-Port cuts. Too big, too soon, and you can loose velocity and do nothing for muzzle flip. It's all about controlling the gas.
Look at any "race" gun; you will find a multi chamber compensator past the rifling. Those really do work, keeping the muzzle rise flat for faster second shots.
Higher pressure rounds, or using powders designed to create gas (think Winchester Auto Comp) will also see a more noticeable change when using ports or comps.
Trade offs....lots of smoke and residue going up, LOTS of muzzle flash at night.
Myself, they are great on hunting and competition pistols. I can see the benefits on hard recoiling rounds . But on a daily carry piece, especially in a light recoiling caliber, I don't care for it.

[Bruenor]

Higher pressure rounds, or using powders designed to create gas (think Winchester Auto Comp) will also see a more noticeable change when using ports or comps.

^^
This Absolutely, if you don't have enough gas to make the ports or comp work, it's just a bunch of superfluous holes in your barrel with no positive effect.

[Mr. Glock]

Sevens, I think some thin aluminum and duct tape would solve your issue, to get the "before". You already have the "after".

Ports don't affect velocity if you blank them off.

[TSiWRX]

A lot of the issue depends where the ports are, and how large they are.
Compare the size of the ports on a Shield ,(or a Performance Center M&P) to the ones that Magna-Port cuts. Too big, too soon, and you can loose velocity and do nothing for muzzle flip. It's all about controlling the gas.
Look at any "race" gun; you will find a multi chamber compensator past the rifling. Those really do work, keeping the muzzle rise flat for faster second shots.
Higher pressure rounds, or using powders designed to create gas (think Winchester Auto Comp) will also see a more noticeable change when using ports or comps.
Trade offs....lots of smoke and residue going up, LOTS of muzzle flash at night.
Myself, they are great on hunting and competition pistols. I can see the benefits on hard recoiling rounds . But on a daily carry piece, especially in a light recoiling caliber, I don't care for it.

JimE, what's been your experience with muzzle flash and blast with your comp'ed handguns?

The reason I ask is because there's a current line with Glock owners going with a compensated setup (the Roland, not to be confused with the Rowland), with duty/defensive use in-mind.....

Have your smoke/residue/flash issues been a result of certain types of ammo?

[jeep45238]

The Roland setup is very, very specific in its intended usage, and has a compensator at the end of the barrel (not holes drilled in the slide and barrel).

They work, and I wouldn't have a problem shooting them at night. In the shoot house at TDI they masked off all windows once to make it like night time, and we went in without lights first, with lights second. The first time I couldn't see anything until I shot (.45 acp out of a govt 1911, 200 grain wadcutters). But, the flash from it had a strobe effect and I could suddenly see everything in the room. This was a very, very minimal flash round, and I would have been happy to have more to light everything up. My eyes weren't adjusted, so every little bit helps.

Personally I think the whole night vision shooting thing is overrated unless you're running around with night vision strapped to your face. Your eyes poor night vision degrades very quickly, and using any light source is going to destroy it.


With the Roland setup, the compensator is keeping the gun from going out of battery with a contact shot, period. It's also going to increase the speed of sending rounds down range. The one time I shot a pistol with a red dot I was shocked at how fast it ran but there's a trick to it. The trick is to act like it only has iron sights- this puts the body of the optic in your eyes focal plane and eliminates the dot hunting for most folks- this is for slide mounted. Frame mounted eliminates dot hunting entirely

[TSiWRX]

^ Oh, no, don't misunderstand - I know the purpose of the Roland.

I am just wondering what others' experiences have been in terms of the comp. Trying to gather samples from outside of that specific community, specifically to avoid hivethink.

For example, my previous question to a few friends who have had experience with the Roland was whether if they've experienced debris coming from the comp, as a result of firing "plated" FMJ range ammo. None did, but we couldn't figure out why there was a difference between what they reported and what those with barrel porting report. We of course reconciled this when we realized the differences in function between a ported barrel and a comp.

[Brian D.]

Shot timer and group sizes at speed the best way to evaluate much of the gear we try out. Also, years ago, we were trying to see which compensator worked best in our 1911s shooting .45 acp bowling pin loads. Given that these were 225 grain (and heavier) bullets, a simple single port comp worked as well as anything fancier. We video taped each other with a railroad tie side wall in the background, this was a divider that ran down range to separate the two halves of a pistol range. Anyhow, in slow-motion you could see how high up alongside the wall each pistol with various compensators, loads, etc. the muzzles climbed. That plus the shot timer gave more than enough feedback to figure out what worked best.