The 22UM

[Formidilosus]

@Formidilosus
You might look at the 22 Redline if you haven't yet. It looks like similar powder volume.

The straight SUAM case or the 6UM 30° is worth trying.

Too much of a good thing????

Not too much of a good thing as in too much powder, I think too aggressive of a case shape for the small bullet. The last go round, 6UM 30° cases were splitting at the shoulder- and only producing about 30fps more MV than safe 22CM loads. Certainly there was a brass issue, but I also think there’s a good chance it’s just too fat and sharp shouldered, with too much powder for the .224 bore.


I believe we are going to try a 22-6UM 30° and see how it does, and if that doesn’t work, a 22-06.

 

[Brontosaurus]

The straight SUAM case or the 6UM 30° is worth trying.





Not too much of a good thing as in too much powder, I think too aggressive of a case shape for the small bullet. The last go round, 6UM 30° cases were splitting at the shoulder- and only producing about 30fps more MV than safe 22CM loads. Certainly there was a brass issue, but I also think there’s a good chance it’s just too fat and sharp shouldered, with too much powder for the .224 bore.


I believe we are going to try a 22-6UM 30° and see how it does, and if that doesn’t work, a 22-06.

Ive messed with necking down 25-06 brass on the bench. Even with very cheap brass its very doable. I feel like that might be a better direction. Less hoops to jump through.

 

[Formidilosus]

Ive messed with necking down 25-06 brass on the bench. Even with very cheap brass its very doable. I feel like that might be a better direction. Less hoops to jump through.

That’s been my thought from the beginning.

 

[JBradley500]

Form, are you talking straight necking down and running it or do you think about modifying the dimensions in other ways too?

 

[Brontosaurus]

That’s been my thought from the beginning.

I forget all the measurements and steps I took to get there. But heres an 06 case with a 77. Somewhere i wrote down the h20 cap.

 

[khuber84]

I prefer short fat powder columns VS long skinny. Perhaps 22-284? I know a fella by the name of Dallas Hardaway on FB has one and loves it, runs hammer bullets really fast(3800+) and it's been very lethal for him. I know, hammer solids, they're not my cup of tea, but the case has been a solid design for him.

 

[ACHILLES]

He has a 9 twist 22/284 running 77tmks at 3750fps as well.

 

[WestTN2288]

He has a 9 twist 22/284 running 77tmks at 3750fps as well.

Would a 22/284 fit in ar10?

 

[khuber84]

Would a 22/284 fit in ar10?

Feeding a rebated rim case in an AR, will be a tough challenge. If you're after max sauce with ar10 mag constraints I'd be looking at a 22-243ai, or 22 middlestead. Or just go the easy route 22cm.

 

[ACHILLES]

Would a 22/284 fit in ar10?

Yes it will fit and some company’s used to offer ars in 284win and 6.5-284 10-15years ago like Black hole and now I notice they don’t offer anything that’s not based off the creed/308win case now. I’m sure you would have to tune mags and a few other tweaks to get it to feed consistently but I haven't messed with Ar10s much so I can’t say for sure.
Like Khuber84 said I would think the 22creed/middlestead would be easier with less headaches. But nothing wrong with trying something exotic as long as you realize the challenges that may come with it.

 

[Kaleb]

I guess a fella could have a 1-8 tikka rechambered and if it sucked then just rebarrel to something normal?

Well rechamber and swap out the bolt stop/magazine.

 

[WestTN2288]

Yes it will fit and some company’s used to offer ars in 284win and 6.5-284 10-15years ago like Black hole and now I notice they don’t offer anything that’s not based off the creed/308win case now. I’m sure you would have to tune mags and a few other tweaks to get it to feed consistently but I haven't messed with Ar10s much so I can’t say for sure.
Like Khuber84 said I would think the 22creed/middlestead would be easier with less headaches. But nothing wrong with trying something exotic as long as you realize the challenges that may come with it.

[mention]khuber84 [/mention] I appreciate it.

I currently have 22 creed ar10 and it honestly hasn’t impressed me over the 22 arc at the same barrel length. 10% more speed with 50% more powder. I’ve kind of been looking something to step up to and potentially squeeze a little more out of it

 

[ACHILLES]

In that case, the 22um is still in R&D. Peterson 6.5-284 brass is available or 22-6.5saum.
Seems like the biggest issues with mag cases are mag followers, follower tilt, mag bulging, and mag spring tension. If you’re someone who is dedicated and okay with spending some time working out the kinks it would be worth trying. 2 years ago there was a guy using cnc to build his own lowers that used aics magnum mags and they seemed to run better than current options. Although I don’t know if that option exist today. Either way i bet you could modify an existing mag option to work properly with a little bit of tweaking.

 

[Stocky]

Theres a few 22PRCs around arent there? Plenty of brass options to try. Apart from bolt thrust increase why entertain a longer case?

 

[lil' bear]

The straight SUAM case or the 6UM 30° is worth trying.





Not too much of a good thing as in too much powder, I think too aggressive of a case shape for the small bullet. The last go round, 6UM 30° cases were splitting at the shoulder- and only producing about 30fps more MV than safe 22CM loads. Certainly there was a brass issue, but I also think there’s a good chance it’s just too fat and sharp shouldered, with too much powder for the .224 bore.


I believe we are going to try a 22-6UM 30° and see how it does, and if that doesn’t work, a 22-06.

Have you thrown any ideas around about using the sig fury hybrid cases? I've found some online and from what I've been reading it will push a 6.5cm faster than a 6.5 prc. Haven't found anybody using it on the 22 yet. But I think I'm going to try 25 with it.

 

[khuber84]

[mention]khuber84 [/mention] I appreciate it.

I currently have 22 creed ar10 and it honestly hasn’t impressed me over the 22 arc at the same barrel length. 10% more speed with 50% more powder. I’ve kind of been looking something to step up to and potentially squeeze a little more out of it

The percentage of velocity gained VS % of powder increased is always going to look worse as you go up in case capacity especially at same barrel length. The arc is similar to a BR case, and I see the BR variant as pretty much the pinnacle of efficiency and accuracy stand point. My 28in 22br will run 88s at almost 3100 near psi, my 18in 22cm will run 88s at 3120 not far from pressure. That's 10" of barrel, call it 300fps or 10% velocity difference, 43gr VS 29.7gr. Same to similar results you're seeing.

I have a 20in 6cm and a 20in 6prc, to run the same bullet 100fps in the prc, it requires 14gr more powder. Idk what a 6arc top end load with a 112gr bullet is from a 20in barrel, likely around 2650. The 6cm load 2970 and the 6prc 3080. The case capacity of arc is 33gr, 6cm 51.8, 6prc 68.2 so essentially you're having to double capacity to get another 500fps.

 

[eLightfoot]

22/6mmAI or 22/6.5x55imp would be legit

 

[Stocky]

The percentage of velocity gained VS % of powder increased is always going to look worse as you go up in case capacity especially at same barrel length. The arc is similar to a BR case, and I see the BR variant as pretty much the pinnacle of efficiency and accuracy stand point. My 28in 22br will run 88s at almost 3100 near psi, my 18in 22cm will run 88s at 3120 not far from pressure. That's 10" of barrel, call it 300fps or 10% velocity difference, 43gr VS 29.7gr. Same to similar results you're seeing.

I have a 20in 6cm and a 20in 6prc, to run the same bullet 100fps in the prc, it requires 14gr more powder. Idk what a 6arc top end load with a 112gr bullet is from a 20in barrel, likely around 2650. The 6cm load 2970 and the 6prc 3080. The case capacity of arc is 33gr, 6cm 51.8, 6prc 68.2 so essentially you're having to double capacity to get another 500fps.

I find the biggest step is when a case gets large enough to take a "miracle powder" ie once its overbore enough for RL26 it steps more like you would hope. Otherwise it really is diminishing returns. GRT models very little gain in the 22PRC vs a 22 Creed.

 

[TradLife406]

What about a 22 GT?


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[Coleredding00]

What about a 22 GT?


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22GT owner here. I find the GT case to be the happy medium between the 22 arc and the 22 creed. I'm running an 80 ELDM out of an 18" 22gt at 3080fps with 36.8 gr of h4350. So basically, the same as what I've seen Hornady factory 22 creed ammo do. Saves some powder and a lot of barrel life. The 22GT is essentially the same case capacity as a 22-250 just shorter with a 35 degree shoulder. Just a more efficient case design.