Throating ????

[fknipfer]

How can I tell if a rifle (BC 45-70) has been throated?  I have three 45-70 rounds with a COAL,  a PMC  350gr that measures 2.535, a Remington 405gr  that measures 2.550 and my buddies Handload 535gr lead that measures 2.825.  They all go into chamber and the BC closes no problem.  I measured the length of the chamber from where the bullet would go into chamber to the face of the receiver it measures 2.180 as close as I could get it.  The cartridgre drawings say that should be 2.179 so it is within tolerance length wise.  The nose of the 535gr bullet measures .448 it would appear to me that there isn't a problem for shooting 535gr's but I don't know.  Before I go and load some 535gr's and practice for buffalo I would like some comments from you guys.

Thanks ahead
fknipfer

[quickdtoo]

Smoke or lipstick the the ogive of the loaded round, then chamber it, if there are no marks on the bullet after removing the round from the chamber, you should be good to go, if there are marks from the lands, pressures may be higher than you like and you'd want to load a bit shorter.

Tim

[Ireload2]

If a 45-70 has been throated you can easily see it.
A standard SAAMI 45-70 chamber has a very short leade from the case mouth to the full height of the rifling. Maybe only .050 long. There will be no extended smooth bore diameter ahead of the case.
A throated chamber will have a smooth bore or long taper just ahead of the case for as long as 3/4" but usually less.
It is unlikley that your rifle has been throated not does it need to be for that bullet. The original 45-70 bullet weighed 500 grains.
Many 45-70s have bore diameter larger than .450 and may not shoot well with a long nose bullet that is undersize for the bore.
Some of the old Lyman mold for the 500 grain government bullet cast a bullet only .440 dia on the nose. They never shot well in my rifle.
You can check with the BPCR guys too.

[Mac11700]

Many 45-70s have bore diameter larger than .450 and may not shoot well with a long nose bullet that is undersize for the bore.

I haven't heard of too many Handi's or  BC's that has an undersized bore on them...Now the Target 38-55...well that's a different story...

Mac

[Ireload2]

Many 45-70s have bore diameter larger than .450 and may not shoot well with a long nose bullet that is undersize for the bore.

I haven't heard of too many Handi's or  BC's that has an undersized bore on them...Now the Target 38-55...well that's a different story...

Mac

Bore diameter is the hole drilled before it is rifled.  A bore larger than .450 would be oversize.  I have not checked my 45-70 BC yet but from looking at the shallow groove depth I would bet the bore is larger than .450.

[fknipfer]

I think I answered my question by taking a look at the front of the bullet.  It is a round nose bullet and I can see a small indentation or circle on the front of the bullet where it is just beginning to touch the lands.  If I back it off .010 or .015 thousands it would be perfect.  So I don't think it has be throated.   If I can shoot a 500gr round nose with the COAL of 2.815 I think I can live with that.

Thanks again the info on the orginal 500gr bullet was very helpful.


fknipfer

[Ireload2]

fknipfer,

Here are links to two of the premium mold makers on the planet. So far as I know all of their 45 caliber grease groove bullets will work work in any standard SINGLE SHOT 45-70 barrel as long as the rate of twist is fast enough.

http://www.pauljonesmoulds.com/45_caliber.htm

http://www.brooksmoulds.com/bullets.html