Forcing cone question

I recently had my S&W model 14 tuned up and the gunsmith reamed a 5° angle in the forcing cone. I've seen there are 11° and 18° reamers as well. What's the difference (besides 6&13°, ha!)? Are the steeper angles for hotter loads? or .357's? I would imagine the wider angle would let more of the explosion gasses vent... maybe even more bullet wiggle at the jump from cylinder to breech?

Thanks.

Kevin

Forcing cone answer!

Well, necessity being the mother... and all that, I found the answer to my question about the forcing cone degree of chamfer. No wonder no one responded, it's a fair long treatise in Brownells instructions for the tool... but it did get a number of looks, so there's a bit of curiosity. At any rate, here's the link to the pdf on the Brownells website;

http://www.brownells.com/aspx/NS/GunTech/Instructions.aspx?p=26157&t=2&i=413

Here's the short version copy/pasted from the pdf;

The Chamfering Cutter (“D”, Fig. 1) is threaded onto the Extension
Rod after the appropriate Brass Pilot is in place. Three Chamfering Cutters
are provided: an 18° Cutter for 9mm to .41 caliber barrels; an 18° Cutter
for .44 caliber to .45 caliber barrels; an 11° Cutter covering all calibers from
9mm to .45. Also available is a 5° Cutter for .38/.357 which duplicates the
Ruger factory chamfer for these calibers. The 18° chamfer has been used
quite often by firearms manufacturers, and in most instances, will provide
a slight accuracy advantage when shooting jacketed bullets. The 11° Cutter
was designed by Ron Power after extensive research and experimentation
during which Ron found that the 11° chamfer provided optimum accuracy
when using hollow-base lead wadcutter bullets, the type most often used
in PPC guns.

Regards,
Kevin

Kevin;

If you are looking for improved accuracy, do away with the forcing cone...They are archaic and antiquated..The Taylor Throat is far superior in performance. The standard forcing cone starts to disrupt and upset the projectile before it is even out of the chamber. With the Taylor system, the bullet is completely suppported and centered as it enters the rifling leade. Indicate the barrel on both axis and then make the cuts. After the freebore is made, I pick up the very edge of the existing forcing cone and blend it with a 1.5/2 degree taper into the freebore with a single point tool.. There are many such guns setting records and winning matches regularly.

Take care

Jerry

I getting ready to rebarrel a S&W .38spl with 4 inch heavy barrel can you post more information on the Taylor Throat.

Taylor throating is simply a 1.5-2 caliber long free bore of the revolver barrel. Ideally, the reamer leaves the free bore at exactly bullet dia. and does not leave any of the lands in the free bored section. It is most useful on loose or less accurately aligned guns. Hamiton Bowen says accuracy gains can approach 30-40% on those guns. Line-bored guns generally show little to no improvement.

Brownells sells a kit to Taylor throat a revolver barrel while installed in the frame.

RWO

Thank you RWO this is exactly the info I wanted I'm going to rebarrel the revolver anyway so I'll do the work on my lathe. I'm going to take a guess that most of the accuarcy comes from removing the crushed area caused by treading the barrel, which is extreme cases squeezes the bullet smaller than groove diameter.

That's right. Taylor throating removes any thread choke and allows the bullet to take the rifling squarely with no base distortion.

RWO

It seems that, except for the .38 / .357 kit, the "manufacturer has discontinued making the Taylor throating reamers" (Brownells). Who else makes this style reamer for the other calibers, 44, 45, 9mm, etc?

Jerry,
Thanks for the reply. I didn't think to ask for a "special." I'll try that route.
Gerry

GerryR said:

It seems that, except for the .38 / .357 kit, the "manufacturer has discontinued making the Taylor throating reamers" (Brownells). Who else makes this style reamer for the other calibers, 44, 45, 9mm, etc?

Click to expand...

There may be a valid reason for that.

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flashbang said:

There may be a valid reason for that.

Click to expand...

8 year wait for THIS?

Royldean said:

8 year wait for THIS?

Click to expand...

I was busy.

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I asked S&W what the forcing cone angle they use on the 629.

They told me to go scratch, that's propriety information.

So I got out the tools and from measuring found it to be 4.5 degrees from 90 degrees.

That's 9 degrees total.



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Since you just posted again, I figured throwing a like on a 4-1/2 year old post was ok.

And, I agree on the Taylor throating being mainly a way to 'unchoke' the barrel at the frame*. The idea that it 'aligns' the bullet with the bore just seems a bit ... ummm, 'fanciful', I think the phrase from my childhood was. It's probably already going a couple hunnert fps by the time it gets there, although, not yet spinning. I've often wondered ... no, more like fantasized, if somehow rifling the cylinder throats in time with the barrel would improve accuracy. But considering what a well setup revolver *Can Do* as is, it's probably best reserved as a thing to do just for the sake of figuring out how to do it.

* I've slugged 22 barrels and found all sorts of ways to constrict the bore. Some 'easily measurable', some just obvious by feel. An aluminum ladder sight base on a .750 muzzle, with 2 8-32 screws at an appropriate torque is noticeable ... possibly beneficial? A simulated barrel block at 1" Dia, with 3/8-16 screws tightened with 'Jim Bob's breaker bar' was several 'tenths'. Without digging thru boxes of 'papers' I'm gonna pull 75 lbs-ft out of my head as a guess.

I have a barrel bedded aluminum stock, Ross Precision. I did all that just to alleviate any concerns I might have about this. He used 10-24's. I tested that too and didn't see anything that concerned me.