6mm 105-115gr Coefficients

[jrbet83]

I have two main questions? What are the BC of the 115 DTAC's? My other question is Noslers BC on their 105 correct?

Berger 105 BC .493 (use to be .532)
Sierra 107 BC .527
Nosler 105 BC .593

Why is Nosler's so high, I've heard good things about those bullets.

Berger 115 BC .545-551
DTAC 115 BC ??????

 

[7.62willdo]

Re: 6mm 105-115gr Coefficients

.525+-

 

[jasonk]

Re: 6mm 105-115gr Coefficients

Most guys use closer to .575-.585 on the Dtacs I believe.

 

[7.62willdo]

Re: 6mm 105-115gr Coefficients

The quote on d.tubbs site is 10 points lower then the 6.5mm 142 SMK, which is .595 just remember reading that, it might have changed.
(oops just read my post) yes its .585 sorry dyslexic today

i meant to put .585

 

[jrbet83]

Re: 6mm 105-115gr Coefficients

What about the Nosler BC? How is there 105 numbers so high?

 

[Wild_Bill]

Re: 6mm 105-115gr Coefficients

because they are wrong. Nosler is closer to .493 than .593 it is around .5 a little less than the 107 Sierra.

I have been playing with the 117gr Plastic Tipped DTAC's i have shooting them at 3180fps in a 8.44 twist barrel starting to get onto a great load but will have to swap to the 115's soon as i only have 300 of the tipped ones left.

I am driving them in a 6mm55SMc with 56gr retumbo and a 30" barrel they get to 1000 yards quickley. just tuning with seating depth and slight powder weights now and also different primers to get the best groups.

 

[IanB]

Re: 6mm 105-115gr Coefficients

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Wild_Bill</div><div class="ubbcode-body">
I have been playing with the 117gr Plastic Tipped DTAC's i have shooting them at 3180fps in a 8.44 twist barrel starting to get onto a great load but will have to swap to the 115's soon as i only have 300 of the tipped ones left.

I am driving them in a 6mm55SMc with 56gr retumbo and a 30" barrel they get to 1000 yards quickley. just tuning with seating depth and slight powder weights now and also different primers to get the best groups.
</div></div>

Hi Bill, can you give us a little bit more information on the 6mm55SMc ??

 

[Wild_Bill]

Re: 6mm 105-115gr Coefficients

Ok it starts with a SAUM or WSM case and you push the shoulder back to 1.550" and then the case neck is .380 long making the case 1.930 long. it has a radial shoulder like a ball baring sitting on top of the case body. when chambering the barrel you have th throat the barrel to suit the projectile you will be using. the base of the projectile should be seated to the base of the neck to make a round combustion chamber that in theory allows the best powder burn. also the design of the case means that you should have 2.5 times the projectile diameter inside the case shoulder so the 7mm case needs to be built on a chey tac case. it holds 80gr of powder. the 55 on the case stands for the volume of water the case holds at the base of theneck but i am using Norma WSM cases and they hold 2gr more. the starting load with Rem SAUM cases is 56gr retumbo and a 107 matchking. having more capacity it is allowing me to run that with the 117's. Another thing is only standard primers work magnum primers dont work in this case as they blow the powder forward and the groups go to the shit. i have been using CCI BR2 primers but fed GM210's are ment to be better and i will be trying them and RWS primers this week.

Search Superior Ballistics. the patent owners are Mic McPherson and By Smalley they gave me permission to have a reamer made and make barrels for my own use. teh capacity is similar to a 6mm284 but so far barrel life looks good and that is wnat this design is supposed to do.

 

[IanB]

Re: 6mm 105-115gr Coefficients

Cheers Bill.

 

[ranger1183]

Re: 6mm 105-115gr Coefficients

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: jrbet83</div><div class="ubbcode-body">fyi guys this isn't a 6mm55SMc thread. </div></div>

You are correct, my bad!


<span style="text-decoration: line-through">Will_Bill,

Excellent article! I looked through the Superior Ballistics website (massive amounts of information) and saw the 17 step process required if you're making your own brass. Is this what you have to do to shoot the 6mm55SMc? You mentioned a 7mm version, do you know anyone who's shooting those?</span>

 

[jrbet83]

Re: 6mm 105-115gr Coefficients

fyi guys this isn't a 6mm55SMc thread.

 

[Roscoe_M4]

Re: 6mm 105-115gr Coefficients

Ive been using 0.511 for the Nosler 105s, just a little South of the 107 SMKs. I believe that came from Midway's website.