Rem700ML/Brux

I take it you have a Rem 700 M/L action with a Arrowhead breech plug. As long as your primers seal up good and they don't stick. You are really not handicapped by using a 209 system. Do you have a sizing die which you will need. I have posted many times that 70-73grs of IMR 4198 with a heavy wool wad has proven to produce outstanding (Repeatable results) in my rifles. Some barrels will shoot without a wad most like a wad over the powder charge for better ignition.

IMO, It is foolish to take a 209 gun hunting in cold weather using straight 4198 without a duplex. A .040 bushing will help though.

The AccuMax will shoot better with a duplex when using a 209 primer. Follow Richard's threads for further proof

If I was dead set on using a single charge, I would use Reloder 7. I would start around 74 grains.

I think that's a pretty foolish statement to say you can't get good ignition in cold weather with a Federal 209A primer or a CCI mag primer. I have left guns out in -10Deg over night with straight powder chargers of IMR 4198 and have never had any problems with ignition. And I have never had to resort to duplexing a load to achieve accuracy if you have to do that you have something wrong. This idea of duplexing powder charges is for the birds. It is a flat out dangerous practice. No powder company would ever approve of its a bad practice and should not be promoted on this board.

If your gun has ignition problems the problem is in the design of the breech plug nothing else. And 74grs of reloader 7 is way to hot of a load to recommend.

There have been several people that I know of who swore by 4198 and 209 primers but ended up being burned by a ftf at a most inopportune moment. To each his own. I will bow out of this discussion.

It's a sendero configuration 25" long I have a swing lock smooth die, I have the arrow head plug in my Rem 700ML/Brux I got everything from Luke

Modified Sendero 1.200" X 5", ST .950" @ 8.5",  ST .835" @ 25"

Ourway77 most guys use a wad with smokless powder and the Accumax bullet .Expecially for hunting they think the wad helps with ignition.( I personally found better accuracy without a wad and with no ignition problems ) 70 grains of 4198 would be a good starting point with a 275 grain bullet . Also most guys get their best accuracy with just a snug fit accumax . (Not tight just sung )Please chime in fellows if I'm steering Ourway77 in the wrong direction .

That's the same contour I have, only my barrel is an inch longer.  Been shooting 74gr of I4198 and 300gr bullets with no issues.  I have a Harrel's brake.  

You should have alot of options.

What works for Elkman may not work for you? I have gone round and round with that "old codger" on the phone and with private e-mails. We have our own opinions. I have proven over and over that in my case, where a single would not work or not work well?..............That a duplex works VERY well! Just ask the members here who have attended the Kentucky Challenge? There is absolutely nothing wrong with a duplex and it is perfectly safe. Any mix up in putting the two powders in your rifle only result in lower velocities. I have put them in backwards and have shaken them completely up and loaded them with only lower velocities.
It is good insurance and makes good sense to use a faster powder to start the slower powder. You use tinder to start a fire don't you??

Duplexes not only are for good ignition ,they were developed to be temp insensitive,meaning poi being consisstent through a large temp range....Savage Shooter came up with the 10/50 4759/h4198 and it worked well and grew into the 10/60 sabotless
275 gn bullet ....which works well in a 209 gun....Duplexes work and have been proven to do so imho....