Baker rifle velocity and load questions

[Mattox Forge]

I thought I would post this here since there is a lot of shooting knowledge. I have been trying to work up loads and get a TRS Baker rifle I am working on sighted in. Over on the British Militiaria Forums a topic was started that caused me to dive into ballistics, so I started a small study on 1800 Infantry rifle sight settings.

I was fortunate enough to obtain a very nice aerodynamic code that I could use to generate very accurate 4 degree of freedom flyout model based range tables. I created an aerodynamic model of a .600 round ball and generated a series of range tables for different velocities ranging from 1150 to 850 feet/second.  The numbers in excel indicated that three of the original carbine bore rifles (P1800 IR, CHY Nock Rifle, Brander & Potts Target rifle) I collected sight angles from all have the same elevation angle for their short rear sight leaf, and the two with second leafs, P1800 IR and the Brander & Potts Target rifle, have the same elevation angle for that leaf. The TRS rifle happens to match the ordnance P1800 sight setting for the short leaf. The LVH Nock rifle does not match any of the other rifles. The "sameness" falls into a margin of error that is caused by measurement error and other randomness. However, the data lines up pretty well.
Since we know that the Baker rear leaf is supposed to be set for 100 yards, I wanted to find out what velocity would use these sight settings. The following plot shows the sight angle data interpolated for velocity to show what velocity would cause the ball to hit the mark at 100 yards. The data showed a really good correlation for a 875 feet per second muzzle velocity for all of the rifles except the LVH Nock. It is also worth noting that the second leaf of both the P1800 and B&P rifles could hit the mark at 200 yards, but with a higher velocity.



I created a ballistic table for 875 f/s and plotted the sight data interpolated by the range to fit onto the velocity curve. The data indicated that the sight settings for all three original rifles and the TRS rifle was exactly what was needed to hit a mark at 100 yards with a muzzle velocity of 875 feet per second. This indicates to me that there was some sort of standard charge and being used to regulate these rifles.



Assuming that troops were not expected to load heavier charges to hit more distant targets, the range correlating to the second leaf elevation setting would indicate what the second sight setting was regulated for. This seems to indicate that the second leaf was set for 180 yards.



There are clearly a number of if’s here. I have not measured any muzzle velocities. It is interesting that there was such good correlation with three disparate rifles, and a reproduction one. I would love to have more data to see if this trend is real.

So, to finally get to the questions: has anyone worked up a good load for a .600 ball in a 30 inch .625 bore rifle? Do you happen to know the muzzle velocity?

Cheers,

Mike

[smylee grouch]

I get 1700+ fps out of a 31" 62 bore-610 ball using 110 grains of 1&1\2 Swiss. I know this is not what you asked for or if any repeatable comparisons can be made with this data. I only offer it as a for what its worth statement.

[Mattox Forge]

smylee,

Thank you very much, this is perfect. The service charge for the Baker was 110 grains with a .596 patched ball. Their powder probably wasn't quite as good as what you are using.

If I run the numbers for an MV of 1600 fps, 24 minutes hits at 200 yards and 43.2 hits at 300 yards. This almost exactly corresponds to the two sight settings on the original Baker rifle I have.





It seems that the sights were probably designed for 200 and 300 yards on the Baker, not 100 and 200 as normally thought.

Mike

[Daryl]

Military rifles, I thought, were sighted to shoot quite high at close ranges due to the elongated target,  an enemy soldier, thus "centre of mass" aiming would give hits over longer ranges.
This "sighting" also held true with military revolvers of the mid 1800's.

[Mattox Forge]

One of the issues is that the exact design requirements for the sighting were not written down, or the records are lost or undiscovered. The term "point blank" for the 100 yard sighting has been kicked around.

Around WWII rifles were sighted so that at normal battle ranges, no sight adjustment would be necessary to hit a target. This was one of the earliest military rifles, but the same logic you describe, and what was used on M1 Garands and M14s seems to have been true then as well, and would seem to fit the evidence.

If it was sighted in at 200 and 300, aiming a the center of a 5' tall target at 100 yards would still get a hit somewhere on the target.

Mike

[longcruise]

I don't think it would take much powder to get 875 fps.  Would like to see some chronograph data.

[Daryl]

875fps would be achieved with around 40gr. powder, I would expect. Of course this is just a wild guess.