270 Win and 165/175 Matrix Range Report

[cowboyarcher]

Well finally was able to lay hands on the 165 and 175 Matrix and got out this morning to do some testing on them. Load and climate data are on the target:

As you can see I hit the upper limit with the 165's and H1000. There were no pressure signs at 58gr, but at 59gr there was sticky extraction and extractor marks on the case head. I did not hit the max end with the 175's, but was pleasantly surprised to find that they would indeed stabilize out of my rifle. I stopped at 54gr as that is all I had loaded. Any guess as to where I might hit pressure signs?

I do not have a chrono so I cannot provide speeds on these yet. . .

The rifle is a Model 70 that has been worked over some. Barrel is a 1:10 twist McGowen, 24", SS, #2 Shilen contour installed by Sin Arms. Stock is a B&C ultralight medalist. Scope is a Nikon Monarch 4-16x42. Rifle as pictured is 9.5lbs:

God bless fellas!

Adam

 

[ScottMcc]

Nice! The 270 is long overdue for some new modern bullets. I have had good accuracy and down range performance with sierra 140 gr spbt hunting loads, at least as far as I am willing to shoot at game.

 

[coues52]

thats a nice looking set-up..bringing my 270 win out of the closet..picked up the new Accubond 150 long range bullets a couple days ago..they claim a 0.625 G-1 BC... what sold me was they only need a 1-10 twist..mines a rem 700 classic (20+ years old ) was told that the matrix needed a 1-9 twist, but looks likes your sure shots..Hope mines shots as well as yours..Danny PS: my present load is the 140 seirra game king with IMR 4350 chrono @ 2797 fps & ES at 62 fps, not good #,s but for under 350 yds shots good enough for deer.. read there getting 2900 with H-4831 with the 150 LR

 

[cowboyarcher]

I have seen that the 165's shoot fine in a 1:10. The 175's are a bit more suspect, but at my altitude I can get a lot of things to stabilize that others cannot.

Both seem to be very forgiving in terms of seating depth and bullet jump to the lands, which is great in a hunting rifle because it allows me to seat them to fit the mag box.

The LRAB's look sweet too! I'll be interested in seeing some of the reports from them when they start getting sent downrange. . .

 

[CobraRed]

Good to see more fellow McGowen barrels out there

 

[cowboyarcher]

Well I tried to get out this afternoon and run some drop tests to figure velocity from, but I must have had my zero set wrong. My bullets were basically hitting the same groups at 100 and 200 yards. . . I may have to rezero the scope and runs the tests again.

I did load the 175's up some more (up to 58gr of H1000) and was very surprised that I still was not getting pressure signs. These were still grouping down around the 5/8 MOA mark.

Anyone near Laramie have a chronograph and want to help a fella out?

 

[cowboyarcher]

Finally some velocity numbers for the 175's for you guys. By shooting at 300 and 400 yards and then working back I was able to calculate that the 175's over 58 gr of H1000 are leaving at about 2710 FPS, based on the average drop from 3 shot groups, and using a .680BC. These maintained sub-MOA at 400 yards. I have not hit any pressure signs with these yet, so I may work them up more when I get another batch of bullets.

The 165's jumped up to 2 MOA at 400 yards, so the average drop was not a very precise way to calculate speed in my opinion. I was disappointed in these, and am out of them, so I'll concentrate on the 175's for now.

Here is the target:

 

[cowboyarcher]

3 shots over a loaner chrono tonight averaged 2840 FPS. That's the 175 over 58 gr H1000 in a 24" McGowen tube.