I am a beginner reloaded with a new 7mm Rem Mag. For deer and elk I am pretty set on the 175 grain Nosler Partitions. From the 4th Edition manual it looks like 62.5 grains of RL22 looks pretty promising. I have some questions however:
First off, reguarding maximum overall length, the book says this is 3.290 inches, but that optimum accuracy may be found with a slightly longer OAL. Does anybody have any experiences or suggestions with longer overall lengths in the 7mm Rem Mag? Again, I have a Rem M700 BDL.
And less specificly is there any real cautions or hazards I should be aware of when reloading for the 7mm? Any hints? And how exactly do I go about headspacing off the shoulder instead of the belt?

Again thanks guys.

I will make a stab at your questions Far Right , even though I am a piss pore typist , but first if you are a beginner read through the parts your reloading book that discusses bullet seating and resizing , and get one or two more good manuals for reference. If you could find some old articles or his books , an old writer by the name of Bob Hagel did an excellent job explaining the details of sizing and seating depths for belted cases.

To headspace on the shoulder , back off your sizing die a couple of turns from bottoming out and resize a case . You can usually see by the lube smear on the neck how far you are from touching the shoulder . Then try chambering the case , much of the time it will go slightly hard . Now screw your die in further a little at a time until you are just getting easy chambering . Then lock your die ring and you have it headspaced on the shoulder . For target or varmint work you could stop when you have just a bit of "feel" when you close the bolt , but for your hunting rounds you want slick chambering .

For seating depth , there are a couple of gizmos you can buy to guage the distance to the lands , but I have always used Hagel's trial and error method . Take a dummy case and partially size the neck . Then seat the bullet of your choice well out . Use a kitchen match to black the bullet , or a black magic marker can work too . Chamber the round and withdraw it . You should be able to see marks where the bullet contacted the lands. Screw in your bullet seater a little at a time until you are just barely getting no marks and just touching the lands. Then I screw the seater in one more full thread turn and lock it . That gets you about 1/16 inch from touching the lands but for hunting loads you do not want the bullet touching them or stuck hard into them . If you need to play with the accuracy you can try going a little deeper , but I normally get very good results about 1 thread short of the lands. Magazine length should not be an issue with your M700 as it will take cartridges up to 3.6 inches .

RL22 should be a good choice for your 7mm . I have always used H870 in mine , but I think RL25 may be one of the best choices , and I am going to work with that the next time I load for my rifle . Alliant has data online for their powders ......

The 7mags are great all around hunting rounds. I like the 160grNP for mine but I have some 175gr I want to try for elk size game. I have had good luck w/ RL22 in the 7RM & 7mm Dakota. As far as seating depth, the 1st place to check is your magazine length. Some mag boxes limit you to 3.30". Then you can check for OAL as sdgs outlined. Every rifle is different & when you find a powder/bullet/primer/case combo that shoots well, experiment w/ the seating depth in .01" increments to find what works in your rifle. My #1S has a rather long throat & I can seat passed the 3.290" mark by quite a bit.

Since nobody knows what the headspace it like from your bolt face to the shoulders of your cases you should feel inside each case for insipiant head separations with a wire.

This should be done for all belted cases and even rimless and rimmed if they are fired in guns with rear lock lugs.

I would seat the bullets out til they shot the best. If the magazine is the limit then so be it. Try the rounds in the mag before you put them in the box.

Another way to set the distance to the lands is to seat a bullet way out in a test case and just force the bolt closed. I would not use a part sized neck for this. Use a full length sized case. The bullet will get pushed back of course. Now put it in the seating die and bring the seating screw down to the bullet, back the cartridge out of the die and now turn the die in 1/2 turn. This is about .015" off of the lands.

I like 4831 and mag primers for that cartridge.

Faright I've found that with 160 & 175 gr bullets IMR 7828 gives the best performance & accuracy.RL 25 should also be good. For lighter bullets either 4831 or RL 22 work well.

In regards to powders, I like RL22 as the top choice for 150-175 gr. bullet weights. I've also used IMR 4831, and it will also work well. Others I'm sure will work well are AA3100, H4831, IMR 7828, and H1000. I'm just starting to try RL25, so we'll see how that goes.

For bullets, I like 160 gr. for all purpose use. 150 gr. may be slightly better for medium game, and 175 gr. slightly better for large game, but the 160 gr. is a great comprimise. I really like the CT Partition Gold. Premium bullets are really needed in the 7mm Mag, as it's high velocity will blow standard bullets to peices when hitting heavy bone at close range. I wouldn't bother with the 140 gr., they are better suited for use in the 7mm-08 and 280 Rem. Few hunters can utilize that much range.