Swiss compression

[jednorris]

I just bought a .40/65 Shiloh Sharps Rifle and I have had some surprises loading for it. I shoot a R.C.B.S #40-400 CS 400 gr. bullet and they are very long and tapered. To have the bullet just off the lands and grooves the O.A.L. of the round does not leave much room for powder. 42 gr. of FFG Swiss just touch's the bottom of the bullet WITHOUT compression. I have been told Swiss does not like very much compression and need advice of how much I should compress the charge.

[Ozark mike]

Up to 1/4inch

[country gent]

I load and shoot a 400 grn Nasa bullet and the 400 grn lyman postell in 40 - 65. I have used swiss, Olde Ensforde and Goex all with good results. Mine is a cpa silhouette model 30" 1-16 barrel. Im a little heavier than your 42 grn charge. I have found Swiss to work around .060 -.090 compression Olde Ensforde in the .100 - .140 rang and goex to like up to .200.
What I do and recommend is to start at no compression no airspace, and work up in 2 grn increments choreographing as you go. Watch group sizes as you go. Also watch the extreme spread, SD and velocity. Shoot for around 1150-1200 fps velocity. Also watch fouling as you go. When you find the best 2 loads in line ( 57 grn and 59 grn) test at the mid point ( here 57.5 grns)

I started with 2f and went to 1 1/2 f olde ensforde. In my rifle olde ensforde does as well as the swiss.

[Lead pot]

CG the correct name for that powder is Olde Eynsford.......

[rfd]

there are lotsa stories about compression for different bp brands and granulations. i've used more than a few bp brands/grans and long ago have settled on swiss for all my bp needs, both breech and muzzle long guns. to the point about compression - it's whatever the load likes best though i mostly find that light is the ticket with bp ppb cartridges for me and .45-70 (83 grains) or .40-65 (72 grains) of swiss 1-1/2f. ymmv.

[jednorris]

I have compressed 45 gr. of Swiss FFG .150" with a 400 gr. bullet in my .40/65 Shiloh Sharps and cannot get any more in there. My other .40/65 (Browning) has the bullet set out further and I can get 55.0 Gr. Does the Shiloh have that much shorter throat ?. I am beginning to think my only other option is to buy a $180.00 mold that has the front bands reduced.

[Chill Wills]

I think it is the bullet design causing this. All body and short nose. I know the bullet design you are using. It takes up powder capacity, but that does not sound right. I would think you might get another 7 to 10 grains under it with no compression. Some of the 2014 -2016 date code Swiss powder is not very dense and if you are using some of that .... well. Put some more powder in the case and work up (compress as needed) until you like what you see on paper.
That bullet should shoot well in that rifle but it may be that you will never get 60 or more grains in it like some other bullet designs can be loaded.

And, yes, a reduced band bullet will allow a lot more powder. Just choices you have to make.

Good luck and have fun.

[Ozark mike]

I think it is the bullet design causing this. All body and short nose. I know the bullet design you are using. It takes up powder capacity, but that does not sound right. I would think you might get another 7 to 10 grains under it with no compression. Some of the 2014 -2016 date code Swiss powder is not very dense and if you are using some of that .... well. Put some more powder in the case and work up (compress as needed) until you like what you see on paper.
That bullet should shoot well in that rifle but it may be that you will never get 60 or more grains in it like some other bullet designs can be loaded.

And, yes, a reduced band bullet will allow a lot more powder. Just choices you have to make.

Good luck and have fun.

This is a good point a rb will seat further than a pb

[beltfed]

Setting up a nose sizing die, say for example a 0.401 for the 40s
works. Size the bullet nose first to reduce however many drive
bands on those long bodied bullets. Make up or buy a flat "nose" punch
to push with. NOE has them.
I got good accuracy from my 40-65 with the Lyman 410663 with top three bands
sized to 0.401. Could get "lots more" powder in that way.

beltfed/arnie

[yulzari]

Could someone explain why compression is a good thing? I can understand squeezing more powder into a small case but the the big user, the military in the day, did not compress their powder. In muzzle loading they went to a lot of trouble to avoid it as far as possible, even making rammers that bottomed out on the muzzle just short of the ball reaching the powder to avoid the powder grains being bruised.

In my Martini Henry with the full 85 grain service load it is loose in the case with the space left empty. No this is not a problem despite internet lore, but that is another subject and not the OP.

[Chill Wills]

I sure can't explain it. I have always had the best accuracy in the range of about 95% to 105% capacity. I avoid heavy compression.
I know that heavy compression can produce accurate BP loads as well. National match records (accuracy) have been produced both ways.

Yes - as you say " In my Martini Henry with the full 85 grain service load it is loose in the case with the space left empty. No this is not a problem despite internet lore" The nineteenth century arsenals and civilian factory's produced it by the bazillions. But I have no intention of litigating the subject past agreeing with your point.

[Don McDowell]

Compression in a muzzle loader can plug flash holes and cause erratic ignition problems. Couple that with if you need more velocity in a muzzle loader you simply just add more powder.
You can do that in principle to a cartridge gun, but the cartridge case limits just how much extra powder you can add.

[Gunlaker]

The idea that you can't compress Swiss and get good results is one of those internet myths that keeps perpetuating itself. I've had excellent results using Swiss in amounts from zero to as much as 0.3" compression. I don't like the 0.3" compression much though as it's about as far as you can go with annealed cases and not risk bulging them.

Don't worry about compression as an important variable by itself. Start with zero and keep working up. You will find a load that shoots well and has good velocity statistics somewhere along the way. That is all you really need to worry about.

Chris.

[MT Chambers]

Even just the sound is better and sounds more powerful when using a compressed load. When you take apart an old factory (Gov.) BP cartridge, the powder is a solid "plug" from compression.