chamber throat diameter

Always been a little fuzzy on this. What is the ideal chamber throat diameter in relation to bullet diameter?

Bob

I believe most would recommend between .0005 and .001 greater than bullet diameter for cast bullets. This is generally what is spec'd by SAAMI for most cartridges. Matters less for jacketed bullets since they do not need to completely obturate to work well.

My 'smith who loves to experiment and play with such things has a basic rule.

Ball leads (chamber throat) +.002" --> Bullet 0.00" --> -.002" "Two over/two under"

Thanks for reply.
Bob

I take a cast bullets of known sizes. Drop into the cylinder. The size that sticks and won't go completely through is the one I use. No leading! 8)
gramps

gramps said:

I take a cast bullets of known sizes. Drop into the cylinder. The size that sticks and won't go completely through is the one I use. No leading! 8)
gramps

Click to expand...

+1 .... been doing that for over 40 yrs with no lead problems and I shoot over 1000 rds of cast bullet a month on the avg for the last 30 yrs .

One should also be concerned with the throat diameter relative to the groove diameter of the barrel as well as the diameter of the bullet.

I had four 44-40 and 2 of them I sent back to Ruger and they replaced the barrels and cylinder to made them shoot . Read this file below will show you the problem with Ruger's 44-40 on chamber throats .

http://singleactions.com/files/4440Vaqueros.pdf

If you get it right

Of course you bullet to throat numbers don't mean all that much if your throat to barrel numbers are out of whack.

Often there are uneven sizes in one cylinder. Check all of them and see how even they are before deciding on what does or does not need to be done.

Dan in MI said:

My 'smith who loves to experiment and play with such things has a basic rule.

Ball leads (chamber throat) +.002" --> Bullet 0.00" --> -.002" "Two over/two under"

Click to expand...

Can you interpret this to english?

Snyd said:

Dan in MI said:

My 'smith who loves to experimment and play with such things has a basic rule.

Ball leads (chamber throat) +.002" --> Bullet 0.00" --> -.002" "Two over/two under"

Click to expand...

Can you interpret this to english?

Click to expand...

The throats are .002" greater than the bullet, and the bore is .002" less than the bullet?

frankenfab said:

Snyd said:

Dan in MI said:

My 'smith who loves to experimment and play with such things has a basic rule.

Ball leads (chamber throat) +.002" --> Bullet 0.00" --> -.002" "Two over/two under"

Click to expand...

Can you interpret this to english?

Click to expand...

The throats are .002" greater than the bullet, and the bore is .002" less than the bullet?

Click to expand...

^yup

I did notice after I posted that I missed naming the barrel.

Ball leads (chamber throat) +.002" --> Bullet 0.00" --> barrel -.002"

Example -> .431 ball leads, .429 bullet, .427 bore

Got it. Never heard it put that way before and have never hear the term "ball leads".

Snyd said:

Got it. Never heard it put that way before and have never hear the term "ball leads".

Click to expand...

New to me as well.

I would guess it is an old cap and ball term as my smith works on anything and everything and always has. He is somewhat of a firearms historian too.