Before having read your article on barrel porting I had the 28″ barrel of my Perazzi MX8 ported and choked. Over the years I have found that only the very heavy loads work well on it. This barrel is used for pigeon shooting and any time I try to use the light pigeon loads by Winchester or Federal the result is the same. Lots of feathers and lost birds. As soon as I switch to the heavy loads results improve dramatically.
Could it be possible that with the porting of such short barrel the light loads loose speed or pressure so as to deem them inefficient? I’ve patterned these lighter loads and they pattern beautifully, yet have no killing power. Also when I use another longer barrel that is choked but not ported they do work well, although I continue to favor the shorter barrel because of its handling. What do you think about this?
I haven’t done a lot of work on the burn rates of pigeon loads, though I do shoot the occasional flyer and have come to prefer the Winchester 3-1/4 dram 1-1/4 oz pigeon loads. They have always had plenty of killing power for me and are by far the more popular of the two pigeon load “strengths” at the shoots I attend. Personally, I find that the 3-3/4 dram pigeon loads give me a little too much gun movement for a quick second shot if I use an O/U. When I use the gas gun, the heavy loads make it grunt.
I don’t own any ported guns, though I have fooled with a bunch of them. Porting is quite popular in pigeon shooting because the “pigeoneers” will do anything to keep that first barrel flat on firing to enable a quick second shot. While I don’t like porting on clay target guns, I do have to admit that the more gas you can run through those holes, the better the porting works. I have always maintained (well, at least for the past day or so) that porting in target guns with light loads does work technically, but it doesn’t work well enough to matter. The heavier loads used in flyer shooting might just make porting more practical.
The only real way of finding out whether or not your short barrel is causing a loss of velocity is to chronograph it. Until you do, you just aren’t going to know any facts for sure. Clay target powders like Red Dot, 700X and Clays generally burn within the first 14″ to 18″ of the barrel. Even if your porting on the 28″ started at 22″, it really shouldn’t effect velocity with target loads. The pigeon loads use a slower powder. It is just possible that you are losing a bit of velocity, but I doubt if it is more than 50-75 fps. Longer barrels usually have a bit more velocity than shorter ones anyway.
The difference between the standard pigeon load of 3-1/4 1-1/4 at 1220 fps and the heavy pigeon load of 3-3/4 1-1/4 at 1330 is 110 fps. It takes a pretty slow powder to get that 1330 and that might be a factor considering your porting.
One thing you shouldn’t forget: Your short barrel may slightly shift impact depending on the recoil of the shell you use. This is not at all uncommon. This, rather than velocity or “killing power”, could be the reason why your 28″ bbls seem to change efficiency with the shell. This may not show up in patterning an “aimed” gun, but might when shooting dynamically. You could test this by shooting some 30-40 yard clay targets with your pigeon loads to compare. PAST makes a great strap on recoil shield. It will keep your body from self destructing.
Shotgun Report’s Technoid
(Often in error, never in doubt.)