Usable Barrel Length?

[Deleted]

In my loaded Savage / 67gn H4198 / 300gn Remington / BCR sabot it measured 16 3/4" from the tip of the Remington to the end of the barrel. Is that what you would call usable barrel length? I cut 3" off the stock barrel, so that would make the stock barrel measure out at 19 3/4" of usable length. Not really the 24" they are advertised at. Is that common practice?
A couple of weeks ago Rossman wrote that he had heard that N110 burns out within 16". I just ordered some N110 to see if it shoots as fast in the shorter barrel as it does in a stock barrel. In my recent velocity testing 4759 kept the same speed with the shorter barrel as it had in the stock barrel.
Just sharing some thoughts.......
Zen

[Al]

I think commom practice for barrel length, is the overall length of the barrel, not the useable length as mentioned.

Useable length on a ML, I'd say it would be from the muzzle to the face of the BP.

[fowlplay]

Zen,
Look forward to your future testing of N110. If you are not duplexing, IMO N110 is a excellent choice for a short barrel.
Steve

[dougedwards]

I would consider the usable length to extend from the powder column to the muzzle. I am sure others will chime in.

Doug

[edge]

IMO, the question can't be answered with a single number!

Certainly from the vent liner to muzzle is usable, but I don't think that is not really what you want, but it might be.
Since powders take up more or less space from one another, the bullet base to muzzle can change dramatically which changes the expansion ratio.
I don't remember, but I think that the Savage ramrod is 22 inches long, which would also be the distance from vent liner to muzzle. (Someone correct me if I am wrong.)

If you shoot 67 grains of H4198, the bullet/sabot base should be about 1.4 inches from the vent liner. ( If you switch to 45 grains of N110 that will become about 1.040, or about 3/8 longer travel for the bullet)

edge.

[Harley]

Edge, "...can't be answered with a single number!" I wouldn't have expected anything less from you. That's a compliment, and I agree.

Maybe we need two terms:

Usable barrel length - might refer to the total column space between the muzzle and the BP, taking into account that the total will be influenced by the type of BP used (OEM-type or recessed).

Barrel length available for powder burn - would reflect the net column space from the muzzle to the top of the settled powder charge. It would vary depending on the powder(s) used.

Harley

[rbinar]

8-)The usable barrel length has to be the distance from the plug to the muzzle. The reason is that will relate to how it's done in other rifles. By that I mean the length of the case and position of the bullet may be used in some computations but it is derived from the full barrel length minus the length of the case.

The above is better explained if you compare three cases (.308 Winchester, 30-06, and 300 Win Mag) they are different lengths giving three different powder columns and three different bullets positions but all have the same usable length barrel if the barrel is the same.

In a sense the three different cases can be compared to the 10ML shooting three different powders. That's basically the same as the cases because you generally shoot more of a slower powder in a bigger case. The bullet is more forward in the barrel but the usable length would still be considered the same.

In pressure estimates the usable length should be the plug to muzzle length and then using the variables to design a case with the correct length to position the bullet at the proper place in the column. To get it close the sabot (and wads) must be considered part of the bullet.

Using the above examples the 10ML has a 22" usable barrel length. Shooting the 40+ grain factory loads it emulates a 50 caliber rifle shooting a short case. As slower powder is shot then the emulation changes to a longer case. If enough powder is shot then real life cases (like 50-90 or 50 Alaskan) can be emulated. But it's still an emulation not a real case.