The 6UM

[6.5x284]

Looking into a 6UM or similiar for a sheep rifle. If sheep or deer were the primary target, does the below fit the bill? My main concerns are barrel twist and preferred bullets for deer sized game. 115’s DTAC seem to be favored for elk but wasn’t sure on deer. Currently I’m leaning towards below:

Barrel length: 18”
Twist: 1:7.5
Bullet: 103 ELD-X
Powder: N570


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[Ryan Avery]

Looking into a 6UM or similiar for a sheep rifle. If sheep or deer were the primary target, does the below fit the bill? My main concerns are barrel twist and preferred bullets for deer sized game. 115’s DTAC seem to be favored for elk but wasn’t sure on deer. Currently I’m leaning towards below:

Barrel length: 18”
Twist: 1:7.5
Bullet: 103 ELD-X
Powder: N570


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A sheep was shot with a 6UM/115 Dtac this year at 670 yards, and it worked well.

If I were to target sheep or deer only, I would use a 108 ELD-M.

 

[85zero17]

Ryan

Current thoughts on Barrel lengths…running the 115nrdtac. Elk, and deer, suppressed.

 

[Ryan Avery]

Ryan

Current thoughts on Barrel lengths…running the 115nrdtac. Elk, and deer, suppressed.

20” is the sweet spot


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[Clarktar]

20” is the sweet spot


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Guess I'm 4" short ! Pun intended.

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[Jimbee]

20” is the sweet spot


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Care to elaborate? Please and thank you. I am having UM plumb me a 6/7prc when possible and was going to go 18". I've noticed some of the cool kids are going/recommending 20".

 

[B_Reynolds_AK]

Looking into a 6UM or similiar for a sheep rifle. If sheep or deer were the primary target, does the below fit the bill? My main concerns are barrel twist and preferred bullets for deer sized game. 115’s DTAC seem to be favored for elk but wasn’t sure on deer. Currently I’m leaning towards below:

Barrel length: 18”
Twist: 1:7.5
Bullet: 103 ELD-X
Powder: N570


Sent from my iPhone using Tapatalk

While I’m shooting a slower 6 mm, I’m also targeting sheep primarily. I opted to try the Barnes 112 Match Burner. Higher B.C. than the Hornady 103 & 108 and upsets quicker than the DTAC, according to the experts here.

 

[6.5x284]

While I’m shooting a slower 6 mm, I’m also targeting sheep primarily. I opted to try the Barnes 112 Match Burner. Higher B.C. than the Hornady 103 & 108 and upsets quicker than the DTAC, according to the experts here.

Been following that with interest as well!


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[khuber84]

While I’m shooting a slower 6 mm, I’m also targeting sheep primarily. I opted to try the Barnes 112 Match Burner. Higher B.C. than the Hornady 103 & 108 and upsets quicker than the DTAC, according to the experts here.

This bullet shoots very well in my 6gt at 2920fps approx 10k off lands. A 6cm would likely node in around 3020-3050. I have not yet killed anything with it, that'll be next year.

 

[85zero17]

20” is the sweet spot


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Any further testing on 18”…. Or is 20 going to be the conclusion?

Also, any down sides to to running a .30cal can?

-thnx

 

[khuber84]

Any further testing on 18”…. Or is 20 going to be the conclusion?

Also, any down sides to to running a .30cal can?

-thnx

A 6cm is losing 25-30fps per inch at 22", under 20 that number jumps to 40-50 fps/ inch. The heavily over bore 6um will only be worse due to it being less efficient and much slower burning powders. I'd say Ryan's suggestion of 20 being minimum is a good recommendation, it's quite possible you could see 100fps difference between running the same load in a 20" VS 18" barrel.

 

[Formidilosus]

Care to elaborate? Please and thank you. I am having UM plumb me a 6/7prc when possible and was going to go 18". I've noticed some of the cool kids are going/recommending 20".

You can shoot it at any length you want. It will always be 250-300fps faster than a 6cm at the same barrel length. I would have zero issues shooting a 16” 6UM.

 

[Formidilosus]

A 6cm is losing 25-30fps per inch at 22", under 20 that number jumps to 30-50 fps/ inch. The heavily over bore 6um will only be worse due to it being less efficient and much slower burning powders. I'd say Ryan's suggestion of 20 being minimum is a good recommendation, it's quite possible you could see 100fps difference between running the same load in a 20" VS 18" barrel.

No. Not even close. I have shot many 16-24” barreled 6cm’s and 20-30fps per inch has been the average for all. I also have had multiple 12.5” barreled 6.5cm’s and they too averaged 30fps per inch less. Ryan had a 17.5” barreled 6UM and it was just fine.

 

[khuber84]

No. Not even close. I have shot many 16-24” barreled 6cm’s and 20-30fps per inch has been the average for all. I also have had multiple 12.5” barreled 6.5cm’s and they too averaged 30fps per inch less. Ryan had a 17.5” barreled 6UM and it was just fine.

You have more experience than myself. Im only going off what I've observed in 18", 22" 24 and 26" using barrels chambered with a saami spec jgs 6cm using same bullet and powder lots. 20" is where I saw the stopping point unless I was building a special purpose built weapon system.

 

[85zero17]

You have more experience than myself. Im only going off what I've observed in 18", 22" 24 and 26" using barrels chambered with a saami spec jgs 6cm using same bullet and powder lots. 20" is where I saw the stopping point unless I was building a special purpose built weapon system.

Having zero experience with either caliber in these shorter length…reading every word of this thread, my monkey comprehension lead me to the conclusion that Form just lay’d out.

That is also what led me to ask, as Ryan’s suggesting of a median length had me wondering If there had been a more recent finding relative to length.

My thought was that an
18 in standard/ non+P would still be sufficient terminally at the ranges we are mostly rapping about.

All good discussion to me….regardless

 

[khuber84]

Having zero experience with either caliber in these shorter length…reading every word of this thread, my monkey comprehension lead me to the conclusion that Form just lay’d out.

That is also what led me to ask, as Ryan’s suggesting of a median length had me wondering If there had been a more recent finding relative to length.

My thought was that an
18 in standard/ non+P would still be sufficient terminally at the ranges we are mostly rapping about.

All good discussion to me….regardless

Most guys running short barrels also want to run suppressors. I'd contact the manufacturer of your can and ask what barrel length they'll warranty use with a 75gr capacity 6mm cartridge. Chances of a failure are low, but possible going under their ratings. I'd think you'd be okay going 2" less than their suggestions, but you're operating in a gray area there since I really doubt anyone has performed any muzzle pressure/hoop stress testing with a suppressed large capacity 6mm. The largest saami 6mm cartridge to my knowledge is a 240wby which holds roughly 10gr less than the UM. Suppressors do fail from time to time when operating on approved barrel lengths for a given cartridge.

 

[Formidilosus]

You have more experience than myself. Im only going off what I've observed in 18", 22" 24 and 26" using barrels chambered with a saami spec jgs 6cm using same bullet and powder lots. 20" is where I saw the stopping point unless I was building a special purpose built weapon system.

I am certainly not saying anything about what you’ve seen, just going on a lot rifles and barrels that I have. I have used and shot with a bunch of 6mm’s and big 22 cals that started at 22-26” and were cut down to 16-20”. All averaged 20-30fps per inch.

In the beginning- starting around 2009-2010 or so, I fully expected to see terrible loss in MV in short barrels. Back then people thought I was nuts for getting a 300WM with a 22” barrel and not 26”. But, the supposed massive loss in MV never materialized.

 

[85zero17]

My boner is materializing the closer I get to narrowing down the consensus on the barrel config for the DTAC

#latenightoil

 

[sierracharlie338]

After a season of hunting with this 6 UM, just wanted to circle back with an update. I am shooting the 115 Dtac with nose ring, velocity is 3440. I took 4 animals with it, two of which were elk. Both elk were at 500 yards plus, both one shot through the ribs and very quick kills. The Dtacs performed very well on all shots, with one being through the offside shoulder on a bull at 640.

My kids and I have taken 7 animals with a 6 CM and 108 ELDM in the last two years. While all were efficient kills, I have found I prefer the 115 to the 108 as the performance has shown itself to be more predictable when we hit bone. This being said, the 108s have performed well, but I will be switching the kids 6 CM over to 115 next fall based off my experience. with the 115 in the 6 UM.

Overall I am extremely pleased with the 6 UM, I did not change any load data or set up on the rifle during the season. It will be the rifle I use next year, and I don't have any plans of any additions other than hopefully buying some factory brass when available

Best
Kurt

Do you expect any change in performance at the slower speeds of the CM compared to the UM? I know of the DTACS from reading and hearing people that have used them talk about them but no first hand experience.

 

[Wyo_hntr]

All I want for Christmas is a 120gr eldm or tmk. If you will it dude, it is no dream