New TMK announced

[43.6N]

I hope the numbers for the .264 bullets are better than your calculations. Knowing what I know with personal experience with 147 eld and 153 Berger and what a good friend has seen with the 150 match kings. The new tmks need to be in my opinion .330+ G7. I’m coming at this from a competitive mindset. For shooting animals to me bc isn’t a main concern.

Like I’ve seen the 150 match kings true out at a .350 g7 the new tmk should be on par with a Berger 153. I’ve trued that out at box BC of .356.

Where i hope sierra pulls through is the 147. I’ve seen eld M 147s true out at a .311 and .330 with different barrels with an advertised BC of .351. So if they can make a consistent 147 that kills with a high bc it’ll be a winner over the eld m.


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And yes, I 100% hope that I’m underestimating the BC for these bullets. If the .264 bullets get close to the 150smk bc, that will be an absolute monster

 

[Q_Sertorius]

I did a little math yesterday evening trying to come up with the likely ballistic coefficients for these new TMK.

BC is sectional density multiplied by its form factor.
Sierra has 2 lines of tipped bullets with similar form factors. The TMK line, with a generally better form factor. And the TGK line with a slightly lower form factor. Example: .264 130TMK with g1 bc of 0.518 vs 130 TGK with g1 bc of .510.

If only using the current TMK line, I didn’t have enough data to build a good model. So I also included the TGK line. As a result, these estimated BC values will likely be slightly low compared to what Sierra ultimately reports.

Final caveat, these are simply estimates. I have no first hand experience with these bullets, and no inside info from Sierra. I’m simply a guy with an Idaho public school education and a ti84 calculator. I just wanted to see where these new bullets are likely to end up ballistically, and thought others here might want to know the same!

First is the spreadsheet with the TMK and TGK bullets listed by caliber.View attachment 991922
Next I sorted by sectional density.
You can see a clear trend in BC between bullets with similar sectional density. This trend is the bullets form factor, and can be used to estimate the BC for our new TMK line:
Also you’ll notice outliers in BC for the light for caliber 150gr 7mm and 120gr 6.5mm. This is where these bullets have departed from the form factor model due to their low weight.

The Green highlighted numbers are the new TMK bullets. And my estimated G1 BC is the far right column:

View attachment 991923

Finally, comparing my numbers to the BC numbers in the heavy TMK testing thread, it looks like my estimate is close at least for the 116 bullet. 0.595-0.600 seems to be what those guys have reported so far.

Any idea on the new .257 bullet?

 

[43.6N]

Any idea on the new .257 bullet?

Haha. Sure man. Give me a minute to find some fresh double A for the Ti84

 

[NWBLKTAIL]

Haha. Sure man. Give me a minute to find some fresh double A for the Ti84

You know the less fancy calculators can write”80085” just as well as the ti84….

 

[43.6N]

Any idea on the new .257 bullet?

Probably about 0.610 is a safe assumption.

-The 133 version will have the same SD as the 195 30 cal TMK. And the 140 6.5mm TGK. Between the two, it will almost certainly favor the TMK form factor.
-The 135 version will have the same SD as the 165 7mm TGK (so underestimation of BC)
-Both of those bullets list out their g1 bc at 0.610.

 

[nm.otter]

I still have my HP-25C someplace.

Saved up most of my junior year in HS to pay for it -- RPN for the win!

 

[43.6N]

You know the less fancy calculators can write”80085” just as well as the ti84….

8008135

Fixed it for you pal

 

[NWBLKTAIL]

8008135

Fixed it for you pal

That’s reserved for the pros