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Beginning loading 7mm Rem Mag

Discussion in 'Handloading and Reloading' started by MovedWest, Sep 12, 2011.

  1. MovedWest

    MovedWest Well-Known Member

    I've been loading for 44mag for quite a while now. I'll gladly admit being a pistol guy and don't have a great deal of exposure to centerfire rifle reloading. At this point I only reload for 44 and have a solid pattern and equipment to produce consistent rounds.

    My questions are:

    What things do I need to give attention to for a necked down case during the prep process?

    How many rounds will the 7mm case handle? (Is that extra collet die for belted cartridges worth it?)

    Any advice or even powders to consider for this caliber?

  2. Zak Smith

    Zak Smith Moderator Staff Member

    Load like any other centerfire rifle cartridge.
    Typically this means, for me:

    1. tumble to clean
    2. resize/decap, use one-shot or sizing wax as appropriate (I minimally size per the rifle in question using the Redding Competition Shellholders)
    3. tumble to remove lube
    4. make sure no media is in primer hole and reprime by hand
    5. use Chargemaster 1500 to load

    I do not use the collet resize, just a regular Redding or Forster die.

    For 160-180 gr bullets, you can use RL25, H4831SC, H1000, and some others in that range. I use RL25.
  3. oneounceload

    oneounceload member

    I have only ever neck-sized for my 700 BDL - some cases are on their 10th reloading (trimming as necessary, etc.)

    I do not load for max velocity, I load for max accuracy - with IMR 4350, 7828, 4831 - that means somewhere in the 60-63 grain range with 160 bullets (the optimum bullet weight IMO for the 7mm for antelope to elk)
  4. Funshooter45

    Funshooter45 Well-Known Member

    The biggest difference you will find between 44mag and 7mm mag is in the sizing and trimming required. With the 44, basically you run the case through your carbide sizing die and you're done, ready to prime and powder. With the 7 mm, it's way different.

    To begin with, you definitely have to lube your cases before you run them through the sizing die. Otherwise you will DEFINTELY stick the case in the die. I've tried a few different lubes. RCBS lube2 worked well but it's a messy process. One Shot worked out OK for me, but I could feel a few times where I was almost about to stick the case. I have settled on Imperial sizing wax. Easy to do and no mess.

    So now you have a case sized. Unfortunately you have to remove the lube you just applied or it will gum up the works. You can tumble again, or in my case I wipe it off with an alcohol-soaked rag. Not too bad.

    For a long time I full-length sized my rifle brass. But I finally tried neck sizing for my .243 and .308 and I really like it. No more lube! I am thinking of giving that a try on my various magnum cases too. But to begin with, the safest thing to start out doing is full-length sizing. Eventually, you will have to do it anyway, so start with the basic way and avoid the shortcuts.

    So now you have a perfectly sized case, it is absolutely critical to trim them down to the correct length. You see, every time you are bumping that shoulder back to spec, the brass has to go somewhere and it goes into the neck, making them too long. Trimming is a real pain. There are a myriad of ways to trim, each with their own benefits. Personally, I went with the Wilson trimmer with the drill adapter and it works good. But now I've discovered the Possum Hollow with the drill adapter and it's a lot easier.

    This is where you'll discover why you really need a set of calipers. You didn't need them with the .44 but you will now. It is absolutely essential to get that trim length right.

    But you still have another step to do. You will want to chamfer the inside and outside of the mouths of the cases to remove those burrs caused by the trimming.

    Finally, you can prime the cases and put powder into them. As a general rule you will find that rifle powders come out of the dispenser a lot more inconsistently than pistol powders do. So you will spend a lot of time trickling powder into your scale pan to get the right weight.

    Now when you get ready to seat the bullet, the actual seating operation is the same as a pistol, but the seating depth is a black art. You dont just seat to the cannelure and be done with it like your .44. They publish a standard overall length for your cartridge and bullet, but that's just kind of a rule of thumb. Your accuracy will be influenced by that depth and you will have to experiment in increments to find out what works best for your rifle with that bullet. Again, here is where your calipers come into play. You might as well start with the "standard" spec length, but you have to measure closely to make sure you have that seating die adjusted right.

    One step you DON"T have to do compared to your .44 is to crimp. No need, in fact it can have a negative impact on accuracy.

    As for bullets, I have found that different bullets of the same weight have drastically different accuracy. For my 7 mm, I found the best luck with 160 gr Sierra BTSP and 150 gr Nosler Ballistic tips, but that's just me.

    For powders, it will be in the slow burning end of the spectrum. For me, I have had the best luck with RL-22 and W-780. But I had pretty good luck with H-1000 and Ramshot Magnum as well. H4831 is another good one as well as IMR-7828. A lot of choices out there, but for me, the particular powder was secondary to the bullet I used. Naturally, the amount of powder you use is extrememly important to the accuracy you get.
  5. Zak Smith

    Zak Smith Moderator Staff Member

    If you use the Competition Shellholders as I recommended, you get the benefits of full sizing but don't work the brass excessively, and trimming becomes unnecessary in almost all cases.
  6. beatledog7

    beatledog7 Well-Known Member

    I'm getting geared up to reload 7mm RM also. Thanks for the tips, guys.
  7. MovedWest

    MovedWest Well-Known Member

    Thanks guys. I knew there would be some significant differences and this info gets me pointed in the right direction. The feedback is VERY much appreciated.

  8. gamestalker

    gamestalker member

    7mm RM, my favorite high power rifle to load and shoot! Yes, a good load is a 140 gr. or 145 gr. jacketed what ever with a low to middle of the road RL22 powder charge. Don't crimp anything for this round, it isn't necessary and will likely have a negative effect on accuracy and could open a can of worms in trying to figure out why necks are producing poor tension and some other issues to deal with. And also if using the slower burning powder's such as RL22, don't reduce the charge below minimum published data. Slow burning powders are not temparmental to work with as long as you remain within the published minimum and maximum data. Things like bullets getting stuck in the barrel and primers backing out can tend to happen. But the good news is RL22 will not suddenly jump sky high when you work the charge up, or drop drastically when you start at the minimum. In general your performance level will be magnum as should be, and accuracy should be very good as well.
    Make sure you maintain your brass so far as trimming it is concerned, when it is at maximum SAAMI length. I also wouldn't advise using a standard large rifle primer with those slow burning powders, only magnum primers or that stuff just won't light correctly and you could get a face full of hot and still burning powder, as I experienced back when mag. primers were hard to find.
    If you have any other questions or concerns feel free to ask.
    Have fun !
  9. Skyshot

    Skyshot Well-Known Member

    ditto: My 700 shoots 160 Accubonds under 1/2 MOA with 62.5 grns of IMR7828

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