500 mag barrel damage questions

I’m requesting help from veteran 500 mag reloaders and shooters. Personal experience in the form of barrel damage and how to avoid it drives this request. Since my questions concern the revolver as well as reloading I will post this in the modern revolver section of the forum as well. I have been reloading several rifle and handgun calibers for over 50 years using a variety of components. I surely don’t know it all, but I’m not a novice. I tend to make middle of the road loads as there isn’t a need for me to make max loads my go-to ammo, but occasionally I like to touch off a few factory rounds to experience the real fun of the big 500. Eight years ago I bought a new S&W 500 with the 8 3/8” fixed comp barrel and 20 rounds of Winchester Supreme 400 gr PTHP. Two trips to the range used 15 of them and I soon began loading 14 gr of Titegroup with the Hornady 350 gr XTP in Winchester and Starline (R) brass. I estimate that from then until about a year ago I shot 400 of those loads. The only effect on the gun was a little forcing cone wear and a mild flame cutting of the underside of the top strap, but I expected that, and the cutting didn’t progress. The barrel face remained smooth and undamaged. Due to possible detonation concerns (small charge in a huge case) about a year ago I ceased to use Titegroup in the 500. I had some Lil Gun powder (dated 5/09) and, using the same bullet and case, went to a 38.0 gr load. More recoil (fun) and a great hunting load. Long story short, since abandoning Titegroup, I have shot 130 of the Lil Gun loads plus the remaining 5 Win factory and 5 Cor-Bon 440 gr Hunter hard cast factory. The problem is that now there is noticeable barrel face roughening and erosion (see photos) which internet chatter would blame on the powder. There is no doubt in my mind that Lil Gun and the 350 XTP’s caused the damage as that never occurred with Titegroup and surely 2 cylinders full of factory ammo wouldn’t have much effect. Once again I’m concerned about safety, the last thing I want is to be touching off a round in a gun with a cracked throat. For safety’s sake I will have the gun re barreled. Here are my questions:
1. Have any forum members exclusively shot factory ammo, not even one reload, in their 500 and experienced barrel face and/or forcing cone erosion? If so, what ammo was used?
2. Does anyone know what powders the ammo manufacturers use? Does Winchester, for example, use W296 in their Supreme 400 gr load, and what do Hornady and Cor-Bon use in their loaded ammo? My opinion is that they would use “stock” powders the same as you or I.
3. Why is there no trace of erosion on my gun’s cylinder face around the charge holes (see photos)? Is it due to different steel or heat treatment?
4. Are S&W 500’s of more recent manufacture subject to the same potential erosion damage?
5. I have read on the web that a 350 gr bullet is “light” for .50 caliber. What would be considered “normal” and “heavy” for that, or any, caliber? I think those terms would be dictated by the intended use of the load rather than just the caliber, hence a 350 gr would be light for Cape buffalo and off the charts heavy for rabbits.
6. What causes that barrel face/forcing cone erosion? Is it a mismatch of powders with different burn rates to various bullet weights, or is it cylinder to barrel gap, or maybe powder composition or granulation? Perhaps it’s just the nature of the beast – a 50 caliber revolver launching huge bullets at top speeds is going to beat the daylights out of its barrel.
7. Finally what load (please be as specific as possible) would allow me to continue shooting for years and avoid damage to the gun and the shooter? I would like to continue using the 350 gr XTP or Sierra 350 gr JHP bullet so recommendations taking that into account would be very helpful. I would especially like to hear from anyone who has experience using H322 and/or H4198 (Mr. John Ross, if you are reading this, if you have the time, your comments would be highly regarded and very much appreciated). Thanks in advance to everyone who replies!

I think you made a good decision to stop using Titegroup. It’s always a good idea to use full or nearly full case loads to avoid the possible but somewhat rare issue of detonation. Ball powders like H110/296 are the worst offenders in that area.

If you want something fun and absolutely harmless, use Trail Boss. Light, fluffy powder fills the case and has very low pressure. Very gentle, feels like a big .38 Special. Best to use a cast slug here, might not work well with jacketed slugs. That’s a view on my part, not proof.

Some erosion is always going to happen with medium to heavy loads but I’d suspect yours will slow down and stop long before any safety issue comes up.

You might also try 4227 or IMR 4227 which are identical. Not as powerful on the top end as LilGun or H110/296 but more than enough for anything that walks with the proper slug. Try using Hodgdon’s reloading data, very complete and includes pressure data.

I don’t consider myself the .500 Mag expert but I’ve been shooting and reloading for it for 11 yrs. Good luck. Don

Freedom Arms voids the warranty on any gun which has been used with Lil Gun powder. It is VERY hot burning, and apparently causes lots of erosion.

My one experience with the powder, is with a .221 Fireball rifle. I used a load that had been pressure tested by two individuals, and it resulted in over 450 fps over the manual results. Flattened primers like I have NEVER seen in 50 years of reloading.

The barrel gets EXTREMELY hot with this powder, even with reduced loads. As you might expect, only a few were fired, and the rest of the powder is now fertilizing my lawn.

Never again..........

Thanks DonD and JohnK for your comments and suggestions. I'm going to check out any load suggestions that come from the forum and then decide on a couple to try. That remaining Lil Gun is going to be handed off to a shotgunner in my gun club.

2. Does anyone know what powders the ammo manufacturers use? Does Winchester, for example, use W296 in their Supreme 400 gr load, and what do Hornady

Click to expand...

Personal communication with Hornady says the use H110 in both the 500 and 460 factory ammo.

What causes that barrel face/forcing cone erosion? Is it a mismatch of powders with different burn rates to various bullet weights, or is it cylinder to barrel gap, or maybe powder composition or granulation?

Click to expand...

Much has been discussed in this area. In general the light for caliber bullets in combination with powder that burn at higher temperatures (don't confuse with burn rate) lead to accelerated forcing cone erosion and flame cutting.
Lil Gun is probably the most sited powder when it comes to this. It should be be noted that all the magnum powder tend to be hotter burnning. Most avoid the issue using IMR 4227 or 2400 which seem to be more forgiving. They wont get that last bit of velocity, but in either the 500 or 460 it is really not required to bring home the bacon.

Personally I use 2400 with the 350 gr. and IMR 4227 with the 500 gr..

Hope this helps

Good luck and be safe
Ruggy

Thanks ruggyh. I have thought about using 2400 with the 350 XTP. Do your loads of it erode the barrel face? I hope I did the PM reply successfully, thanks for offering more info that way. If you could include the charge of 2400 that you use that would help. Thanks again buddy.

Thanks for posting this thread, as a lot of these questions are ones I was wondering about as well, while setting up to start loading for mine and choosing powders, etc. I've got 231, Trail Boss, Unique and IMR4227, as well as about 500 of the Rainer 335gr plated bullets and the RCBS die set and Lee #16 bases (from my set-up for loading 7.62x54R) and am looking around for brass for it, as well as other bullets and loads. So it's good to hear was is and isn't working in these, and what to avoid. I've got about a half a box of Hornady XTP 350gr factory rounds, so I was considering buying more Hornady brass. But I understand that Starline makes (made?) some as well as MagTech. Any to avoid?

I have used only Winchester and Starline brass, both nickle plated, and can vouch that both are really quality cases. Never have had any type of problem with either brand so never had to scrap any. I have read that there can be quite a bit of volume capacity between all the many brands so it would probably be wise to not load from a mixed bag of cases. I don't know how fast you can drive those plated bullets, nor do I know if they perform more like lead or jacketed. Hopefully someone else can give you some good info on that. When I posted my original questions in this section I also posted the same (with photos) in the reloading section of this forum but strangely enough no one has made any replies in the reloading section! It doesn't matter where the replies are posted but I would have bet that the reloading section would have been pretty vocal.

I am currently doing a brass endurance testing on 460 and 500 brass. I would say Starline, then Winchester, Hornady.
I would use any of the 3 without reservation. If you you use H110, A9, 2400, N110, IMR 4227 with data published in Hornady or Barnes manuals you will not have any issues with accelerated forcing cone erosion or excessive flame cutting in my experience.

If you shoot enough flame cutting and forcing cone erosion are going to occur with these calibers, you don't get something for nothing.

That said my 12" 460 has nearing 7000 rounds down the pipe with most rounds powered by H110 and shows erosion across the entire forcing cone surface but still shoots as well as the day it came home.

I don't worry about it until accuracy is degraded.

Good luk and be safe
Ruggy

Rough rule of thumb : Larger quantity of faster burning propellant is more erosive than a smaller charge of slower burning propellant.

You will see the impact on revolvers at the forcing cone and the flame cutting line on the top strap above the cylinder gap.

I prefer heavier bullets with a smaller powder charge and they can still easily produce LOTS of energy. I purchased a MIHA custom mold for my 500 S&W (600 grain bullet solids or HP). I can launch this at non-magnum velocities and have tons of power or load it "down" and still surpass .44 mag revolvers. No leading issues or flame cutting issues firing heavy slugs at non-magnum velocities. I use WW-296 powder.

I do shoot the Sierra 400 JSP on occasion but the cost and availability is a factor. Having a mold I never have to worry about finding bullets and they perform well.

500 S&W

When you reload brass for the 500 be aware that some is large pistol and some is large rifle. I shoot the 500 out of a NEF-H&R Handirifle. When I first bought it I took one look at the price of factory ammo and ordered casting and reloading equipment. One of the things I discovered was the Lee 50 caliber muzzle loading 50 caliber projectiles will work in the 500 S&W. I like the modern minie which is a large 365 grain hollow base wadcutter. The only load I have tried is 6.4 grains of Unique loaded with the 0.7 cc Lee dipper. It seems to be an ok load. I have just loaded this projectile over loads of WW 231thrown by 0.5, 0.7, and 1.0 cc Lee dippers but haven't shot them yet. I don't use pure lead in these minie balls but use a harder alloy. I think any fast hand gun or shot shell powder could be used to with the muzzle loading projectiles to make a mild load that would shoot through a hog legnthwise.

Keep those replies coming!

Thanks to all who have replied so far. It's given me a lot to mull over. I'm particularly interested in trying some of the slower single base powders bc I don't need max velocities and I think they will be less damaging to the barrel face and forcing cone. I'm considering H322, IMR 4759, IMR & H4227, and IMR & H4198 . If anyone has some great load data and input on these powders, it would be very helpful. Thanks again, guys!