JimGnitecki
Member
- Joined
- Mar 28, 2010
- Messages
- 1,258
I have a recently acquired brand new Pedersoli Sharps rifle in .45-70, and have started ladder testing of loads for 405g bullets (since I cannot seem to find readymade 500g bullets reasonably available to me). But a friend gave me 13 of the 500g .4585" diameter bullets that he had left over from the last batch he cast. So I did a very MINI ladder test, using a published Hodgdon loading table. I loaded up all 13 bullets using Accurate 5744 pwoder, making 4 cartridges with 20.5g of powder, and 3 each of 21.0g, 21.5g, and 22.0g.
The results were both satisfying and VERY definitive.
I should note in advance that I am not yet used to the ergonomics of this rifle, so am not yet shooting it at all well, as I try to figure out how to hold it steady enough for ladder testing on a Rock Jr. front rest in front and a rear bag in back, and not yet having any clue as to where the "node" point might be on that 30" long and 1" diameter barrel.
My attempt to try to determine the node via the baby powder process proved to be impossible with the historically semi-authentic 35" scope with external adjustments installed (no way to properly sprinkle the barrel with the scope above the barrel its full length).
In addition, the 45-70 recoil (which has necessitated a recoil pad even with CAS-level loads!), had me developing a flinch because once I started the ladder test I did not want to abort it, as I has ONLY those 13 500g bullets from my buddy - no more available until I can be equipped for casting my own (soon).
But as you will see, all the above did not matter much. The results, while defective, are definitely definitive.
Here they are:
Note the following:
1. One of the four 20.5g shots (the first shot fired) was deleted from the analysis because the Labradar said its muzzle velocity was 30 fps above the other 3, which were all in contrast REMARKABLY close together in velocity. I attribute the odd 1087 fps reading for that 1st shot fired being because it followed the firing of 30 shots with 405g Missouri Bullet Company bullets that were coated with Hi-Tek from the factory. My theory is that the Hi-Tek coating of those 405g bullets, coupled with whatever lubricant my buddy used on the 500g bullets, somehow interacted and made that 1st 500g bullet speed through the barrel faster than all the rounds that followed. Maybe one of you has a bette explanation?
2. Note that the Standard Deviation for the 20.5g bullets was just "3", and the Extreme Spread was just "6"!
3. Note that the extreme spread (group size) for the 20.5g bullets was 1.125", at 100 yards. This struck me as remarkably good for the first 3 shots fired with a brand new handload, with a tiny smokeless charge inside a cavernous Old West case, and with a shooter still trying to figure out how to shoot his brand new rifle.
4. Note that the rifle expressed its extreme displeasure with every one of the other 3 loads tried. You can see from the fact that the worst results was the 2nd group fired, not the 3rd or 4th groups fired (which were BOTH better than that 2nd group), so it was NOT due to the shooter either flinching more or getting tired. The rife simply hated that 2nd load specifically.
Note that the increase in muzzle velocity was almost perfectly LINEAR with powder increase, except at the 4th load (22.0g) where the increase in velocity from 21.5g was only modestly lower than the other 2 increases - still very close to linear though:
BUT, now take a look at the graph below where I plotted grains of powder versus the height of POI versus the POI height of the 405g ladder loads. I did NOT change the scope elevation setting when I switched from 405g to 500g bullets. I left the scope elevation unchanged, because I wanted to see how much higher the 500g bullets would impact, given their longer barrel time versus the 405g bullets. And, the impact height was DRAMATICALLY different in 2 different ways:
I had the scope elevation set such that the 405g loads all had POI between 1.5" to 3.0" above POA (so that I would not perforate my aim point).
Note how the POI for all 4 of the 500g loads was WAAAAY higher than for the 405g loads, even at just 100 yards range. The POI for the 500g loads was at LEAST 5.8" - 3.0" = 2.8" to 9.4" - 3.0" = 6.4" higher than for the 405g loads. That strikes me as a HUGE elevation change, even allowing the fact that the 405g loads were in a higher muzzle velocity range of 1253 fps to 1352 fps.
Now, note how the height of the POI for the 21.0g load was NOT higher than for the 20.5g load! I do not actually believe that the POI necessarily DEcreased in height for the 21.0g load versus the 20.5g load, as my group placement was probably varying because I do not yet have good positional control of the rifle from shot to shot, let alone the "right" point of support for the barrel. However, it is indisputable that the POI height for the 21.0g load did not INCREASE. This suggests that there is a rather strong node being manifested in the 20.5g to 21.0g powder range.
In fact, since the ENTIRE load range in the Hodgdon load table I used is just 20.2g to 23.8g, it is possible that this node may even be the ONLY node.
It does illustrate what other buffalo rifle shooters have been telling me: the most accurate load in these rifles is usually near the bottom of the safe range, and only rarely above that,
That is good news to me too, because until I fired THIS rifle I have never before been sensitive to recoil, whether firing rifles or handguns, and having even fired a .338 Lapua rifle and a .44 Magnum revolver. But THIS rifle has necessitated a recoil pad for me for the first time ever. I guess a power factor of 500g bullet x 1126 fps / 1000 = 563 IS going to hurt a bit, because so much of the PF is in the WEIGHT of the BULLET versus in the velocity.
Anyway, I regard myself as having "beginner's luck" on this ladder test. Now I am really fired up about getting into casting my own 500g bullets.
These old buffalo rifle calibers combined with a modern Pedersoli replica rifle can SHOOT, despite the assumed foolishness of just 20,5g of powder in a case that can hold 70 grains of black powder.
I am mightily impressed.
Jim G
The results were both satisfying and VERY definitive.
I should note in advance that I am not yet used to the ergonomics of this rifle, so am not yet shooting it at all well, as I try to figure out how to hold it steady enough for ladder testing on a Rock Jr. front rest in front and a rear bag in back, and not yet having any clue as to where the "node" point might be on that 30" long and 1" diameter barrel.
My attempt to try to determine the node via the baby powder process proved to be impossible with the historically semi-authentic 35" scope with external adjustments installed (no way to properly sprinkle the barrel with the scope above the barrel its full length).
In addition, the 45-70 recoil (which has necessitated a recoil pad even with CAS-level loads!), had me developing a flinch because once I started the ladder test I did not want to abort it, as I has ONLY those 13 500g bullets from my buddy - no more available until I can be equipped for casting my own (soon).
But as you will see, all the above did not matter much. The results, while defective, are definitely definitive.
Here they are:
Note the following:
1. One of the four 20.5g shots (the first shot fired) was deleted from the analysis because the Labradar said its muzzle velocity was 30 fps above the other 3, which were all in contrast REMARKABLY close together in velocity. I attribute the odd 1087 fps reading for that 1st shot fired being because it followed the firing of 30 shots with 405g Missouri Bullet Company bullets that were coated with Hi-Tek from the factory. My theory is that the Hi-Tek coating of those 405g bullets, coupled with whatever lubricant my buddy used on the 500g bullets, somehow interacted and made that 1st 500g bullet speed through the barrel faster than all the rounds that followed. Maybe one of you has a bette explanation?
2. Note that the Standard Deviation for the 20.5g bullets was just "3", and the Extreme Spread was just "6"!
3. Note that the extreme spread (group size) for the 20.5g bullets was 1.125", at 100 yards. This struck me as remarkably good for the first 3 shots fired with a brand new handload, with a tiny smokeless charge inside a cavernous Old West case, and with a shooter still trying to figure out how to shoot his brand new rifle.
4. Note that the rifle expressed its extreme displeasure with every one of the other 3 loads tried. You can see from the fact that the worst results was the 2nd group fired, not the 3rd or 4th groups fired (which were BOTH better than that 2nd group), so it was NOT due to the shooter either flinching more or getting tired. The rife simply hated that 2nd load specifically.
Note that the increase in muzzle velocity was almost perfectly LINEAR with powder increase, except at the 4th load (22.0g) where the increase in velocity from 21.5g was only modestly lower than the other 2 increases - still very close to linear though:
BUT, now take a look at the graph below where I plotted grains of powder versus the height of POI versus the POI height of the 405g ladder loads. I did NOT change the scope elevation setting when I switched from 405g to 500g bullets. I left the scope elevation unchanged, because I wanted to see how much higher the 500g bullets would impact, given their longer barrel time versus the 405g bullets. And, the impact height was DRAMATICALLY different in 2 different ways:
I had the scope elevation set such that the 405g loads all had POI between 1.5" to 3.0" above POA (so that I would not perforate my aim point).
Note how the POI for all 4 of the 500g loads was WAAAAY higher than for the 405g loads, even at just 100 yards range. The POI for the 500g loads was at LEAST 5.8" - 3.0" = 2.8" to 9.4" - 3.0" = 6.4" higher than for the 405g loads. That strikes me as a HUGE elevation change, even allowing the fact that the 405g loads were in a higher muzzle velocity range of 1253 fps to 1352 fps.
Now, note how the height of the POI for the 21.0g load was NOT higher than for the 20.5g load! I do not actually believe that the POI necessarily DEcreased in height for the 21.0g load versus the 20.5g load, as my group placement was probably varying because I do not yet have good positional control of the rifle from shot to shot, let alone the "right" point of support for the barrel. However, it is indisputable that the POI height for the 21.0g load did not INCREASE. This suggests that there is a rather strong node being manifested in the 20.5g to 21.0g powder range.
In fact, since the ENTIRE load range in the Hodgdon load table I used is just 20.2g to 23.8g, it is possible that this node may even be the ONLY node.
It does illustrate what other buffalo rifle shooters have been telling me: the most accurate load in these rifles is usually near the bottom of the safe range, and only rarely above that,
That is good news to me too, because until I fired THIS rifle I have never before been sensitive to recoil, whether firing rifles or handguns, and having even fired a .338 Lapua rifle and a .44 Magnum revolver. But THIS rifle has necessitated a recoil pad for me for the first time ever. I guess a power factor of 500g bullet x 1126 fps / 1000 = 563 IS going to hurt a bit, because so much of the PF is in the WEIGHT of the BULLET versus in the velocity.
Anyway, I regard myself as having "beginner's luck" on this ladder test. Now I am really fired up about getting into casting my own 500g bullets.
These old buffalo rifle calibers combined with a modern Pedersoli replica rifle can SHOOT, despite the assumed foolishness of just 20,5g of powder in a case that can hold 70 grains of black powder.
I am mightily impressed.
Jim G
