Markwell, thanks for that input. If you may, can I ask a few more questions since your son has had experience with hardcast on bears?

• Which of the bullets on MBW's site for 10mm did you use?  I don't see a RN model as they describe them: https://www.montanabulletworks.com/product-category/pistol/?filter_caliber=10mm
• What was the context for shooting bears, e.g. over bait or from a tree with hounds, and approximately how far of a distance?
• How did the bears react when shot?  DRT or did they run? I have heard some complaints about hardcast sailing right through animals when shot in the vitals, allowing them to run a little before expiring. Not that there are a lot of deep penetrating and expanding bullets in 10mm such as the newer Swift A-frames and and Hornady XTPs.
• Did you have any feeding problems at any point, assuming you used these bullets with the wide .325 meplat? https://www.montanabulletworks.com/product/10mm-lbt-200gr-wfn-pb/.
  

Thanks much.

Interestingly, Rimrock lists an almost identical bullet with a BHN of 22: https://rimrockbullets.com/xcart/tsh-10mm-200-gr-fp-per-300.html.  Same meplat and bullet weight, but cheaper. Listed as TSH vs TC for the bullet your referenced.  Not sure the difference.

So far I have the suggestion of Rimrock Bullets, and in another forum, Badman.  Seems like there should be more than that. I guess it depends on what makes a tough lead bullet. I am not fully knowledgeable about this subject, but know a high BHN is not the key factor, as high BHN bullets can be fragile.  It depends on the makeup of the bullet, but identifying the important criteria for a lead bullet to work on a large, tough animal, and finding the manufacturers of said bullets, seems a more difficult task than I thought.

I want to source some 200 grain hardcast, wide meplat bullets for use when hiking.   I have bunch of bookmarks to bullet manufacturers, but most that offer 10mm bullets are meant for target/competition. They don't have the hardness or wide meplat for defense of four legged critters.

The only company I have in my collection of bookmarks that makes a bullet that I want is Montana Bullet Works - https://www.montanabulletworks.com/product/10mm-lbt-200gr-wfn-pb/.  Nothing wrong with them. Seem pretty expensive and just want to see if any of you know of other companies making something similar.

Thanks much.

Yes, that is what I was hoping. However, I always hear people saying you need to slug to be sure. I was hoping the groove diameter would be fairly consistent in the Sigs and I wouldn't have to do that.  I still might, but rather avoid it if possible.

I am wanting to shoot cast bullets in my Sig P220 10mm. I have read you want to size the bullets .001-.002 above the groove diameter in your barrel.  I know I will need to slug my barrel to find this out, which I am a little concerned about screwing something up.  I know Meister's Bullets sells a kit for doing this:https://www.meisterbullets.com/slugyourbarrelsdetails.asp. 

However, I am wondering if anyone has found the groove diameter in Sig P220's varies much and has anyone slugged their barrel to find out the measurement? 

Thanks much

Quote from: therognp on January 20 2021 01:45:22 PM MST
Accurates data with AA#5 is 7.5 gr with a 175gr cast bullet or 7.8 gr with a 180 gr Hornady jacketed. Velocities are suggested to be in the 1025-1050 range.  And as suggested a lighter recoil spring might be needed.
On the other hand if she is just going to try shooting the P220, if its functioning as a single shot semiautomatic that may be just fine for the trial stage. Recoil springs for the Sigs seem to be more complex and expensive than for many other SA. Wolff does not think the P220 exists as far as their springs go

Yeah I was looking at that load, but it is a little higher fps than I prefer in this situation.

The recoil spring for the P220 10mm is interesting issue. It is only sold as a captured recoil assembly with the guide rod. I haven't tried to remove the guide rod cap and replace the purple colored spring with one of a different spring weight.  Someone on the SigTalk forum used HP38 to get a 180gr cast bullet down to 872 fps with no problem cycling the slide. He also reported having a 24# recoil spring in a Sig P226 40 S&W, but that seems a high spring weight for that model. I am not sure he was right on that.

Quote from: The_Shadow on January 20 2021 01:28:57 PM MST
kmcdonou, Welcome to the forum... Low velocity/Low pressure rounds FTF has a lot to do with the recoil system.  You might need a lighter recoil spring for better function...
Using a faster burn rate powder would be a good choice for better burning characteristics and cleaner burns.  Loading at 40S&W powder charges and using 10mm case with the longer COAL will yield lower velocity and pressure.
Lighter bullets will also help with recoil management.  That being said...
With Accurate #5 you might want to try the following:
180 grain bullet over 6.8 grains A#5
200 grain bullet over 6.2 grains A#5

Yeah, those look like good loads to me as well. My guess is they will be right in the ballpark of my desired fps when using the longer COAL of the 10mm.  I am hopeful those will cycle well.

Ken,

I assume you don't have chrony?  Alliant shows a 180 GDHP at 11 grains of BD going 1295 fps.  Are you thinking you are getting around 1,000 fps?

Long time lurker.

I am thinking about developing a lighter load for my Sig P220 10mm SAO for my wife, just to see if she likes shooting centerfire cartridges, as that is the only platform I have at the moment. She has only shot rimfire previously. Her hands are pretty wore out from massage work for many years. I have 180 and 200 grain cast bullets. Before I start with load development, anyone have a good idea of how low in FPS I can get before I get FTF?

I did look at some loads and was thinking something in the 40 S&W range using Accurate #5. I would love to get a load around 850 fps, but think that will be too low with a 24# recoil spring. Just curious if anyone has tried this and how low they got. It will reduce some time on my part.  Thanks much.