Quote from: Bluebird5000 on September 26 2019 10:02:15 PM MDT
Has anyone reached out to Underwood and asked them why they are not calling them 215gr hardcast?

The_Shadow has posted a generous amount of data showing the 200gr XTP to be about 201gr (which is fine with me rounding it off that close) so I have a hard time believing they are loading 220gr. Technically that's about 2.3% off so ... not HUGE but would seem better to market it as 215.

When I order some more later this month I can weigh them myself and post here.

RIGHT......a good ways off to be considered a 220 grainer.

Hello,

I pulled a couple of bullets and also noted the sub-215 grain weight. I also tested the bullet hardness and am curious as to whether someone can replicate what I'm seeing. As I'm relatively new to casting, I figured I'd post here to see what folks' thoughts are.

Using the Lee lead hardness tester, I measured a diameter of 0.055" to 0.056", which puts these between 17.2 and 16.6 BHN. (I have attached an image of one of the measurements to this post.)

According to the documentation that Lee provides with their tester, 17.2 BHN corresponds to a max pressure of 22002 PSI. Given the high pressures of 10mm, I was expecting a harder bullet. Underwood's website states their hardcast bullets have a Brinell hardness of 21. (https://www.underwoodammo.com/frequently-asked-questions/). Thoughts?

Thank you.

Richard Lee's thoughts about pressure and accuracy sound really good in print, but don't actually translate to real world performance that well.  I was shooting some full bore 357 magnum earlier today from a S&W 28-2 with a 6" barrel.  Loads were 16.1-16.9 grains of H110 behind a 150 grain Keith SWC cast from air-cooled isotope load.  BHN would be around 14-15, maybe a little less since they had only aged about two weeks. 

I had three shot groups that were touching at both the starting load and the max load at 25 yards.  Certainly better than I can shoot.

According to the Lee method I was WAY past the pressure envelope for those bullets, but the accuracy was fine.

Seems like my Underwood stash of 220 HC from a few years back are not red, but could be mistaken, nice pull down by the way!

Ken

Quote from: sqlbullet on May 15 2021 11:00:25 PM MDT
Richard Lee's thoughts about pressure and accuracy sound really good in print, but don't actually translate to real world performance that well. ... According to the Lee method I was WAY past the pressure envelope for those bullets, but the accuracy was fine.

Thank you for your reply. I ended up getting a copy of Lyman's Cast Bullet Handbook (one of the few things not sold out out my local store). The alloys that it lists for the 10mm loadings (which include 200gr but not 220gr) are either 10-to-1 or Lyman #2, so I feel better about the BHN now.

If anyone else is trying to duplicate this round, I will also note that these Hi-Tek coated bullets failed (pic attached) Hi-Tek's acetone test.

Quote
Use a clean rag or paper towel and moisten with acetone. Rub the test bullets back and forth for 30 seconds. If proper curing has been obtained, there should not be any of the coating removed from the bullet and the towel should be free of any colour transfer from the bullet. - http://hi-performancebulletcoatings.com/coating-instructions/

I'm not sure how important this test actually is when it comes to firing the round, but figured I'd include this info for anyone who also likes to obsess over details.

Maybe just a ideal
They call them 220gr so if they add a gas check it will be close too 220gr.
Just a Ideal.
I noticed my cast bullets called 220gr or actually 214/213 gr also.

Have been spending a lot of time lately reading Lyman?s Cast Bullet (4th edition) lots of great info

I beleve they use to add a Gas Check and that brought the bullet up to 220gr. Now they removed the Gas Check and added the coating reduced the weight and never changed the bullet description weight in packaging.

Easy when they had Gas Checks the bullets weighted 220gr.
Since they went to coating and no gas checks it reduced the weight.

Just changing the lead/antimony/tin content of a "220" grain mold can have more effect on weight than you would think until you experience it.  Heck, even changing the lead temp 100 degrees can make a couple of grains difference.

I always consider the stated weight a guideline to be checked, not an absolute value.

They originally had a Gas Check until they coated them. With the Gas Check they were 220gr !

The 220gr Hard cast they removed the Gas Check from the bullet design when they coated the bullet.
My other 220gr weight the same around 214gr without the GC and coated.

Was 220gr when they had a Gas Check !
When they started coating the bullets without GC the weight dropped to 214gr
But they kept their marketing at 220gr.

Alaska, I don't know when Underwood changed over as things do change over time.  Underwood may have decided to use the coated bullets and move away from the Gas Check as Gas Checks have gotten more expensive and some were harder to get because of copper pricing.