Need a 15/16" smooth bore octagon barrel 12ga.

[gmww]

I'm trying to find a 15/16" Octagon barrel in 12 ga. for my new underhammer. I would like to have it as a bird hunting barrel. Anyone have one or know where I can find one? I figure I can have another breech plug made to fit my Underhammer.

 

[Mike Brooks]

In my opinion, 15/16ths is not enough breech for a 12 ga.

 

[Harddog]

Have to agree with Mike, that would only leave a little over .100 for barrel thickness. Not near enough for safety.

Harddog

 

[Harddog]

GMWW,

You would also not have enough wall thickness for any kind of breech plug.

Harddog

 

[gmww]

Thanks, I guess I'll have to go for possibly 20 ga.?

 

[WV_Hillbilly]

I'm trying to find a 15/16" Octagon barrel in 12 ga. for my new underhammer. I would like to have it as a bird hunting barrel. Anyone have one or know where I can find one? I figure I can have another breech plug made to fit my Underhammer.

I've got to agree with the others 15/16" doesn't leave nearly enough breech thickness to have a healthy margin of safety.

I wouldn't go over 28ga (approx. .55caliber), and that would be my uppermost limit. So, even your 20ga idea wouldn't be safe (in my estimation).

I think a lot of times when people are considering a muzzleloading 12gauge swap-in barrel, they immediately start comparing the thickness to a modern 12ga barrel, BUT it's "apples & oranges"--the steel used is completely different, and the pressure curves also.

IMO, I would want 1 1/4" across flats (or O.D.) at the breech for a 12gauge barrel, and probably 1 1/8" for the 20gauge.

Those larger barrel sizes may look somewhat "out of place" relative to your receiver and to the original rifle barrel's thickness. When it's a matter of (my) safety VS (the gun's) aesthetic beauty--my safety is ALWAYS FIRST!

BTW, my 15gauge smoothbore flint gun had a barrel that was
1 1/8" AF at the breech--I still always felt the gun could have stood a heavier breech though...

Back when gun barrels were made of iron, damascus, or very poor quality steel; most people decided that a "SAFE" barrel should be TWICE the thickness of the ball it used, and that was a good "rule of thumb".

Nowadays, if we could know exactly what kind of steel every barrel was made from, we could get away with thinner barrels. BUT, most barrels are still made from low carbon & mild steels (read that as cheaper to use!), so we probably ought not to take chances.

I still think it's a good idea (though maybe not very practicial) to make every manufacturer build their barrels thickness at twice the diameter of the bore. I just don't want anyone (especially me!) to get hurt needlessly.

ALWAYS use a BIG enough gun, and shoot safely!
WV_Hillbilly

 

[Mike Brooks]

Many of the cheap 20 ga barrels on the market today have 1" breech . TOTW sell tons of them. I certainly wouldn't want anything bigger than a 20ga in a 1" breech.

 

[Mad Professor]

Many of the cheap 20 ga barrels on the market today have 1" breech . TOTW sell tons of them. I certainly wouldn't want anything bigger than a 20ga in a 1" breech.

A similar thread came up regarding 58 cal in 15/16" barrels. Again with claims that there was not enough barrel thickness.........

I've a lyman factory barrel in 20 ga 15/16", the barrel made by Investarms with their proof marks. Do you really think 20 ga is too big for 15/16" ? Have not blown up mine yet. Do you consider Lyman/Investarms cheap too?

With 12 ga this is another story.......

 

[Mike Brooks]

Well Proffesor, obviously your 15/16ths breeched 20 ga is fine. Just in my own personal opinion, I'd not want to go smaller than 1" for a 20 bore I'd want to sign my name to..
I havn't held a Lyman gun in my hands for probably 20 years or more and never heard of invest arms before, so have no opinion on their quality.
If you feel comfortable shooting a 15/16 20ga , go for it. It's just not something I'd choose to do if there were other options.

 

[gmww]

My first ML is the Cabelas in .54 cal. Hawkens. I never heard of Investarms until I brought the Cabelas home. It is acutally a very good shooter and well made in my opinion. If anyone has their web sight I'd sure like it as I'd like to see about getting their fouler barrel.

I've been emailing back and forth with Bruce from Blue Grouse about putting a shotgun barrel on my Underhammer. The barrels he is suggesting are the 1" and greater ones.

 

[uncrichie]

20 ga nominal bore is .612". 15/16" is .937", difference between the two is .325 divided by 2 to give measurement on both side of the bore would be .162" which is a little better than 5/32" thickness between the edge of the bore and the flats of the barrel. I don't know if thats enough or not, but if my math is correct there you have it. Uncrichie...

 

[TANSTAAFL]

I agree with you Mike, too thin is not good. Then, I get to looking at my wheel guns and think, damn, those cylinder walls ARE thin.

 

[WV_Hillbilly]

I agree with you Mike, too thin is not good. Then, I get to looking at my wheel guns and think, damn, those cylinder walls ARE thin.

I definitely agree about the "thinness" of cylinder walls, and that applies to just about ANY & ALL revolvers!

What's EVEN SCARIER is that the bolt cutouts in many revolvers are directly in line with the chambers--now think about how much thinner the metal is in the chamber wall there...?!?!

At least, "some" of the newer heavy caliber 5-shot cylinder centerfire modern guns have bolt cutouts that are between the chambers. I think that makes a whole lot more sense.

The type of steel or alloy used in making that cylinder makes ALL the difference in the world though...

Shoot Safely!
WV_Hillbilly

 

[WV_Hillbilly]

Do you really think 20 ga is too big for 15/16" ? Have not blown up mine yet. Do you consider Lyman/Investarms cheap too?

I don't consider ANY of the Lyman/Investarms guns to be cheap or otherwise unsafe. My comments were intended to cause us to consider that we really do NOT know how good (or bad) the steels & alloys are in gun barrels of various manufacturers.

Do you wonder why Green Mountain Black Powder Cartridge Barrels are still "Recommended For Black Powder Use ONLY"...? It's because they (and others) use steel alloys that are "just strong enough" for the purpose, and NOT any stronger--which "might" tempt or encourage a person to try smokeless powder in them.

Do you know what the barrel was proofed at for ANY of your original guns' barrels? Are they made of iron, damascus, low steel, high steel, stainless, forged, cast, milled, OR whatever...?

Wouldn't you like a little more "margin of safety" rather, than make the barrel look thinner?, or have a gun that is a few ounces lighter?

Just for an example... the Armi Sport manufactured 1842 Springfield Muskets in .69 caliber have a barrel that is
1.215" diameter (round barrel) at the breech end. Now if you would, think about having a 12ga bore (.729") with a 15/16" AF octagon breech end... there's quite a bit of difference there.

I just don't want to read or hear about ANYONE wrecking their gun, themselves, or others due to a barrel being lighter (thinner) than it properly should be for safety.

Safety First, Fun Second! Please take care...
WV_Hillbilly

 

[Deadeye]

I think I've mentioned it before but I have a 12 ga 15/16 1/2 oct. 1/2 rnd. barrel. It was made in Toledo,Spain and imported by Navy arms as a drop in for TC Hawkins and Lyman
Trade guns, it's blued outside , hard chromed inside. I've proofed it myself with 150 grs. 2F and 2 1/2 oz. of shot, which is twice the load I normally shoot in it. Not sure but I think the Spanish proof is for 40,000 lbs. Most ML shot loads run around 6 or 7000 lbs.

 

[jimbo15563]

Interesting Thread

I'm having a custom underhammer built (see my thread Jimbo's Underhammer). I ordered a barrel from Ed Rayl in .54 caliber. It tapered Octagon-to-Round. The breech end starts at 1.200" to match up with the H&A action and ends up at 7/8" (.875).

Since starting this project, I have come to admire the Zephyr Underhammers and would like to order a second barrel patterned after their 20-Bore. These barrels are Forsyth Rifled with a 1:104 pitch and shoot PRB's at 1700 FPS using 175 gr FFG charges. The muzzles are ported to reduce recoil.

I would like to have the second barrel follow the dimensions of the first as closely as possible: however, I realize that the 7/8" muzzle is insufficient to handle the pressures associated with these loads. Any recommendation on a minimum muzzle diameter? I'm thinking that somewhere around 1" would be necessary.

Thanks,
Jimbo

 

[faw3]

Hate to tell you this last thing i saw was Spain proofed at 13,000 1st proof 17,000 2nd proof not to high at all fred

 

[varsity07840]

I've always found this subject interesting. I think the quality of the barrel steel on a particular gun is a factor along with the knowledge of what constitutes a safe load in it.

My Mortimer flint 12 ga. and Garner 20 ga fowler both have 1" barrels that I'm totally comfortable with because I have confidence in the builders and I don't overload them. On the other hand, I used to have a Beretta/ASM over&under with breeches that I'm pretty sure were under an inch. The walls at the muzzle were so thin you could cut yourself putting a card wad in the muzzle. Although I never heard of any problems with them regarding wall thickness, I didn't have the same comfort level with it. I don't miss that gun.

As a related subject, check out the forum on
American Longrifle's site. Don Getz has some
interesting comments about .50 cal barrels he's made in 13/16"!!

 

[dd832]

Jimbo, FYI - my Zephyr mikes @ 1.128" (1 1/8") at the breech and .935 (15/16") at the muzzle. (30" barrel). Mike

 

[Stophel]

Green Mountain uses 1137 steel (VERY tough) and is probably strong enough for dynamite, but like ALL ML gun barrel makers, quite rightly, say Black powder ONLY. :winking:

A 15/16" barrel would be strong enough for up to about .58 cal., but good luck finding anyone to make you one....

I have a 175 year old rifle with a barrel about 15/16" and around .58 cal. Dead soft iron, short breechplug and ain't blown yet. Even I wouldn't go any bigger than this, though!