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Very Hot Topic (More than 25 Replies) What is the optimal throat design for BS'ing (Read 12128 times)
frnkeore
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Re: What is the optimal throat design for BS'ing
Reply #45 - Mar 13th, 2018 at 3:25pm
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These two drawings, may be of help in describing throats.

The first one is very simple and is the throating type, that the 32/40 uses.

aB is the throat angle, per side and not included. Most reamer maker use "per Side".

A - C, is the total of the throat and goes through the lands.

2. The next one, is normally what the chamber of a freebore throat looks like.

A, is the neck

aB, in this case is the transition of the case neck to the freebore. It may or may not, be considered part of the "throat".

C, is the start of the freebore and almost aways groove diameter or larger.

D, is the end of the freebore, usually inline with C (straight), but sometimes may have a little taper to D.

bB, is the lead angle, again, per side and goes all the way through the lands. The only exception to that, that I know of, is the 303 Brit, that has a double angled lead.

3. Third is the type that the 30/40 Krag and 30/06 have. Generally, on this type, the lead begins at something larger than the groove diameter.

There are other types but, these are the ones that we deal with, the most.

Frank
« Last Edit: Mar 15th, 2018 at 12:32pm by frnkeore »  

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JLouis
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Re: What is the optimal throat design for BS'ing
Reply #46 - Mar 13th, 2018 at 7:38pm
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Frank's second drawing shows a transition angle at the end of the case into the freebore and another transition angle into the start of the leade and then the leade angle it's self. My reamers have a transition angle at the end of the case into the freebore and then the leade in angle starts at the end of the freebore. 

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Jeff_Schultz
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Re: What is the optimal throat design for BS'ing
Reply #47 - Mar 14th, 2018 at 4:14pm
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  BS'ing back! Smiley
  

"We have met the enemy and he is us." Pogo

“There is no situation so bad that it cannot be made worse."

  Confidence- The feeling you get before you fully understand the situation.
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Schuetzenmiester
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Re: What is the optimal throat design for BS'ing
Reply #48 - Mar 14th, 2018 at 6:53pm
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Drawing "B" would be the traditional BS throat. All rifles would have been that way when the first BRer switched from ML  Roll Eyes
  

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corerftech
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Re: What is the optimal throat design for BS'ing
Reply #49 - Mar 14th, 2018 at 9:51pm
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Frank that B picture Ive never seen before. Thats what I have been hoping would make its way to my eyes (relative to A which is what I have memorized for a form). That also verifies both schuetzendaves PM to me and also the need for tapered bullet. (at least with that specific chamber). Very clear now.

Many thanks.
  
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frnkeore
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Re: What is the optimal throat design for BS'ing
Reply #50 - Mar 15th, 2018 at 12:00am
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JL, that angle connects to the end of the freebore. Drawings are made like that for clarity. The basic drawing, was copied from SAMMI, I added the terms.

I added a third basic throat to the other two. This is the throating that came after the 32/40 type throat.

corerftech,
I don't know who designed the type throat that has a freebore and then a lead but, I think the first to use it was Remington in their 222 Remington chamber.

I must correct myself, after I wrote the above, I realized that the 300 Savage had that type of throating, long before the 222. The reason for theirs, was to be able to shoot heavier bullets in the short neck of that case.

Frank
« Last Edit: Mar 15th, 2018 at 12:23pm by frnkeore »  

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