Sierra Heavy TMK 6MM Testing

[gabenzeke]

I ordered a custom build from UM and said I wanted to shoot the 116 tmk. They suggested a 7.5 twist. On the most recent podcast they said a 7.5 would lose some bc. How much am I giving up? Should I be reaching out and asking them to change this? It's been a few weeks so not even sure I can make the change.

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[B_Reynolds_AK]

I ordered a custom build from UM and said I wanted to shoot the 116 tmk. They suggested a 7.5 twist. On the most recent podcast they said a 7.5 would lose some bc. How much am I giving up? Should I be reaching out and asking them to change this? It's been a few weeks so not even sure I can make the change.

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I heard that too and was thinking the same thing, as the 16” 6 CM will only be sending them at 2750-2800 fps. & want the BC to hold up to 1,000-1200 yards.

 

[Matt5266]

I would think a 7.5 would be perfect

 

[IrkedCitizen]

Not enough to matter for the distances I shoot

 

[ImperialBull]

I ordered a custom build from UM and said I wanted to shoot the 116 tmk. They suggested a 7.5 twist. On the most recent podcast they said a 7.5 would lose some bc. How much am I giving up? Should I be reaching out and asking them to change this? It's been a few weeks so not even sure I can make the change.

Sent from my Pixel 9 Pro XL using Tapatalk

And I believe he said he was going to a 1-7” in a 6um too. My three 6 creed barrels are 1-7.5 so it is what it is for me but I think it’ll be ok.

 

[WyldGoose]

My 18” 6cm is a 7 twist but I don’t reload. Kinda tempted to start just to try these 116’s…

 

[Treelineasassin]

And I believe he said he was going to a 1-7” in a 6um too. My three 6 creed barrels are 1-7.5 so it is what it is for me but I think it’ll be ok.

3300mv from 7 tw, that's 340K rpm. I'd sacrifice a lil bc for less probability of jacket failure in flight. I shot some the 115-117 prototypes, 300g7 was what I needed for proper dope(860y) from a 7.5tw at 2870mv. I don't think you're losing much from 7.5 VS 7.

 

[justin davis]

I’m shooting a 1:7.5 twist. Seems to be working g just fine.

5 shots with the 116’s from 100 yards with 42 grains of N555. When I get some time I plan to shoot long range

 

[JM151]

I ordered 7 for my 6UM build, that was couple weeks ago

 

[B_Reynolds_AK]

Just text with Jake and emailed Blaine.
Jake said that my 6 Creed already would be 7 Twist. Blaine updated my Build to specify 7, in either an Ace or Benchmark. I don't really have a preference, just told him whichever is available soonest.

As this 16" 6 CM will be purpose made for the 116's, I figure it may as well be completely optimized per Sierra's guidance.

 

[schmidty3]

I have no idea what im doing, but at sea level (which i am) the stability numbers looked better with the 1:7" on the ab app.

Ive got a 18" 6 creed pbb coming.

 

[Jordan Smith]

I ordered a custom build from UM and said I wanted to shoot the 116 tmk. They suggested a 7.5 twist. On the most recent podcast they said a 7.5 would lose some bc. How much am I giving up? Should I be reaching out and asking them to change this? It's been a few weeks so not even sure I can make the change.

Sent from my Pixel 9 Pro XL using Tapatalk

In general, for a stability coefficient (SG) between 1.0-1.5, you lose about 3% of BC per 0.1 SG below 1.5.

I’d be in 1:7” twist mode, for sure.

 

[wind gypsy]

I ordered a custom build from UM and said I wanted to shoot the 116 tmk. They suggested a 7.5 twist. On the most recent podcast they said a 7.5 would lose some bc. How much am I giving up? Should I be reaching out and asking them to change this? It's been a few weeks so not even sure I can make the change.

What cartridge and how low of a DA would you want it to be stable at?

 

[nphunter]

The 107’s out of the .243 worked great on a big spring bear. A little over 400 yards, shot was me laying side hill using a rock as a rest on a steep hillside. Bear was quartered toward and facing downhill, first shot entered though the top of his front shoulder with no exit. He dropped but was squirming, shot again shot went lower shoulder while he was on his back into vitals, no exit, still moving and I didn’t want him to move, shot again in the neck, no exit and he stopped moving.

First shot killed him, he ended up on a road that if he would have left if still be getting him out of the canyon. He’s 381lbs, 7’ long with flat teeth to his gums.

 

[806guns]

6-284 116gr
3.150 oal
This places the boat tail just under the neck. Not sure if its ideal or not. Buddy has a .150 freebore barrel. Will see where his barrel has them seated at and go from there.

 

[BearGuy]

I tested 5 shot groups with 40.0gr (2812 fps avg), 40.5gr (2806 fps avg), 41.0 gr (2824 fps avg) of H4350 with 116 TMK, 2.80" COAL. 18" 6 Creed tikka w/prefit, 200 rounds down the barrel. Saw best accuracy (0.7" 5-shot) with 40.0gr, barely any velocity gain going to 41gr, group size opened up more as I went up in charge. Going to retest at 2.850" at 40.0gr and 41.5gr just to see, have a bit more room in std tikka mag.

Is that the M or M+ magazine?

 

[Sako300]

The 107’s out of the .243 worked great on a big spring bear. A little over 400 yards, shot was me laying side hill using a rock as a rest on a steep hillside. Bear was quartered toward and facing downhill, first shot entered though the top of his front shoulder with no exit. He dropped but was squirming, shot again shot went lower shoulder while he was on his back into vitals, no exit, still moving and I didn’t want him to move, shot again in the neck, no exit and he stopped moving.

First shot killed him, he ended up on a road that if he would have left if still be getting him out of the canyon. He’s 381lbs, 7’ long with flat teeth to his gums.

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Congrats! If you don’t mind me asking, what was your load? Did you recover any bullets?
Thanks

 

[nphunter]

Congrats! If you don’t mind me asking, what was your load? Did you recover any bullets?
Thanks

H4350, 41.5gr CCI BR2 Peterson Brass COAL 2.918”, .020ish off lands 2760fps 16” barrel with a OG6.5 can.

Didn’t try, I doubt there was much left to recover since there was no exit. I was up until 3 this AM dealing with the bear and didn’t want to take the time to mess with it.

 

[huntsd]

tested out the 107 & 116. 20” factory tikka 1:8. My goal is to have impact velo of 1800 fps at 700. So I need a muzzle velo of either 2700 with 116 or 2775 with 107.

107 - just under the speeds desired with h4381sc & h4530. Staball 6.5 gets me there but has a pretty crappy es. Virgin lapua brass loaded to m+ mag.

42 - 4 shots 11es - average speed 2744
42.3 (book max) - 4 shots 97 es wtf?! - average speed 2778
42 - 4 shots 43 es -average speed 2799

116- couldn’t get the speed I wanted and doesn’t look like this gun likes the 116 anyways.

About 40 rounds on this barrel. Hope it speeds up a smidge with more shooting . Going to call it good, load up a bunch at 42.2 zero and send it long!

 

[huntnful]

116 TMK
6 creed SAMMI
26” CF Benchmark 1-7.5 twist
2.920” COAL. Lands are at 2.940”
42.5gr. N555

I had to get a new mag to accommodate the longer COAL. My other mags had binder plates in them. Just went out to function test the new mag.

Two 5 round groups fired consecutively just loading the mag in between.