Sierra Heavy TMK 6MM Testing

[amassi]

Is that fairly low for what should be expected with a 116? The 108 eh is a .287

I think the goal is maximum effectiveness on game and not maximum BC
That big hollow point and general TMK form factor will keep BC lower


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[Carl Ross]

Is that fairly low for what should be expected with a 116? The 108 eh is a .287

It's a little low from what would be possible if optimizing only for BC. As amassi noted that wasn't the sole aim on this projectile, and many things are compromises. I won't speak to the terminal side, you'd be better off reading what Form has covered there. Regarding external ballistics, if you look closely through what Litz has published, you will find his data shows often the bullets most optimized for BC will show less BC consistency bullet to bullet.

What's the barrel length on that 243? I was hoping these might work for my Tikka 243. Mine is throated out 0.100 and I use LA mags, so I can cram a good bit of h1000 in there for the 115-117 should I get them.

That's a 22", loaded 41.0 gr H4350 for it tomorrow, we'll see...

 

[mxgsfmdpx]

This thread is changing my outlook on running a 16” 6 Creed build. Specifically with the talk of the 107 TMKs


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16” 6 Creed is the way





115 Bergers.

 

[mxgsfmdpx]

I think the goal is maximum effectiveness on game and not maximum BC

As it should be

That big hollow point and general TMK form factor will keep BC lower


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And totally worth it. I’ll jump from the 115 Bergers to the heavy sierras if…

1. I can ever get them.
2. They fly true and are as easy to load for (seems like a win so far).
3. They kill like the 95 TMKs and 103 ELDXs.

 

[CJ_BG]

Just as I was wrapping up design on a 113-118gr prototype to get dies made for.

Oh well, might still do it. Not sure how much commercial viability that would have now but personal projects are always fun

 

[mxgsfmdpx]

Sounds like we need a research group to volunteer for a NZ or AUS culling trip. NZ for goats and deer , AUS for camel (elk size animal). I’ll volunteer to organize, but likely need Sierra to call and explain to my wife that my presence is critical.

I have contacts (friends) in both NZ and OZ if you need assistance.

 

[mxgsfmdpx]

View attachment 984652

First pitch with a Tikka 243 1-8 - factory barrel. This rifle usually shoots around 1.0's for 10 with 109 ELD-M's. Was a little concerned there could be twist issues, but it doesn't seem like it. ~ 4500 DA today.

Had to jump ~ .040" to fit in the M+ mags, that's where these were seated.

40 gr H4350 gave low 2800's. No pressure signs, lots of radius left on the primers, could turn it up a bit for certain.

Two bullets put 10 rounds into 1.1's, one was .8's.

Shot the 116's at 1011, a .290 G7 worked out just right. There was some wind in some terrain, so take that for what it's worth. The 7 rounds I shot at distance had very low vertical, less than the mechanical size of the group at 100.

More to come.

View attachment 984662

My stock pile of 8 twist Tikka .243 barrels says bless you!

And for folks wondering, these barrels work great on rechambered 6CM Tikkas.

 

[HighUintas]

And for folks wondering, these barrels work great on rechambered 6CM Tikkas.

Are you saying Tikka factory 243 barrels rechambered to 6cm work well?

 

[khuber84]

Are you saying Tikka factory 243 barrels rechambered to 6cm work well?

That's not possible without setting it back.

 

[mxgsfmdpx]

Are you saying Tikka factory 243 barrels rechambered to 6cm work well?

I save the Tikka barrels mainly for my 243s but I’ve had the smith chamber them onto my 6 creeds as well. They don’t just twist on and go if that’s what you’re asking sorry. I was unclear as usual.

 

[Gribley]

Do you guys think the 115/116/117 will be too heavy for a 6 arc?

 

[bonepoint]

When the pics were shown comparing the bullets to the ELD, construction looks very similar.

What about antimony % for the core? Do you know what each manufacturer uses for each of these bullets it is being compared to? I know that % antimony varies depending on manufacturer, model, and use design - and has a significant impact on wound channel shape. Or maybe their is a standard % across the industry for match bullets?

I have used the Lapua scenar 155g in a 308, which looks to have a similar design (probably actually a LARGER open cavity behind the hollow point), yet it is a harder bullet that penetrates deep and does not fragment much. While it is a "match" bullet, it seems to be made with a much higher percentage of antimony in the core.

 

[43.6N]

Do you guys think the 115/116/117 will be too heavy for a 6 arc?

Depends on your application.
I couldn’t find any published data for 6ARC heavier than 110gr.

But for example:
24” barrel
110gr Hornady manual lists 30gr cfe223 going about 2700fps at 62kpsi
110gr Hodgdon manual lists 28gr cfe223 going 2600fps at 55kpsi
110gr Sierra manual lists 31.3gr cfe223 going 2800+ at “bolt gun” pressures. (FYI I’ve popped primers and had case head separations at Sierra book max loads for a different cartridge)

I’d say a safe expectation would be 28-30gr of cfe223 with a 115gr bullet would be in the 60kpsi range. Probably doing 2600fps out of a 24” barrel. 2450 out of an 18” barrel.

If that sounds like it fits your application, then have at it. I think the 95gr TMK would be a better fit for the application, but don’t let that stop you. I mean they made the 338 arc for crying out loud!