barrel length and muzzle velocity

[School Belle]

I have looked at muzzle velocity tables for bp powered prb out of a 28-inch barrel. How does the length of the barrel affect the muzzle velocity? Is it so many fps +/- per inch of lengthened or shortened barrel?

Cordially,
Michelle

 

[Lonegun1894]

Michelle,
You didnt list a powder load, so I will use the 70 grain load I use in my 28" CVA St.Louis Hawken.

Per the Lyman BP Handbook:
26" --- 1574 fps
28" --- 1587 fps
32" --- 1663 fps
43" --- 1725 fps
( these will vary with each rifle as each will behave somewhat differently )

So it appears to provide some increase in velocity on paper, but most here will tell you to go with your most accurate load, and I agree there. Your .50 will do the job if it strikes the vitals, and the velocity actually needed is surprizingly low for anyone accustomed to modern firearms. About all velocity will do for you is allow longer effective range before range estimation becomes critical, but that really shouldnt be an issue for you in most areas deer are taken. Find a load you and your rifle like and are comfortable with and you'll do fine.

 

[zimmerstutzen]

There are some minor loads which do not develop the same ft/sec velocity per grain of powder as higher loads. For instance in a 50 cal, a load like 25 grains. Likewise once you reach an upper point, the velocity increase starts to drop off This point in a 50 cal is around 110 grains of powder. While ft/sec continues to climb, it does so at a decreasing rate, until the increased velocity is negligible. However, muzzle velocity isn't everything. all patched round balls lose velocity as they travel down range, due to air resistance. Not even this is at a standard rate. As the patched round balls exceed the speed of sound, their rate of deceleration (loss of velocity as they travel down range) seems to increase. So a ball launched at 1,000 ft per sec, will lose a certain amount of velocity by the time it reaches 100 yards. A patched round ball launched at 2,000 ft per second actually loses a higher percentage of it's velocity by the time it reaches 100 yds. Some say this may be due to air piling up in front of the ball and causing increased drag.
This becomes important when some shooters increase powder to flatten their trajectory or increase their hunting range. According to the Lyman Book's ballistic tables, (which some have said are abnormal figures) it can take as much as 50% more powder just to increase range in ft/lbs by 15 or 25 yds. (this of course depends on barrel length, powder and caliber)

Also according to the Lyman ballistic figures, in 54 and 58 caliber guns, the extra powder for extended range idea seems to be born out by their tables to an extent. I'm not sure why the larger calibers tend to keep increasing velocity per grain better than the 50 and under calibers. Part of it is probably due to the fact that the larger caliber balls carry more of their initial muzzle energy down range than smaller caliber balls. (a 36 cal ball loses about 65% of it's intial muzzle energy at 100 yds. A 45 caliber loses about 55%, a 50 caliber loses about 50% and a 75 caliber loses only about 25% of it's intitial ME at 100 yds. These are pretty rough figures but the Lyman ballistics tables show the trend of energy retention by ball weight at 100 yds.)

 

[longcruise]

does the length of the barrel affect the muzzle velocity? Is it so many fps +/- per inch of lengthened or shortened barrel?

Barrel length does effect muzzle velocity. However, true comparisons can only be made by using the same barrel at various lengths. Reason being, that not all barrels are exactly the same and not all loads have the same fit in all barrels.

If you compare one barrel at 28" to another at 44", the variations you see will not all be related to barrel length even though you will see a difference in the velocity. Compare that same 28" barrel to three other 44" barrels and you will probably see that they do not all provide equal differences.

I once compared a 28" .54 rifle to a 32" .54 rifle shooting the same exact powder charge, patch, ball, etc. on the same day over a chrono. The 28" barrel shot about 100 fps faster than the 32" barrel :shocked2: The only observable difference was that the 28" barrel was a bit tighter bore and showed more resistance to loading the patch ball combo. This also supports the idea that a tighter load will shoot faster than a looser one from the same barrel.

Here is a test done by Rice barrel company that will shed some light. Rice barrel length test

Hope this helps.

 

[GANGGREEN]

That's fairly interesting Marmot. While interesting, I don't think there's enough difference in velocity to make it a very worthwhile consideration for most types of hunting.

 

[Ron_T.]

In truth, due to the relatively rapid deceleration of the prb, 100 fps or so doesn't really make much difference in killing power.

As has been stated many, many times... bullet PLACEMENT is ultimately "THE" most important aspect in hunting. :bow:


Strength & Honor...

Ron T.

 

[longcruise]

Yes, but School Belle did not ask about hunting, etc. Just about velocity variations. Got no idea why she asked. Maybe she will tell us.

 

[School Belle]

Yes, but School Belle did not ask about hunting, etc. Just about velocity variations. Got no idea why she asked. Maybe she will tell us.

Okay, I will tell you. My mom and sister gave me flintlock for my birthday. It is used, but the first hand-made gun I've ever owned. The wood is beautiful. The barrel is 40 inches long, and the caliber is .36. Over the past several weeks, I have been getting to know it at the range and in the cleaning process afterward. Having never shot this caliber before, I was curious about what to expect.

Cordially,
Michelle

 

[paulvallandigham]

Now that we understand the caliber, and length of YOUR gun, we can be a little more specific.

Squirrel and rabbit loads are often fired no further than 25 yds. a lot of shooters will load only 30 grains of FFFg powder for this purpose. Velocity at the MUZZLE in a .36 is going to be around 1500 fps. Its going to lose about 25% of its MV in the first 50yds. The .36 throws a large enough ball ( In weight) to take large varmints out to 50 yds, and sometimes further. I am talking ground hogs( 10-15 lbs.) fox( 10-15 lbs.) and Coyote( 15-30 lbs.)

For longer range target shooting ( out to 10 yds. on a calm day) increase the powder charge to 40 grains( 1750 MV), 50 grains( 1975 fps), and even 60 grains(2088 fps)! I don't recommend that 60 grains load in most .36 cal rifles, but if the barrel is long enough to burn the powder you send the ball out the barrel at those "Gee Whiz" velocities.I have my doubts as to how well MOST shooters can shoot such loads, however.

30-40 grains of FFFg powder by volume is the normal range of loads used in these caliber guns to hunt about everything. Take a look at the thread down on the index to this page on traditional muzzleloading hunting. Read through several pages of the thread to find posts by our successful small game hunters. You will get information on the loads they use, and the kind of range at which they kill their game. :thumbsup: :hatsoff:

Best wishes with the new, "OLD" gun. With care, your children and grandchildren can be shooting your rifle as their first "muzzleloader".

 

[gearheart]

Have fun with the new toy and Happy B'day :thumbsup: I think the "long barrel is better" idea came from the fur trade when the NDNs had to pay for the gun with a stack of furs equal in height to the gun's length. The traders put on a spiel about how the longer barrels were more accurate. :rotf:

 

[Zonie]

Years ago the folks at Dixie Gunworks asked the same question about barrel length and velocity.

They used a .40 caliber Dixie Percussion rifle and started with the guns 40 inch barrel. They shot 5 shots with a fixed size powder load and then recorded the average velocity. Then they cut off 2 inches and repeated the test.

For the lighter powder loads they continued to fire and record and cut until the barrel got down to 20 inches long.

The velocity given by the chart will be different than your .36 Flinter but the general idea is pretty easy to see.

I'll list their data for a 47 grain powder load of DuPont 3Fg (I said it was a long time ago. )
40"=1770
38"=1747
36"=1735
34"=1610
32"=1654
30"=1642
28"=1523
26"=1596
24"=1593
22"=1553
20"=1509

Hope this helps to answer your question.

 

[Stumpkiller]

Have fun with the new toy and Happy B'day :thumbsup: I think the "long barrel is better" idea came from the fur trade when the NDNs had to pay for the gun with a stack of furs equal in height to the gun's length. The traders put on a spiel about how the longer barrels were more accurate. :rotf:

When you get old you will find a front sight closer to the deer is easier to pick out. :haha: There is something to be said for a l-o-n-g sight radius.

 

[gearheart]

You have a point there. My eyes are still OK but my arms are too short. :bow: I use a peep sight from TC to overcome the blurs. My vision went south about 15 years ago in my mid 40's. Back in the days on the frontier that may have been ancient. :grin:

 

[David W.]

Longer barrels give the powder enough time to burn on heavier charges. It also gives a longer sighting plane that helps line up to the target.

Typically, target charges are on the low side for most rifles. My .36 uses 22 Gr FFFg Swiss very well. Good enough for rabit, squirrel, or just puching holes in paper.

I would also concider using 000 buckshot in your .36 as it is cheaper than cast or swaged balls.