The 22UM

[Formidilosus]

Thanks for explaining that, I appreciate it. So, conceptually, the higher the arc a bullet needs to travel to hit at a certain distance, the narrower/shorter the danger zone is? As in, at 700 or 900 yds, etc, a .308 will have a narrower danger zone than something flatter shooting, like a .300WM or .22UM?

Exactly.

The main functional purpose is in something like rutting deer where they are constantly chasing and changing distances rapidly.

 

[Formidilosus]

So in theory, @Formidilosus... Could a guy take a factory 22" or 20" 8 twist .223 Tikka barrel, cut to 18" and thread, spin onto a Tikka action, have UM do some gunsmithing, and make this all work? Essentially a "factory tikka" 22 UM?

That’s exactly what this one is. Magnum bolt face, 223 barrel rechambered and threaded. We’ll see how it performs.

 

[RockAndSage]

Exactly.

The main functional purpose is in something like rutting deer where they are constantly chasing and changing distances rapidly.

I didn't know this term existed, but it really nails the why behind my preference for small, very fast, flat-shooting cartridges on things that move a lot or are just fast, like antelope and especially coyotes. The hits just happen more easily. Until your explanation above I tied it to having the furthest MPBR, and the bullet just getting there before they could move too far off of point-of-aim - but that didn't explain why it still always seemed easier to hit with those same cartridges at distances beyond MPBR too, especially with movers quartering-to and quartering away. Danger zone explains it perfectly.

Those comparative danger zones between 6.5PRC and possible velocities of .22UM were eye-opening; a 130-yard danger zone at 500yds would be such an immense advantage...

I just went to the JBM ballistics website shown in your screenshot and tried to get similar danger zone data for a 30-06 load, but frankly it was way beyond my present skill level. If you don't mind...what would the danger zone be for a 165gr .308 bullet at 2850 mv, BC of .470, zeroed at 200yds, at 4500ft altitude?

 

[pods8 (Rugged Stitching)]

I just went to the JBM ballistics website shown in your screenshot and tried to get similar danger zone data for a 30-06 load, but frankly it was way beyond my present skill level. If you don't mind...what would the danger zone be for a 165gr .308 bullet at 2850 mv, BC of .470, zeroed at 200yds, at 4500ft altitude?

Just select danger space at the bottom of the calc, its preloaded for a 5" radius on impact (ie 10" vitals). https://jbmballistics.com/cgi-bin/jbmtraj-5.1.cgi

What distance you're zero'd at doesn't matter for this calc, its only looking at the the distance in front/behind your target that you're 5" high an 5" low respectively from your correct aim point. I swagged your atmosphere at 23inHg (didn't look it up). At 500yd you're about 465-529yd with that assumption.

 

[RockAndSage]

Just select danger space at the bottom of the calc, its preloaded for a 5" radius on impact (ie 10" vitals). https://jbmballistics.com/cgi-bin/jbmtraj-5.1.cgi

What distance you're zero'd at doesn't matter for this calc, its only looking at the the distance in front/behind your target that you're 5" high an 5" low respectively from your correct aim point. I swagged your atmosphere at 23inHg (didn't look it up). At 500yd you're about 465-529yd with that assumption.

That's awesome, thank you. Missed the checkbox for danger zone entirely. Went in and messed with it a bit, and at 500yds, the danger zone for that 30-06 load for me is about 70yds. At 1000 yards it drops to a 20 yd window.

 

[Formidilosus]

 

[ChrisAU]

Reminds me of this

 

[Big_wals]

Reminds me of this

View attachment 750009

That’s coming next!

 

[Formidilosus]

Reminds me of this

View attachment 750009

I’m not above trying…

 

[NSI]

22-300 WSM (22 FORM) is inevitable now.

-J

 

[ChrisAU]

I think that’s more like 22 BMG lol

 

[WestTN2288]

View attachment 749995


View attachment 749996

Serious question… we using like 50bmg or us869 powder??

 

[WestTN2288]

22-300 WSM (22 FORM) is inevitable now.

-J

Now you’ve got me thinking I could do something interesting with this pile of wsm brass I have

 

[atmat]

View attachment 749995


View attachment 749996

This looks ridiculous lol. I’m in.

 

[Formidilosus]

22-300 WSM (22 FORM) is inevitable now.

-J

Already in the works.

 

[Formidilosus]

Serious question… we using like 50bmg or us869 powder??

This started with N570 and 77gr.

 

[The Fish Box]

I think the 22 redline which is very similar to this cartridge found good success with n570 burn rate powders.

 

[Formidilosus]

Only had 6 rounds initially.

66gr N570
77gr TMK

5 at 100y-



#1 is the lowest. There was a lot of oil still in the barrel, and had a “poof”.


Guessed at 3,400fps MV, 740 yards hit on a sub MOA target.

 

[Gstew1930]

@Formidilosus 18” barrel?

 

[Formidilosus]

@Formidilosus 18” barrel?

20”.