Author Topic: Barrel weights (Read 2232 times)

Top Jaw · « **on:** March 20, 2020, 11:20:20 PM »

Been trying to find a reference table on line. Found something but info seemed questionable.
So I’ll ask here:

1). What is the weight of a 13/16” straight barrel, 45 caliber, 42 inches long?
2). And, what is the weight of a 7/8” straight barrel, 50 caliber, 42 inches long?

One source gave me 4.3 lbs for #1, & 5 lbs for #2.
Your confirmation, or corrections appreciated.

WadePatton · « **Reply #1 on:** March 20, 2020, 11:44:45 PM »

The engineering type would calculate the amount of steel there and multiply by the known weight of the steel and find get the answer within fractions of an oz. Pretty simple for straight bbls, less simple on all the other shapes we use.

Sorry that's not a quick answer but could be used if you wanted to.

flinchrocket · « **Reply #2 on:** March 20, 2020, 11:53:35 PM »

Tow gives the shipping weight of all their barrels.

Elnathan · « **Reply #3 on:** March 21, 2020, 12:23:16 AM »

Area of an octagon is A~.828S². S is the span, the dimensions from flat to flat.

Use that formula to find the area of an octagon, multiply by the length of the barrel, then subtract the volume of the bore (Pi times bore/2 squared x length of the bore). That will give you the volume of the barrel (ignoring stuff like the rifling and the metal machined away to make the breechplug threads. Then use multiply that figure by the weight of steel by volume (I've found a couple different figures online).

For finding the weight of a swamped barrel, you have take the areas of key points down the barrel (key points being where the rate of taper changes), figure out the radii of circles with the same area, and then use that radii to calculate the volume of a series of truncated cones. Add the volume of those cones together and subtract the volume of the bore, and then calculate the mass as above. Complicated, but once you've done it a couple times it gets easier. Depending on the exact sequence of the calculations you can start with the dimensions of an original barrel and fiddle around with different calibers, keeping the weight the same or reducing it by a given percentage throughout, all kinds of things. The first time I did it I was trying to scale a barrel with a 1.20 breech and a .60 bore down to .50 caliber and a 1.125 breech (D weight) - I found that keeping the barrel the same weight resulted in a breech about 1.14, IIRC, so I just reduced the rest of the barrel wall areas by the appropriate percentage and then work backwards to figure out what the span should be.

Harder to explain than to do, though I always make a chart so I can keep my figures straight.

davec2 · « **Reply #4 on:** March 21, 2020, 12:54:21 AM »

I didn't check my numbers but my going in assumption was that the .50 cal barrel would be lighter. I calculated

.45 cal x 13/16" x 42 inch barrel weight of 4.85 lbs

.50 cal x 7/8" x 42 inch barrel weight of 3.85 lbs

(Area of octagon - area of bore) inches^2 x 42 inches = Volume of steel in in^3 x 0.3 lbs / in^3

Ky-Flinter · « **Reply #5 on:** March 21, 2020, 06:24:14 AM »

Here ya go Top Jaw.....

https://americanlongrifles.org/forum/index.php?topic=37630.msg361444#msg361444

-Ron

BOB HILL · « **Reply #6 on:** March 21, 2020, 07:20:05 AM »

I’ve got one of each. I also have a gun with each. The 7/8 .50 is the heavier of the two
Bob
Sorry I think someone has already responded.

Top Jaw · « **Reply #7 on:** March 21, 2020, 11:06:49 AM »

In my mind, the 45 should be lighter.

Bill Raby · « **Reply #8 on:** March 21, 2020, 11:53:34 AM »

When I was in college I had no problem doing the math to figure out orbital trajectories for satellites. That was 30 years ago. Today questions like this are more than I want to deal with.

BOB HILL · « **Reply #9 on:** March 21, 2020, 11:56:01 AM »

A little better than a half pound lighter, Top Jaw. All of the early guns I built were straight octagon. If I wanted a light deer rifle, I used a 13/16 .45.
Bob

smokinbuck · « **Reply #10 on:** March 21, 2020, 03:54:03 PM »

I keep an old Dixie catalogue on the shelf for all the information in the back, including barrel weights.

snrub47 · « **Reply #11 on:** March 21, 2020, 04:31:11 PM »

7/8x50x42 5.1 lbs
13/16x45x42 4.5 lbs

Top Jaw · « **Reply #12 on:** March 21, 2020, 05:35:30 PM »

Thanks for the input.

WadePatton · « **Reply #13 on:** March 21, 2020, 09:10:13 PM »

Quote from: davec2 on March 21, 2020, 12:54:21 AM

I didn't check my numbers but my going in assumption was that the .50 cal barrel would be lighter. I calculated

.45 cal x 13/16" x 42 inch barrel weight of 4.85 lbs

.50 cal x 7/8" x 42 inch barrel weight of 3.85 lbs

(Area of octagon - area of bore) inches^2 x 42 inches = Volume of steel in in^3 x 0.3 lbs / in^3

Quote from: snrub47 on March 21, 2020, 04:31:11 PM

7/8x50x42 5.1 lbs
13/16x45x42 4.5 lbs

Those are wildly different results. So, who is correct?

snrub47 · « **Reply #14 on:** March 22, 2020, 02:47:30 AM »

Good question, I'm not sure........Here is my formula.

=((3.314*(C22^2))-((3.14159)*((C24/100)+0.012)^2))*C26*0.283/4

c22=barrel dia. c24=caliber c26=barrel length

Marcruger · « **Reply #15 on:** March 22, 2020, 03:18:26 AM »

Who is correct? I’d say Bob, as he has both in hand and gave the answer. The makers give charts so you don’t have to do the math too.

BOB HILL · « **Reply #16 on:** March 22, 2020, 03:35:17 AM »

Just for the record and the mathematically challenged like me, here are the track of the wolf weights
Colerain. .50x7/8x42=5.0 lb
.45x13/16x42=4.4 lb
Green Mountain. .50x7/8x42=5.0
.45x13/16x42=4.4

I didn’t look up Rice weights thought this would be enough. Hope this is of help.
Bob

G_T · « **Reply #17 on:** March 23, 2020, 07:46:40 AM »

Steel density varies with type of steel, and not every barrel maker uses the same type of steel.

Gerald

Marcruger · « **Reply #18 on:** March 23, 2020, 03:20:52 PM »

"Steel density varies with type of steel, and not every barrel maker uses the same type of steel."

Which amounts to about a 3.5% swing in steel weight. That gives about 1/10th+ of a pound difference in these barrels.

If you are comparing barrels from the same maker, what's the point? I am pretty sure I cannot feel the difference in a 4.4 or 4.5 pound barrel in an 8 pound rifle. If you can, then I am betting you can feel a pea through a mattress.

I'll choose to follow the makers' charts. They put the barrel on a scale versus relying on math and assumptions.

sdilts · « **Reply #19 on:** March 23, 2020, 04:57:16 PM »

Rice has a chart for their swamped barrels.
http://ricebarrels.com/barrelweights-b.jpg

WadePatton · « **Reply #20 on:** March 23, 2020, 08:32:22 PM »

Bob said "heavier". Everyone else gave numbers. The numbers don't line up. That's my point. Shouldn't we be able to calculate similar figures? Some of the figures are quotes from other sources--those I trust the least because errors happen and there are things like Rice's old chart which uses completely wrong formatting-- only makes sense if you understand that.

It's a point of curiosity only as I've got no call for a straight bbl, and don't give bbl weight much thought as I've gained experience. But shouldn't the math --add up--?

Daryl · « **Reply #21 on:** March 23, 2020, 10:58:08 PM »

As long as the finished rifle is between 8 and 12 pounds, it's fine with me.

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Author Topic: Barrel weights (Read 2232 times)