Introducing the 300 Tyrant

[Tumbleweed]

Hey all, wanted to give an update on the project. The barrel now has 215 rounds on it. Keep in mind the first 100 were just a light, fireforming load with no load dev whatsoever.

My last update showed the results of the powder charge tests with Fed215M’s and Retumbo. The ES was a little higher than I like. I started by testing some different “neck tensions” of which made no impact on ES. So, I went on to test CCI250’s and even CCI200’s with their own charge tests to see if I could get ES down under 20. CCI250’s were about the same as the Federals and while the CCI200’s tightened up ES some, the powder charge accuracy window became extremely narrow. Too narrow for my comfort.

Towards the tail end of this testing, the barrel sped up a little. Velocity went up 15-20fps and groups opened. I ran another powder charge test with Fed215’s and trickled it back down until I was in the sweet spot again. Side note…I’ve been mocked for this, but this target shows exactly why I test in 2/10 increments at times when it’s a lighter profile barrel with heavy bullets. It matters. You can see the incremental change to group size that happens.

Today, the ES was down under 15 on all of these charges, maybe the barrel internal landscape has something to do with it? Time will tell. My next step is to take it to 1000 plus yards and see how it holds vertical, that will be telling. Could be a bit before this nasty, coastal weather allows for that. That should be my next update!

 

[trod76]

Super cool project, can’t wait to see what it does at 1000 yards. Keep us updated !

 

[Taudisio]

I'm potentially interested in the brass.

Thread '33 Nosler brass and Redding die'
https://rokslide.com/forums/threads/33-nosler-brass-and-redding-die.437122/

 

[easternoregonballistics]

I'm having a 33 Nosler built right now, and I really like your thinking on this project. I'm interested to see how it turns out.

How did it turn out?

 

[turbobrick]

How did it turn out?

Still waiting on it, its a low priority build for the gunsmith, but he does have everything needed to finish it.

 

[Tumbleweed]

It’s been a bit, time for an update!

NOTE: There is now a 300, 7mm and 6.5 Tyrant fully designed and reamers on file at Manson. They are publicly available and all use the same headspace gauge!

So I left off with trying to wrap up load dev with 225 ELDM’s. That was our preferred bullet because they work so well on game, especially at distance. While I did get some tiny groups with the 225’s, they just would not shoot under .7MOA consistently. For most this would be fine, but I know the system will do better. I did test those at 1022 yards and while they shot good, there was too much vertical dispersion. I’m looking for .75MOA or less at 1000 yards in calm conditions. This could be a bullet powder combo issue, it’s possible testing other powders could have brought it in. I just didn’t want to go that route

As this chamber is throated for 225/230 grain bullets, the next logical bullet to try was the 230 Berger Hybrid Target. We have quite a bit of experience using these on game years ago, and they work excellent. The pressure test showed they will actually run slightly faster than the 225’s at the same pressure levels. I reached 3035fps with Retumbo before seeing faint ejector marks on the case. Extraction was fine.

I set the bullets .020” off and set up a charge test 1 grain below pressure signs in 2/10 grain increments as this is a fairly light profile barrel and the harmonics with big bullets are more aggressive. No groups were larger than 1 MOA and most were in the .6 to .7MOA range. The ES for individual groups were no higher than 25fps.

81 grains produced a .5 MOA group in a flat spot relative to groups above and below in charges. ES was less than 10fps. I took this charge and moved to seating testing .010” though .030” in .005” jumps. .010 through .025” all shot well and the average point of impact remained the same across these seating depths. Looks like .015” is where it wants to be. ES on that group was 18fps. My next step is to verify .015” and then test and distance to observe vertical spreads.