Loads and measurements for the Smith cartridge?

[Swede68]

I´ve finally got all the stuff for making my original Smith Carbine go "bang!".
I do have a couple of questions though.

1. Powder charge. I will be using Hogdon Triple Seven FFFG, and I know that it (like Pyrodex) is a substitute that should be measured by volume compared to blackpowder. I´ve heard everything from 25grains to 35 grains (35 Grains Goex FFFg).
The gun is in absolutely pristine condition, and I´m not looking for "target loads", if anything, I´d like to avoid using any kind of filler if possible (and I know not to leave any air in the cartridge). I´d like to aproximate an original load for the Smith. Is the volume equivalent of 35grains about correct?

2. Cartridge length/bullet seating. How long should the total cartridge length be (as a starting point)? I´m using cast Smith bullets from Dixie and plastic cartridges from S&S.
If you can´t provide a measurement of total cartridge length, then there´s allways the option of just starting the bullet in the case, pushing the cartridge into the chamber until the rifling pushes the bullet back, and working from there. But if I use this method, how far from the rifling should I back the bullet into the case?

Anders Olsson

[Lou Lou Lou]

Good Luck
I have been using 25 grs FFFg asnd reduced capacity cases for 25+ years. If you want to try them contact Lodgewood or another sutler

[Swede68]

Thanks Lou Lou Lou!
I´ve got 5 brass reduced load cartridges also, but as I understand it they need fitting to the individual firearm to seal well.
I prefer using the plastic cartridges, and as I mentioned, unless there´s a serious safety hazard, I´d prefer using a charge consistent with what was used "back then".
As far as safety goes, my Smith is in the same condition as when it left the factory, the only difference is that the case hardening has faded just a bit. So I see no reason for using reduced loads (correct me if I´m wrong here).

I´d say that the biggest question for me is what total length the cartridge should be (as a starting point) to achieve good accuracy.

Anders Olsson

[Mike w/ 34th]

Bear in mind with any load using Triple 7, unlike black powder, Triple 7 does not like to be compressed.

[Swede68]

According to Hodgdon´s manual for Triple Seven, it can be lightly compressed (.100") but the best result is to just rest the bullet against the powder. Fillers should not be used. Reduced loads are therefore out of the question.

I´m aware that charges using Triple Seven should be reduced by 15% (volume) compared to blackpowder.

I also need to seat the bullet correctly in the case for optimum precision.

Whether all these factors are even possible to reconcile is the question. But as long as the range from 25 to 35 grains of Goex FFFg is correct, and as long as an 85% (measured by volume) load of Triple Seven FFFG in that 25-35 grain range gives me correct seating of the bullet, I´m home.

So, could anyone please tell me the total length of their Smith cartridges, or at least how far from the rifling you seat the bullet in the case, so I can start measuring and finding out whether Triple Seven is even apropriate for this?

Regards!
Anders Olsson

[Tom Magno, 9269V]

When I shot my original, my best groups were with 28 grains 3F, no filler, and a 360 grain RNFP pure lead bullet. The bullet seated on top of the powder, and it stuck out with the first grease groove (closest to the nose) just barely covered within the case. When loading the round into the Smith, I would push it completely into the breech, and when closing the action it would seat the bullet against the rifling. The accuracy was better than I could hold it. I tried harder bullets (50/50 lead/wheelweights) and did no better.
I tried lighter bullets (250gr) and heavier (425gr), still the 360grain bullet did the best overall.
If you are expecting MOA accuracy in the Smith, with 777 ( or even BP), you will be disappointed. NEVER shoot any smokeless powders in this gun.
I have clover-leafed several rounds in a target or two, but that is not the norm. You can expect the best accuracy with ideal conditions to be 2-3" groups at 50 yds, and 4-5" groups at 100 yds - and that's from a benched gun. Offhand expect the groups to be a bit larger.
But most of all have fun, it's the experimenting with different loads, projectiles, OAL lengths, etc that makes it fun.
Good luck.

[Swede68]

Thanks Tom!
Okey, bullet against the rifling it is then!
I started playing a bit with the cases and bullets yesterday, and I realize that while using Triple Seven (which should not be compressed much at all) I will probably not be able to pour in more than the volume equivalent of 25 grains Goex FFFG (or thereabout), perhaps even less. Since the Triple Seven is about 20% more powerful for the same volume, that would correspond with a 30 grain load.

In other words, as long as I´m not compressing the Triple Seven much, I should be able to find a good load without worrying about overpressure.

Best regards!
Anders Olsson

[Tom Magno, 9269V]

Also, it is important to know what the barrel groove-to-groove diameter is, and size your bullet .001-.002 over that. In my original, the grooves were .514, and I sized to .515. Originals can be as large as .519. If your bullet is too small, you may not get best accuracy. What size does the bullet drop from the mould, and what size is your barrel?
Tom

[Swede68]

The bullets I have bought (from Dixie) are .515"
I haven´t slugged the barrel yet. I´m aware of the importance of correctly sized bullets, but I have actually overlooked it here (partially because .515" bullets were all I could find anyway), so thanks for the headsup!

I got a mould also, and unless I´m mistaken, it too is for .515" bullets.

I will get to the bottom of it, first though I´ll slug a bullet and see what the bore groove diameter is.

Anders Olsson

[Swede68]

I´ve slugged the barrel and measured the bullets from Dixie. An exact measurement was hard to achieve, but I believe I´m close enough. The barrel was .514-.515". The bullet was .516-.517".

The barrel seemed to tighten towards the muzzle, which I suppose is a good thing.

With the bullet seated against the rifling, the amount of Hogdon 777 FFFG that it takes to fill the case is 27 grains (actual wheight of the 777), or 36 grains of FFG blackpowder.
With the 777 being lighter, and more powerful than the corresponding VOLUME of BP, I believe this 27 (actual wheight) grains of 777 is too much to start out with anyway.
If I have it right, 27 grains of 777 corresponds with 50 grains of FFG BP.
The way I reached this number is by assuming that the "correct" actual load wheight of 777 is roughly 55% of the actual wheight of FFG BP for the same pressure and muzzle velocity. I extrapolated this 55% figure from this thread: http://n-ssa.org/phpbb/viewtopic.php?t= ... hlight=777 (http://n-ssa.org/phpbb/viewtopic.php?t=7032&highlight=777)

I´m going to back down to 23grains (actual wheight) of 777, which should correspond with about 42grains of FFG blackpowder, and which should be a safe load without having to back the bullet too far into the case (777 should not be compressed, but the use of fillers of any kind is also a no-no).

Do you think this sounds about correct?

To be quite frank, I´m a bit surprised that Hogdon does not supply a chart for for loads measured in actual wheight when it comes to the 777. Seems like a pretty unsafe practice to measure by volume. When it comes to Pyrodex, I do understand why. Pyrodex wheighs less, but can be substituted by exact volume safely. 777 both wheighs less, AND is more powerful at the same volume. The only way to be completely safe when using 777 is to know exactly what (actual) wheight the 777 charge should be, OR to know the percentage of volume compared to a BP charge (for instance my 55% charge, if that is correct).

Anders Olsson

[Swede68]

Check my math please! :oops:

Hmm..., I went over my figures again, and I think I was a bit conservative before. On the other hand, it´s better to be conservative than the opposite when dealing with explosives and guns! :lol:

Okey, here´s what I´ve got. The volume equivalent of 36 grains of FFG blackpowder (which is what my case holds with the bullet to the rifling) is 27 grains (actual wheight) of FFFG 777.

36 grains of FFG BP should be a perfectly safe load for my Smith. To find the power/pressure equivalent of 777, I should reduce the volume by 15%. This is about 30,5 grains by volume.

Now, I know that the same volume of FFG BP and FFFG 777 wheighs 36 and 27 grains (actual wheight) respectively. That meens that FFFg 777 wheighs 75% of FFG BP.

75% of 30,5 is 22,8grains. Very close to the 23 grains I had in my previous calculation, but then I thought that corresponded with 42 grains of real blackpowder, not 36 grains.

In other words, since I´m not allowed to use any filler, and since there must be no air in the case, I could most likely up the actual wheight of FFFG 777 to the 27 grains I need for a full (non compressed) charge of 777 with the bullet to the rifling. This would correspond with a 42 grain BP charge.
I WILL start at 23 grains actual wheight though, and work my way up.

Does this seem correct from where you´re sitting?

Anders Olsson

[Swede68]

Today I´ve testshot the Smith.
I ended up using 25grains (actual wheight) of 777 FFFG. There were no signs whatsoever of excessive pressure, quite the opposite. After a quick wipedown, the plastic cases looked brand new.

Precision wasn´t great, but not too shabby either. I didn´t focus on maximum precision today, I focused on finding out point of impact, and checking that everything seemed okey. I shot from 50 yards standing without support, and the groups were around 3".
Point of impact was about 3" to the right and 7" high from 50yards. The high POI is no problem, and adjusting the sight for windage is easy enough.

Anyway, just wanted to let you know that I´m still alive, and that the gun is still in one piece. :lol:

Thanks for all your help on this matter!

Best regards!
Anders Olsson