45/70 throater coming. Need some advice

[Badge54]

I am waiting for it to arrive.  Now what


For those of you that have done the Modification,  How deep do I cut it?  How did you measure it? 
Once you throat it did you stick with one bullet or find that it still performs with the lighter ones?


Any thing you can think of to help, please.

Badge54

[AtlLaw]

I throated my 45-70 and 45-120 to the depth Tim suggested.  He also said how he measured the depth. Seems to work fine in both rifles.     'course I have no memory of what that depth was...     I think I marked the depth on the throater though. 
 
But I'm sure Tim remembers!     He's much younger and still sharper then I am...   
 
.24 Tim?   

[Jimbo47]

The reason I rented the throater was because mine had a shallow throat and I couldn't seat the 405 grain Remington jacketed bullet on the cannelure without digging into the lands.
 
It shot great though even setting my COL a little deeper, and not seating on the cannelure, but I still wanted to be able to reach the factory COL for that bullet without a problem.
 
I took an empty piece of brass and using a dremmel I cut a slit about a half inch long lengthwise on the side of the casing, which allowed me to insert a bullet and line it up at the cannelure.   I then placed the dummy cartridge into the chamber and closed the action, and when the bullet touched the lands it pushed the bullet back into the case, which I then measured to see how far it pushed back, and and then I just added about another .002 to that measurement which gave me the depth that I needed to stop at.
 
Take it slow and measure as you go.    I could have gone a lot deeper and probably wouldn't have made any difference, but I didn't want a long jump to the lands, and I'm not going to be using any bigger bullets than the 405 grain Remingtons.
 
That's the way I did it, and hopefully someone will come along and tell you the proper way to do it though!   Good luck!

[quickdtoo]

I am waiting for it to arrive.  Now what


For those of you that have done the Modification,  How deep do I cut it?  How did you measure it? 
Once you throat it did you stick with one bullet or find that it still performs with the lighter ones?


Any thing you can think of to help, please.

Badge54

What Richard said, about .250" on mine, both of your questions are addressed in the FAQs and Help sticky, see Throating the 45-70 and Simple COL gauge.  I lost about 50-75fps on the 300gr bullets, 2425fps Nosler Partition loads dropped to 2350fps in the 22" barrel, but that was loaded to 2.55", the velocity can be gained back with a bit more powder since the bullet can be seated shallower making it a 457 WWG Magnum.

Tim

http://www.gboreloaded.com/forums/index.php/topic,100524.msg1098265499.html#msg1098265499

http://www.gboreloaded.com/forums/index.php/topic,112672.msg1098350243.html#msg1098350243

[Badge54]

Done!  Now my only question is, did I do it right?


At least I can now chamber the 350 Hot-Cor with it crimped at the cannelure.  Probably a little long for it now.  Yet I have a 400 lead bullet that smashed into the lands before and now has just enough room to be set to the COL. 


I guess I will know how bad it went when I go to the range.


It was really easy... I guess that is the basis for my apprehension.


Badge54

[Jimbo47]

Do you remember that song, "don't worry, be happy?"
 
It's going to shoot just like it did before, and it may even shoot better, so just shoot it and.....Don't worry, be happy!

[Badge54]

thinking out loud here...  What if I stick a bullet in backwards, flat forward and seat it.  Then measure the overall chamber.  Would that help?  It seems that reaming the throat is for a specific bullet.  I would feel more comfrotabel if I knew exactly how deep to cut it.


I used the slit case and a 350 Hot-Cor bullet.  Then chambered and found mine is at... 2.36


I then used a lead bullet and a heavy crimped case that was seated long.  After cambering it I measured where it started to shave lead off the bullet at  2.25. The diameter at the shaved lead is .458.


(edit to remove a Faux paux.)


Tim, if you had time would you try it?


Badge54


Edited to add specs

[Badge54]

It's going to shoot just like it did before, and it may even shoot better, so just shoot it and.....Don't worry, be happy!

I couldn't get anything better than 4 inches at 100 and had to seat them up past of the cannelure to get them to chamber.  I now am itching to go to the range.  Maybe Monday.


Badge54

[quickdtoo]

Depends on the bullets you're considering, there's a big difference in the ogive shape and diameter even in like weight bullets.

Tim

[Badge54]

I  understand the different Ogive shapes... I was thinking if using the base of the bullet if it would stop at the throat and give a more accurate measurement to where the lands start.


That way a person could ream to more of a general length than one specific to a bullet design.  We all understand the chambers are "cut short."  What length is "cut right?" and whats "too long?"  It can't be bullet specific.  The manufactures have to have a standard length.  I have searched for Sami specs, Chamber specs... 


I am more of the follow directions to a "T" than experiment and see what happens.


Badge54

[quickdtoo]

Not really because seating a bullet straight would be near impossible because there's no ogive for the seater plug to align the bullet, any measurement taken on a bullet seated with yaw would be inaccurate.

Tim

[Flashole]

Hey Tim
Are you talking about the 500gr partition.  WOW that is 458 Win Mag strong.   I think I just figured out my next purchase.  I don't need that kind of brute force but it sure would be fun to touch a couple off now and then.  Let me  get back to some of the discount websites and see what I can find.
 
 
=FLASH=

[quickdtoo]

Hey Tim
Are you talking about the 500gr partition.  WOW that is 458 Win Mag strong.   I think I just figured out my next purchase.  I don't need that kind of brute force but it sure would be fun to touch a couple off now and then.  Let me  get back to some of the discount websites and see what I can find.
 
 
=FLASH=

The only partition I've mentioned is the 300gr, not 500gr, maybe ya need to put on your readin glasses! 

Tim

[Flashole]

No Tim
 
I just looked at the Nosler website the only thing I saw listed in Partition was a 500 in .458 and assumed that was the one.  Looked at two suppliers and saw only a 500.  If they dropped one from the line than I missunderstood the post.  I still have a few boxes of a 44 cal Partition that is no longer available.  So when I looked up  .458 Partition and only saw 500,  a simple mistake.  Never saw a 300 Partition and never knew there was one produced.
 
=FLASH=

[quickdtoo]

The 300gr NP was discontinued a couple years ago, much to the disappointment of many, supposedly it's to be offered in limited runs sometimes tho.  It was replaced by the 300gr BT which is no longer lister either.  Fortunately I have about 100 of each just in case.

Tim

http://www.marlinowners.com/forum/45-70-govt/47292-nosler-458-cal-300-gr-pp-partition.html