New Barnes 7mm LRX 152 gr for 7SAUM?

[CoHunter1991]

Definitely going to pick some of these up. 152g seems a bit heavy for a 280ai copper bullet but ill give it a go.

 

[A382DWDZQ]

B.C. is 0.467 per their spec sheet.

https://www.barnesbullets.com/wp-content/uploads/2024/03/Web-Ballistics-3.21.24.pdf

 

[35WhelenAI]

WTH? The 7mm 139 LRX and 145 LRX both have higher BC's and it's de-facto they would have better velocity based on lighter weight.

280 AI with the 152 LRX as the only Barnes factory loading is not impressive, IMO.

On a slight tangent, the .270 Win with a 110 TTSX or 129 LRX each carry over 100 fps velocity advantage at 500 yds over the 280 AI 152 LRX. In Barnes factory loads.

Edit: Agree with the post below, something in the BC isn't adding up. I talked with Ty at Barnes years ago. They derive BC calculations based on time of flight in a 300 yd indoor range. They are pretty close to what a guy should expect when fired in real life.

However, looking at the chart, downrange numbers match the BC they printed.

 

[A382DWDZQ]

Appears that there is a discrepancy in the BC published on the load data vs the ammo chart. The 7mm RUM with 145 LRX is showing 0.449 B.C. on that same chart.

 

[Mikey_B79]

Yeah, according to their ammunition ballistics chart the LRX factory loaded BCs are as follows:

0.434 for the 139 LRX - 7mm Rem Mag
0.449 for the 145 LRX - 7mm Rem Ultra Mag
0.467 for the 152 LRX - .280 AI

 

[35WhelenAI]

Component bullets are listed as:
139 LRX .470
145 LRX .486

 

[Mikey_B79]

Component bullets are listed as:
139 LRX .470
145 LRX .486

Which is a little strange, I mean I could see them using an average velocity to calculate the G1 BC of the component bullets but it still wouldn't make sense that the 7-RUM factory load BC is lower than the component bullet G1 BC, because there isn't anything that'll skew the results *above* that. Unless they have some .284-378 Weatherby in the lab or something.

Worth an email Monday morning.

 

[35WhelenAI]

It'll be interesting what Barnes says if you email. If the bullet comes out as a component at some point, interesting to see what is advertised for BC.

As it stands, it doesn't make sense the 152 LRX has a lower BC than lighter weight LRX bullets of the same caliber.

 

[Tmac]

Component bullets are listed as:
139 LRX .470
145 LRX .486

I had some 145 LRX’s loaded at 3,013 fps. Zeroed at 300, calculator said dial 8.2 MOA for 600, dialed it and it was correct. So I’m guessing that .486 is pretty close.

 

[35WhelenAI]

Take a look at the table in that link, specifically the 7mm Rem Mag numbers with the 139 LRX, 140 TTSX and 150 TTSX.

3210 fps mv 139 LRX
3100 fps mv 140 TTSX
3060 fps mv 150 TTSX

The 139 LRX factory load has a higher published velocity than their load data shows for handloader. Problem with the load data is they lump the 139 LRX/140 TSX/140 TTSX in the same group. Load data has to be geared toward the bullet with the highest pressure within limits at a given charge, and I would bet the 139 LRX is not it. There is probably more to get with that bullet in handloads given their factory load velocity.

Worthy of note for .270 Win fans... in factory loads according to the table the .270 Win pushing a 129 LRX holds more velocity at 500 yds than the 7mm Rem Mag with the 139 LRX at 500 yds. Who'da thunk it.

 

[A382DWDZQ]

I’m going to guess 0.491