Maximum load for 7mm Rem Mag 160 gr Nosler Accubond

Discussion in 'Reloading' started by 270Buck, Mar 18, 2015.

  1. 270Buck

    270Buck AH Senior Member

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    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
     

  2. PHOENIX PHIL

    PHOENIX PHIL AH ENABLER AH Ambassador

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    Vihtavouri's website has the maximum load for a 160gr Partition at 66.7gr of N-165. So yes, I'd say you've got room to increase. Going up in 0.1gr increments may be a bit conservative. I think I'd go up in 0.5gr increments until I started getting up to about 63-64gr and then back down to 0.2gr at a time. Use your chrony during this process and record the results for each shot.

    http://www.vihtavuori.com/en/reloading-data/rifle-reloading/7-mm-remington-magnum.html
     
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  3. 270Buck

    270Buck AH Senior Member

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    Cheers Phil. It looks like the data on the link is for 150 grain Partitions, not 160 grain?

    But I am confident that I can go up to 65 grains without spoiling my "good looks" :LOL::ROFLMAO::cry:

    I will let you know what results I get from a higher load.
     

  4. JimP

    JimP AH Elite

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    If you are not seeing any pressure signs with your reloads now then it should be safe to increase the powder some, but you need to be careful and watch for pressure signs. Pay close attention to how the bolt opens on your rifle after a round is fired, check the cases after extracting them and look at the head stamp area to see if you see brass flowing into the extractor grove or flattened primers. If you have a caliper you can measure the diameter of the case in several places and compare it to a factory fired case for pressure signs.

    Remember that when a powder manufacture dose their test firing they don't usually use a rifle but a test barrel to get their pressure readings and velocities from and their velocity readings are usually higher than what you will get in a standard rifle.
     
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  5. 270Buck

    270Buck AH Senior Member

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    Cheers Jim.

    There was no pressure signs at 61 grains. I will increase my loads very very carefully. I have 3 young kids and I want to see them all grow up!!
     

  6. PHOENIX PHIL

    PHOENIX PHIL AH ENABLER AH Ambassador

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    Sorry about that, early morning old and bleary eyes.
     

  7. 270Buck

    270Buck AH Senior Member

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    No worries Phil. I know the bleary eyed feeling all too well.
     

  8. gillettehunter

    gillettehunter AH ENABLER AH Legend

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    If you have access to some H-1000 you may wish to try that. It is often considered a great powder for the 7mm. I am doing some similar testing preparing for Africa myself. Bruce
     

  9. flatwater bill

    flatwater bill AH Elite

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    270...............Was the rifle new when you purchased it? If the rifle was shot a lot before the 90 rounds that you put thru it, your velocity may always be a little low.................FWB
     

  10. 270Buck

    270Buck AH Senior Member

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    I want to stick with European powders as the Hodgdons powders are not always available in the UK. But thanks for the suggestion.

    I got the rifle brand new, it is built on a Remington 700 action and has been rebarrelled. So never been fired other than when being "proofed" which is usually 3 shots.
     

  11. blackdog001blackdog001

    blackdog001blackdog001 AH Senior Member

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    Non-factory chamber? Maybe a bit off SAAMI spec on the loose side? Are you seeing any un-burned powder residue? Maybe ream out your flash holes?
     
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  12. JGRaider

    JGRaider AH Fanatic

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    I have worked up several loads for 160's in my 7RMags. 66.5g RL22 got me 3063, and 71.5g Retumbo got me 3117. The 160 AB's worked perfectly in Namibia last year, and I'll be taking the same combination back there in April.
     

  13. lcq

    lcq AH Elite

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    http://www.nosler.com/nosler-load-data/7mm-remington-magnum/

    Nosler says in their test barrel N165 shot best but it is the slowest performer listed. Magpro will get you another 170fps according to nosler but do you really think the animal will notice?

    With my cheap disposable Remington 783 I'm getting 2945 with 65.5gr H4831, win brass, win mag primer and a 160 accubond. They group well under an inch, 0.47 best group. No pressure signs even with the soft win primers and it is 5.5gr over Hodgdon max. Your rifle will tell you when you are pushing it. If you load to the max do your development in the heat of the summer to be safe

    As blackdog stated you may have a loose chamber which could account for the lower velocities
     
    Last edited: Mar 20, 2015

  14. 270Buck

    270Buck AH Senior Member

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    Right, well I ended up going with the viht data and went over the Nosler maximum load.

    I got an average of 2850fps when I went up to 66.3 grains. Interestingly enough 66.6 grains had pretty much the same average fps as 66.3 grains did.

    I am now in a position where I have used 80 of the 100 pieces of brand new Norma brass. I have neck sized and cut to my desired length.

    I have measured my case expansion, new VS once fired brass. On average the cases have expanded by 3.5%.

    I know that every rifle is different, but any idea what the likelihood is that my load will not lose, first and foremost accuracy and secondly velocity.

    I will more than likely make 3 rounds using 66.3gr with new brass and the same charge with once fired and see what difference it makes on accuracy and velocity.

    I will also try a load working up to a 3.5% increase as I now have 3.5% more case capacity. This will mean my load could be 68.6 grains. Although the viht data says the maximum is 68.1 grains.

    The new brass case capacity is 5.456 ml.

    The once fired case capacity 5.647 ml.

    Barrel length is 25.5"

    I am leaving for South Africa for a PG hunt on Tuesday so I have limited time available for another serious batch of load testing!!

    Any help/advice would be appreciated.

    Cheers
     
    Last edited: Mar 26, 2015

  15. blackdog001blackdog001

    blackdog001blackdog001 AH Senior Member

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    Um . . . call me skeptical, but if you are getting 2850 at 66.3, why muck with it any further, particularly given your limited time. I am assuming you have acceptable accuracy. As lcq notes, do you think the animal will notice 2950 vs. 2850?

    Guys way smarter than me with pretty sophisticated testing equipment come up with those max loads for a reason (and it is not just for product liability).

    I shoot a 7mm Weatherby Mag with a 26" barrel. Max is 3250 fps but I shoot right arund 3000 and the rifle is more accurate than I am. 160 grain Noslers at 3000 will kill just about anything in North America and almost all non-DG in Africa. I get around an inch (usually a little more) at 100 yards. The rifle is not pushed, my shoulder is in one piece, the brass holds up, etc.

    My $.02.

    Good luck on your trip.

    BlackDog
     
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  16. 270Buck

    270Buck AH Senior Member

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    My reason for needing to potentially work a new load is the once fired brass has a different capacity, so theory will be that the velocity will reduce. The reduced velocity could also potentially affect accuracy.

    I agree that 2850 fps is plenty fast enough, but it may drop with the extra capacity the case now has.
     

  17. lcq

    lcq AH Elite

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    Try it for accuracy with the fired cases my guess is any drop won't be statistically measurable ie within the std dev. Blackdog said it best "I get around an inch (usually a little more) at 100 yards. The rifle is not pushed, my shoulder is in one piece, the brass holds up, etc." Can't add much to that.
     

  18. 270Buck

    270Buck AH Senior Member

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    Finally I have a load that meets all my requirements.

    66.3gr - 2863fps
    66.6gr - 2923fps
    66.9gr - 2940fps
    67.2gr - 2951fps

    The 67.2gr load started showing pressure signs. There was a circular mark from the extractor plunger. Plus there was only 11fps increase from the 66.9gr load.

    Given there is negligible difference between velocity of the 66.9gr and 66.6gr, I made my decision based on accuracy. The 66.6gr load was just over a 1/2" group. More than accurate enough for my PG hunt next week.

    I went home and promptly pulled the 9 remaining rounds.

    I dare say if I had more time before I went to SA and played with the seating depth, I could tighten the group a bit more. The bullets are seated 20 thou off the lands, when I get home I will try 10 and 15 thou off the lands to see if that reduces my group size, although a 1/2" group is plenty good enough for hunting.
     

  19. PHOENIX PHIL

    PHOENIX PHIL AH ENABLER AH Ambassador

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    You're there I'd say and I'd second your on 66.6gr load accurate and you've backed away from the pressure limitation and your velocity is good. From what I've seen with Accubonds, they do like to be seated long, but you can play with that when you get back. Your velocity is solid and I wouldn't try to go faster than that with AB's anyway. The only negative I've read about them is related to having too high an impact velocity.

    Have a great hunt!
     

  20. lcq

    lcq AH Elite

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    unless you are shooting at extreme ranges 1 to 1 1/2" accuracy is hunting accuracy. we all get a little OCD looking for sub 1" loads but the reality is even a 2" group works for big game out to 200 yds. (6" vital zone) if you are hunting small varmints things are different

    my $0.02
     

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