270-300 Win Mag now feasible

[Buckammo]

I have the first data. I have to admit, I chickened out when I saw the Berger data. I loaded 10 more rounds. Six rounds with 65grs. H-1000. Four rounds with 69grs. Retumbo. All in new Nosler brass with Fed. 215 primers with a COAL of 3.390". It took three rounds to zero at 100 yards. I ended up with a 1.1" three shot group with the H-1000 load with all six rounds averaging 2852fps +/- 4.5fps. Four shots from the Retumbo load gave a scattered 2 inch group and 3026fps +/- 9.0 fps. Neither load had a hard bolt lift or any other pressure indication. Since this is a new barrel I was cleaning between each shot.

I also noticed quite a bit of variance in bullet seating effort. I will have to track that down.
John

 

[Longtooth32]

I have the first data. I have to admit, I chickened out when I saw the Berger data. I loaded 10 more rounds. Six rounds with 65grs. H-1000. Four rounds with 69grs. Retumbo. All in new Nosler brass with Fed. 215 primers with a COAL of 3.390". It took three rounds to zero at 100 yards. I ended up with a 1.1" three shot group with the H-1000 load with all six rounds averaging 2852fps +/- 4.5fps. Four shots from the Retumbo load gave a scattered 2 inch group and 3026fps +/- 9.0 fps. Neither load had a hard bolt lift or any other pressure indication. Since this is a new barrel I was cleaning between each shot.

I also noticed quite a bit of variance in bullet seating effort. I will have to track that down.
John

Stoke those fires...

I do not think that I ever started with any load of H-1000 lower than 70grs and that was 3004fps at a 3.36 COAL. On the Hodgdon reloading site the starting load of H-1000 for a 160 gr Nosler is 74grs.

At 70grs of Retumbo, 3.36 COAL, I was running 2865fps.

Stretch out the legs of your 30" tube...

 

[Longtooth32]

Buckammo...

Some data with a Pro Chrony in my Mark V at 3.36" COAL. 170 Berger, 28", 1-9, my gun, my chamber...

All H-1000...

72gr ave 3019fps

73gr ave 3126fps

74gr ave 3162fps

75gr ave 3195fps

76gr ave 3233fps...hot, but had ES of 8...

 

[Big Jake Duke]

You had a good accuracy node at 75 gr of retumbo, it was the same i the 270-300 win mag. How was the accuracy with h1000?

 

[Buckammo]

I certainly will generate a ladder working up from where I am.

After inspecting the brass a little more, I realize the Nosler brass has substantially more headspace in my chamber than the Remington brass does. This resulted in substantial thinning of the brass in the web with the loads I fired last night. I will have to leave a "false shoulder" with the rest of this brass when I neck it down.

In addition the Nosler brass varies in wall thickness by .0008". I guess I could turn it just enough to remove the high spots.

 

[Buckammo]

I was able to load a shoot a bit more yesterday evening. Here is what I have so far:

Brass - Nosler New, Primer - Fed. 215, 3.390" COAL Berger 170gr. Range - 100 yds.

Note 1 - Case neck sized with .302" bushing the full length of the neck, bullet seating was pretty hard and quite variable. There was considerable case stretch upon firing.
Note 2 - Case neck sized with .304" bushing after neck turning the high spots. The case was neck sized leaving a false shoulder for better chamber fit. This seemed to fix the case stretch. 70.0 grs. of Retumbo is beginning to show pressure signs.
Note 3 - Brass prep the same as Note 2 except the brass is fire formed with 18 grs of Unique and the case filled with grits. This seemed to give quite a bit more powder capacity. The load with 70 grs. of Retumbo showed no signs of high pressure.

It looks like I will need to fire form the Nosler brass before I start ladder testing this weekend.
John​

 

[CogburnR]

One of the reasons I chose to build a 270-300WM is component availability.

I was walking around the local farm store today and on the end of the isle hangs bags of new Winchester 300WM brass for 34$.

I also picked up 400 of the 170EOL Bergers from Midway at their sale price of 28$ a hundred.

The other day I was in another LGS and on the shelf are hundreds of 150ABLR's

I bought literally thousands of de-milled bullets cheap, 150g Tipped Trophy bonded, Accubonds, Triple shocks, Fusions, etc..

Marshal at Matrix Ballistics seems to always have 165's on hand.

My 300WM bushing die and .304 bushing...were in stock at Midway when I bought them.

Looks like I am going shooting again sometime around the 7th of July. Probably not real long range tho' because I will be limited to shooting off a good bench.

I will load up some of the 170 Bergers to try though.

Soon I will be starting coating the bullets and bore with HBN.

 

[Buckammo]

After shooting last evening, attached is my updated data. The notes for the brass prep is the same as before with the addition of Note 4 which is: Cases necks sized 0.304" partial length (just till bolt closes easily). Fire formed with 12 grs. Bullseye, grits to fill and paper plug. Neck sized again 0.304"

The fire formed brass has a water capacity (to the mouth of the neck) of 87.5grains of water, the non formed brass has a capacity of 85.0grains of water.
Thanks,
John

 

[CogburnR]

I went out and shot up the ammo I had loaded.

Group 1 and 2 were 165 Matrix with 75g Retumbo, W-W case(except the last shot in group 2 which was a Federal case-oops), 215 primer, 3.6". Group 1 1.202" Group 2 .633" Velocity was 3180 or so.

Group 3 was 4 shots with 165 Matrix, 75g Retumbo. Federal case, 215 primer, 3.6" Group 3 was .5"! Velocity also around 3180 with a hot one at 3212fps.

Group 4 was 170 Berger, 75g Retumbo, W-W cases, 215 primer, 3.615" (.071" off lands"). Group 4 was a pretty good start for the first 5 Berger 170's loaded, .680" These were also a little hot showing ejector marks, These went around 3140fps.

 

[Longtooth32]

I went out and shot up the ammo I had loaded.

Group 1 and 2 were 165 Matrix with 75g Retumbo, W-W case(except the last shot in group 2 which was a Federal case-oops), 215 primer, 3.6". Group 1 1.202" Group 2 .633" Velocity was 3180 or so.

Group 3 was 4 shots with 165 Matrix, 75g Retumbo. Federal case, 215 primer, 3.6" Group 3 was .5"! Velocity also around 3180 with a hot one at 3212fps.

Group 4 was 170 Berger, 75g Retumbo, W-W cases, 215 primer, 3.615" (.071" off lands"). Group 4 was a pretty good start for the first 5 Berger 170's loaded, .680" These were also a little hot showing ejector marks, These went around 3140fps.

Wow!...It seems that 75gr of Retumbo is the go to loading for both the 165 and the 170...good shooting...

I actually got the best accuracy around 3150fps too...for both the 165s and the 170s...

 

[Buckammo]

I am not at max yet with Retumbo; this 3150 node is beginning to look promising in my rifle also. Although, the node with R-26 at 2890 is flat and wide with very low velocity SD's.

 

[Big Jake Duke]

I went out and shot up the ammo I had loaded.

Group 1 and 2 were 165 Matrix with 75g Retumbo, W-W case(except the last shot in group 2 which was a Federal case-oops), 215 primer, 3.6". Group 1 1.202" Group 2 .633" Velocity was 3180 or so.

Group 3 was 4 shots with 165 Matrix, 75g Retumbo. Federal case, 215 primer, 3.6" Group 3 was .5"! Velocity also around 3180 with a hot one at 3212fps.

Group 4 was 170 Berger, 75g Retumbo, W-W cases, 215 primer, 3.615" (.071" off lands"). Group 4 was a pretty good start for the first 5 Berger 170's loaded, .680" These were also a little hot showing ejector marks, These went around 3140fps.

Great info- .071!!! Off the lands- talk about a jump! Ill give that a try since my lands are at 3.68 and i didnt back it off that far in my Berger quest! Nice shooting! My velocities were a little over 3200 with that load out of a 28" barrel, but i couldnt find any accuracy consistency.

 

[CogburnR]

I'll add the chrony info later but looking at the orientation of the groups I think that the first groups would benefit from a slight increase in powder charge and the last group needs a slight decrease in powder charge. The shape of the group remains consistent but rotates clockwise with increased pressure and shrinks at the node displayed by group 3. Say 75.5g or 76g with the 165 Matrix and W-W cases. The 170 Bergers may be better at 74g Retumbo. Sounds good in theory anyway-LOL.

I am happy that these bullets both show good grouping at my max mag length. The seating depth for the Bergers was arrived at by seating the bullets at the same die setting as the 165 Matrix which resulted in the oal being .015" longer or so but due to ogive differences the Berger had .060" more jump. Sometimes the Bergers may like quite a bit of jump,they recommend changing the jump in .050" increments when looking for a seating depth node.

I was shooting off a bench and the stock I have is not made for that, my attempt at a 300 yard group was not good as I could not get settled in with a good sight picture and also had a 15mph side wind. It was about 4.5".

 

[CogburnR]

All of this brass was necked down with a 270WSM die and a spacer. This results in quite a bit of neck tension. The W-W brass is used with an unknown number of firings. The Federal brass is from new de-mil'd commercial ammo. I have to use this die to neck down from .308 to .277.

I have a 300wm bushing die now that I am using on fire-formed brass. I hope to get better ES numbers from the brass resized with the bushing die. Also, I will soon be coating the bullets and barrel with HBN.

The Fed brass chrony info is on the right side of the right card. Separating the W-W brass info and Fed brass info results in a ES closer to 50fps.

Here is the chrony info: