Partial underlug vs. Full underlug.


September 5, 2008, 09:39 AM
Bear with me, I'm still learning. Can someone explain to me the difference in the function of a partial underlug vs. the the full underlug on a revolver? Is it just an aesthetics and looks issue, or does the full or partial underlug function differently than the other? Is there a benefit to having full or partial? Also, I've noticed the tapered underlug as well, another aesthetics option? I personally perfer the look of the full underlug. Thanks.

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September 5, 2008, 09:50 AM
The partial underlug 'looks' traditional - and 'points' better in the hand, as it has less muzzle mass. The full lug does stay 'down' more, ie, has less muzzle rise, during recoil - important in heavy recoilers. I prefer the partial lug.

Here is a full lugged 625JM (.45 ACP) - with a tapered lug 627 Pro (.38/.357M) beneath it, both current S&W offerings:

Here is a 6" 629 (.44M), my potentially heaviest bouncer and also a current S&W offering, yet with a partial lug:


September 5, 2008, 10:01 AM
Thanks stainz, it makes sense now that I think about.

D Boone
September 5, 2008, 10:03 AM
I prefer the Full Lug look, but only own a GP100... I want an SP101 for my next purchase, but that full lugged 625JM you have there has my mouth watering. Especially after I saw JM on the History Channel shooting one the other day.

September 5, 2008, 10:19 AM
While there are a few minor reasons that full underlugs exist, 90% of the reason is aesthetic marketing.

September 5, 2008, 11:35 AM
IMHO the guns center of balance is more important than the barrel being tapered or full lug.

My 4" 686 & 5" 629 are perfectly balanced with the full lugged barrel.

September 5, 2008, 12:26 PM
I think my 'Stocking Dealer Exclusive' 5" 686+, my only 686 variant, from a few years back is extremely well balanced - and came as depicted below - then for $10 less than rubber gripped 686's!


Phil DeGraves
September 5, 2008, 02:43 PM
From a purely subjective point of view, I found that guns with no lug at all, (old Colts, S&W 14, 15) were more diffcult to shoot well than guns with partial and full underlugs. The Colt Police Positive MKV and Colt Diamondback (full underlugs) are great shooting little .38s, more so than the old Colts or older K38 Smiths. The partial underlugs, (S&W M19, 27 and equivalents) shoot very well for me. The L Frames and the Python also shoot very well, but not significantly better while adding a great deal more weight and changing the subjective "feel" and balance. The size of the lug is inversely proportional to the amount of muzzle flip, so if you intend on shooting really hot loads, maybe the full lug would offer a slight advantage. Since the Python, L-Frame and the GP-100 are all about the same frame size and all have the full underlug, it seems that each manufacturer came to the same conclusion on that size gun. The N-Frames are about the same weight without the full underlug and therefore, to me at least, redundant, at least in the .357 caliber.

September 5, 2008, 03:11 PM
I am partial to partial underlugs. I just don't like, and never have, the looks of a full underlug.

September 5, 2008, 03:58 PM
I much prefer full underlugs. I own mostly partial underlugs.

This is no doubt due to my singular bad luck with Pythons and the observation that 3 identically configured 686s are boring.

Former revolver noob confession of the week: the first time I bought a partial underlug stainless (model 66), I rushed to THR to announce that I got a hot deal on an older revolver no doubt due to the gross grinder marks some bubba had put on the underlug in an apparent attempt to smooth its entry into a holster.

Took a couple weeks before somebody told me S&W put that grinder mark there. How embarassing. I still maintain the ground bevel which occurs on the right side of S&W partial underlugs was singularly inept on that 66. They're evidently put there by hand without benefit of template or jig. A model 57 has a nice polished transition that looks like:

The 66 is more like:

Nasty affair.

Tough warming up to partial underlugs when some are nicely executed and some look like they were done with a 32-grit cut-off wheel. I've since gotten another 66 in much more pristine shape. The grinder mark isn't that much better. Must be a "K" thing.

September 5, 2008, 04:06 PM
I think my 'Stocking Dealer Exclusive' 5" 686+, my only 686 variant, from a few years back is extremely well balanced - and came as depicted below - then for $10 less than rubber gripped 686's!

I want one. That is beautiful.

Brian Williams
September 5, 2008, 04:11 PM
I prefer no lug at all.
I have a real nice 581 with a full lug and would like to remove all of it to look like a model 58 or 13.

September 5, 2008, 04:23 PM
The lugs came from the days of the old Bullseye shooters. They wanted more mass out front to steady their aim.

dagger dog
September 5, 2008, 05:01 PM
Muzzle heavy was always the way with the target shooters, The models 19 and 686 are two good examples I can think of at the moment. Take the two with 4" bbls. probably not more than 2 oz. difference in weight , but the weight is added to the other end of the teeter totter. The muzzle heavy feel will be greater with longer bbls. Muzzle rise will be reduced. Sight picture can be recovered faster, etc etc.

But there were so many bullseye records and high scores set by those long, skinny pencil bbls.

I think the full length under lug revolver look better, all and all equal, the expert shooter could most likley shoot either well.
September 5, 2008, 05:35 PM
The full under lug does benefit by helping control heavy recoiling calibers and due to its greater moment of inertia, helps in steadying and recovering the sights on target. As well, less body/hand vibrations are transferred to the revolver because of the heavier overall mass of the gun.

On the other hand, no lug or half lug will not give the above benefits, but because of its lesser moment of inertia, it is easier and quicker to swing the gun left to right or up and down, like when shooting multiple targets. The shooter will feel more recoil for the same reason.

For example, a full-lugged 4 incher would feel somewhat like a no/half lugged 6 incher in recoil and swing. Haven't tried this they because we Canucks are prohibited from owning anything shorter than 4 1/4 inch barreled handguns.

I do have full lugged 6 inch L-frame and a no-lug 6 inch K-frame. The lighter gun swings so much more quickly. Can't comment on recoil because the K is in .22 lr.

The longer sight radius of the 6 incher is a benefit in terms of shooter influenced accuracy, and you probably squeeze an extra 50 to 100 fps to boot.

The idea is to find what is the ideal combination of recoil management, swing-ability, and overall feel/balance in your hand.

Aesthetics is a personal criteria so choose what appeals to you. Personally, I like them both and would love to have a 5 inch half lugged 686.
September 5, 2008, 05:48 PM
Stainz, your 5 inch 686 is my ideal L-frame.

Beautifully proportioned, it offers the best overall balance between recoil and quickness and sight radius(at least for me), but I've never seen one here in Vancouver, British Columbia. Not in the range or gun shops. Perhaps I don't go often enough?:)

I like it so much that I downloaded the picture. Hope you don't mind. I hope my 686/586 family doesn't get jealous.

September 5, 2008, 06:05 PM
Well, my 625JM and 696 have a new full-lug safe-mate. I just bought a new 4" 617 10-shot! What was I thinking? Now, a quick sale of my MKII - and I will be all-roundguns! Oddly, that .22 just cost me $40 more than my 6" 629 did three years ago - both new!

My 6" 66, shown above the 5" h-l 686+ below, looks perfect at the lug. It was made new, a 66-6 (w IL), 1/03 - I bought it new from a mail order TX site reknown - then (9/03) - for their closeout deals - $350! I also got a new 2" 10-11, also made 1/03, for $280 - my first-ever .38/.357Ms - never even shot one before that, I was a .44/.45 guy. I made ammo for them before they arrived. The 66 got a pinned HiViz and the Ahrends square conversion fg cocobolo stocks the day it arrived. Oddly, that h-l 5" 686+ was similarly equipped - and out a month or two later - I traded for one within a year - great bargain, too. Oh, I just borrowed the 66's stocks - put it's OEM UM's squared Combats back on. I hope it won't mind... for a bit. Gotta save sheckles for more wood grips.


September 5, 2008, 06:14 PM
stainz, what are the grips on that 5" 686? Those look great.

September 5, 2008, 07:04 PM
They are Ahrends square conversion finger-grooved cocobolo grips in round butt K/L size - the 5" 686+ h-l came with them, the HiViz front, and a V-notch rear sight - it was the '04 'Stocking Dealer Exclusive' from S&W. The grips are available from Ahrends for $60 + $6 s/h - I bought a pair the year before for the 6" 66 above (The grips are the same - just vastly different grain patterns.).


September 5, 2008, 07:49 PM
Underlugs are pure silliness. In a survivalist or combat situation, they are also a liability. If you drop your revolver in the mud, then open it and try to close it again, the gunk will get into the lug and block the ejector rod from it's "nest" and you won't be able to close the cylinder...YOU'RE SCREWED.

No lug is best.

September 5, 2008, 08:29 PM
If you drop your no-lug revolver on a rock and the ejector rod bends... YOU'RE SCREWED.

Just another way to look at that. Both problems can be solved by not dropping your revolvers. ;)

September 5, 2008, 08:39 PM
Murphy's law.

September 5, 2008, 09:11 PM
I don't understand something. Folks are saying that revolvers with no underlug have more muzzle rise than those with full underlugs but mine has no underlug yet it jumps less. How come? :p

September 5, 2008, 09:17 PM
Hmm, no idea. Are you using proper ammo?


General Geoff
September 5, 2008, 09:24 PM
but mine has no underlug yet it jumps less.

Jumps less than what? The same model revolver with the same barrel length, just with a full underlug?

September 5, 2008, 09:32 PM
My 686-3 357 felt VERY well balanced with the full underlug:

My Ruger SBHH 44mag also feels very well balanced, sans full lug:
Pick up the revolver, feel the balance, go from there. My hands are inherently shaky, so I like the weight.

Gary in Pennsylvania
September 5, 2008, 09:42 PM

September 6, 2008, 12:35 AM
Easyrider nailed it. Sure, the underlug is great on a 6" gun until you have to transition to the next target. All asthetics aside of course. My preference in a defensive gun is no lugs and could even care less about ejector shrouds. Tapered barrel for me please.
September 6, 2008, 05:43 AM
Hey Woad Yurt, please stop showing off your $300 M-14. It pains me to remember the one I gave away. It had the wide target trigger and hammer.
6 out of 6 into a 6 inch gong at 50 yds standing, slowfire but in DA.

That 8 3/8" barrel spit out 158 grn LSWC over 3.0 grain Bullseye at over 1000 fps, and provided that looong sight radius so beneficial its like cheating.

Looking back, that was my best range .38 revolver.

September 6, 2008, 05:44 AM
full underlug looks cooler

Brian Williams
September 6, 2008, 07:01 AM
If it was not for the coolness of an original 60-4 in 38, the 60 would be delugged.

September 6, 2008, 08:05 AM
Hey, W.Y., that's no revolver... it's a rifle! I'll bet the bullets get tired halfway down that tunnel and start slowing down, that's why there's no muzzle rise. I'll bet you get powder burns on the targets, too. Good grief what a barrel!

And I thought my 6" 66 has a long barrel... at least it stays in the same time zone!


PS Neat... real neat...

September 6, 2008, 08:23 AM
I prefer the Full Lug look, but only own a GP100
I think the GP100 is a good gun, but I hate the full lug on it. It's one of the things which deters me from getting one. Half lug guns are hard to find, but they look much better.

there are ONLY two full lugged guns that look good to me, the Python and the Diamondback, neither in production nor likely to resume production.

The Dan Wesson doesn't look bad, but the shrouds are interchangeable. You can change lugs with your mood if you want.

September 6, 2008, 09:05 AM
Stainz: Thank you for the "neat." It is, isn't it? The one in that picture is almost a snubby. When I really want to shoot a long barrel, I have the one in the picture below. And, yes, I do carry it sometimes. Anyone here familiar with trailer carry? :D

September 6, 2008, 10:04 AM
Put a paper punch on the muzzle - and you won't even need ammo for it!

Good grief!


PS Didn't Davidson's have a neat 5" GP100 half lug in the grey color of the .454/.480 SRH's a few years back? That was one I would like...

General Geoff
September 6, 2008, 02:12 PM
I've had wheelguns with both partial and full underlugs, but given the choice I like full underlugs better. They just have a sleeker, more solid look to them.

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