Cylinder Throat Diameter

xcpd69 · #1 10-03-2009, 04:26 PM

After reading the thread on Taylor Throating and discussion about sizing of forcing cones on barrels and chamber mouths, on cylinders I got curious. I dug out my 696-2 and decided to check how tight the chamber throats were on the cylinder.

Uhhhh....Can you say TIGHT? As in taking a loaded cartridge and inserting the bullet into the front of the chamber, it only goes as far in as it would at the muzzle. The bullet, when fired, would be swedged, before jumping to the forcing cone.

Going back to the safe, I extracted my 1950 Target 44spl and my 29-2. I then tried the same test, inserting a cartridge in the front of the chamber. On these two, the bullet went in all the way to the casemouth on all chambers, but with little or no play.

To make a long story short, I'm wondering if my 696-2 did not get the final reaming on the chamber throats, or if this is a deliberate safety design to ensure clearance on that notoriously thin forcing cone. Maybe one of the updates making my gun a "dash2?"

Some expert want to chime in, or other 696 owners that have checked their guns.

diamonback68 · #2 10-03-2009, 04:33 PM

My 696-1 does the same thing.

500 Magnum Nut · #3 10-03-2009, 04:54 PM

All the new gun throats are tighter than the old guns. This is why they shoot better. You need to measure the throats will a plug gauge or holemic. I prefer the mics over plugs.

Gun 4 Fun · #4 10-03-2009, 05:14 PM

Both of the .44's that you mention should have throats that will mic out at .432"-.433", while all .44 bullets will run .429" -.430" for jacketed, and up to .431" for cast lead. Smith didn't tighten them until about late 1989.

They have even used undersized thoats on some of their guns made back in the early 1990's, such as the Magna Classic series. Those generally run around .428". How Smith got them to shoot so well with undersized throats is a bit of a mystery, but those were the most accuarate guns Smith has produced. Obviously, they were .44 magnums, and that round builds enough pressure to cause the bullet to slug back up once it hits the resistance of the rifling, making them fit snug in the bore after being swaged down by the undersized throats. I have an excellent article on PDF that I have sent to a lot of guys who are interested in the model 29, and its various changes over the years. In it, there is a small discussion about the undersized throats. I would be glad to send it to anyone who wants it. Just send me an e-mail asking for it.

diamonback68 · #5 10-03-2009, 06:36 PM

Quote:

Originally Posted by Gun 4 Fun

Smith didn't tighten them until about late 1989.

Exactly, but the 696-1 and -2 were not shipped until after 1998.

xcpd69 · #6 10-03-2009, 06:47 PM

Quote:

Originally Posted by diamonback68

Exactly, but the 696-1 and -2 were not shipped until after 1998.

I think he is referring to the 29-2 and 1950. Both of which have the larger throats and predate 89. The 696 series, being much later than 89, would have the newer spec smaller throats.

I may have confused things by listing three different guns.

Gun 4 Fun · #7 10-03-2009, 06:49 PM

Quote:

Originally Posted by xcpd69

I think he is referring to the 29-2 and 1950. Both of which have the larger throats and predate 89. The 696 series, being much later than 89, would have the newer spec smaller throats.

I may have confused things by listing three different guns.

Yes Dick, that is what I was referring to, the older guns dimensions. Maybe I should have been more clear, so I apologize if I confused anyone.