Shotgun Smithing and Modifications 101.....


Dave McCracken
May 27, 2008, 04:10 PM
Queries in Yr Humble Scrivener's E mail box tend to run in bunches.

I had five requests to recommend a good 00 buck load in 24 hours once.

And "should I buy this?" questions show up in droves in August and after New Years.

Lately, it's been people asking about tweaks for their pet shotguns, both field and clays, and even a couple about defensive weaponry.

While I've written reams about this stuff, it's not all in one place. So, here it is with an apology for being repetitious.

And note these are opinions and not on stone tablets.....

Shotguns are not terribly complicated. They ARE built to contain pressures of up to 13,000 PSI and handle up to 70 ft-lbs of recoil. As with all power tools, they can be misused and can cause injury or death.

This is why I often say that trigger and barrel work should be left to folks who know what they're doing. Figuring it out as you go along is not a good approach.

Trigger work first. Many shotguns have triggers heavier than they should be. Due to litigation issues and cost cutting, often these can stand to be made lighter and crisper.

And it's my opinion that crisper is as important as lighter.

A decent trigger can often be had for $50 or less. Money well spent. The old British rule of thumb said that the front trigger should be half the weight of the gun, the back trigger 1/2 lb more. I'd go for 3-4 lbs, if possible,and clean.

As for barrels, the most common query I get is about shortening them.

I've had it done a few times, and it's been 50-50 as to whether I regretted it afterwards.

Since most modern repeaters have easily replaceable barrels, a better approach is to buy a short barrel and change them as desired.

And if you have an old 97,12 or A-5, let them retain their barrels and go buy a Maverick or something for defense.

On doubles, it's usually not a good idea. Barrels can become deregulated and POIs go south big time. And there's probably not a 26" barreled grouse wand hiding inside great uncle Zeb's duck gun anyway.

Internal barrel work can be beneficial or just a waste. Let's look at a few processes.....

Chokes can be opened if they're too tight or in many cases replaced with interchangeable tubes. Making a choke tighter is like cutting something longer.

Not every person with a choke hone is qualified to work on even an inexpensive barrel and choke. But, good people are common enough that you can get your money's worth with some research and googling.

Same goes for tubes. If I were getting tubes installed or fixed chokes opened, I'd send the barrel to Briley, Carlson's or Mike Orlen. These firms have plenty of experience and good reps. Good things don't come cheap, but botched work can be very expensive.

You see a lot of ink these days on overbored barrels. These are barrels made larger than the standard bore. Supposed bennies include better patterns, less kick, higher velocity, world peace and the cure for cancer.

Backboring is reboring barrels larger.Overbores are from scratch.

Bores on these run as big as .750", with a few up to .800". The standard 12 gauge is .729"

I remain unconvinced.

The big money in Shotgunning is in live Pigeon shooting. Thousands of bucks can ride on a single shot. The pros in Europe tend to like tight bores, down to .720". If a bigger bore helped, they'd be swinging what looked like 10 gauges.

Another mod ballyhooed by many is porting. This involves making lots of tiny holes in the barrel to pipe gasses off and reduce kick and muzzle jump.

Still unconvinced. It may reduce muzzle rise a bit, but shotgun velocities are not high enough for the vented gasses to make much difference.

Porting does make the shot much louder. It complcates cleaning also.

The third common mod for barrels is to give a slower taper to the forcing cone. This cone is the funnel between the chamber and bore. This is supposed to give the same benefits as overboring.

In fact, this does work. The gentler taper eases the pellets into the bore with less deformation. The pressure spike is a bit lower and recoil is spread out just a hair. I defy anyone to tell the difference in kick at the shoulder, but the patterning board never lies.

One cylinder bore 870 barrel here was patterned with a favorite load of 00 before and after a cone job. About 4" less spread at 25 yards.

Results with smaller shot are not as dramatic, but more pellets staying in the pattern are almost always good.

As with all barrel mods, the concentricity of the cone in relation to the bore is important. Were I getting a cone done, I'd want the smith to set it up in a lathe, work slow, and polish it slick afterwards.

Moving on.....

Other smithing includes anything done to improve fit and comfort.

Stock work done by someone who is fecally cognizant can improve one's shooting incredibly.

Adding a good pad is also a very good idea on anything bigger than a 28 gauge.

As for sights, the plain bead works for many folks. Mid beads can do some good when shooting a premounted shotgun, but I doubt they help much when shooting low gun.

The newer and increasingly common Fiber Optic "Green Worm" sights may help also, provided one stays focussed on the target and is not distracted. The three shotguns I shoot the most are a Beretta O/U and two 870s. All three have F-O front beads and mid beads. I can do without the mid beads, but I don't feel strongly enough about it to remove them.

My F-Os are from Hi Viz and come with user friendly instructions. They were easily installed.

Open and Ghost Ring sights are popular with both slug shooters and the black BDU folks. For home defense, the single bead works well and is faster than anything elsel though not by much. I'd work with a bead lots before trying out other styles and that's exactly what I did.

To summarize, here's my answers and opinions on what smithing and mods to do.

Triggers, yes.

Chokes, yes if needed.

Bobbing barrels, probably not.

Overboring, the same.

Porting, heck no.

Long cone, heck yes.

Stocks, yes.


Sights, maybe.


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May 27, 2008, 04:23 PM
Right on, Dave! Thank you!

WRT the forcing cone, I definitely could tell the difference.

Obviously, it would be nearly impossible to know what caused any felt difference between two different guns.

However, on a relatively light 20 Gauge O/U (old Ithaca SKB), a friend reamed out the short cones it had from the factory. Comparing Remington Sport loads (7/8 oz. of 7.5 shot), I could feel the difference on my shoulder immediately. I won't say it has less recoil; it just isn't the same "hammering" feeling. It's more comfortable to shoot it a lot.

Again, unless you take a particular gun, probably one with snappy recoil, shoot it, ream out the cones, then shoot it again, it would be very hard to tell the difference, or what caused it anyway.

One way or another, Dave knows of what he speaks, and then some! Great post!

One further caveat about triggers, that Dave touched on. I had a gun with a worked trigger that would have been beautiful -- on a target rifle. It made for a few AD's on the trap range. Fortunately, it was a trap gun and I never touched the trigger until it was pointed over the house. Cost me a few points in trap league, though. The same trigger could have been really dangerous on a gun used for anything else. Light target rifle triggers are not the same as what you want on a target shotgun; the weights Dave suggested are much better.:)

May 27, 2008, 07:29 PM
I got one for you to expound upon Dave. Have you any experience or personal knowledge of the C& H mercury filled recoil tubes? I bought one and it works to a degree. What I don't know is if it works for the reason as advertised or would the same amount of solid weight would achieve the same recoil speed reduction. Does the mercury sloshing back and forth really help at all? I am considering buying another or making a lead slug to put in the stock hole with the goal being to slow the recoil on my other pump. The extra weight is not so much a problem for what I use the shotgun for at the trap range

Could you expound upon your own or witnessed experiences with such recoil devices?

Excellent collection of items for this thread btw. I can't say I disagree with any of them I am qualified to voice an opinion about.

May 27, 2008, 07:35 PM
Back before steel shot, I was a long range waterfowling fanatic. I killed a ton of patterning paper - good thing I worked for a paper company. I wholeheartedly agree that lengthened and polished forcing cones helped, but, I also found that backboring, when used with fitted/matched choke tubes, also helped increase pattern percentages.
Using first an 870, and then an 1100, I had the forcing cone lengthened and played around with choke tubes until I got the best (tightest) patterns I could, and when I backbored and played around with the tubes again, the best was about 2% better than the best had been.
On the 1100 I did the backboring first, and got about a 3% improvement, and then got a lesser improvement from the forcing cones, but the total improvement was around 6-9%.
All this was with Ballistics' Products, Remington, Winchester, and some of the old Alcan Flite Max wads, mostly Blue Dot Powder, and nickel plated shot from Italy in sizes 4 thru BB.
I learned a lot. In one particular instance a choke difference of 0.003" gave a 14% pattern improvement. I know, I couldn't believe it either at first, so I triple checked the final result.

May 27, 2008, 07:36 PM
But Dave,
What's the best most Tactical man-killin' 00 buck load of all time that can knock-down a Mongolian horde of home-invaders from at least 100 yards away? Preferably, it should be configured into an Aguilla mini-shell to go with my PG-only shotgun!

May 27, 2008, 07:43 PM
Triggers, yes.

Chokes, yes if needed.

Bobbing barrels, probably not.

Overboring, the same.

Porting, heck no.

Long cone, heck yes.

Stocks, yes.


Sights, maybe.

On my shotguns, I leave the triggers alone, I cut the barrels myself if I find it necessary, install my own bead sights/pad/stock mods. I haven't had a problem yet, but then again I went to school to learn how to do this stuff. :)

May 27, 2008, 08:13 PM
Dave - I agree with most of your comments, although I may take some issue with the overboring.

Overboring does two main things:

1) Removes weight from the barrels, along the barrels... not just at the end.
2) Provides a bigger tube down which the ejecta moves. The idea is that you get less resistance and maybe less shot deformation. The downside is that you could possibly also get decreased pressure and velocity.

My Kolar carries 32" .750 bore barrels. It handles perfectly (for me) and produces very good, even patterns. The same gun with .740 bore barrels is too nose heavy and feels out of whack to me.

There are a lot of folks who think that the .750 bore Kolars are the softest shooting O/U to be had. I wouldn't open up an existing barrel that much, and I know that Perazzi gets great performance out of tight bores... but I'm sold on the big-bore Kolars.

IMO, if I had a gun that I was going to set up to be "perfect" for me, I'd make the mods in the following order:

1) Stock and pad
2) Sight (for me, I like the short Hi-Viz FO tubes)
3) Trigger
4) Chokes
5) Cones

No ports, no bobbing of barrels (unless the gun is destined for a very specific purpose). The only way I'd overbore an existing barrel would be if the following conditions were ALL met:

1) The gun was too nose-heavy
2) There wasn't a good way to otherwise alter the balance
3) A reputable 'smith (probably Briley, Cole or Simmons) inspected the gun and said that it was safe for them to do so.

May 27, 2008, 08:22 PM
I'm inclined to say that, if the gun was too nose-heavy and there wasn't some simple and good way to alter the balance, I'd just ditch it, if I ever got it in the first place.

Isn't it a bit of a gamble that you'll like the gun's balance after someone has done some grinding on the barrels, when you didn't like it before? (This would be different, of course, if you were sponsored by some gunmaker and had to use a particular gun. I'm not that good, so that's not a worry for me.:))

May 27, 2008, 08:37 PM
AB - I'd like to say I wouldn't get a gun that's too nose-heavy, but I'd be lying, since I shot a Browning 425 for several years. ;)

There are a very, very few instances where I could see getting a barrel backbored... but it's unlikely. It's why I didn't list it with the main modifications. Frankly, the guns that see the most use around here are either bone stock or nearly full custom jobs.

In a way, the folks I know from shooting sporting clays are kind of like motorcyclists. Some get a new toy, leave it as is and never change a thing. Others will make a couple purely functional mods. Some will mod the heck out of it, just for the sake of doing it. I don't much care how other people spend their money.

The one thing I'd say is that this all applies to guns for clay games and maybe hunting. Shotguns for HD use (IMO) are best fit to the user and otherwise left alone, aside from shooting, cleaning, and shooting some more.

Dave McCracken
May 27, 2008, 08:50 PM
Thanks, folks.

AB, maybe it's noticeable on a light 20 gauge O/U. The ones I've had done were on 870s and mostly on accessorized PracTacs. 9 lb 12 gauges do not kick all that much anyway. When I had the choke opened and cone done on the TB's overbored barrel, I gained a couple inches of good spread at 32 yards and maybe 50 8.5 pellets. The new owner agrees that it's a dense shooter.

I've had bench rifles with 8 oz triggers and some caplocks with set triggers in that zone. Not for hunting or "Serious" use with shotguns.

Milk, back on TFL, I did a thread called "An Experiment In Recoil Reduction" or such. I had taken some empty hulls and filled them with shot. Positioned between two halves of a mag spring in the tube of my old 870TB and with another similar setup in the stock, the thing made a light kicking 12 into a 22. But, that added at least 12 oz to the OA weight.

Roster says that the mercury reducers do nothing the same amount of weight will. I'm inclined to agree.

Virginian and TR, I agree that there's some advantages in SOME cases to go large on bore diameter. However, the 9% increases mentioned could be duplicated by going to better ammo for most folks. This is a 101 thread, and the expense of backboring by Briley or Stan Baker's company isn't worth it to a new shotgunner.

As for lightening the barrels, great! There's some clunky water pipes out there masquerading as barrels. That's why I like very old 870 barrels and the Light Contour new ones.

And TR, every Kolar I've been privileged to try has been on the plus side of 9 lbs. Great guns, but not rapiers.

CWL, excuse me while I rein in my choler.....

PTK, not everyone has the experience or talent you do.

May 27, 2008, 09:38 PM
Roster says that the mercury reducers do nothing the same amount of weight will. I'm inclined to agree.

I've always wondered how they were supposed to work. How is the mercury supposed to reduce recoil, exactly?

I also wonder if they might do something more effective when you have something like a Benelli with more of an inherent "double bounce". The Benellis I've tried, with all the fancy-schmancy recoil reduction in them, were really comfortable and smooth, with light recoil. And the only autoloader I own is an 1100 Magnum in 12 Gauge, which has little felt recoil, so my judgment is skewed. I found a Cordoba to feel easier on the shoulder than the much heavier gas-operated 1100.

Could it be that the mercury system might do something useful to kill the double bounce of a Benelli system, whereas it's just dead weight in an O/U?

May 27, 2008, 09:49 PM
AB - I'd like to say I wouldn't get a gun that's too nose-heavy, but I'd be lying, since I shot a Browning 425 for several years.

Hell, I shot an old-style BT-99 34" with the boxy foreend and Invectors for a year or more, before I finally sold it. The 425 is probably butt-heavy compared to that thing. Didn't Browning lighten up the muzzle end on the X25 Citoris, anyway? It's the humorously-named "Lightnings" that are the real slugs.

May 27, 2008, 10:18 PM
Citoris can be a bit chunky, which is a shame, my Belgium Liege is downright light and whippy in comparison.

Of all the shotguns I've shot, I've never really paid much attention to the trigger, not like I would a pistol or rifle.

May 27, 2008, 10:26 PM
And TR, every Kolar I've been privileged to try has been on the plus side of 9 lbs. Great guns, but not rapiers.

Mine is right at 9.5 lbs. I'd describe it as well-balanced, but stable. I can drive it with ease at the close, fast stuff... but on the long birds, it's very smooth. It's heavy, but feels lighter in the hands. Most folks who've shot it guess it to be around 8.5 lbs.

WRT, mercury reducers and such, let's just say that my preferred method is one or two spent hulls filled with shot, crimped and taped. On an O/U, I fit them into the bolt hole, using a piece of cut-to-length rubber tubing to prevent movement under recoil from battering the action or wood. In a synthetic-stocked gun, I'll take off the pad, fill part of the open area with shot in a thick plastic bag and then hold it all in place with duct or electrical tape. Replace the pad and you're good to go.

Pssst... Dave... do you want to know a little secret (one that I bet you already know)? If you take a beginner with a bone-stock gun, and then make even one minor modification for them... it makes it THEIRS! On numerous occasions, I've made very minor changes to a beginner's gun. They probably help a little with the mechanics, but the mental aspect of "having a gun that's fit just to me!!!!" can be a real confidence booster.

May 27, 2008, 10:30 PM
I've never really paid much attention to the trigger, not like I would a pistol or rifle.

I never paid any attention until I started shooting a gun with a truly great trigger. Last year, when I was bird hunting with a gun that has a distincly less-than-great trigger :uhoh:, I pulled the trigger (twice), checked the safety, and finally took it off my shoulder and inspected it, thinking that I'd had a malfunction.

Nope, it's just that my reflexes were conditioned to the trigger on my target gun and the heavier pull on the field gun just felt wrong.

May 27, 2008, 11:33 PM
Mercury recoil reducers were always something of a mystery to me. Mercury is IIRC about 20% denser than lead so it's just plain heavier but I don't know what, if anything, could be gained by the "sloshing around" that the marketing folks seem to have latched onto.

Whoever first figures out how to blank out porting invisibly will make, if not a fortune, at least a couple of bucks from me.

May 28, 2008, 12:16 AM
Mike Orlen did a 4" super cone and installed chokes on my Mossberg 930 SPX. It patterns very well now and it lessoned recoil some. It also made my SPX reliable with cheaper ammo because when he did the super cone he polished the chamber and cone. I am very pleased with the work and highly recommend the the 4" extended cone and Mike Orlen.


May 28, 2008, 07:03 AM
Great post on smithing and modifications. You saved some beginners a lot of money on useless modifications IMO.

I am also a "skeptic" on long forcing cones. Did it once and could detect no difference in recoil and I didn't pattern before and after...but could be wrong!

May 28, 2008, 08:07 AM
I have done some mercury tube work.... always at the customers insistence.

From what I can tell is that given that the mercury is liquid encapsulated... with the liquid being more dense... What happens is that the shock waves from the recoil hits the liquid first, which takes some of the bite out of the recoil.

I have tested the guns with the mercury reducer and without, same makes/models and there does seem to be a slight difference, but not enough to make it worthwhile.

Dave McCracken
May 28, 2008, 09:20 AM
As I understand it, the mercury has a finite time to slosh around and reduces the spike on the rearward shove like a gas auto does.

The recoil stays the same, but takes more time to move the same amount. This feels like less kick. Adding weight does the same.

As for the effect of mercury reducers on Benellis, can't say. I don't have easy access to any. Maybe someone can give their experiences.

TR, every Kolar I've shot has been like that. Stable but agile.
If I hit the Lottery big, a Kolar would be on the short list.

That tip makes sense to me and I've used it. Modding the gun makes it theirs, and we all shoot better with our own guns.

GC, thanks for the endorsement on Orlen. Feedback seems universally positive.

Re triggers, most of us have never had a good one. But, like tasting Eggs Benedict for the first time or Chateau D'Yquem, once you know what's good it's hard to settle for less.

May 28, 2008, 10:36 AM
Dave McC,

What about pistol-grip forends, and crenellated breaching cones on the muzzle, and quad rail systems, and heatshields, and lasers, and...


May 28, 2008, 12:46 PM
"Stock work done by someone who is fecally cognizant can improve one's shooting incredibly."

Fecally cognizant? At first I thought 'xxxx for brains' and was confused, then I realized you were saying somebody who knows their xxxx... Funny stuff.

Between the NEF of many barrels and the BPS 10 bore I have shotgun projects to keep me busy for a long time. I appreciate you putting this all in one place.


May 28, 2008, 01:09 PM
PTK, not everyone has the experience or talent you do.

Dave, thanks for the kind words. Funny that I'm "just a young punk" to a lot of folks before they actually converse with me.

This thread, much like the ones Steve starts, is a great resource already. And "wait until I get going!" :)

May 28, 2008, 07:08 PM
Great post Dave

I 110% agree about the plain bead being the best option for a sight. The tacticool crowd always hold Ghost Rings on top, when the bead is perfectly fine (if not better). Too many people buy all this cool crap for their shotguns instead of just shooting them.

May 28, 2008, 07:24 PM
There are some damn good shooter who take their beads off, even...

I've missed because of my bead. Night shooting with lights behind me, that sudden flash of gold draws my focus away from the bird if I'm not really careful.

May 28, 2008, 10:16 PM
AB - Some like no bead, some like a plain brass or white one and others like fiber optic. The key is to find something that works for you. Heck, earlier in the year I shot sporting clays with a guy who was using a red-dot. He had eye dominance issues, and the red-dot seemed to help him. I was sceptical, but he was shooting reasonably well.

For sporting clays and hunting, I do best with a small green FO bead. Then again, I'm not shooting under lights. ;)

Dave McCracken
May 28, 2008, 11:11 PM
TN, you go sit next to CWL in the corner.

gp 911, glad you like this.

I learn from young people every day, PTK.

Silver Bulllet, I went through that phase in the early 80s. Peep sights, extensions,side saddle, trigger work ad infinitum. This resulted in two fine defensive shotguns, but a bone stock short barreled 870 with a self applied set of wear marks does very well also.

One of these days I'll get to a Practical range and do some fast COFs with both the Rambo Signature Model 870 and Frankenstein. Betcha scores will match and times will be better with ol' Frank...

AB, the plain fact is, in an adrenaline dumping scenario where the pucker factor redlines, we're going to be looking at the target, not the bead, because the target is the threat and a million years of evolution has us concentrate on the threat for obvious reasons.

This is why training HAS to continue and be repeated frequently.

Brian Dale
May 31, 2008, 01:12 AM
Thanks, Dave. Lots of insight in one place makes this thread another handy reference.

I've gotten as far with my 870 as adding a Limbsaver pad to increase the LOP. The trigger is already nice and crisp (1956 Wingmaster). Right now, the modification I'm doing is to increase the round count through the gun. :)

Dave McCracken
May 31, 2008, 10:35 AM
Good plan, Brian. Be safe, have fun and.....

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