Thoughts on compressing BP.

oldrodder

oldrodder

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I'm in the process of working up a load for my 40-65 using Goex FFg. A full case of this powder weighs 63 grs. I'm using a 400 gr Snover bullet that must be seated to the first driving band in order for the round to chamber in my rifle, a Uberti 1885. I've decided to use 55 grs of Goex FFg, dropped thru a 24" drop tube and a milk carton wad that leaves .230" of space in the case. The Snover needs .655" of space, calling for .425" of compression. I'm using fired & unsized Starline brass. The bullet is finger seated and a small amount of neck tension is applied with the sizing die (de-priming stem removed)
Is this much compression considered excessive?
 
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First question - are you using a drop tube to dispense powder to your case? That's the first step in reducing powder volume, prior to compression in loading.
 
This is just a personal observation from loading BP in muzzle loaders and carried over to cartridges.

I actually made up a brass tamping/ram rod for my muzzle loader so that I could compress the powder charge more.

My reason for this was a more consistent burn rate. Velocities didn't increase but they didn't vary as much from shot to shot.

The first BP cartridge rifle I used was a an original Sharps, that someone else wanted more than I did and paid accordingly.

The first cases I loaded had barely compressed charges. Accuracy suffered accordingly.

An old mentor asked me what I did with the muzzle loader to get consistent burn rates.

The light finally came on.

BP likes to be compressed, as much as you can get away with.

Before the switch from BP to Smokeless powder, cartridges like the 8mm Lebel/8mm Krop/ 303 Brit actually used a compressed pellet of powder in a straight case, which was formed ''after'' the powder pellet was put into the case, then the bullet was inserted to compress it further and the case neck was heavily stab crimped to keep it in place.

I have hand loaded 8mm Lebel/8mm Krop and 303 Brit with BP, to suit the older rifles I have on hand that were transitional at the time of their build.

I have never been able to duplicate the stated velocities of the issue ammo from pre 1900, loaded with Black Powder.

I have actually shot some of that old issue ammo, loaded with BP, and the stated velocities are very close.

I have a Swede built 50-70 that I use a 36 inch drop tube for and IMHO, that isn't enough compression. I press down the bullet and crimp heavily.

It's a single shot, so the crimp really isn't necessary for anything, other than to stop the bullet from being pushed forward by the compressed charge.

These are just my observations. I'm sure others have their own observations.

One of the fellows from the old Monashee Mountain Men Club used to be so anal about consistent compression that he had a ram rod with a leather stop glued onto it, for the specific powder charge/ball he used for his rifle.

He didn't compress as much as I did but he didn't shoot any better than I did either.

He shot a lot though, under extreme conditions and knew his stuff.

I tried his rifle out a few times, with his loading system. I couldn't shoot it any better than he could.

I even went so far as to use my heavy brass ram rod to compress his charge more, there wasn't any difference.

The one thing that did help, was to use a thicker patch, made from Linen, measuring .016 in. His patches measured .012. This isn't relavent to your cartridges, but I thought I would just throw it in.
 
Bearhunter,
I've read most books by Paul Mathews on the subject of BPCR reloading and he states that while compression is needed, it should be kept around .90 to .100"
if one compresses heavily, one crushes the powder granules and you end up with a mix f 1Fg, 2Fg, 3Fg, instead of the original granulation one started with.
I was looking for other shooter's insights and experiences.
Your comments are much appreciated!
 
I use a compression die for all my loads. Each powder will like a different amount of compression, for example; Goex likes lots of compression, Swiss likes a small amount. My loads range from 70-80 grains of FFG in my 45-70 for example, which can be up to 0.25" of compression. That is a lot of compression already, I can't imagine 0.4" or more. 40-65 is a tough cartridge to balance powder charge v. bullet weight.

I would suggest a 36" drop tube to get that last bit of natural compression. Using your current wad is fine. If you're set on that bullet weight, possibly consider a PP bullet, which will allow you to seat into the bore. My lube groove bullets I generally seat such that the first band is about 0.015" off the beginning of the lands. My PP bullets are into the bore, which allows a heavy powder charge. If you wipe between shots (equally historically accurate as a blow tube) you don't have to worry about lube.

Unfortunately with BPCR, it's a lot more playing with factors that are generally overlooked with smokeless loading.
 
Sharps45-70 said:
I use a compression die for all my loads. Each powder will like a different amount of compression, for example; Goex likes lots of compression, Swiss likes a small amount. My loads range from 70-80 grains of FFG in my 45-70 for example, which can be up to 0.25" of compression. That is a lot of compression already, I can't imagine 0.4" or more. 40-65 is a tough cartridge to balance powder charge v. bullet weight.

I would suggest a 36" drop tube to get that last bit of natural compression. Using your current wad is fine. If you're set on that bullet weight, possibly consider a PP bullet, which will allow you to seat into the bore. My lube groove bullets I generally seat such that the first band is about 0.015" off the beginning of the lands. My PP bullets are into the bore, which allows a heavy powder charge. If you wipe between shots (equally historically accurate as a blow tube) you don't have to worry about lube.

Unfortunately with BPCR, it's a lot more playing with factors that are generally overlooked with smokeless loading.
Click to expand...

I don't have a PP mold for the 40-65
I shoot PP in 30-30, 38-55, 9.3X74R, 45-70 & 45-90. All are heavy-for-caliber bullets. Iron Cat did send me a few PP bullets (400 grs) to try but I had limited success with them. I have 3 molds for the .40 cal., 2 are 400 grs (Snover & NOE) and 1 is 385 gr. (Lyman) The rifle shoots the heavies well. I've attached a target.
Un8j72Ql.jpg


I'm working towards 1.5 - 2" group. I've always had more success with greasers than PP. I have compression dies in 38, 40 & 45 cals.
 
My advice is try it and see. I have found that compression is often a good thing. I even compress Swiss, contrary to what most people do. I've placed quite well in the American matches and even set a 1000 yard record using Swiss with compression. With that said I don't think I've ever gone much beyond 0.3". Most of my loads are compressed 0.250" - 0.275" or so.

Chris.
 
a number of years ago, I thought that like scotch whiskey, if a little compression is good then a lot is better. I can't remember what cartridge but 32-40, 38-56 are the most probable. Anyway, the gun shot a lot lower at 100 yards and I think it is because I compressed the 3F into Colonel Hawker's Punting Powder. I have always used a roughly 30" drop tube and now compress the powder only a little after dropping through the tube and that seems to work best. I suspect the coarser powders can be compressed more because by being coarse they are less likely to compact into miniature bricks

cheers mooncoon
 
In my Shiloh 40-65 I drop tube 53gr 2F Old Eynesford 24", top with a .060" vegie wad and compress .225". Hand seat the 410 gr bullet, cartridge is neck sized to get rid of the bell. I seat to the lands. Very accurate load. As each rifle is different you will have to see what works well in your. Have you done a ladder test yet?
 
1N7JOKDl.jpg


In order to determine the available powder space, I made up this dummy round. The bullet is a 400 gr Snover. The slit in the case allows me to start the bullet in the case by hand and complete the seating to the lands by pushing the dummy into the chamber until I can close the action, arriving at maximum C.O.A.L. The heavy black mark on the case is the seating depth & the light mark above it indicates the height of the powder column & milk carton wad with no compression. I will try a longer drop tube.
 
I have experimented alot with black powder compression and various wad materials and wad columns in both 45-70 and 50-70. I switched from using FFg to using FFFg which helped with case volume. The FFFg burns cleaner and has also given me tighter groups at 100 yds. You will find that Goex in particular "likes" to be compressed more than other powders or substitutes. In 45-70, I'm using Starline brass with a magnum rifle primer, 70 grains of Goex FFFg loaded thru a 24" drop tube, compressed 0.320" with a compression die, then topped with a 0.060" veggie wad and a 0.020" card wad. Bullet is a 430 grain NOE bullet sized 0.4605" and lubed with SPG. Superb accuracy ��.
 
gunlaker said:
My advice is try it and see. I have found that compression is often a good thing. I even compress Swiss, contrary to what most people do. I've placed quite well in the American matches and even set a 1000 yard record using Swiss with compression. With that said I don't think I've ever gone much beyond 0.3". Most of my loads are compressed 0.250" - 0.275" or so.

Chris.
Click to expand...

Today, I took Gunlaker's advice and tried it! I fired maybe 40 rounds total: 20 loaded with 55 grs of Olde Eynsford 1 1/2Fg and 20 loaded with 55 grs of Goex FFg. Loading protocol was this: Starline fired, unsized cases. Win LP Magnum primers, Newspaper wad against the primer, powder charge was dropped thru a 24" drop tube, milk carton wad over the powder charge. Compressed .440" with a compression die. Lastly, a 400 gr Snover bullet (1-20 alloy) sized .410" was hand seated in the case & neck tension was achieved with the sizing die (de-capping stem removed) Here are a few targets:

40lHW9Al.jpg

kC4td92l.jpg


I suppose I could reduce the amount of compression by reducing the powder charge or possibly switching to Goex FFFg.
Comments are invited and appreciated!
 
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