Sierra Heavy TMK 6MM Testing

[mtnbound]

116 TMK, 2.90coal, 16.5” PBB 7.5” twist, Hornady brass, Fed215M.
Left - N555, 42.5gr, 2680av, 22sd
Middle - H4350, 41gr, 2680av, 9.5sd
Right- Staball65, 42gr, 2622av, 12.8sd

 

[huntnful]

116 TMK, 2.90coal, 16.5” PBB 7.5” twist, Hornady brass, Fed215M.
Left - N555, 42.5gr, 2680av, 22sd
Middle - H4350, 41gr, 2680av, 9.5sd
Right- Staball65, 42gr, 2622av, 12.8sd

Looks beautiful. H4350 is tough to beat!!

 

[Q_Sertorius]

116 TMK, 2.90coal, 16.5” PBB 7.5” twist, Hornady brass, Fed215M.
Left - N555, 42.5gr, 2680av, 22sd
Middle - H4350, 41gr, 2680av, 9.5sd
Right- Staball65, 42gr, 2622av, 12.8sd

6 CM?

 

[Kaleb]

I think a 1-8" is on the bubble. Hopefully a powder change fixes everything but if not 1-8 might be marginally stable back this way. I've chased my tail before with a 1-9.

 

[Sako300]

I’m having issues as well with the TMK 107’s and factory Tikka .243 1-8’’ 20 inch. Both H4350 and H1000 loads. Best I can get is 1.25’’
108 eldms group .5 -.75 moa. At a higher, consistent velocity. Probably will stick with the 108s.

 

[Q_Sertorius]

I’m having issues as well with the TMK 107’s and factory Tikka .243 1-8’’ 20 inch. Both H4350 and H1000 loads. Best I can get is 1.25’’
108 eldms group .5 -.75 moa. At a higher, consistent velocity. Probably will stick with the 108s.

Do you mind sharing the loads you tried with each powder? And your COAL?

 

[Sako300]

Is this a tikka? If so this is a silly stance to take when loading LONG bullets since M+ length mags (~2.97") work just fine in the same gun (same bolt stop). If you have interest in loading LONG bullets try loading them closer to the lands (single load them) and see if they improve, then you know if its worth pursuing the easy route of a longer M+ mag or not without having to buy anything initially. If they don't improve then different powder, etc. or move on from the bullet.

I tried loading my 20 thousands off! 2.920.
Still no bueno!

 

[Sako300]

Do you mind sharing the loads you tried with each powder? And

Do you mind sharing the loads you tried with each powder? And your COAL?

20 thousands off
2.920 on my Tikka

 

[huntsd]

That would work.

The carbon shouldn't cause too many problems, as long as it's consistent.

What about the rifle? How fouled is the bore? Is there a carbon ring built up? Those things can affect bullet release and cause speed variation.

Has 100 down the tube. I cleaned at 20 so I doubt it’s that? Going to try primer swap. Will report back.

Thanks rokslide! Always a huge help!

 

[YaakRiver]

I've got a 6mm ARC in a Tikka action. Kempfield modified the bolt face from .378 to .445 (PPC) and UM chambered and installed the 20" ACE barrel. I'm getting 2740 FPS with 108 ELD-Ms 25 thou off the lands over 30 gr of Staball Match in Starline brass. Not statistically relevant but still nice to look at:

 

[mtnbound]

6 CM?

Yes, 6CM, that would have been helpful if I had added what the hell I was shooting.

 

[Sako300]

20 thousands off
2.920 on my Tikka

H4350 41.5 gr, 42 gr (shoots .5 moa with 108 eldms 2945 fps)
H1000 48.2 gr. 47.3 (definitely need to load long .020ths because of powder amount
Starline brass
Fed 210M

 

[Pistolpete28]

I’m having issues as well with the TMK 107’s and factory Tikka .243 1-8’’ 20 inch. Both H4350 and H1000 loads. Best I can get is 1.25’’
108 eldms group .5 -.75 moa. At a higher, consistent velocity. Probably will stick with the 108s.

This is my exact experience with the 107 tmk and the 108 eldms out of a tikka 243 with h1000

 

[ckt3]

Would you all do 7 or 7.5 twist for an 18" 6 ARC shooting 95 and 107 TMK likely.

Other potential bullets if those don’t shoot well could be the standard recs around here.. 105 HPBT, 95 NBT, 103 ELDX, 108 ELDM.

I think 7 should be ok and has slight benefit of shooting even heavier bullets. 95 TMK may get 2650-2750 fps with a fairly stable powder or higher with lever. Is there a risk of over rotating the 95s? Could do 7.5 if it'd be better for the 95's and just as good for everything else

PVA Osprey if that makes a difference.

 

[Jordan Smith]

Would you all do 7 or 7.5 twist for an 18" 6 ARC shooting 95 and 107 TMK likely.

Other potential bullets if those don’t shoot well could be the standard recs around here.. 105 HPBT, 95 NBT, 103 ELDX, 108 ELDM.

I think 7 should be ok and has slight benefit of shooting even heavier bullets. 95 TMK may get 2650-2750 fps with a fairly stable powder (?). Not sure how much of a risk over rotating these bullets is... could do 7.5 if it'd be better for the 95's and just as good for everything else

PVA Osprey if that makes a difference.

There's no downside to going 7", IMO.

 

[coya]

It dawned on me that the 107 & 116 both require the same 7.5 twist. For whatever reason, in my head they were different

 

[Castle Rock]

I've got a 6mm ARC in a Tikka action. Kempfield modified the bolt face from .378 to .445 (PPC) and UM chambered and installed the 20" ACE barrel. I'm getting 2740 FPS with 108 ELD-Ms 25 thou off the lands over 30 gr of Staball Match in Starline brass. Not statistically relevant but still nice to look at:
View attachment 1052033

It is relevant, guns that do that keep doing that.
Work on your trigger control, that is where horizontal at 100 comes from.

There's no downside to going 7", IMO.

Unless you are sending them real fast, I would definitely go 7 in an arc.

 

[bhylton]

Do you mind sharing the loads you tried with each powder? And your COAL?

For what it’s worth, my factory tikka 243 shoots the 107 to about 1.5-1.7 (3 - 10rd groups). I’m using H3450 and have tried loaded short and long.
Rifle shoots everything else 1-1.5moa. Several 1.0-1.2in 10shot groups with 108 Eld m.

Seems like everyone is trying to tell you something is wrong, but I have seen several reports of factory tikkas shooting this bullet around 1.5-1.7. Might just be the way it is.

 

[KyleR1985]

Would you all do 7 or 7.5 twist for an 18" 6 ARC shooting 95 and 107 TMK likely.

Other potential bullets if those don’t shoot well could be the standard recs around here.. 105 HPBT, 95 NBT, 103 ELDX, 108 ELDM.

I think 7 should be ok and has slight benefit of shooting even heavier bullets. 95 TMK may get 2650-2750 fps with a fairly stable powder or higher with lever. Is there a risk of over rotating the 95s? Could do 7.5 if it'd be better for the 95's and just as good for everything else

PVA Osprey if that makes a difference.

I have 7 twist 6ARC and 6dasher that both shoot the 95 TMK’s well at 2700 and 2800 fps respectively. If I knew I wouldn’t be anywhere near 3000fps I’d spec 7 twist with a new barrel. There’s no downside at the speeds the ARC will make.