45-70 compression on BP?

[Babbott213]

I’m loading up some 500 grain Buffalo .459” round nose cast bullets from Buffalo Arms. Is .227” too much compression on 70 grains of Swiss 2F? I loaded up 70 grains by volume and placed a thin cardboard wad over the powder. I just want to be sure that isn’t too much compression on the BP load. I’m loading for my 1884 Springfield Trapdoor. The OAL is 2.850”. I loaded a dummy round and placed into the breech and closed the trapdoor and it set the OAL to 2.885” so I back it off just a tad. My Lyman Black Powder loading manual only shows a 60 grain load for a 500 grain bullet and a OAL of 2.835”. Thoughts on this? Should I back my grains off to 65 or 60? I’m hoping to reach out to 300 yards at least with this old girl, but I don’t want to over work her either. Thanks ahead for your input. I’m just checking everything twice or more before pulling the trigger.


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[Ozark mike]

I have compressed bp to the point that it took too much effort to seat and get a crimp to hold so id say you are golden but if ya want to go ahead and back er down for accuracy ya may have to to achieve the accuracy ya want

[Babbott213]

I have compressed bp to the point that it took too much effort to seat and get a crimp to hold so id say you are golden but if ya want to go ahead and back er down for accuracy ya may have to to achieve the accuracy ya want

Sounds good. Thanks for that input. Not sure why the Lyman’s book only shows 60 grains of 2F, since I know the original was 70 grains with a 500 grain bullet. I’m going to crimp these and I’ll probably do another 5 at say 65 grains and compare the groupings at 100 yards and then go from there.


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[Ozark mike]

Because when you seat a 500 @2.550 for yer favorite lever gun its mighty hard for ya to fit 70gr of powder under it unlike yer great grandaddys buff gun in which ya could seat a bit longer. Same applys to smokeless if it says x amount of powder with bullet seated to 2.8 ya better use caution with your lever gun because pressures will be higher

[Ozark mike]

Lyman shows less because the gun is ooold and may have had the snot beat out of it. I personally would try the 60 gr load just for the oldtimers sake her bones have seen her fair share

[Babbott213]

Because when you seat a 500 @2.550 for yer favorite lever gun its mighty hard for ya to fit 70gr of powder under it unlike yer great grandaddys buff gun in which ya could seat a bit longer. Same applys to smokeless if it says x amount of powder with bullet seated to 2.8 ya better use caution with your lever gun because pressures will be higher

Not a lever gun though. Springfield Trapdoor.


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[Ozark mike]

I was just using it as an example

[Babbott213]

Lyman shows less because the gun is ooold and may have had the snot beat out of it. I personally would try the 60 gr load just for the oldtimers sake her bones have seen her fair share

The book shows the shots were fired through a Universal Receiver with a 30” barrel with a 1-18” twist.


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[Babbott213]

I was just using it as an example

10-4!


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[Deadeye Bly]

I shoot a 535 grain bullet with 60 grains of 1 1/2 Swiss in my trapdoor and it works very well to 600 yards. Most Swiss black powder does not like a lot of compression whereas many lots of Goex respond well to compression. Let your rifle tell you what works best. You won't over work it with any black powder load.

[greenjoytj]

Hey Babbott213 did you compress the BP with a compression plug or the bullet?
I’m hoping it was with a compression plug.

[Babbott213]

I did some with a compression die and the rest I did with the bullet on top of a cardboard wad. What’s the results though with compressing with just the bullet? I use this compression die for my black powder blanks mostly.


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[greenjoytj]

I would be concerned about causing damage to the bullet by the application of the pressure required to compress such a large charge of BP.
Bullet nose damage or swelling the bullet shank to a larger diameter.
If these problems are not occurring then carry on as you’ been doing.

[Dapaki]

Black powder loses its fire front from grain to grain under heavy compression and will actually burn slower. Compression on the grains won't hurt anything as long as they don't start to fragment and crush.

[Babbott213]

I would be concerned about causing damage to the bullet by the application of the pressure required to compress such a large charge of BP.
Bullet nose damage or swelling the bullet shank to a larger diameter.
If these problems are not occurring then carry on as you’ been doing.

I didn’t notice anything unusual. My compression die is one I made from a universal decapping die. I use a wooden dowel that I have marked and I compress until I’m at or near that mark, then just a little more is added with the bullet for the final home position.


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[country gent]

Compression varies from different cases , weight of bullet and brand granulation of powder. I work up by BPCR loads in this manner. I start with my known componets ( cases wads primers lubes known to perform from past repeated experiences). I then prime some cases, Start with a powder charge that is no air space no compression and load 10 rounds. I then up the charge 2 grains and load another 10 the only things changing are powder charge and compression. I continue this in 10 shot groups to where what I feel is max compression has been reached. I then shoot chronographing and watching group sizes. On the chrono I watch these 3 things velocity, o want to be 1150-1250 fps. Standard Deviation this is a measure of the loads consistency. Extreme Spread this shows the actual highs and lows. What I have seen is as compression goes up velocity slowly increases, SD and ES numbers drop. This continues to a point then start to increase again then Ive been told shrink again in cycles. If the velocity is in range at the first spot I then test at the mod[point. I have found this in my testing Swiss in the coarser granulation ( 2 1 1/2 1) seems to like around 060 - .080 compression , Olde Enforde in the coarser granulation ( same as Swiss here) seems to like a little more compression in the .090 to .125 range, Goex seems to want alot of compression .160-.180
This has seemed to hold true in all I load 38-55 335 - 360 grn bullets. SD deviation of 2.3 for best load. 40-65 400-425 grn bullets. SD of 2.6. 45-70 with 500-550 grn bullets I have a SD of 3.6. 45-90 with 550 grn grease groove or paper patch the best loads are 3.0 SD. All are in the 1200 FPS and all perform excellent out to 500 yds. The rifles are High walls , rolling blocks, hepburns 1874 sharps cpa and a brochardt.
In closing the best thing to do is let the rifle and numbers tell you what it wants. THe other is I also see fouling drop down as you get closer to the ideal compression

[Big Mak]

I'll weigh in and say that my 1883-cartouched Trapdoor performs well with 62 grains of 1.5f (Old Enysford) dropped thru a drop tube, with a 500 gr pill, .030 veg was, compressed at .175 with compression die and about .050 with the seating of bullet (total compression roughly .225. The reason I let the bullet do some compression is to give me peace of mind that their is no air gap.

[greenjoytj]

I over compress the powder just a few thou to compensate for my cases not being perfectly length matched, they all are very close to the same length.
The few thou air gap I suspect expands back up to press on the bullet base through handling in the days or weeks between being loaded and fired as the cartridges are stored bullet down in cartridge boxes.

[country gent]

62 grns is the load for 2 of my 45 - 70s with both 500 and 550 grn bullets. This is with Olde Ensforde 1 1/2f powder also.

Here is my process for loading ( fired cases)
Soak in dawn lemi shine mix after firing. dry and clean
Hand deprime and dry
when dry hand seat primers and primer wad if needed
Drop powder charges weighed and dropped thru 3' drop tube with a slow pour.
Add thick wad into case mouth
Seat wad and compress charge to seating depth with compression die.
insert 2 tracing paper wads into case mouth and HAND SEAT bullet onto them.
Set neck tension by running into bushing die or short into seating die ;
You want light tension bullet wont fall out but can be pulled by hand or turned. On these single shots a crimp isnt needed and will at times adversely affect accuracy. My bullets are cast from 20-1 lead tin.
Usually raising the sizing die about .400 high is right to set tension