Sierra Heavy TMK 6MM Testing

[Chris in TN]

I used the 107 TMK projectile that was on the discord. using 53.3 for case capacity (SigSauer brass)


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So, to be clear here, I don't have a 6cm, but I have used GRT a lot with a lot of calibers.

Your case capacity is significantly larger than what I would have expected, but then again I am using Peterson brass (in my 6.5cm) and am used to it and its thicker walls or lower capacity.

If that 53.3 figure is accurate, you're probably ok.

What length barrel and what speed are you getting thus far?

 

[HNTR_NW]

@Formidilosus what is the lower limit of velocity for the TMK from what you and people you are around have seen?

Specifically where the tmk 6mm’s and 6.5’s do not consistently upset and fail to produce larger than “ice picking” size wounds.

Thanks!

 

[philcox]

I used the 107 TMK projectile that was on the discord. using 53.3 for case capacity (SigSauer brass)


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Just measured … 50.5 and 51 … for new brass


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[cq0302]

Got my 116s, put in my rifle build.

Terminus Kratos Lite
PPB 18” 7 twist (hopefully this is right?)
Manners Pro Pack Folder

6um-40?


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[Bluumoon]

Seems like a lot of folks are running around 41 or 41.5 each 4350 for the 107 TMK in the sixth Creed. I’m looking at GRT, and 42.5 isn’t even at pressure. Wondering if I am missing something?

41.5 has no pressure signs. I’m gonna try 42 and 42.5, but wondering why others not pushing similar?


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One of my rifles showed pressure at 41.5gr. Admittedly, I did not check lands.

 

[Formidilosus]

@Formidilosus what is the lower limit of velocity for the TMK from what you and people you are around have seen?

Specifically where the tmk 6mm’s and 6.5’s do not consistently upset and fail to produce larger than “ice picking” size wounds.

Thanks!

No one knows. I haven’t found the lower limit of any TMK. 1,440fps (IIRC) with the 77’s, 1,700fps with the 116gr and 107gr 6mm, 130gr 6.5, and 168 and 175gr 30cal: all have upset correctly.

I still say 1,800fps impact to be safe, but I honestly don’t know.

 

[Hurley88]

Seems like a lot of folks are running around 41 or 41.5 each 4350 for the 107 TMK in the sixth Creed. I’m looking at GRT, and 42.5 isn’t even at pressure. Wondering if I am missing something?

41.5 has no pressure signs. I’m gonna try 42 and 42.5, but wondering why others not pushing similar?

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I’ve only loaded up 20 for a couple 10-shot groups, just used the same charge in 6CM as I use for the 109 ELDM. I intend to use these in 6ARC if the ‘smith will ever get it finished.

So I never ramped things up bc it’s not a bullet I’ll use in that cartridge. I’d probably have gone up to 41.5 though, doubt I’d have pushed higher due to results with similar weight bullets. I tend towards the shallow end of the pool until published load data becomes available.

 

[HNTR_NW]

No one knows. I haven’t found the lower limit of any TMK. 1,440fps (IIRC) with the 77’s, 1,700fps with the 116gr and 107gr 6mm, 130gr 6.5, and 168 and 175gr 30cal: all have upset correctly.

I still say 1,800fps impact to be safe, but I honestly don’t know.

Interesting. I appreciate the response. I have been using the 147 and 143eldx primarily, but after using the 77gr tmk and seeing its results first hand in multiple animals I’m curious about testing them in other calibers this year. I may have to load up some 130s or 116s for this season. Thank you.

 

[Chris in TN]

Just measured … 50.5 and 51 … for new brass


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Please note that 50.5 and 51 are significantly different than 53.3. I’d measure them when once fired then resized to get a better idea of full capacity.

You’ll probably be around 52 grains with 1x fired. If that’s ~1.3 grains less than what you are currently inputting into GRT, expect its predicted max charge to be ~1 grain lower.

Those are spitballed numbers. Don’t go making ammo from them. Measure your 1x fired capacity, adjust it in GRT, and work up slowly from there.

Do you have a chronograph?

 

[philcox]

Please note that 50.5 and 51 are significantly different than 53.3. I’d measure them when once fired then resized to get a better idea of full capacity.

You’ll probably be around 52 grains with 1x fired. If that’s ~1.3 grains less than what you are currently inputting into GRT, expect its predicted max charge to be ~1 grain lower.

Those are spitballed numbers. Don’t go making ammo from them. Measure your 1x fired capacity, adjust it in GRT, and work up slowly from there.

Do you have a chronograph?

Yup. Garmin. I loaded up a 42 and 42.5, we’ll see what I get for speed and pressure.

Gonna try tomorrow and will respond here.


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[Plague]

First 10 round group with the 107 tmk in my 6 arc tikka. 31.5 gr of lever. Seated the boat tail at the neck junction. Didn’t have a chrono with me. So no idea of muzzle velocity. Prone off my pack with my sleeping bag liner in a sack for a rear support. Gonna have to move my zero if I run with this load. Which I think I will