Help! 45 70 cast

N

norland

CGN Regular
Rating - 100%
72   0   0
Location
oshawa ont.
Im shooting 300 gr cast" 459 with gas check using 19 gr. of trail boss. My problem is that the first 9 rounds are 4 inches apart left or right ,when around the 10 round I can 1moa the next 3 rounds what gives.I pushed 1 cast bullit down barrel not a lot of effort measured 459
 
Last edited:
norland said:
Im shooting 300 gr cast" 359" with gas check using 19 gr. of trail boss. My problem is that the first 9 rounds are 4 inches apart left or right ,when around the 10 round I can 1moa the next 3 rounds what gives.I pushed 1 cast bullit down barrel not a lot of effort measured 359" .
Click to expand...

Do you mean .459
are they your cast or purchased
undersized will play with what a target look like (groups)
lube will affect it as well (cold to warm barrel)
a warm barrel will also affect the way powder burns(or dirty barrel)
are you getting any leading ?
are you using a mic or a vernier to measure bullet?

pushed 1 cast bullit down barrel not a lot of effort = could mean undersized bullet try .460
or by the time you shoot 9 rounds barrel gets dirty
 
The Hodgdon data site lists a starting load of 14gr and a max load of 16.5gr for Trail boss and a 300gr bullet.
Trail boss can do some weird things when pressure goes too high so that may be causing it.
I know I used the IMR published method of load development for Trail boss (fill to bottom of bullet, subtract 20%, that's your starting load) with my 45-70 and 340gr cast bullets and they where all over the map. I think I was around 18gr but when I reduced it to 15gr they shoot fine.
 
Think sentences and punctuation.
No lube will cause 'em to key hole. You're just having an accuracy issue. You need to work up the load, not just pick one and hope.
 
Why are you trying to make trail boss work?
Why don't you use the powder that has been used very successfully and extensively in the 45-70 for over a hundred years? Unique.
And the man is right, lube will not cause the bullets to key hole.
 
You must log in or register to reply here.
Back
Top Bottom