Porting, Again


Bruce,

I am appealing to you on a disagreement I have had with a couple of shooters at our sporting clays club recently. The question is about recoil.

They are telling new members to have the barrel of their shotguns ported to reduce recoil. The concern is coming from people who have their guns kick them in the face when they are shooting targets. I disagree with the porting idea to stop this. I suggest they take their gun and have it fitted properly first of all. Then practice mounting the gun correctly. If they want to reduce recoil get a Kick-eez pad or something similar to stop the recoil to the shoulder.

I have always been under the impression that proper gun fit and mounting of the gun is the most important way to reduce recoil and barrel kick to the face. So we are asking what your opinion on the matter is. We couldn’t find anyone at the club who we though knew more than you so your answer has dinner riding on it. Don’t feel too cocky now about being an expert or anything, we are just a young club. Sorry couldn’t pass that up.

We appreciate you help in the friendly disagreement.

David

Dear David,

In general, I side with you. I think that face slap is a gun fit situation. Anytime you get hit in the face, you have a gunfit or shooting technique problem- probably the former, but not always. One thing is for sure, it isn’t a standard recoil problem. No matter how hard a gun “kicks”, it should never whack you in the face if it fits properly and is being mounted correctly.

A perfectly fit gun with a ton of recoil will push your shoulder like crazy and perhaps radiate a shock pulse up through your neck into the cranium, to give you a headache. But it won’t whack your cheek.

If a gun does whack your cheek, lowering the recoil by reducing the load or increasing the weight of the gun will help, but will never eliminate the problem.

Now to porting: I’ve never been a fan of barrel porting in shotguns. I can’t tell you how many of my friends have had their fancy target guns ported, raved about how it reduced recoil, then admitted a week or two later that it didn’t really reduce “recoil” all that much, and finally tried to sell the guns only to find out that not only couldn’t they get their money back for the porting, but many potential customers didn’t want to shoot a ported gun!

Let’s look at what porting is claimed to do: 1) reduce “recoil”, 2) reduce muzzle jump. As to reducing rearward recoil, it can only do that to the extent that it directs gas jetting rearward like a muzzle brake. I know from first hand experience that a muzzle brake is a very effective recoil reduction device on a light weight .338 rifle. I’ve used one set up with a brake and couldn’t believe the reduction. That .338 felt more like a .308. I was amazed. The muzzle blast was amazing too.

Of course, magnum centerfire rifle cartridges produce very, very different pressures at their muzzles than 12 bore shotguns with target loads do. The pressures are so vastly different that rifle pressures were measured in COPPER crusher units of pressure (CUP), rather than the LEAD crusher units of pressure (LUP) formerly used on shotguns.

In addition to the very different pressures involved, take a look at the thickness and porting arrangement of a rifle muzzle brake. The rifle brake is THICK so as to give the gas a broad surface to push forward against and a more fluid channel for redirection of the gas. Look at the muzzle brake on a tank cannon too. Neither of these look anything like that little row of holes on the top of a shotgun barrel.

As to muzzle jump being reduced by shotgun barrel porting, I do think that porting has some slight effect, but not enough to matter with the typical target loads being used. The way that porting is supposed to reduce muzzle jump is by directing the gas jet vertically so as to push the muzzle down at the moment that normal recoil wants to push it up. Sounds good in theory.

In practice, I think that it is marginal or less. First of all, many of the ported barrels have some of their holes on the SIDES of the barrel. How is this going to push the muzzle down? Only holes on the top can push down. Problem with that is that with most guns, there is either a rib or another barrel on the top so, at best, the porting is placed at 10 and 11 o’clock and 1 and 2. Every bit the ports are off top dead center dilutes their effect for muzzle jump. One company did try drilling right through the top rib, but found that ribs were loosening up.

Now lets look at just how much gas pressure is going through those ports. The more gas you can jam through that porting, the more the “push” down. Heavy hunting loads will obviously work better than light target loads because they generate higher gas pressures longer, thus closer to the muzzle. But do you see porting on hunting guns? Nooooo. Only on the target guns. The lighter the target load, the less gas and the less effective the porting. People who go to porting to reduce “recoil” and muzzle jump generally use the lightest shells anyway, so porting works the least effectively for them. It’s a Catch-22.

Again, my bottom line is that technically shotgun barrel porting DOES work, but my opinion is that for target shooting it doesn’t work enough to matter. On the downside there is the expense of the porting operation, the resale problem and, of course, the noise which offends everyone.

There is one area where porting may have some benefit. No one talks about it, but I wish that I could have the test machinery to study this more: wad stripping. I recently did a gun review for Clay Pigeon on the Browning XS 12 gauge sporter. It has over bore (.737″) barrels and porting (though with short cones). It had all the performance aspects of a short shotstring gun- not particularly choke sensitive, threw hard hitting patterns with open chokes, that sort of stuff. I don’t know whether to attribute that to the bigger bores or the porting or both.

Many makers go to great lengths to try to strip (retard) the plastic wad so as to keep it out of the shot column. Wad designers work at this by making some brands flare out more quickly. Barrel makers (Lutjic) scribe the insides of their barrels. Pattern Master chokes uses studs inside the choke. I have the suspicion that porting might in some way help this stripping action. On the other hand, if it does, it only does it on one side of the wad and could thus produce slightly cocked wads on exit. I’ve seen no evidence of this in my testing of ported guns, so perhaps porting does nothing for stripping.

Let’s say that porting does slightly reduce muzzle jump. Will that reduce face slap? If you lock in tight to the gun, it might just help. As the muzzle rises, the gun pivots on the shoulder and will rise very slightly at comb. This might possibly produce some face slap. If the gun is held more lightly at the shoulder, muzzle rise will push the stock down away from the face and reduce face slap. Depends on how you hold the gun. Still, in either case, I don’t think that it is enough to matter.

Like you, I think that face slap is a gun fit deal. My general gun fit changes for face slap victims (once I have seen that they are holding the gun correctly and have the right stance) is to start to 1) lengthen the stock to the maximum comfortable length, 2) make the comb more parallel, 3) reduce cast, and 4) reduce pitch. I don’t include porting on my list.

One of the biggest problems in evaluating porting is that it is seldom done alone. Generally it is done in conjunction with lengthening the forcing cones and/or backboring. In order to test whether porting really works, you have to shoot the same gun before and after porting, with porting being the only barrel change. I did just this with an 1100 and the old Pro-ports. None of us testing it could tell any difference, but this was a gas gun and a difference would be harder to notice. I haven’t done the experiment with any of my good O/Us because I don’t want to ruin them just for an “iffy” test.

Whew! That’s a lot of bovine effluent for a morning. I hope that this doesn’t cause more argument than it answers.

Best regards,

Bruce Buck
The Technoid writing for Shotgun Report, LLC
(Often in error, never in doubt.)

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