I want to get a new 460 Rowland barrel for my .45 XDM and am wondering about these differences.  Is a ported barrel louder than comp'd, and is there more of a slow down with the comp'd barrel???  Also is there a difference between brands of compensators in effectiveness if they both have the same basic port sizing and number of ports?

I think it might just be semantics??  But, I have always thought of porting as something you cut into a barrel and a comp as an add on to the end of a barrel (or slide).

I'm pretty sure Rich10 is exactly right about the semantics part; they're pretty much always interchangeable it seems. A barrel port, itself, is a specific method of recoil compensation often used when fitment of a secondary device for compensation isn't needed or wanted. To me, as well, the term "comp'd" usually means that there's some sort of muzzle device or other item fitted to the weapon to compensate for the recoil in one way or another. Basically a port is always a port but "comp'd" can mean anything to compensate for recoil, including (but not limited to) porting.

Not what I'm asking...I want to know the difference in noise made and whether they both accomplish the slowing of the slide equally.

They slow the slide and reduce sound??

I think what they do is reduce muzzle rise and maybe reduce muzzle flash.

Well neither of them are going to reduce the sound signature in any way since neither of them is designed for suppression. Perhaps there might be a distinguishable difference in sound signature as far as perception of direction (more from the side with a comp, generally more from the top/front with porting). In general they will both have a very similar report to that of an unmodified weapon, as far as measurable loudness is concerned, unless you're doing close-in manipulation. In that case you will definitely perceive it to be louder as much more of the report is directed up toward/around you instead of away from you. Regarding the reduction in slide velocity during rearward travel: that's mostly a function of the volume of the modification; if you have multiple large ports, or a significant comp, it will reduce the slide velocity much more than fewer, smaller, ports or a relatively small comp. However much of the expanding gas you're able to redirect from the path it normally takes straight out of the barrel (and consequently pushing straight back on the slide) is a function of how much less velocity you can expect. The equation for this probably involves some wacky math that I won't even pretend to understand. That being said, however, it probably won't reduce the velocity of the slide nearly as much as you'd think, unless you're talking about a significant amount of comp or several large ports, enough to allow a sufficiently large volume of gas to escape prior to the slide reaching its extreme rearward travel. As Rich10 mentiond: mostly they're designed to assist with reducing muzzle flip more than anything else.

I had thought that the noise would be greater with a ported barrel, but am unaware of how a comp barrel would sound.  Also it seems your saying that there is no appreciable reduction in slide velocity with comp or porting yet the 460 Rowland conversion uses the comp or porting to do that unless I am completely missing the point.  It was also inferred that the reduction would be be relative to the number and size of ports in either the comp or ported barrel.  This makes sense to me.  What I am trying to ascertain is whether to get a threaded barrel and place a comp from Lone Wolf on it or get a ported barrel.  If they are both relatively the same I guess the ported barrel would be the way to go for cost and added size/weight to the front of the gun. In this last post it was stated that the reduction would be attributable to bullet velocity which I am hoping is not correct as I don't want to reduce but rather find increased velocity as a result of a slightly longer barrel though much of that is taken up by the porting.

Yes, adding porting or a comp will alter the sound signature of your weapon, but it won't necessarily make it louder or quieter; you will probably perceive it to be louder just because of the redirection of some of the expanding gas from the front of the barrel being channeled either up or to the side (or both) instead of directly out and away from your gun (and your ears). This can be particularly annoying when in close (think weapon retention) and the concussion from the muzzle blast is partially directed into your face because of the porting. It won't be any louder, technically, but it will certainly seem that way just because you're now experiencing it more directly.

As for the reduction in slide velocity: this is a function of the ammunition along with all of the parts of the gun, to include a compensator or porting; Adding a compensator to a 9mm barrel will have little effect on the slide velocity simply because there's not much expanding gas for the compensator to act on. Now when talking about a .460 Rowland or a .50 Action Express you will definitely notice a reduction in slide velocity as the compensator has more expanding gas to work with and can have a proportionally larger effect on the slide velocity (and muzzle flip). However: the recoil spring upgrade in these conversions plays a more significant role in reducing recoil (obviously) and slide velocity and shouldn't be neglected.

Regarding your question about which to get: that's really up to you. All things considered, it really boils down to which you think you'll need more or get the most use out of. This obviously depends on what you're going to be using it for. If you don't mind the extra weight out front and the added length, a compensator is a tried and true method of recoil and muzzle flip reduction. Porting doesn't add weight out front but rather the opposite, especially if you get an internally ported barrel (which can also be more expensive than just adding a compensator) because you'll have to mill out your slide to accommodate this type of porting (versus extended barrels with external porting, which is also an option). This change is obviously irreversible, however, so if that's a concern you should take that into consideration.

If you're looking to keep velocity up but reduce the recoil/slide velocity of the round I would definitely recommend the compensator as it has several advantages over just having porting: added weight out front, greater barrel length (threaded barrels typically have an additional half-inch or so on the ends to accommodate the threads) which should raise velocity a tiny bit, and an appreciable reduction in muzzle flip and felt recoil because of the action of the gas on the compensator (the act of compensation itself).

I didn't mean to get so long-winded but I hope that helps!

Thanks for the detailed response.  I was going to buy a ported barrel that was the same length as a threaded barrel and after these responses I see no distinct purpose of the compensator except to be able to remove it.  I can swap the barrel back to my original barrel if I want a shorter length system.  Thanks...

No problem, glad to help! One more note about the compensators though: they are probably more efficient when given the right media to work with. There's typically much more surface area in the multiple channels of a compensator for the gas to work against than most porting options so if you need the most efficient method possible, especially when using loads that generate lots of gas, it might be more useful than porting alone. Standard loads, for the most part, will tend to see similar levels of improvement with either option so the cheaper/easier/faster option is probably the best bet. Also: compensators could actually affect the function of the weapon when using lower-powered loads so that's something to keep in mind as well, if that's a possibility. Good luck! Let us know what porting option you go with and how well it works for you!

Sounds like your saying a comp has ports that are not seen so the gases don't just travel straight up from the barrel like they would on a ported barrel???
I'm very new at this and have not seen either up close.

It depends on the particular brand/model/style you go for but there are several different variations. Typically porting is directed straight out the top as in normal Glock "C" models seen here: http://www.lonewolfdist.com/itemmedia/10000/10000_747.jpg or as some aftermarket companies do here: http://www.lonewolfdist.com/itemmedia/10000/10000_939.jpg Compensators, however, typically operate mostly out toward the sides, bust some have a combination of both as seen here: http://www.lonewolfdist.com/itemmedia/10000/10000_1070.jpg Some other comps don't have any ports on top and look more like a "brake" like those found on rifles and so forth but will obviously have less of an effect reducing muzzle flip versus just reducing recoil: http://sgcusa.com/images/supporting_images_large/Barrett_M82A1CQ_Muzzle_Brake_F.jpg

Ported barrels just have holes.

A compensator has a cavity that is larger than the bore, and it has a surface at the front for the gasses to bounce off of forcing the compensator and whatever it is attached to forward.

Both reduce recoil to some degree (mathematically), but you may not always feel it like in a 45 ACP or 38 special. The compensator should reduce recoil better than barrel porting.


.

Quote from: ram1000 on December 12 2014 11:48:22 PM MST
Not what I'm asking...I want to know the difference in noise made and whether they both accomplish the slowing of the slide equally.

I doubt either will slow the slide to any degree if the compensator is attached to the barrel (Glock). If the compensator is attached to the slide (1911), than it will slow it down. The increased weight of a compensator on the slide will also cause it to slow down. A compensator on a Glock barrel may reduce slide speed by pulling the barrel forward and causing it to wedge against the top of the slide increasing slide-to-barrel friction.

It also depends on when you want to slow down the slide. With either the ports or compensator, the slide speed isn't effected until the bullet passes the ports or exits the muzzle, and by that time the barrel is unlocked from the slide.




.

Since the slide and barrel are locked together for the initial phases of the action cycle, mass added to the barrel, eg compensator, will absolutely have in impact on slide velocity.

A 5oz comp will reduce slide velocity on 460 Rowland by about 25% versus a stock barrel just from weight alone.  That will depend a bit on the load.  For my calculation I used a 230 grain load at Wikipedia spec 1350 fps.  The hypothetical gun had a 13 oz slide and a 5 oz barrel.  Slide velocity without/with compensator when the bullet leaves the barrel is 39 fps / 30 fps.

I can't find good data on how much a ported barrel weighs.  I would guess about .5 to .75 oz more than a stock length.  Comparing those to barrels you get 37 fps slide velocity with the ported barrel vs 30 fps with the comp'd barrel.