Sierra 6mm 107HPBT Matchking caution

[K31Scout]

Bought from Midway, Sierra makes 2 versions of this bullet. I ordered (and returned) a 250 count box and they have 107gr HPBT-CN on the box. Product #1570MP. These are a copper/nickel jacket and seat .020" deeper in my chamber according my Hornady gauge. Midway does not say anything about the copper/nickel. The are a dull copper color and the ogive is obviously different.

My 100 round boxes I've been using are #1570 and have no CN.

I would have tried them but I have a great load worked up with the all copper jacket #1570 tuned up for a set COAL.

 

[pabrousseau]

I always expect ogives might be different on different lots of the same bullet . What are you saying that I'm missing?

 

[K31Scout]

It's a different construction and shape. It's Copper-Nickel product number #1570MP.
The bullets I've been using for years are copper jacket only, no nickel product number #1507.
I sent them back, otherwise I'd take a picture but they are obviously different.

 

[sig2009]

Bought from Midway, Sierra makes 2 versions of this bullet. I ordered (and returned) a 250 count box and they have 107gr HPBT-CN on the box. Product #1570MP. These are a copper/nickel jacket and seat .020" deeper in my chamber according my Hornady gauge. Midway does not say anything about the copper/nickel. The are a dull copper color and the ogive is obviously different.

My 100 round boxes I've been using are #1570 and have no CN.

I would have tried them but I have a great load worked up with the all copper jacket #1570 tuned up for a set COAL.

CN stands for Closed Nose.

 

[45-90]

Serria jackets are all the same composition, 95% copper and 5 % zinc.
The lead alloy ...or pure lead adds or detracts from the bullet hardness, depending on use, or recommendation...hunting or target.
The "C" or "CN" suffix is the closed nose design, which brings a higher BC to the bullets.
I like them and prefer them in various calibers...

 

[K31Scout]

Here's an explanation on the #1570MP. It's not the same bullet as the #1570. The ogive is the biggest difference.

• 1570 (Standard MatchKing):
  This bullet is a well-established and respected design known for its accuracy and consistency in competitive shooting, especially in high-power and silhouette competitions says OpticsPlanet. It's a boat-tail, hollow-point bullet designed for accuracy and long-range performance.
  
  
• 1570MP (MatchKing with Modified Ogive):
  The "MP" designation likely refers to a modification of the bullet's ogive, or the curved section of the bullet from the tip to the base. Some users have found that a particular pointing system, used on the 1570MP, creates a less uniform ogive, which could lead to reduced performance compared to a different pointing system. This might affect aerodynamic performance, particularly at higher velocities.
  
  
• Possible benefits of the 1570MP:
  While the 1570MP's ogive may be less uniform than the standard 1570, some users may find the 1570MP more suitable for specific competitions or with particular pointing systems, as it might be designed for specific ballistic characteristics.

In essence, the 1570MP is a variant of the 1570, with the primary difference being the modified ogive, which could impact its performance in specific situations.