New 6.5mm 123gr Sierra MK

[Forum Boss]

Guys, here's a hot news item,we're the first site to release the info as far as we know).

Sierra has begun production of a NEW 123 grain, 6.5 mm MatchKing. It will look much like the Lapua Scenar 123 in shape, and will have a similar BC. But, with a specified shank diameter of .2642-.2644, it should be about .0005",one-half thousandth) fatter than the Lapua 123.

The fatter design may work a little better in some barrels. We suggest you try both bullets in your 6.5mm gun. Darrell Jones recently tested the 123 Scenar and 120gr Cauterucios in his new 6.5x47 rifle. The Cauterucios did shoot tighter, due possibly to their slightly fatter diameter.

 

[sewwhat89]

Are they still going to produce the old style? Do you have/know what the new bullet # will be yet?

 

[Forum Boss]

The 120 SMK will remain in production for the time being. The new stock number is 1727 for the 100ct box, 1725C for the 500ct package.

 

[mikecr]

I gotta ask:
What do your 123 Lapuas measure?
.262-.264??

My 139 Lapuas measure between .2635.and 2640,depending on temp). Same with 140 Bergers, and 142 Wildcats.
Just wonderin

Editor: Mike, I'm sorry, there was a typo in my first post. The Sierras are spec'd to .2642 to .2644 .

The 123s that Darrel Jones shot in his new 6.5x47 were running about 1/2 thousandth less than that. They shot very well, but the Cauterucios shot better.

 

[RickB]

About a week ago one of their people was saying that the 123 gr bullet was a "proprietary" bullet and would not be offered for sale by Sierra if it was offered for sale at all...sounds like it was a disinformation campaign.

The bullet that really seems to be in trouble is the 107 gr MK about which I continue to get reports of all manner of difficulties. On the other hand, the 120 gr MK shoots without much trouble although it is probably a rather dated design in terms of its ballistic coefficient.

I can see where barrel with oversize dimensions would be a problem with any bullets that might be at or slightly below .264, but this bullet will require a good bit of explanation from Sierra and testing in the field before it is likely to be worth the trouble of making a switch...particularly with know workable combinations already out there.

I would be curious to know exactly how this bullet measures as most custom bullet manufacturers do not make the entire bearing surface of the bullet the same. There is a pressure ring, yes even on boat tails, to deal with such things withoit creating unnecessary engraving forces and/or pressure.

I suppose David is one of the few people who knows at this stage.

 

[chrisj]

I am surprised the 107 may be in trouble. it has been by far the most accurate 6.5 bullet in my 6.5-284 by far. I use 107's at short range with reduced loads in my 6.5-284 and get consistent 1/4 to 1/2 moa @ 200 yards.

Chris

 

[JER]

I just ordered 100 each of the Sierra MK 123 and the Sierra MK 142 from Grafs to test as possible replacements for the Lapua 123 and 139 that I use now in my 260 Rem.

I love the way Lapuas perform and their cost is actually on par or less than Sierra if you buy from Grafs. But I have always been concerned about availability.

 

[Forum Boss]

The Lapua Scenars are great bullets--very consistent dimensionally and weight=wise. I've also found they tend to fly up to their stated BC, at least beyond 500 yards.

We've found that, with some barrels, the Scenars tend to be a little loose in the bore. Many of the Scenars are about .0005,half a thousandth) narrower in the max shank diameter than a typical Sierra or Berger.

My PacNor 6BR has a tight bore and it loves the Scenars. But it's a good idea to test both the Lapua and the fatter domestic bullets in your rifle.

 

[JER]

I'm going to have to try the new Bergers coming on,120 LTB and 130 VLD), as well as their older 140 VLD.

All of a sudden the old .264 caliber is looking interesting, after several years of 6 mms stealing the limelight.

 

[JavierMena]

I can't wait to try it !!!

JM.