The 22UM

[Formidilosus]

By my “poof” comment, I meant of smoke from the oil. Not bullet blow up.

 

[Conman243]

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

-J

Search up 22 Hardaway Hammer, basically this.

 

[HighUintas]

Not sure how this cartridge would be that useful. The recoil would be higher on Form's tmk load than a 6cm. For an 8.5 pound gun, 12.2 ftlbs.

For an 8.5 lb 6cm, 41gr charge hitting 3000fps muzzle velocity for a 108eld, that's 10 ftlbs.

As for the ballistics, 750 yd, DA 11k ft, 25F, 10mph full value wind.

22um: 3.4mil up, 1.1 mil wind
6cm: 4.2mil, 0.9 wind



22cm w 75eldm at 3280fps (20" barrel from Peterson psi data) same conditions.

6.8ftlbs recoil, 3.9 mil up, 0.9mil wind


I think I'd go with the 22cm if I wanted to maximize shootability and ballistics

 

[HighUintas]

Looking at the numbers again.... Maybe for the 77tmk it could get to 3700fps. That's based on the 220 redline getting 75 jlks to just under 3900 and I think he had a 27-28" barrel. However, if the 77tmk was moving at 3700fps, that's about 340k rpm. Would it stay together?

Ballistics. 77tmk at 3700 gives 2.8mils up and 0.9 miles for wind in the conditions previously mentioned. That's pretty good on the elevation side, but without a significant advantage on wind I wouldn't be able to justify nearly double the recoil of a 22cm including more expensive cases, case prep, and powder consumption.

 

[Split toe]

As a fan of 22 creed, I'm tuned in!

 

[ACHILLES]

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

-J

One has been built although he may have moved the shoulder forward slightly and shortened the neck to gain capacity.
He’s running 76gr absolute hammers at 4068fps in a 26” Bbl.

 

[Formidilosus]

The first barrel (a rechambered Tikka) was questionable. There were issues and it wasn’t certain if it was a brass issue or a barrel issue. It turned out to be at least partly a brass issue. Got different brass, and a new barrel to rule that out.
As expected, it’s a bit picky to start. I believe that I stated 40 rounds from brand new to find a load to hunt with- and it will be under that. 20 inch barrel.


H1000 load with 80gr ELD-X, 3,612fpw average




N570, 3,626fps MV average-



Retumbo, 3,708 fps MV-





Do not copy these loads. This is experimentation, and we don’t know what is correct yet. Clearly the Retumbo was too hot.



Dropped 2 grains on Retumbo and tried again- 3,556fps MV




All groups are ok and usable, but not great. I believe it is primarily a not using the correct powder issue, and the brass is a potential problem (reusing 6UM brass as no new is available). But I expect this to settle in at around 3,550fps MV with 80’s (maybe a bit faster). Recoil is a same/same to a 6cm.

 

[ID_Matt]

Did you decide the retumbo was too hot on the 1st blown primer or the 3rd??

 

[Formidilosus]

Did you decide the retumbo was too hot on the 1st blown primer or the 3rd??

Shrug.

 

[Dobermann]

The first barrel (a rechambered Tikka) was questionable. There were issues and it wasn’t certain if it was a brass issue or a barrel issue. It turned out to be at least partly a brass issue. Got different brass, and a new barrel to rule that out.
As expected, it’s a bit picky to start. I believe that I stated 40 rounds from brand new to find a load to hunt with- and it will be under that. 20 inch barrel.


H1000 load with 80gr ELD-X, 3,612fpw average

View attachment 754974


N570, 3,626fps MV average-
View attachment 754975


Retumbo, 3,708 fps MV-
View attachment 754976




Do not copy these loads. This is experimentation, and we don’t know what is correct yet. Clearly the Retumbo was too hot.



Dropped 2 grains on Retumbo and tried again- 3,556fps MV
View attachment 754978



All groups are ok and usable, but not great. I believe it is primarily a not using the correct powder issue, and the brass is a potential problem (reusing 6UM brass as no new is available). But I expect this to settle in at around 3,550fps MV with 80’s (maybe a bit faster). Recoil is a same/same to a 6cm.

Form, what cover are you running on the Xero? Any good?

 

[atmat]

Form, what cover are you running on the Xero? Any good?

Looks like Gray Ops bump cover?

 

[Mike D Texas]

Hmmm, makes me wonder if there is a point of diminishing returns.

My 22-250AI with a 25” barrel shooting 90 grain A-Tips has gone over 3400fps during load development. This is with Lapua LRP brass.

I’m currently playing with fireformed 22CM Alpha SRP brass to check results with them.

I also have some necked down and trimmed 277 Fury hybrid brass that I’m working on getting loads for. I expect to be able to hit 3500+ with under 50 grains of powder. The primer will be the weakest part in this setup.


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[Formidilosus]

Hmmm, makes me wonder if there is a point of diminishing returns.

My 22-250AI with a 25” barrel shooting 90 grain A-Tips has gone over 3400fps during load development. This is with Lapua LRP brass.

So that would be 3,275 fps (ish) with a 20” barrel, and at around 80,000 psi.

I’m currently playing with fireformed 22CM Alpha SRP brass to check results with them.

At 65k chamber pressure and a 90gr bullet, it’ll still be around 3,150’ish with a 24” barrel. Of course if one ups the pressure, velocity will be much higher.

I also have some necked down and trimmed 277 Fury hybrid brass that I’m working on getting loads for. I expect to be able to hit 3500+ with under 50 grains of powder. The primer will be the weakest part in this setup.

That is the way to do high pressure loads.

 

[waspocrew]

Following along to see how this shapes up - huge fan of fast 22 cals.

 

[JBradley500]

When do you start stuffing the golden god (77 tmk) in there? You're going to be 1,000fps faster than my 16" .223s. Crazy.

 

[atmat]

When do you start stuffing the golden god (77 tmk) in there? You're going to be 1,000fps faster than my 16" .223s. Crazy.

I think the whole point is to shoot even heaviers in the 22UM

 

[Formidilosus]

When do you start stuffing the golden god (77 tmk) in there? You're going to be 1,000fps faster than my 16" .223s. Crazy.

Tomorrow. However, as @atmat stated the main goal was to shoot 88’s or 80gr ELD-M/X.

 

[Cameron.25]

Tomorrow. However, as @atmat stated the main goal was to shoot 88’s or 80gr ELD-M/X.

You dont think they'll go poof at those velocities?

 

[Formidilosus]

You dont think they'll go poof at those velocities?

Nope. Maybe, but they’ll do 3,500fps at least I think.

 

[Mike D Texas]

So that would be 3,275 fps (ish) with a 20” barrel, and at around 80,000 psi.








At 65k chamber pressure and a 90gr bullet, it’ll still be around 3,150’ish with a 24” barrel. Of course if one ups the pressure, velocity will be much higher.





That is the way to do high pressure loads.

No doubt I’m running over pressure but I don’t see anything that would indicate 80k psi.

The only thing I have is primer flow but it’s an unbushed R700 so that’s pretty typical.


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