The Firing Line Forums

Go Back   The Firing Line Forums > The Skunkworks > Handloading, Reloading, and Bullet Casting

Reply
 
Thread Tools Search this Thread
Old March 12, 2009, 01:45 PM   #1
Barnacle Brad
Senior Member
 
Join Date: March 12, 2009
Location: Greybull, Wyoming
Posts: 410
Advise for BP Sub (777) Volume Measure

Springfield 45-70 Trapdoor Cartridge.

I am new at reloading BP Subs and did a test to find how full a case is when using a drop tube versus straight from the powder measure (RCBS). The result is that the case containing the charge from the drop tube is maybe .25 lower in the case than the other (to be expected).

My question is about compression. For the 60gr charge specified in the Hodgdon manual a compression of .100 is noted. So when does powder compression begin for unsettled powder thrown from a powder measure? Is it when the bullet/wad touches the powder, or when it reaches the level of the settled powder as from the drop tube?

On another note, what is the best primer to use for the triple seven/45-70 trapdoor?

So many questions - so little time...
__________________
Brad
Barnacle Brad is offline  
Old March 12, 2009, 02:36 PM   #2
darkgael
Senior Member
 
Join Date: February 9, 2006
Location: Homes in Brooklyn, NY and in Pennsylvania.
Posts: 5,418
BP/compression/777

Hodgdon tells us that 777 should not be compressed to the same extent as either BP or Pyrodex. Because compression, in any case, is so small, comparatively, when I used 777 I did not bother with compression.
You may get other answers about compressing BP and Pyrodex but here's mine: I use a drop tube to load the case and then, when seating the bullet add an additional bit - just a crunch.
I use your basic Win or CCI LR primer but a magnum primer might work better with 777.
Pete
__________________
“Auto racing, bull fighting, and mountain climbing are the only real sports ... all others are games.” Ernest Hemingway ...
NRA Life Member
darkgael is offline  
Old March 12, 2009, 02:48 PM   #3
Barnacle Brad
Senior Member
 
Join Date: March 12, 2009
Location: Greybull, Wyoming
Posts: 410
BP/compression/777

I am concerned about increasing the chamber pressure, by getting too much compression. I can calculate how much compression I get if I know how full the case is. Trouble is, measuring the distance from the powder to the top of the case is difficult. And this goes back to my original question - the settling issue.

I guess I just shouldn't be overly concerned, but it is hard not to be!

Thanks for your help!
__________________
Brad
Barnacle Brad is offline  
Old March 13, 2009, 05:25 PM   #4
Barnacle Brad
Senior Member
 
Join Date: March 12, 2009
Location: Greybull, Wyoming
Posts: 410
One final word on the subject. I re-read the 777 information on the Hodgdon website and they say that minimal compression is recommended up to .100. So going forward, my technique will be to use a bullet with a dia smaller than the case so that I can get a better idea where the bullet will seat and adjust the volume of powder accordingly.

As long as I don't exceed the 60gr charge, it should be a winner...
__________________
Brad
Barnacle Brad is offline  
Reply

Tags
777 , charge , compression , trapdoor

Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump


All times are GMT -5. The time now is 02:55 PM.


Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2022, vBulletin Solutions, Inc.
This site and contents, including all posts, Copyright © 1998-2021 S.W.A.T. Magazine
Copyright Complaints: Please direct DMCA Takedown Notices to the registered agent: thefiringline.com
Page generated in 0.03010 seconds with 8 queries