I played around with my 460 WBY MKV ( with break) this weekend and made some interesting observations. In my rifle, a load of 118 gr of IMR4350, Fed 215 primers and Hornady 500gr FMJ was over the top at 2621 fps. The powder was added by drop tube and compressed sligtly in new Norma cases. Their were slight ejector marks on the case head and the belt expanded .005 inches, interestingly, the primers looked fine and no evidence of sticky bolt lift or other pressure signs occured. I wonder if anyone here has measured how much belt expansion occurs with factory 460wby rounds? Using 115 gr of powder over the same bullet the belt expansion was only .002 inches for 2551 fps with the same bullet.Powder charges below 115 grs i.e 114-110 grs showed no increase in belt expansion over virgin brass. Interestingly, the 600gr Barnes original over 110gr of IMR4350( all I could get in the case and still feed thru the magazine) and 550 woodleighs ran about 2350-2400 fps with no signs of high pressure. Since many of the manuals list a top load of IMR 4350 in this case of 123.5grs with the 500gr Hornadys and others here have achieved these levels,I wonder if I just have a hot lot of powder or soft brass. Accuracy was excellent with sub 1 inch groups in all cases.-Rob

This weekend I fired 3 Weatherby loaded 500gr FMJ cartridges. All three expanded at the magnum ring 0.002". By comparison, my load of 123 gr IMR 4350 with 500 RN (2685 fps)produced an expansion of 0.003" over virgin brass. I have never tested my 600gr loads. Normally, I retire my cases with this load and do not use virgin brass. Although I did not chronograph the factory load this time, in the past they have always been exactly as stated (w/in 5 fps).

As a side-note, the 'felt' recoil from the factory loads were noticably worse than with my loads. Obviously, powder and bullet selection are important for optimum accuracy and power, but this may be at the expense of felt recoil.

Shawn

Shawn- Thanks for the info on the belt expansion of factory ammo.That is about what I'd expect. Do you see any ejector marks on your cases with the 123 gr load?. I also wonder what lot of IMR4350 you are using, since I was getting 2621 at 118grs of powder with clear over pressure signs?. Of course you might also be the lucky one in having a gun whose barrel is faster/smoother and will operate with lower presures. Each gun is a law unto itself and it proves once again that you can't generalize.-Rob

I always see ejector marks from Wby rifles unless I fired a mild load from a nickel case. The "depth" of the ejector marks in my loads are comparable to those found in factory loads. The 600 gr loads produce slightly deeper marks, but they are still not "shinny." Ejector marks are one of the indicators that I use when checking for hot loads. 125 grs of IMR4350 with 500gr RN will produce much deeper marks that are shinny- hence, an excessive load. Note: there were others signs for the hot loads as well- stiff bolt, marks on side of shell, dimpled primer, etc).

Shawn- Thanks for the info. Without access to a strain gauge,and based on the belt expansion I observed at 118 gr of IMR4350, I think I'm at Max in my gun. Or at least, I don't have the nerve to push it further. I have seen ejector marks on WBY factory loads in .257,and just wrote it off as hot factory loads. Since I've never shot factory ammo in my gun, I don't exactly know what to expect. You have helped me alot with your info. In my 460, I see no ejector marks or belt expansion till I hit 118 grs. The primers looked fine ( no cratering) and the bolt lift was fine,nevertheless,I think I will stick to the 115 gr load at 2550 fps and consider it max in my gun. Interestingly, the 600gr Barnes load at 110 grs seemed to produce lower pressures and even at 112grs appeared OK. I also suspect the lots of IMR4350 we are using may account for the difference. By the way have you tried any of the VitaVoury powders in this gun?-Rob

Sadly, my experience with the 460 Wby revolves around only 3 bullet weights (465gr TCCI Bronze, 500gr RN and Barnes-X, and the 600gr Barnes O) and one powder type IMR 4350. According to the Hornady Reloading Manual, this powder produces by far the highest velocities, and so, I have never tried any other powder.

I have not yet been able to get any overloads with my 460 wby, with any european powder. I have been up to 126 grs of Norma MRP (heavely compressed load)behind a 500 grs Hornady. And still not seen any inications of to high pressure.
Maybe the reason is that i don't have any muzzle breake on my Brno 602??
It hurts in the bench!!!!

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Shoot well, and hit hard.

Arild.

[This message has been edited by 460wby (edited 09-14-2001).]

I have owned my 460 for more than 11 years, and I have used 4350 a lot. I would not exceed 2600 fps. while using IMR 4350 with a 500 bullet.120 to 121 grs(less with a Barnes X). gives me about 2600 fps in my rifle. Every pressure test that I have seen indicates that you are at 50,000+ cup when you are running 2600 fps. when using IMR 4350 in a 460 wby. In a well made rifle like a Weatherby or a good custom rifle it is possible to go well beyond normal operating pressues and not see any pressure signs what so ever. I watched my friend fire loads with 130.0 grains of Reloader 19 under a Hornady 500 gr. RN. in his 460 the velocity registered 2722 fps. There were no signs of pressure what so ever, there is no way you can achieve that kind of velocity without ecceeeding normal operating pressures, I would quess my friend was running at least 70,000 PSI. If you have the A-Square manual checkout pressure interpretation(it is sobering).

[This message has been edited by Mitch (edited 09-13-2001).]

Mitch- I'm in total agreement with you. At 2621 fps there was .005 belt expansion and slight ejector marks on my cases. I did reload these cases and the primer pockets were not noticibly expanded, nor was there any evidence of sticky extraction, but I strongly feel that going past this point is just asking for problems in my gun.Shawn460 points out that virgin 460 WBY ammo expands the belt by .002 inches and probably also leaves ejector marks. This is the basis for my conclusion that 2600 is the max limit in my gun. Depending on the lot of powder,bullet jacket thickness, barrel internal dimensions etc. higher loads might be totally acceptable ( and others here have proven that), but I don't want to chance it at least not without the use of a strain gauge.-Rob