The 6UM

[Formidilosus]

7mm and Winchester…..

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Your favorites. Don’t lie.

 

[BAKPAKR]

Your favorites. Don’t lie.

I bet Ryan comes around. IIRC correctly, it wasn’t too long ago that he curled his lip at the mention of “Tikka” or any elk cartridge that didn’t start with a 3…

 

[Ryan Avery]

I bet Ryan comes around. IIRC correctly, it wasn’t too long ago that he curled his lip at the mention of “Tikka” or any elk cartridge that didn’t start with a 3…

Never had any issues with Tikkas… back when I was a little girl I played around with a 7mm then I transitioned and will never use a 7mm again.

 

[Formidilosus]

Never had any issues with Tikkas… back when I was a little girl I played around with a 7mm then I transitioned and will never use a 7mm again.

Ok. That was good.

 

[khuber84]

So I went a lil different route. Built a 6saum with the long 6um reamer throat geometry, with 0.552 0.200 line dimensions. Barrel is a Hawkhill 7.75tw rem varm finished at 24" with 5/8x24 muzzle, cut for my Origin short action. It was done just before hunting season. I had loaded 100pcs adg 6saum brass with 57gr H1000/115 dtacNR to break in the barrel. The break in loads showed preference to 25-30k jump and 70-85k jump. I initially tried RL23 with 115 NR dtac and it shot very well at 3220-3240fps, but showed high pressure right at 3300fps. Hunting season started and the rifle was put up. I wanted more speed, so last week I loaded N570 with 115nr at 28k off lands. I usually shoot my pressure tests at 300-400y with each pair of charges shot at seperate points of aim all on a horizontal plane, but fog was so bad, I couldn't see past 150y. Ended up shooting at 100y. Here's my data:

N570 115 -28
62.5 3257,3281
63.0 3287,3287
63.5 3319,3324
64.0 3345,3347
64.5 3377,3393
65.0 3389,3399
65.5 3419,3426
66.0 3465,3461

63-64gr was 6 shots in a half moa group. It opened up above that, but 65.5 did tighten up again. I didn't find bolt lift or ejector marks, however web expansion was growing at 64.5-66gr. Took that data and loaded some for 300y testing seated 28k off.

63.3 3344,3334,3333 2.7"
63.6 3349,3342,3353 1.2"
63.9 3345,3339,3346 1.5"
64.2 3372,3364,3356 1.7"

63.3 was an odd group, as 3344 was 2.5" higher impact of the next two, but the two rounds in 3330 range were just a half inch at 300y.

63.6 and 63.9 had same poi in reference to poa and held good velocity spreads.

64.2 was poor group shape, stringing.

I'm now going to test 63.6gr at a few seating depths around current one to determine the stability and consistency of the load. The rifle liked the longer jumps in inital testing, and may try them as well if decent enough accuracy doesn't repeat itself at the 25-30k jump range. Round count is currently right at 142 rounds, may not be fully stabilized yet, but has to be pretty close.

Attached are the 300y powder test, and the group of 63-64gr at 100y.

 

[brucevalley20]

Man this just keeps getting more tempting I got an aero Solus magnum bolt face that is looking for a barrel and it’s probably gonna be a 6 UM

 

[clperry]

Bergers generally aren’t my preference. They kill fine, including the 108gr. But they have a long neck length in tissue and they don’t exit.

I have around a dozen kills with a 130 vldh from 30 yards to 300 and have yet to not have an exit. I don’t mean that as a challenge at all, but rather more of question as to what you think the difference may be.


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[Formidilosus]

I have around a dozen kills with a 130 vldh from 30 yards to 300 and have yet to not have an exit. I don’t mean that as a challenge at all, but rather more of question as to what you think the difference may be.

I was responding about 6mm Bergers.

 

[clperry]

I was responding about 6mm Bergers.

Understood. Thanks.


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[RWT]

Have to ask the silly question before I put a rifle up for sale. I have a model 7 in 300 SAUM and about 10 boxes of factory ammo. I cannot thread the barrel and stay above 16” so if I can’t run a suppressor it is going to be sold. Before I sell it, is it candidate for a rebarrel in the 6UM ? Is the bolt face the same? If It is a simple rebarrel I may consider keeping it.

 

[IrkedCitizen]

Have to ask the silly question before I put a rifle up for sale. I have a model 7 in 300 SAUM and about 10 boxes of factory ammo. I cannot thread the barrel and stay above 16” so if I can’t run a suppressor it is going to be sold. Before I sell it, is it candidate for a rebarrel in the 6UM ? Is the bolt face the same? If It is a simple rebarrel I may consider keeping it.

The 6UM and 300saum are both magnum bolt faces. If there is room in the magazine then a new barrel is all you need.

 

[CT_MS]

Have to ask the silly question before I put a rifle up for sale. I have a model 7 in 300 SAUM and about 10 boxes of factory ammo. I cannot thread the barrel and stay above 16” so if I can’t run a suppressor it is going to be sold. Before I sell it, is it candidate for a rebarrel in the 6UM ? Is the bolt face the same? If It is a simple rebarrel I may consider keeping it.

Pretty sure it is. The 6UM is based on the SAUM with improved shoulder if I’m not mistaken.

 

[OneSkinnyHunter]

Call Unknown Munitions

 

[Inky_22]

After listening to the podcasts and reading here I’m pretty excited about this whole concept. I shoot a 6dasher for practice and hunt with a 300 wsm. My confidence with the 6mm is solid, but “you NEED a large caliber magnum” was driven into my skull. My dasher doesn’t have the velocity I’d want but my WSM just may need to get re-barreled..

 

[Muledeerfanatic]

I shoot the 109 hybrid out of a 6 creed at 3100 fps
Have had exits on everything from coues deer to cow elk
They work very well
Probably around 20 ish animals

 

[gabenzeke]

I shoot the 109 hybrid out of a 6 creed at 3100 fps
Have had exits on everything from coues deer to cow elk
They work very well
Probably around 20 ish animals

Barrel length?

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[khuber84]

Have to ask the silly question before I put a rifle up for sale. I have a model 7 in 300 SAUM and about 10 boxes of factory ammo. I cannot thread the barrel and stay above 16” so if I can’t run a suppressor it is going to be sold. Before I sell it, is it candidate for a rebarrel in the 6UM ? Is the bolt face the same? If It is a simple rebarrel I may consider keeping it.

The model 7 has a 2.8" magazine box. The trigger group distance doesn't allow bolt stop mods and opening feed port to add a wyatts box like a normal 700 short action. PTG and Badger sell detch mag bottom metal, that utilize aics mags, which give up to 2.97 internal space, which is enough to run the 6um. The model 7 definitely isn't an ideal donor action.

 

[Muledeerfanatic]

Barrel length?

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23"

 

[Floridave]

No, not necessarily. It’s what specific behavior each person weighs most. The DTAC’s below 2,400’ish FPS impact, generally penetrate 4-6 inches then begins to yaw. Sometimes fragmenting and sometimes not. Generally exiting elk, and so far always exiting deer. It also doesn’t really seem to have a lower limit velocity to that upset- at least to around 1,500fps. The benefit is very wide velocity impact range, exits, and good wound channels after 8’ish inches. The con is the neck length and variable behavior.

ELD-M and X’s upset near immediately, about 50% of the time they will exit deer sized animals, or maybe a bit more. They generally do not exit elk, though they consistently do make it to the offside. They have a lower limit of 1,800fps+ impact for consistent upset. Their advantage in tissue is immediate and consistent upset in tissue and a relatively wide and long wound channel. The price is lower limit upset velocity, and reduced chance for exits on large animals.

Berger Hunting, and VLD’s generally penetrate 4-6 inches before yawing and fragmenting heavily. They only sometimes exit deer sized animals, and almost never elk, though consistently make it to the offside. They have a lower limit impact velocity of 1,900 to 1,800fps. On chest shots, the neck length and rapid fragmentation generally occurs center of the chest cavity, and on the whole will result in the fastest time to incapacitation. The cost, is that long neck length, lack of exits, and somewhat variable performance.



For me-

DTAC’s- very good elk bullets. Ok I’m deer, would not use on black bear by choice.

ELD-M/X- Consistent and solid performance in all animals. Excellent in deer and bear, good in elk. The 103gr ELD-X I need more experience with, and will get more this year.

Berger Hunting/VLD- on good chest shots very good wounding. On high or low edge hits, the neck length can and will result in minimal wounding. For me they are not my choice for how and what I hunt, and how animals are missed or wounded.

Is there anything else that can be done to the DTAC's to shorten that neck length specifically for deer? Filing or cutting the tip? I ask because my initial testing has them shooting better than the Hornady and Berger bullets I've tested, I'd love to have 1 bullet and load for everything target and hunting, but my hunting is currently 95% whitetail inside 300 yards.

 

[Formidilosus]

Is there anything else that can be done to the DTAC's to shorten that neck length specifically for deer? Filing or cutting the tip? I ask because my initial testing has them shooting better than the Hornady and Berger bullets I've tested, I'd love to have 1 bullet and load for everything target and hunting, but my hunting is currently 95% whitetail inside 300 yards.

No. But at sub 300y impact velocities they fragment well.