First look at the 180g MRX

[Coyote Hunter]

Tonight I built a dummy round for the .308” 180g MRX.  While I was at it I decided to see how consistent these bullets were.  I selected 10 at random and measured Overall Length, Length with a Stoney Point Bullet Comparator, and Weight.  Here are the results:

Overall Length
1.3622” Average
0.0070“ Extreme Spread
0.0022” Standard Deviation

Stoney Point Length
0.7418” Average
0.0045” Extreme Spread
0.0014 “ Standard Deviation

Weight
180.0g Average
000.8g Extreme Spread
000.3g Standard Deviation

I loaded these just like I do the TSX – deep enough into the case that the last groove is almost covered by the case.  I then gave it a roll crimp.  Hopefully this weekend I’ll build some test loads and shoot them at the range.

FWIW.

[Redhawk1]

Thanks for the information. 

[Patriot_1776]

Wow, great information CH.  Let us know how they turn out.  What cartridge and what rifle?

[jerkface11]

 Why the crimp? The only rifle i crimp for is my K-31. But then i don't shoot many bolt guns with a lot of recoil.

[Coyote Hunter]

Curiosity got the better of me so I checked the Barnes MRX against several other bullets.  All are .30’s except for the A-Frame which is a .25.  I have to admit I was not surprised the North Fork came out on top in consistency, or that the A-Frame came in second.


Overall Length (Average, Extreme Spread, Standard Deviation)
North Fork .308” 180g SS        (1.3023, 0.0015, 0.0005)
Swift .257” 120g A-Frame        (1.1610, 0.0030, 0.0011)
Nosler .308” 170g Partition RN  (1.0245, 0.0035, 0.0011)
Barnes .308” 180g MRX           (1.3623, 0.0070, 0.0022)
Hornady .308” 168g A-MAX        (1.2789, 0.0090, 0.0028)


Stoney Point Length (Average, Extreme Spread, Standard Deviation)
North Fork .308” 180g SS        (0.7261, 0.0010, 0.0003)
Swift .257” 120g A-Frame        (0.6933, 0.0025, 0.0009)
Hornady .308” 168g A-MAX        (0.6454, 0.0035, 0.0010)
Barnes .308” 180g MRX           (0.7418, 0.0045, 0.0014)
Nosler .308” 170g Partition RN  (0.6417, 0.0075, 0.0020)


Weight (Average, Extreme Spread, Standard Deviation)
North Fork .308” 180g SS        (180.1, 0.3, 0.1)
Swift .257” 120g A-Frame        (119.8, 0.2, 0.1)
Nosler .308” 170g Partition RN  (170.0, 0.2, 0.1)
Hornady .308” 168g A-MAX        (168.2, 0.9, 0.2)
Barnes .308” 180g MRX           (180.0, 0.8, 0.3)

[Coyote Hunter]

Patriot -

The rifle is a Ruger My77 MKII, canoe paddle stock with blue metal, .300 Win chamber.  Not my most accurate rifle (due in large part to the stock, I believe), but capable of sub-MOA with the right loads.

jerkface -

The most consistently consistent loads I have ever built were with the 350g North Fork at about 2183fps for my .45-70.  Those loads got a crimp because of the tubular magazine.  I experimented with crimps on my bolt guns, and the 180g TSX load was one of the loads I tried crimping.  Since my MRX loads are based on my TSX loads, and the TSX dummy is crimped, I also crimped the MRX dummy.  But when I built my loads today, I crimped half and left half uncrimped.  We’ll see which does better at the range.

 

[jerkface11]

 I can see a .300 winmag in a lightweight ruger needing crimp anyway.

[jack19512]

I was curious about the crimp and no crimp thing so I loaded six rounds for my K31.  These rounds were identical except for the crimp and no crimp.  Here is the crimp.


Here is the no crimp.  I myself think the edge goes to the crimp.  But other factors could have been involved.  They were too close to really call for sure though.