The 6UM

[Dobermann]

Yes. It’s a Canadian Belt Knife style. The Cold Steel is fine, I was trying the blade shape- it’s excellent for skinning and quartering.

Huh ... with your love of natural materials and closet nostalgia, is there a reason you didn't go for the Grohman #1?

 

[amassi]

What y'all using for bottom metal, hinged floor plate or det mag setups?

I ask because I'm building a 25 SAUM on a BAT Igniter short action and the short mags don't always feed the greatest so I'm not sure if a 3.100 Baney box and hinged floor plate will feed fine or if I should go with a UM det mag setup with their short XL mags. Shooting the new 134 ELD-M and they are a longggggg ass bullet so something 3.100 - 3.100+ will be a must but I want it to feed well too.

Since you 6 UM guys are using the same parent case, except slightly blown out, I figured y'all would know what setup feeds best with the short fat magnum cases.

If I were building a saum on a non tikka I would use a Wyatt’s center feed or um magazine


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[Formidilosus]

Huh ... with your love of natural materials and closet nostalgia, is there a reason you didn't go for the Grohman #1?

Because I needed it right then, and I was not sure I would like the blade shape. A new one will be procured.

 

[B23]

If I were building a saum on a non tikka I would use a Wyatt’s center feed or um magazine


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I have a Wyatt's 3.100 Baney box to use but I'll need to get a Hawkins hinged floor plate, BUT, if the UM det. mag setups feed these short fat stubby cases, better, then I'll go with one of those instead.

My concern is I don't want to spend the money for a Hawkins BDL setup with my Wyatt's 3.100 mag box just to find out it doesn't feed very well and I should have bought the UM Det. Mag. system from the start because they feed reliably more better'er.

Not trying to muddy up or hijack the 6UM topic but I just thought y'all would know the answer to what works best since some of you have already been down this road and you'd know what works best.

 

[Ryan Avery]

How does it compare to 6 PRC?

Hard to say for sure, barrels vary a lot and I only have data from two 6 PRC that I trust.

I would estimate around 125 to 150 FPS more velocity with the 6UM.

 

[khuber84]

What y'all using for bottom metal, hinged floor plate or det mag setups?

I ask because I'm building a 25 SAUM on a BAT Igniter short action and the short mags don't always feed the greatest so I'm not sure if a 3.100 Baney box and hinged floor plate will feed fine or if I should go with a UM det mag setup with their short XL mags. Shooting the new 134 ELD-M and they are a longggggg ass bullet so something 3.100 - 3.100+ will be a must but I want it to feed well too.

Since you 6 UM guys are using the same parent case, except slightly blown out, I figured y'all would know what setup feeds best with the short fat magnum cases.

Measure the load port on the bottom of the igniter, it needs be over 3.150 to use the dbm from UM. Make sure to be measuring from front to rearest most position of bolt stroke.

 

[Formidilosus]

I hate FFing brass. But we didn’t end up with the 6UM by accident. You would be hard pressed to get more performance out of a SA 6mm case.


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To put a finer point on it- the 6 UM is a hell of a round in performance. Never mind when recoil produced is factored in. It has a beyond 1,200 yard terminal range with multiple bullets from a 20” barrel. Ryan and Jake/UM did a good job on it.

Quite frankly by the time that the 6UM isn’t doing it for hit rates and wound channel size, I am into massive 338’s, 30+ inch barrels, portable benches, return to battery rests, and sighter shots.

 

[Formidilosus]

Yeah that’s a good point. Lethal for sure, eventually. Do you see that impact velocity directly correlates to how quickly a bullet will tumble upon impact if it doesn’t completely fragment?

I over looked this post- Not really. The higher the velocity, the more consistent the fragmentation is however. The DTAC’s have tumbled and/or upset from over 3,000fps impact, to mid 1,500fps impacts.

I’m not a fan of tumbling bullets in case you can’t tell haha. It doesn’t seem consistent enough to me.

It generally isn’t. I would have to look but I/we are over 20, and probably 30 elk with the NR DTAC’s and this shot was the only wound channel that has not been very good. Again, most likely due to the stomach contents. Tumbling is not my preference, however it can be very effective and is about the best way to get very large wounds that also tend to exit.

As an aside, of everything we have shot, the 6mm’s with DTAC’s have averaged less rounds per elk than any other combo. It’s about 2.something shots per elk before they cease all movement. For reference- 30cals are about 4.5 shots per.

 

[huntnful]

I over looked this post- Not really. The higher the velocity, the more consistent the fragmentation is however. The DTAC’s have tumbled and/or upset from over 3,000fps impact, to mid 1,500fps impacts.




It generally isn’t. I would have to look but I/we are over 20, and probably 30 elk with the NR DTAC’s and this shot was the only wound channel that has not been very good. Again, most likely due to the stomach contents. Tumbling is not my preference, however it can be very effective and is about the best way to get very large wounds that also tend to exit.

As an aside, of everything we have shot, the 6mm’s with DTAC’s have averaged less rounds per elk than any other combo. It’s about 2.something shots per elk before they cease all movement. For reference- 30cals are about 4.5 shots per.

Thanks for the reply! And at 20-30 elk with the bullet, or 40-60+ bullet terminal performance assessments, having one mediocre wound channel at an extended range is really no cause for concern at all. Especially when it’s followed up by 3 well performing rounds in a few seconds haha.

 

[Castle Rock]

As an aside, of everything we have shot, the 6mm’s with DTAC’s have averaged less rounds per elk than any other combo. It’s about 2.something shots per elk before they cease all movement. For reference- 30cals are about 4.5 shots per.

I guess I am not the only one who is surprised by those numbers
Would that be a result of better ballistics enabling better shot placement

 

[Formidilosus]

I guess I am not the only one who is surprised by those numbers
Would that be a result of better ballistics enabling better shot placement

It seems to be a combination of things. Primarily that the 6mm’s are shootable enough that most watch exactly where the bullet hits and can immediately place an extremely precise follow up shot. Also, most have been killed with one particular 6mm and that rifle is the most shootable rifle I have personally shot.

For me personally that is it. I watch the bullet strike, can read it and then correct and place the next in the upper CNS. Probably 3/4 of the elk I have killed with the 6XC has been one shot to the chest, then an immediate follow up to the high neck/head.

 

[ElPollo]

I over looked this post- Not really. The higher the velocity, the more consistent the fragmentation is however. The DTAC’s have tumbled and/or upset from over 3,000fps impact, to mid 1,500fps impacts.




It generally isn’t. I would have to look but I/we are over 20, and probably 30 elk with the NR DTAC’s and this shot was the only wound channel that has not been very good. Again, most likely due to the stomach contents. Tumbling is not my preference, however it can be very effective and is about the best way to get very large wounds that also tend to exit.

As an aside, of everything we have shot, the 6mm’s with DTAC’s have averaged less rounds per elk than any other combo. It’s about 2.something shots per elk before they cease all movement. For reference- 30cals are about 4.5 shots per.

Form,

I might be totally misunderstanding what you are saying about this bullet, but I’m hung up on something you said a couple of pages ago:

“The DTAC’s general behavior is to penetrate several inches then yaw (tumble) about half the time fragmenting some when they do, about half the time not.”

I recognize that upset rates are velocity dependent, but I’m having difficulty squaring this 50% upset rate statement with the velocity range you stated above. Personally, I’ve had less than spectacular results with other bullets that are designed to tumble and fragment. All of those I would prefer to keep my impact velocities above 2k to actually fragment. At that speed, I still expect to see long necks in the wound channels with most of the damage happening on the back side of the animal. You mentioned the 1550 fps number above, but what would you estimate a minimum impact velocity for this bullet to reliably upset? Let’s say for argument’s sake that reliable is maybe 85%.

 

[Formidilosus]

Form,

I might be totally misunderstanding what you are saying about this bullet, but I’m hung up on something you said a couple of pages ago:

“The DTAC’s general behavior is to penetrate several inches then yaw (tumble) about half the time fragmenting some when they do, about half the time not.”

I recognize that upset rates are velocity dependent, but I’m having difficulty squaring this 50% upset rate statement with the velocity range you stated above. Personally, I’ve had less than spectacular results with other bullets that are designed to tumble and fragment. All of those I would prefer to keep my impact velocities above 2k to actually fragment. At that speed, I still expect to see long necks in the wound channels with most of the damage happening on the back side of the animal.

That is what generally happens on deer sized game below 2,400’ish fps. The yawing starts about where the offside lung begins on a broadside animal and exits with an obvious yaw. It kills fine, but is not my preference for smaller game as I greatly want a short neck length, and immediate upset.
In elk the yawing seems to happen about mid way through the onside lung, and is fully tumbling by the offside lung, almost always exiting and causing very good wounds.

In elk sized game I like them quite a bit. In deer sized game I don’t prefer them, but they do kill fine. All of this is at lower impact velocities. If your impacts are generally above 2,400’ish FPS, the DTAC’s are very destructive, even in deer.

You mentioned the 1550 fps number above, but what would you estimate a minimum impact velocity for this bullet to reliably upset? Let’s say for argument’s sake that reliable is maybe 85%.

If by upset you mean fragmenting to a significant degree, about 2,400fps impact for the standard NR and 2,300-2,200fps for the “deep cut” version. The “issue” is that about half of the bullets in the 1,900fps impact range or below have either fragmented significantly or have expanded as one would expect an ABLR to do.

 

[Balderdash]

That is what generally happens on deer sized game below 2,400’ish fps. The yawing starts about where the offside lung begins on a broadside animal and exits with an obvious yaw. It kills fine, but is not my preference for smaller game as I greatly want a short neck length, and immediate upset.
In elk the yawing seems to happen about mid way through the onside lung, and is fully tumbling by the offside lung, almost always exiting and causing very good wounds.

In elk sized game I like them quite a bit. In deer sized game I don’t prefer them, but they do kill fine. All of this is at lower impact velocities. If your impacts are generally above 2,400’ish FPS, the DTAC’s are very destructive, even in deer.





If by upset you mean fragmenting to a significant degree, about 2,400fps impact for the standard NR and 2,300-2,200fps for the “deep cut” version. The “issue” is that about half of the bullets in the 1,900fps impact range or below have either fragmented significantly or have expanded as one would expect an ABLR to do.

I apologize if this has already been covered in detail, but is this consistent yawning or keyholing performance a deliberate design characteristic or an unintended consequence?

So long as its consistent and inflicts the requisite amount of tissue damage, its not that it ultimately matters in the context of terminal efficacy, but I've seen this a time or two with other bullets through the years (IIRC, it was with the lower shanks of partition style bullets) and it's never left me feeling warm and fuzzy, eventough I was still examining a dead animal. My main concern would be adequate penetration for less than ideal shot angles. Perhaps the wound channel stays more linear when cleaved through more animal mass? Perhaps my concern is misplaced; however, I haven't carefully examined enough suchlike terminal performance to draw definitive conclusions.

 

[Formidilosus]

I apologize if this has already been covered in detail, but is this consistent yawning or keyholing performance a deliberate design characteristic or an unintended consequence?

In this case it was not designed for yawing, it’s just does relatively consistently shallow enough to be useful.
The idea behind the nose ring was that is would break off and leave an open cavity similar to a tipped bullet. However, the mechanism is different. A plastic tip peels out from getting squished from impact, then reveals the large nose opening required for upset from the front. This happens within the first inch of penetration. The DTAC Nose Ring tip must be ripped off, generally pushed sideways below high velocity. The action required to make the tip come off requires a sideways force on it- aka, yawing.

My main concern would be adequate penetration for less than ideal shot angles. Perhaps the wound channel stays more linear when cleaved through more animal mass?

That’s the beauty of the DTAC NR- they penetrate really well even while yawing. Around 80% have exited even when going through very steep angles and hitting large bones.

 

[atmat]

@Formidilosus — so have you decided that the 115 DTAC is your bullet of choice for 6UM, or do you still need to see more animal autopsies? How many will it take to be confident?

I really like the idea of a bullet that does massive damage while still also exiting.

 

[ElPollo]

That is what generally happens on deer sized game below 2,400’ish fps. The yawing starts about where the offside lung begins on a broadside animal and exits with an obvious yaw. It kills fine, but is not my preference for smaller game as I greatly want a short neck length, and immediate upset.
In elk the yawing seems to happen about mid way through the onside lung, and is fully tumbling by the offside lung, almost always exiting and causing very good wounds.

In elk sized game I like them quite a bit. In deer sized game I don’t prefer them, but they do kill fine. All of this is at lower impact velocities. If your impacts are generally above 2,400’ish FPS, the DTAC’s are very destructive, even in deer.





If by upset you mean fragmenting to a significant degree, about 2,400fps impact for the standard NR and 2,300-2,200fps for the “deep cut” version. The “issue” is that about half of the bullets in the 1,900fps impact range or below have either fragmented significantly or have expanded as one would expect an ABLR to do.

Thanks, Form. That helps and makes me lean back towards slower moving stuff with more predictable bullets.

 

[Formidilosus]

@Formidilosus — so have you decided that the 115 DTAC is your bullet of choice for 6UM, or do you still need to see more animal autopsies? How many will it take to be confident?

I really like the idea of a bullet that does massive damage while still also exiting.

For elk it is right now and I have no real issues with them for that. It is not my ideal though, as that bullet doesn’t exist yet.

I also want to see some animals with really high impact velocities from the 103gr Eld-X, 108gr ELD-M, and more with the 112gr MatchBurners.
The 103gr ELD-X in particular may be solid for the UM. It is in the 2,800’ish FPS to 2,100’ish FPS impact velocity range from 300 yards to near 800 yards which is where most of my killing is done at. At those speeds it might be close to ideal.

 

[atmat]

The 103gr ELD-X in particular may be solid for the UM. It is in the 2,800’ish FPS to 2,100’ish FPS impact velocity range from 300 yards to near 800 yards which is where most of my killing is done at. At those speeds it might be close to ideal.

Are you thinking ELD-X over ELD-M because the M will be too frangible at 6UM speeds?

 

[Formidilosus]

Are you thinking ELD-X over ELD-M because the M will be too frangible at 6UM speeds?

Not really too frangible. The ELD-M has more of a round shape to the wound channel which is quite effective, whereas the ELD-X is typically more of an elongated football. That football shape wound is the one I am looking for.


Any of them would be perfectly fine for killing- ELD-M, ELD-X, 112gr MB, Hornady 105gr HPBT, DTAC NR, etc. I am just being picky.