Ports And Taper Backboring


Technoid:

I have a Beretta 682 Gold Sporting that I’m thinking of dumping a whole lot more money into, but would value an opinion first. My particular model is not ported nor is it backbored, and I’m thinking of sending it out for both. Seminole Gunworks can do a tapered backbore that starts at a hefty .741.

My question is, what can I expect for the money? Hopefully I can expect less muzzle jump and better second target acquisition. Hopefully I can expect a little less recoil. Hopefully I can expect a slightly lighter barrel. Is this wishful thinking? Can I get similar results from lengthened forcing cones at lesser expense?

David

Dear David,

Welllll, since you asked I will abandon my usual reticence and dole out a steaming dose of my usual priceless advice. “Skip the modifications and spend the money on something else.”

About 1/3 of the people that I talk to THINK that their porting does something. About 2/3s of those I talk to don’t think that it does a darn thing. I belong to the latter school and think that porting is a total waste of time and just another sales gimmick. In theory, it should help a bit. In fact, the gas pressures generated by the typical target load simply aren’t high enough to do much. If porting comes on the gun, I wouldn’t worry about it, but I would never pay for it. It will also make the gun harder to resell in some cases because many people find ports aesthetically repugnant on a good gun.

That porting comparison article in Sporting Clays was a bunch of hooey because it shows porting in a free recoil situation. In real life you use a lot of left hand on the gun and stock pitch also comes into play. I never said that porting didn’t work at all. I just said that it doesn’t work enough to matter with commonly used target loads. To be fair though, the pigeon shooters just love it, but then they are always taking two quick shots at the same target and are using Rhino Rollers.

Tapered backboring? I guess that it was bound to happen once the old standard backboring gimmick started to wear off. Taper boring is nothing new and has been around since the original New England Baker gun company back in the late 1800s. Taper boring was quite common on rifles. I had Stan Baker in Seattle backbore some Belgian Brownings for me back in the ’80s and never noticed any reduction in recoil. As a matter of fact, backboring actually increases recoil because it reduces gun weight.

The one thing that I DO recommend backboring for is to alter barrel weight. Many of the modern screw choke guns come with barrels that are far too log-like. The cheap way of installing modern screw chokes used by just about all the current makers adds a bunch of extra metal at the very front of the gun. This destroys the balance of the gun. This is why so many knowledgable shooters prefer the older solid choke O/Us with custom thin wall chokes from the aftermarket. The average new shooter doesn’t know the difference and accepts the poor balance of the current crop of guns. You can’t blame him. If a guy has come into the shotgun market in the past four or five years, he simply doesn’t know that was every anything properly balanced.

One of the problems with aftermarket backboring of a modern screw choke gun is that you can’t pull out too much metal without interfering with the screw choke threads and, of course, recalibrating all the chokes. “Taper” backboring sounds (though I have never measured out a Seminole taper backbored barrel) like a really smart way to sell the product (backboring) without getting caught up in redoing chokes. You just taper the bore down to the original diameter just in front of the chokes. This way you avoid the messy business of mucking about in the choke area and yet you can still advertise “backboring”. Good business for a machine shop.

Does taper backboring work? I don’t have the vaguest idea. I am not aware of any unbiased studies where regular backboring has been actually PROVEN to improve patterns or lower recoil, so I have my doubts as to whether tapering the backbore would do anything. I would just love to hear from some readers who can tell me why backboring can lower recoil. From the shop foreman’s point of view though it is a clever concept.

As to weight reduction: Because I don’t know the dimensions to which Seminole backbores, I will guestimate. If it starts at .741″, as you say, and tapers down to the usual Beretta I.D. of .723″, you will be removing an average of .009″ bore in 30″ barrels (I assume) less the chambers, cones and choke areas. According to the little formula I plugged into my Excel spread sheet, you ought to end up losing about 2.2 oz. This is normally enough to be noticeable, BUT most of that weight reduction will take place at the rear of the barrel and much less at the front. Remember, I am assuming that Seminole will be leaving the choke area alone. Bottom line is that it will not make much of a difference in the way that the gun feels. It may actually make the gun feel heavier up front than it already is. Anyway, that is my best guess.

I generally have found that elongated forcing cones do cut perceived (not measured) recoil by the tiniest percent, but it depends on how long the cones were to start with. They also improve pattern percentages by the tiniest percent in SOME guns when using larger sized shot. Check the cone length on your gun. Beretta Gold’s should already come with long cones. (Beretta believes in long cones, but not backboring. Browning Japan is just the opposite. Browning Belgium believes in neither. Krieghoff believes in both plus a ton of road hugging weight) I don’t think that lengthening the cones on the Gold will be worth it. Besides, you will have to cut through the chrome lining on the bores and that can cause more leading in the cone area.

Bottom line: I think that you would be best leaving your Beretta Gold alone. If you want to reduce recoil and barrel jump to a noticeable extent, take the money you saved by not making the modifications and buy a Beretta 391 or A400 30″ sporter.

There it is. More humble wisdom of the ages from your shy and retiring Guru of Gunning Gear.

Regards,
Bruce Buck
Shotgun Report’s Technoid

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One Response to Ports And Taper Backboring

  1. Ernie says:

    Great response. Ernie in AZ

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