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Thread: Revolver porting question

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    Default Revolver porting question

    Anyone put a small slot perpendicular to the barrel for porting? This as opposed to drilling holes, or the magna-porting (slots on either side, parallel with barrel). It would seem to me to be a decent strategy, both minimizing the reduction in effective barrel length (of revolvers), and would exhaust gases up in a wide band. (I don't have a blade sight on the end of my barrel to worry about) Any detractors?

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    It would likely work. The down side is it would be a bigger surface to shave lead off of the bullet and more likely to cause accuracy issues. All the perpendicular slot type breaks I have seen are counter bored over that area. Also being very near the end of the barrel it would have less time to function before the bullet left the barrel so it would be less effective then a longitudinal slot or hole both of which would be centered further from the muzzle.

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    I think it would be fine from a lead bullet (or any bullet for that matter) stand point. Cant speak to how effective it would be compared to drilled holes or magnaporting for recoil mitigation, but your theory seems sound to me…


    Regarding lead bullets fired thru ported barrels, everyone seems to be under the assumption that they (the ports) tend to “shave lead” and in my personal experience with my guns, this has NOT proven to be the case.

    I think it is important to remember that lead bullets (and to some extent softer jacketed bullets) will obdurate (i.e. compress lengthwise, or “shorten”, e.g. “bump up”) to seal the bore of the barrel (this may also take place to some extent in the cylinder) very near the breach end of the barrel, and quite soon after powder ignition (peak pressure) and far before the bullet has traveled down the barrel towards the afore mentioned ports…. So by the time the bullet reaches the drilled holes, ports, or what ever you have there on the end of your barrel, the bullet has already assumed its “final shape” as the peak pressure is now past (the force that deformed the bullet to the contour of the inside of the barrel) and the bullet is no longer under enough compressive force to make it expand enough to extrude material radialy out into the ports were it can the be “shaved” off by those ports as it travels past them and out the end of the muzzle. Now, that said, you will indeed note an accumulation of lead build up in those ports, but it is most likely due (my opinion here, not necessarily fact) to microscopic lead particles that are partially vaporized from the base of the bullet, or from frictional forces within the barrel, being transported behind the bullet within the combustion gas column and deposited (plated if you will) on the ports as the combustion gasses escape at high velocity thru those ports prior to the bullet leaving the end of the barrel…
    “You’ve gotten soft. You’re like one of those police dogs who’s released in to the wild and gets eaten by a deer or something.” Bill McNeal of News Radio

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    On lead shaving:
    I hadn't really considered that aspect. And frankly, my biggest concern about doing something like this is not knowing how I could effectively deburr the inner surface of the barrel after slotting. Is this what you meant by counter boring? I supposed a lapping bullet(s) would do the trick (assuming we're talking minute burrs). I would think that a slot doesn't necessarily have to have more shaving area and/or edges than a series of drilled ports. Magna-porting is supposedly very small, but I'm not sure of the actual open area.

    On accuracy:
    I hadn't really thought about the impact of porting's proximity to muzzle having accuracy implications. Certainly if the porting impacted bullet spin in some way, or caused a poorly sized bullet to become more unstable I could see it, but otherwise I would think the placement wouldn't matter much (only my guess though).

    Function of ports before bullet leaves barrel:
    I can see how porting closer to the end of the barrel would decrease the quantity of gas escaping (for equal porting area), but I would also think that the placement closer to the end would be more effective at reducing muzzle flip than further back. I would also think the bullet velocity would be slightly better.

    I know Magna-porting has supposedly done many years of research to optimize porting size and location for their patent(s).
    But I'm always looking for alternatives.

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    The type of porting you are speaking of is nothing new. I think if there was a big gain we'd see more of it.
    Vance in AK.

    Matthew 6:33
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    It may not be new, but I haven't seen it. And I've seen many with drilled ports. Just wondering if a narrow slot has any advantages or disadvantages is all.

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    I think I see what your getting at here with the different ports... The slot type ports (my opinion here) are generaly placed on the upper 1/3rd of the barrel and I think are more for mitigation of barrel rise or "jump" than for a noticable reduction in felt recoil. were you have a drilled barrel that is pretty much evenly distributed all the way around the barrel, I think you are looking at something primarily intended to reduce felt recoil. I have examples of both, and they seem to work pretty much as I have described here.

    The trapizoidial cuts you see from magnaporting are cut with an edm machine if I remember correctly, and are there for nearly imposible to duplicate with said edm machine. I have a Tauras T.P.O.C. in a 5 shot, snub nosed 45 colt that has three small holes drilled in the top of the barrel on each side of the front sight (six total) and they seem to do an admirable job of reducint muzzle jump, but dont do much for reducing recoil, at least so far as I can tell. the close proximitay to the front sight does allow a significant amount of crud to sort of plate itself onto the front sight, requireing a fair amount of effort to clean off... no biggie to me, but just thought I would throw that out there...

    the factory ported barrels that I have, are not counter bored and appear to have simply been drilled in some sort of jig, but I do not know the process they used for de-burring the inside of the holes, and there is no countersink or anything that would indicate that they used a push thru de-burring tool (like you would see in aviation for de-burring the back side of rivet holes). I think if I was going to do it myself I would pound a hardwood dowel in to the end of the barrel and drill at high speed with a slow feed when I got close to breaking thru. this might help prevent burrs or at least make them less of a problem for removal using some pollishing compound on a lead lap or something similar.
    “You’ve gotten soft. You’re like one of those police dogs who’s released in to the wild and gets eaten by a deer or something.” Bill McNeal of News Radio

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    Yeah, I'm definitely not talking muzzle-breaking.
    I'm more concerned with whether a perpendicular slot, as opposed to drilled holes or parallel slots is advisable for reducing muzzle flip. I think I could use a regular hacksaw to make a slot (or slots) near the muzzle and work away any burrs with emery cloth. The slot would be narrow (~3/32") and probably only expose 1/4" or less of inner barrel. With a jig it could be done fairly precisely on the cheap.

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    I think you would find it easier to simply drill the holes instead of the hack saw route. and the holes will be far easier to clean that a thin slot if you know what I mean.
    “You’ve gotten soft. You’re like one of those police dogs who’s released in to the wild and gets eaten by a deer or something.” Bill McNeal of News Radio

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    Quote Originally Posted by Porterwagner View Post
    Yeah, I'm definitely not talking muzzle-breaking.
    I'm more concerned with whether a perpendicular slot, as opposed to drilled holes or parallel slots is advisable for reducing muzzle flip. I think I could use a regular hacksaw to make a slot (or slots) near the muzzle and work away any burrs with emery cloth. The slot would be narrow (~3/32") and probably only expose 1/4" or less of inner barrel. With a jig it could be done fairly precisely on the cheap.
    the ones I've seen were much like you describe, except done on precision equipment. I remember seeing them in IPSC, Bianchi Cup, Steel Challenge, & other action shooting matches.
    For some reason it seems like S&W might have done some at the factory, & maybe "Power Customs" among others used the design.
    Never shot one so I can't speak to it's effectiveness. Like any other system, I'm sure you would either have to have computer modeling or a lot of trial & error to find the "sweet spot" of maximum effeciency.
    Vance in AK.

    Matthew 6:33
    "But seek first the kingdom of God and His righteousness, and all these things shall be added to you."

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