6mm CM or 6mm PRC

[Fire_9]

I was bored recently and did a ton of bench racing between 22CM - 6 CM - 6 PRC, all with optimized match bullets. I’m sure I’ll experiment, but the 6 CM seemed like the easiest easy button and was still carrying 1800 fps to 1000 yds or so.

What barrel length were you figuring?

 

[brocksw]

I can’t see you getting the velocities you’re talking about at those barrel lengths in the CM without crazy pressure.

Hodgdon’s data for a 95 Berger (which should produce less pressure than the Barnes) has Superformance making 3300ish @ 24”, the best single base extruded powder is closer to 3200ish. ~60ksi so there’s a little room, but I’d expect to lose 100-150 fps from those numbers just on the barrel length.

I think the PRC should get you in the neighborhood, but might still not make it without some pressure. I’ve followed all the UM stuff myself. I think the PRC case probably gives up ~ 100 fps at like pressures with much simpler logistics. On a Tikka, if running factory mags, a 6-284 is an option too, it’s a whisker short of the PRC in capacity.

I was bored recently and did a ton of bench racing between 22CM - 6 CM - 6 PRC, all with optimized match bullets. I’m sure I’ll experiment, but the 6 CM seemed like the easiest easy button and was still carrying 1800 fps to 1000 yds or so.

I agree. 6 creed isn’t gonna get there with a 20” tube but it is the easy button. I could live with leaning on it a little to get 3200. But that might even be tough. I wish there was some better data out there for the 6 prc. Just having trouble figuring out how much I’d have to stand on it to get it to 3400 in 20”.

 

[Elkmagnet]

I have a 6cm with a 22" 1 in 7.5 barrel and spent the last year loading for it.
I did some pretty extensive testing of the 95gr lrx. please use caution these loads were hot for my gun.

I found the 6cm to be very easy to load for. It has shot everything Ive tried moa or better.
My fastest powder ended up being rl17.
My favorite load was the 95lrx over 42gr of rl17 with a wlr primer. It's hot enough to crater the primers and only 3147 f.p.s. you won't touch 3500 with a 20" tube.
I didn't fire anything above 42.5 gr rl17 because of pressure signs.
The load is great shooting dime size groups at 200yds and 3" at 500 like this picture


Unfortunately it doesn't kill fast. I have been a barnes shooter for the last 15years or so and have had great success with them but the two slowest kills I have had from a barnes both happened this year with this combo. My wite shot a deer 2 times at 400 and 1 at 40yds in the lungs and an antilope shot twice before going down. Both took a long time before they actually stopped trying to breathe.
Yes we recovered both animals and verified shot placement. They should pass quicker then they did.
Here is a pic of the only recovered bullet.
it looks to have done fine. Probably from 400yds and 2200fps.

I am going to load 88gr hammers and 95gr accubonds to shoot next season.
I bought this gun to use as my kids first gun but it will be for coyotes if I don't find a better combo.

 

[brockel]

I was VERY close to putting a 6mm prc together this fall. Decided my 22 cals covered what I was planning to do with the 6mm prc. Id look at 22 creed with a 7-8” twist and an 88 grain eldm or 77 grain TMK. Grabbing a tikka 22-250 8” twist and having it punched out to 22 creed would be the easy button. That’s my plan this spring with my 17” 22-250 since 22-250 brass is such a pain to find anymore. Hornady also came out with an 80 grain eldx

 

[Carl]

What barrel length were you figuring?

Between 16.5" & 24". Here's some of my numbers, the highlighted ones are theoretical and based on extrapolations from Hodgdon's top end data pushed to 65ksi, the top two are actual loads I use (that CM load is pretty soft for competition use).

I agree. 6 creed isn’t gonna get there with a 20” tube but it is the easy button. I could live with leaning on it a little to get 3200. But that might even be tough. I wish there was some better data out there for the 6 prc. Just having trouble figuring out how much I’d have to stand on it to get it to 3400 in 20”.

Based off the 6 UM results and other extrapolations, I think 3400 @ 20" might be do-able but wouldn't be soft. If I was going to use an LRX I'd want it to be fast too.

I have a 6cm with a 22" 1 in 7.5 barrel and spent the last year loading for it.
I did some pretty extensive testing of the 95gr lrx. please use caution these loads were hot for my gun.

I found the 6cm to be very easy to load for. It has shot everything Ive tried moa or better.
My fastest powder ended up being rl17.
My favorite load was the 95lrx over 42gr of rl17 with a wlr primer. It's hot enough to crater the primers and only 3147 f.p.s. you won't touch 3500 with a 20" tube.
I didn't fire anything above 42.5 gr rl17 because of pressure signs.
The load is great shooting dime size groups at 200yds and 3" at 500 like this picture View attachment 307397


Unfortunately it doesn't kill fast. I have been a barnes shooter for the last 15years or so and have had great success with them but the two slowest kills I have had from a barnes both happened this year with this combo. My wite shot a deer 2 times at 400 and 1 at 40yds in the lungs and an antilope shot twice before going down. Both took a long time before they actually stopped trying to breathe.
Yes we recovered both animals and verified shot placement. They should pass quicker then they did.
Here is a pic of the only recovered bullet.
it looks to have done fine. Probably from 400yds and 2200fps.
View attachment 307398
I am going to load 88gr hammers and 95gr accubonds to shoot next season.
I bought this gun to use as my kids first gun but it will be for coyotes if I don't find a better combo.

Nice data. All of it lines up with what I'd roughly expect, might have guessed a slightly higher velocity from R17 though, it seems pretty ideal for velocity in the 6 CM.

 

[Elkmagnet]

Grabbing a tikka 22-250 8” twist and having it punched out to 22 creed would be the easy button. That’s my plan this spring with my 17” 22-250 since 22-250 brass is such a pain to find anymore.

Do you know if going to 22 creed will fix a 22 250 with a shot out throat?

 

[Elkmagnet]

Nice data. All of it lines up with what I'd roughly expect, might have guessed a slightly higher velocity from R17 though, it seems pretty ideal for velocity in the 6 CM.

I did see pressure a little below book max so it may be my barrel.
Barnes book max for rl17 95lrx is 42.5gr At 3239fps from a 24" tube

 

[brockel]

Do you know if going to 22 creed will fix a 22 250 with a shot out throat?

Would depend how toasted your throat is but I bet if you set it back a thread or two and tan 22 creed reamer in you’d be good to go.

 

[brocksw]

I was VERY close to putting a 6mm prc together this fall. Decided my 22 cals covered what I was planning to do with the 6mm prc. Id look at 22 creed with a 7-8” twist and an 88 grain eldm or 77 grain TMK. Grabbing a tikka 22-250 8” twist and having it punched out to 22 creed would be the easy button. That’s my plan this spring with my 17” 22-250 since 22-250 brass is such a pain to find anymore. Hornady also came out with an 80 grain eldx

You and @DougStickney make a good point. The 77 lrx out of 22 creed has better ballistics than the 95 lrx out of 6 cm at 3100. Im not sure how much the weight difference matters on deer sized critters under 600 yds though. Kinda looks like the only thing that makes it worth it from a ballistics standpoint is the 6 prc, 6 saum, 6 UM. But wouldn’t have factory components/options to work with in any of those and the 6 prc runs a fairly decent risk of going through all the work and still not getting where I want.

That 6 UM is probably the only option that would meet my criteria for 6mm.

 

[brockel]

You and @DougStickney make a good point. The 77 lrx out of 22 creed has better ballistics than the 95 lrx out of 6 cm at 3100. Im not sure how much the weight difference matters on deer sized critters under 600 yds though. Kinda looks like the only thing that makes it worth it from a ballistics standpoint is the 6 prc, 6 saum, 6 UM. But wouldn’t have factory components/options to work with in any of those and the 6 prc runs a fairly decent risk of going through all the work and still not getting where I want.

That 6 UM is probably the only option that would meet my criteria for 6mm.

With ADG cutting saum production I’d stay clear of that 6 UM. Great performance but that brass is going to be pricey and they are only seeing really great results with powders that trash throats quick.

 

[mtmuley]

With ADG cutting saum production I’d stay clear of that 6 UM. Great performance but that brass is going to be pricey and they are only seeing really great results with powders that trash throats quick.

I read some of the stuff about that cartridge over there. They are promoting a bullet that tumbles? Or did I imagine it? mtmuley

 

[brockel]

I read some of the stuff about that cartridge over there. They are promoting a bullet that tumbles? Or did I imagine it? mtmuley

You are correct. A tumbling bullet does quite a bit of damage. That’s what a lot of bergers do and look at the carnage they create

 

[Fire_9]

Between 16.5" & 24". Here's some of my numbers, the highlighted ones are theoretical and based on extrapolations from Hodgdon's top end data pushed to 65ksi, the top two are actual loads I use (that CM load is pretty soft for competition use).

View attachment 307399




Based off the 6 UM results and other extrapolations, I think 3400 @ 20" might be do-able but wouldn't be soft. If I was going to use an LRX I'd want it to be fast too.



Nice data. All of it lines up with what I'd roughly expect, might have guessed a slightly higher velocity from R17 though, it seems pretty ideal for velocity in the 6 CM.

Thanks for the info. I was recently trying to decide between the 22 and 6 creed and I had cooked up similar numbers to what you posted. Finally decided on the 22

 

[mtmuley]

You are correct. A tumbling bullet does quite a bit of damage. That’s what a lot of bergers do and look at the carnage they create

No thanks. mtmuley

 

[brockel]

No thanks. mtmuley

It’s actually what makes the smaller rounds as effective as they are. When you use controlled expansion bullets they don’t cause the damage that fragile bullets do

 

[mtmuley]

It’s actually what makes the smaller rounds as effective as they are. When you use controlled expansion bullets they don’t cause the damage that fragile bullets do

Ok. mtmuley

 

[brocksw]

With ADG cutting saum production I’d stay clear of that 6 UM. Great performance but that brass is going to be pricey and they are only seeing really great results with powders that trash throats quick.

You’d think I’d learn my lesson with these wildcats. Thick skull I guess. But I’m trying!

 

[Potsie]

You’d think I’d learn my lesson with these wildcats. Thick skull I guess. But I’m trying!

Just wildcat off a very popular case, like the 7 PRC

 

[Potsie]

Just wildcat off a very popular case, like the 7 PRC

I really want you to Guinea Pig this one for me.

 

[brocksw]

I really want you to Guinea Pig this one for me.

Just found out about the 6 MonDak (creed improved) getting good velocities in the neighborhood I’d want. That makes me think the 6mm-6.5 prc would be plenty to get where I want.