Shiloh Rifle Forums

dc's thread on 50-90s got me to thinking if I'm ever going to shoot my 50-90 again, I at least need a Paperpatch mould for it.
What would be the best length for a pp mould with an eliptical nose in a 1-26 barrel?
Only 50 cal drawing I have is for a GG bullet for a 1-22 barrel. it is about 1.55 in,so maybe a 1.45 length?
Also have a Hoch GG mould that measures 1.41" that shot good what little I shot it.

In running it through my several different bullet length calculators, (0.5" diameter of bullet after leaving the muzzle, 1300 fps muzzle velocity), I get between 1.202" and 1.25".

The 22" twist gives lengths in the low 1.4s.

Might be a good time to go with an adjustable.

Brian are you going to patch to groove or bore? What gun? bobw

Brent
The calculator I tried, I had to know the weight and length, so it was a real guess.

Bob
Groove, Winchester BPCR

I made a spreadsheet to run them all at the same time for comparisons but they don't differ all that much. Some Differ in that they require velocity, but all of them are within a few percent of each other.


For my money I might believe that paper patches require a little bit more twist to be stable then equivalent grease grooves.

I think the bullet profile has a lot to do with stability. Where a Creedmoor ogive compared to a elliptical.
The two bullets I used in my .50-2.5, one a elliptical that is 1.438" long and the creedmoor nosed is 1.509" and the creedmoor outshot the elliptical.
When I used the .50 at gong matches I loaded it with 110 grains of 2F goex express and it pushed the creedmoor at 1293 fps and 110 gr of 2F Swiss at 1306 fps. Right now I don't see what the lighter elliptical tripped the chronograph at but it shot well also but not as good as the blunter nosed creedmoor.
My rifle has a 22 ROT. I put some holes through paper at 1000 yards at Raton testing loads and the holes were round with both bullets.
I see instability in my .44-77 using a 1.498" elliptical that has a 19 ROT at long range but the .44-90 BN with a 19 ROT the 1000 yard holes are round.

Kurt wrote: ↑Thu Oct 31, 2019 6:54 pm I think the bullet profile has a lot to do with stability. Where a Creedmoor ogive compared to a elliptical.
The two bullets I used in my .50-2.5, one a elliptical that is 1.438" long and the creedmoor nosed is 1.509" and the creedmoor outshot the elliptical.
When I used the .50 at gong matches I loaded it with 110 grains of 2F goex express and it pushed the creedmoor at 1293 fps and 110 gr of 2F Swiss at 1306 fps. Right now I don't see what the lighter elliptical tripped the chronograph at but it shot well also but not as good as the blunter nosed creedmoor.
My rifle has a 22 ROT.

So many variables !!
Wonder what they would do if the lengths were reversed.
Might jus have to break down and have Rick build me an ajustabe mould like Brent suggested.

I would go with the flat base adjustable if I was to order one.

Bullet Weight Length 1:36 1:34 1:32 1:30 1:28 1:26 1:24 1:22 1:20
Grains Inches
BACO JIM512450 480 0.970 1.80 2.01 2.27 2.59 2.97 3.44 4.04 4.81 5.82
BACO JIM511500 FN 500 1.010 1.69 1.89 2.13 2.43 2.79 3.23 3.79 4.51 5.46
BACO JIM512515 540 1.100 1.46 1.63 1.84 2.10 2.41 2.79 3.28 3.90 4.72
BACO JIM511600 FN 600 1.220 1.22 1.37 1.55 1.76 2.02 2.34 2.75 3.27 3.96
BACO JIM511650 FN 650 1.300 1.11 1.25 1.41 1.61 1.84 2.14 2.51 2.99 3.61
BACO JIM511670M1 Money 670 1.515 0.75 0.84 0.95 1.08 1.24 1.44 1.69 2.02 2.44
BACO JIM511695C1 Creedmore 695 1.450 0.88 0.99 1.12 1.27 1.46 1.69 1.98 2.36 2.86

Sg of different length bullets for a .50 caliber depending on barrel twist.
You require a Gyroscopic Stability Factor (Sg) of 1.4 to have enough spin for the bullet.
You are over spinning the bullet if the Sg is greater than 2.0 but many long distance shooters over spin their bullet with an Sg up to 2.5 to compensate for drag over long distances.

You require bullets about 1.450 to 1.515 long for 1 1:22 twist.

You require a bullet of 600 to 695 grains or 1.220 to 1.515 inches long for a 1:26 twist.

Thanks
Interesting how fast the sg falls off going from s 650 gr FN to a 670 money bullet for the 1-26 twist