Maximum load for 7mm Rem Mag 160 gr Nosler Accubond

[270Buck]

Hi,

I am looking for some advice.
I have just got my 7mm Rem Mag and working up a load for it. I am using 160 gr Nosler Accubond and Viht N-165 which is easy to get hold of in the UK, so that is my definite powder of choice, although I do have plenty of N-160 but it's a bit fast for a 7mm RM.

I have the 7td edition Nosler reloading manual. It states the starting load should be 57.0 gr and the maximum load should be 61 gr. The 61 gr load was the most accurate being sub 0.5 MOA. I have seated the bullet 20 thou off the lands.

When I chronoed the load the average was a mere but very consistent 2633 fps. The manual says it should be more like 2900+ fps. Their test barrel was 24" whereas mine is 25.5", so in theory should have a higher velocity than the Nosler test.

I realise all the manuals seem to over state the velocity but surely not by 300+fps!!

Looking at other reloading info, the Vihtavouri manual says for a Speer Grand Slam 160gr bullet the start load for N-165 should be 59.1gr and the maximum is 68.1gr this should produce 2982fps. The maximum load is 7.1 gr higher than Nosler state for their similar bullet.

The Hornady manual states for N-165 starting load of 52.7gr and maximum of 62.3gr for a similar bullet offered by Hornady.

My question is, how safe would it be to ignore the Nosler manual and try the Viht suggestion? I am wanting to get as close to 3000fps as possible.

I know I can make some rounds at say 1 grain increments and watch for pressure signs as I go, but I wonder if anyone else may have also done the same. I know all rifles are different so what is safe in someone else's 7mm Rem Mag may not be safe for mine.

I am using brand new unfired Norma brass and Federal Gold Medal Large Magnum primers.

When I have shot 90 rounds I will neck size some brass and compare the same load vs unfired brass.

Any other suggestions would be appreciated.

Cheers

 

[davkrat]

I have ran in to the same issue with 7mm Rem Mag. On the Hodgdon data page you will see for H4831 and a 150 grain Nosler Partition the max is 62.0 grains at 2,986 fps while the same powder behind a 150 grain Barnes TTSX is 68.0 grains at 3,080 fps.

You don't usually hear that you can increase the powder charge when switching from a cup and core to a copper solid!

The 7 Mag data is always complained about for being limited. I have read numerous times that the cartridge should have been set at a higher SAMI max pressure. The .308 Win is "allowed" to be pushed to a higher pressure yet I shoot both out of nearly identical Remington 700's. Basically you may end up treating the 7mm Rem Mag as a wildcat. Play it safe and listen to what the brass and your chronograph are telling you. That's what I do. I've settled on a load that is not hard on my brass and gives me good velocity. It falls somewhere within one of the books ranges but other manuals I am significantly over max. All the other cartridges I load for seem to be very similar when compare between manuals, the Big 7.... all over the place.

 

[270Buck]

I have ran in to the same issue with 7mm Rem Mag. On the Hodgdon data page you will see for H4831 and a 150 grain Nosler Partition the max is 62.0 grains at 2,986 fps while the same powder behind a 150 grain Barnes TTSX is 68.0 grains at 3,080 fps.

You don't usually hear that you can increase the powder charge when switching from a cup and core to a copper solid!

The 7 Mag data is always complained about for being limited. I have read numerous times that the cartridge should have been set at a higher SAMI max pressure. The .308 Win is "allowed" to be pushed to a higher pressure yet I shoot both out of nearly identical Remington 700's. Basically you may end up treating the 7mm Rem Mag as a wildcat. Play it safe and listen to what the brass and your chronograph are telling you. That's what I do. I've settled on a load that is not hard on my brass and gives me good velocity. It falls somewhere within one of the books ranges but other manuals I am significantly over max. All the other cartridges I load for seem to be very similar when compare between manuals, the Big 7.... all over the place.

Thanks for sharing your experiences. I have also looked at various data from powder and bullet manufacturers and they all seem to have vastly different opinions!!

 

[mtwarych]

I have done the same thing you are asking about with the same cartridge and bullet.
When I had worked to book max with no signs of trouble, I continued laddering up in .3 grn increments. .3 might seem light but better safe than sorry.
I finally ended up with a load that was 4.3 grns over max and shot wonderful groups with the 160 accubond at a book like velocity. Approx 2975 fps with no signs of pressure danger.

Every rifle is different.

 

[Radhimself]

Im shooting 162 SST's out of my 7mag remmy... Book max says 65grns of 7828... 3.329 OAL, CCI large rifle mag primers... Nosler brass and federal nickel plates... Ive worked up to 71grns... No pressure, signs.... Fps has hovered around 2950 to 3060 with all the test rounds so far... Hence the different brass. Even tried another batch of 7828 just to be sure... Im stumped

 

[Radhimself]

Might i add COAL i was using was 3.329.... And fps did not steadily increase from 65 to 71grns... It jumps all over the place from round to round

No craters, no ejector marks, no scuffs, no hard bolt lifts... Im starting to wonder ***

 

[264WM]

Finding good powders for the 7mm mag and the 264wm (same case) is very hard it seems that they quit making the best powder H570 a long time ago. But I had a friend that gave me 3 lbs of H570 and it works well in the 264wm and is close to book from the old Hodgdon No. 20 manual. They listed the 160gr hornady round nose at 3067fps with 71gr of H570 and my same load using the Woodleigh 160gr PPSN is 3083fps from a 30 inch shilen barrel. I worked to 73gr H570 and have the 160gr PPSN at 3261fps. But is shows flattened primer and a extractor mark on the brass but the bolt still opens with ease. Some of the 264WM shooters are using the new RL33 and having good success getting higher speeds and accuracy. There is no reloading data for the 264 wm or the 7mm rem mag but there is data for the 7mm stw.

 

[roninflag]

what rifle?

 

[Lefty7mmstw]

The 7rem has a problem.... both with the variances out there in chamber dimensions and the fact that it was hobbled a bit in max pressure. Work up slowly going for BOOK VELOCITY OR SLIGHTLY LESS... At one time people went for broke with the 7rem and tried for 3400 fps with 140's and 3200 fps with 160's, but there are better cartridges to get you that speed now days and pushing the 7rem looks a bit foolish.
I'm not a fan of deviating from book data but 300 fps low is absurd; you either need to go up a grain or two or switch powders. Make sure you have no ejector marks or hard bolt lift on the finished load workup; any brass distress at all is high pressure... Usually at least 75 Kpsi.... Blown brass means you probably have an angel watching over you as you could have been hurt.
My current 7stw is 200+ fps low with one load but the barrel is a bit shorter too. I know where you are coming from on the low vel. thing.

 

[Radhimself]

Its a remmy 700 sendaro, it groups good so far. 80rounds down the pipe. Cases have not changed much. Ive been neck sizing with a lee collet die in hopes they would grow to the chamber then full size as needed to bump the shoulder. Im pretty stumped at this. Velocity climbed at 20fps per .2grn increase from 63.5 to 66... After that fps has been random between 2880 and 3060 with no consistancy