270 Allen Mag, 169.5 gr ULD RBBT, US869 load results....

[Fiftydriver]

To anyone interested. Finally got out to test a new 270 AM with the new US869. The rifle is a Savage M111 with a 29" Lilja #6, fluted 1-8, 3 groove.

The load specs were:
169.5 gr ULD RBBT
Formed Rem 7mm RUM cases
Fed-215
OAL: 3.775"
Seated to just touch lands

Here are the results: Temp was 65 degrees, 30% humidity at 3300 ft altitude.

97.0 gr.............3189 fps
98.0 gr.............3235 fps
99.0 gr.............3282 fps
100.0 gr............3327 fps
101.0 gr............3367 fps
102.0 gr............3414 fps
103.0 gr............3479 fps bit to warm

All loads were fired at 100 yards and all were in the 5/8" to just under 1/2" group size which for an untaylored load was plenty good for me to ship the rifle. Extreme spreads ranged from 40 fps on the lower loads to mid teens on the upper loads. Typical of a ball powder, more consistant burning at the higher pressures.

All primer pockets were very snug up to the 103.0 gr load where one primer pocket was slightly less tight compared to priming before the load was fired. Certainly not loose and still very usible but I do not really like to see any change on the first firing. On the 3rd, 4th or 5th thats fine with me but not the first firing.

Compared to WC872 with the same bullet, it appears US869 is going to produce roughly 100 fps more velocity with 2 grains less powder so it is noticably quicker burning then WC872 in the 270 Allen Mag.

I loaded a dozen more loads up at the 101.0 gr level and will wait for the temps to climb to the mid 80's today and then retest the velocity and see what difference there is. Curious if US869 is as resistant to temp change as they are advertising.

We will see.

This should be a great powder for anything from the 257 STW and 7mm RUM up to the 30-378 class of rounds.

Kirby Allen(50)

 

[royinidaho]

From the above tests would it be fair to say that with room for powder not being a limitation that WC872 would be a 'better' choice with all other considerations being equal? and with a ninch more barrel length?

 

[Eaglet]

NICE!!!!!!!!!!

I really want their advertising to be truthfull.

[ QUOTE ]
Cartridge: .50 BMG
Bullet: 750 grains
MV at 70° F: 2719 fps
MV at 125° F: 2709 fps
MV at -40° F: 2722 fps



[/ QUOTE ]

 

[James Jones]

The more I read about this round the more this Win M-70 wants to be chambered in it rather than 300RUM

Whats involved in forming the cases and what sort of velocity loss is their with the fire forming loads?

 

[Fiftydriver]

JDJones,

Take a 7mm or 300 RUM, run it though a properly adjusted 270 AM Fl sizing die until the case just chambers with a snug fit in the chamber, load with 95.0 gr of 869 or 872 with at least a 140 gr bullet and shoot them.

If I am going to form cases with bullets I generally use the 169.5 gr ULD RBBT with the same powder charge. Accuracy is almost always 1/2 moa with fireforming loads and velocity will be in the 3050-3100 fps range.

With the BC of this bullet your looking at ballistic potential far above anything the 300 RUM can get with full loads even with a 240 gr SMK.

Or you can simply use a corn meal case forming method, burn around 22 grains of Unique and the rest of the case filled with cornmeal and plug the case mouth with a toilet paper wad. Much cheaper and no barrel wear.

I have said dozens of times how the 270 AM is really no different or harder to load then a 7mm RUM but ballistic potential is pretty impressive with the 169.5 gr ULD RBBTs.

Easiest wildcat in the world to load for!!

Kirby Allen(50)

 

[Fiftydriver]

Only got up to 78 degrees this afternoon but went out and shot some rounds over the chrono anyway to see where the velocity was compared to this morning. Six shots averaged 3374 fps for the 101.0 gr load compared to 3367 fps this morning.

No to bad.

Kirby Allen(50)

 

[41mag]

I was out this past weekend with some of the 169.5 Wildcats and 869, temps in the mid to high 80's. Started with 100grs and got mid 3400's, backed down to 95 and was still keeping mid to upper 3300's as the day wore on.

As a side note, I loaded 6 up with 100grs of 872 to check the differences in the powder with all else being the same, and got about the same mid to upper 3300 fps velocities.

Later,

 

[GO-FASTER]

sent you a email on the 270

 

[magicofmt]

Hi Kirby,
How often do you recommend cleaning the barrel using the cornmeal method for fireforming 300 RUM brass in the 270 AM? Brush? Copper solvent? Can't wait to get mine, it's like Christmas.
Thanks!

 

[Fiftydriver]

Was able to get out last night again and dial in this customers 270 AM at 1000 yards. With the same load I used in the previous post I loaded all the data and specs into Exbal and set up on a 10" rock at a measured 1058 yards.

With a 2.2" high impact at 100 yards Exbal was predicting to use -4.75 Mil as a reference hold point for this range. The wind was right in my face at around 8 mph so I did not allow for any windage.

First shot off a 9" bipod and rear bag landed a foot and a half to the right but the vertical was dead on the money.

Made a scope adjustment and the second shot hammered the rock as did the third shot.

Found a new target roughly the same size at 898 yards. Exbal said to use the -3.7 Mil hold. The angle was differnet for this target so the wind was more of a factor. Exbal said to hold .5 mil into the wind. I set up and fired three rounds as quickly but as accurately as I could. Three for three!!!

On a roughly 10" target at that range with a sporter weight rifle I figured was plenty good for the rifle to ship.

US869 stayed consistant enough to make accurate hits at 1K and a bit beyond using the same velocity averges from the earlier test. I did not rechrono this load at the time of the 1000 yard testing and everything appears to be staying very consistant.

Good outing. Only thing I wise is that 869 was a bit slower burning so there would be a bit higher load density in the case but it does not appear to make alot of difference so far.

Kirby Allen(50)

 

[Eaglet]

Nice shooting! gets me going!
Exbal does nicely of course the shooter didn't do so bad! /ubbthreads/images/graemlins/smile.gif I'd be real happy if it was my rifle!