Sierra 6mm 107 SMK revised BC

[BoilerUP]

Noticed on the Sierra website that the BC for the 6mm 107gr SMK has been revised significantly up...

.547 @ 2500 fps and above
.542 between 1800 and 2500 fps
.529 between 1600 and 1800 fps
.519 @ 1600 fps and below

I guess maybe this is from the recent production 'pointing' of certain SMKs that Sierra is doing?

 

[Moonlight]

They are working very well for me and my dad. As well as others we have talked to.
If it wasn't for the St. Louis bench rest holding the Sierra cup the last two years we would have never tryed them.
What is even better is having Sierra's chief ballistician Tommy Todd and his coworker out there on the line, competing with prototype bullets doing real field testing. They both finished in the top 3 in there classes.

 

[XTR]

I shoot them in my 6SLR. I wish they'd just provide G7s and forgo the G1s.

 

[Frankr]

I actually picked up a old box of them 107's at a local sport shop cheep. I was using them to fire form 6 dasher cases
I was impressed how well they shot..I was board fire forming so I found some plastic push tacks and was shooting them off the top of the backer at 100 yards with them 107's. They were extremely accurate.

 

[Zero333]

I actually picked up a old box of them 107's at a local sport shop cheep. I was using them to fire form 6 dasher cases
I was impressed how well they shot..I was board fire forming so I found some plastic push tacks and was shooting them off the top of the backer at 100 yards with them 107's. They were extremely accurate.

I have but haven't shot some of the new pointed 107's because I still have a couple hundred really old 107smk (date on the box is stamped 1996). Base to ogive variation for these old 107's was O.007" and after sorting them base to ogive into 3 groups they shoot excellent !

 

[SteveOak]

When did Sierra publish the revised figures?

What BC(s) did they report previously?

Thanks!

 

[Laurie]

I have but haven't shot some of the new pointed 107's because I still have a couple hundred really old 107smk (date on the box is stamped 1996). Base to ogive variation for these old 107's was O.007" and after sorting them base to ogive into 3 groups they shoot excellent !

Like you, I'm still using up the dregs of a store of 90s era 107s that I got riduculously cheaply due to a gunshop bankruptcy. Good bullets as long as you do BTO batching, and like many SMKs of that era, a bit of trimming and pointing does no harm for long-range use either. I'll likely buy a 500-ct box of the improved model soon for my 6BR as our Sierra importers' website currently shows them in stock.

Steve, my old Sierra Reloading manual lists the original's G1 BCs as:

0.527, 2,500 fps and above

0.522, 1,800-2,500 fps

0.509, 1,600-1,800 fps

0.495, 1,600 fps and below.

So, it's around a 3.75-4% improvement, very much in line with the improvements Bryan Litz predicts through pointing on its own suggesting the overall shape behind the meplat is unchanged. If anything, under 4% may be a little conservative if Bryan L is correct. It's good to see Sierra is retaining its longstanding policy of honesty with its customers.

 

[SteveOak]

........

Steve, my old Sierra Reloading manual lists the original's G1 BCs as:

0.527, 2,500 fps and above

0.522, 1,800-2,500 fps

0.509, 1,600-1,800 fps

0.495, 1,600 fps and below.

So, it's around a 3.75-4% improvement, very much in line with the improvements Bryan Litz predicts through pointing on its own suggesting the overall shape behind the meplat is unchanged. If anything, under 4% may be a little conservative if Bryan L is correct. It's good to see Sierra is retaining its longstanding policy of honesty with its customers.

Thank you Laurie!

In the past I have been using various cartridges in 6.5mm so I have a lot of catching up to do with 6mm offerings. I even bought a Krieger 6.5 mm barrel for my current project but an seriously considering building it in 6mm instead hence the research and questions on 6mm bullets.

 

[Berger.Fan222]

I shoot them in my 6SLR. I wish they'd just provide G7s and forgo the G1s.

It's not hard to compute a G7 from Sierra's banded G1s.

A G1 of:

.547 @ 2500 fps and above
.542 between 1800 and 2500 fps
.529 between 1600 and 1800 fps
.519 @ 1600 fps and below

converts to a G7 of 0.277 over 1000 yards
of 0.273 over 600 yards
with an initial velocity of 2800 fps