So I have read that using non-magnum rated jacketed bullets in the .460 can result in premature forcing cone erosion. While this may indeed be true, I don't understand the logic. Can someone please explain why?

Hmmm...I've not seen this. Following.

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I don't believe I have ever encountered the term "non-magnum-rated jacketed bullets", much less of such causing accelerated forcing cone wear.

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Pisgah

Not entirely certain of what a non-magnum rated jacketed bullet is unless you are referring to copper plated bullets, which usually have a velocity limit of 1200 fps. The issue with these is that the plating can strip and expose the soft lead when driven at high velocity, this will result in lead fouling of the barrel.

Erosion is caused by hot gasses created when the powder is ignited. The worst offenders are ball (spherical) powders. More powder = more gas = more erosion.

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Yes, the Hornady XTP Mag us one example of what I'm talking about. I believe the Speer 300gr Deep Curl is another IIRC.
The stripping of the thinner jacket by the rifling makes sense, but forcing cone erosion is specifically mentioned and it doesn't make sense to me.

First where did you read this?

The jacket material has no bearing on erosion.

The jacket material is one of several factors that determine the pressure and velocity a bullet can manage successfully.

The pressure in cartridges like the 460 require bullets with thicker jackets to deliver the ballistic and terminal performance.

There are issues with using these "thin" jacketed bullets intended for other 45 caliber cartridges.

The pressure rating and velocity limitations of the bullets can/may case uses such as jacket separation, which in my opinion is a good reason alone to not load them in 460.

Back to erosion, at 460 operating pressure some erosion is to be expected especially when shooting light for caliber bullets and ball powders, off coarse this a generalization.

While erosion is not desirable it only is a problem when it effects accuracy.

Because the forcing cone is readily visible, some get excited when their forcing cone starts to erode to the smallest degree.

I have several 460s which have what most would say is excessive amount of erosion but shoot just as accurate as when new.

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Ruggy

Well, I've seen the erosion issue mentioned several times while doing Google searches for .460 loading information. On closer attention, however, I believe it's one particular guy who keeps telling people the same thing, so it may have no credibility. His statement certainly had me scratching my head, though.
Yes, I am aware of and completely understand the need for heavier jackets to hold together on impact particularly, and it makes sense that at extreme velocities a thin jacket could "tear out" on the riflings. For back yard plinking and for accumulating some trigger time with this beast it would be nice to shoot cheaper jacketed bullets, though.

I was told by ballisticians at Alliant that there are a few specific chamberings where you must be vigilant of a problem but it wasn’t erosion.

It was in .327 and .460 Magnum. They were very specific to say that if you were not using stout jacketed bullets under these extremely high pressures, the bullet may distort in the jump from cylinder to forcing cone, and smack the forcing cone slightly out of round.

The .327 Federal runs 45k psi max. The subject bullets were the simple 71gr FMJ .32 ACP slugs. With the space available for propellant and the high pressure, these bullets at only 71 grains are capable of eye-popping speed in a revolver. But not without the risk of damage as explained by the guys at ATK.

Likewise, using thin jacket .45 Colt slugs at 60k psi in .460 S&W Magnum creates the same potential damage. A lightly constructed slug built with 20-25k PSI in mind being pounded at 60k psi can distort the bullet.

I’m not a ballisiltician — I cannot back up ANY of this with evidence beyond many years old e-mails that I likely cannot find. I’m just a hobbyist handloader who enjoys his guns and doesn’t wanna wreck ‘em. Your mileage may vary.

In a situation like this, I absolutely believe it is possible to ignore this possibility, DO IT, and come away smelling like roses. It seems like lotsa folks do that with meth and cocaine also, but that ain’t my path.

This sounds strikingly similar to the effect of shooting the 110 and 125gr JHP's at high velocities in K-frames, resulting in cracked forcing cones.

Exceeding rated pressures, I would be more afraid of injury than eroding my forcing cone.

I did a google search and can find no reference as you describe - why don't you just provide your source?

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Ruggy

The guy who made comment #5 in this thread is the person I see talking about this:
reloading the .460 S&W & H110 - The Firing Line Forums
Same guy, comment #3 here, although the topic is Li'l Gun powder:
.460 loads - The Firing Line Forums
Same guy, comment #4, referring to light bullets in .454 Casull:
.45ACP & .454 Casull - can I use the same bullet - The Firing Line Forums
Comment #2 here:
460 load data | The High Road
Comment #2 here:
Hornady XTP 300gr (not Mag) - The Firing Line Forums

I just now realized he's a member here in this forum as well, which I hadn't realized before. My comments are not intended in any way to call him out in a personal manner.

JC

Thank you, mr.revolverguy, that sort of information makes perfect sense!

I believe you have missed the context he was providing which has nothing to due with the jacket but rather the powder type and bullet weight.

I don't see anywhere he anywhere where he says thinner jacket leads to accelerated erosion.

Take away points for 460 handloaders

Light jackets are potentially an issue when used at higher pressure than intended- regardless of cartridge

Light for caliber bullets when combine with ball (spherical powders) especially double based, will lead to accelerated erosion (as well as top strap cutting).

When loading any cartridge use a bullet intended for that cartridge- validate it for the velocity you intend to run them.

.451 bullet diameters (jacketed and lead) when driven hard in 460 may be prone to "skip"
As such jacket damage/separation is possible, potentially resulting is an barrel obstruction and excessive pressure.

.451 bullet diameters for monolith constructed bullets with driving bands work fine in 460

Light for caliber is a relative term and dependent on whom ask.
For jacketed bullets I personally say anything less than 240 grains and 300 for lead to be light for the 460 cartridge.

Best reloading practices to follow when loading 460-

Use powders that provide case fill of greater than 80%.

Avoid fast powders intended to be use in low volume and or small cross sectional cases. If you are looking for reduced loads use Trail Boss or Tin Star.

Use bullets intended for the caliber - there are numerous bullets made suitable for use in 460. Choose your bullet based on interned terminal performance then select your powder.

Even though bullets can be driven very fast out of the 460 the is little reason to, at he performance levels generated a little more is not going to give you anything in return.

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Ruggy

Glad I found 4 lbs of discontinued 4759 to use for 1st 500 loads. After that I guess there’s CFEBLK to look at. My issue is finding bullets at least more than 300gr.