I have a 7mm Rem Mag Ruger No.1 with quite a long throat.

The barrel is 26 inchs.

I am trying to work up a load with Retumbo and 160gr Accubonds.

I measured the OAL length using the bullet jam into the lands technique and the average came out to 3.520.

Should I start at 3.505 or 3.490?

Will I get more velocity closer to the lands or further away?

I know that pressure will rise sooner the closer I am to the lands.

Anyone have any experience on long throat chambers and if MORE distance to the lands increases velocity?

I am hoping to achieve 2950-3000 fps without pressure signs(of course with MOA accuracy). I know Retumbo would be better with heavier bullets but I wanted to give it a try anyways. I have tried H-1000 in the past but had trouble getting over 2900 fps without getting pressure signs. I also have some RL-22 but haven't tried it yet because of its "rumored" temp sensitivity.

1. Is your OAL measurement to ogive or bullet tip?

2. If ogive measurement start at 3.490".

3. No change in velocity closer or further from lands.

4. A "long throat" or "long bullet seat chamber" does not require any special treatment. The long throat is advantageous when loading heavy for caliber bullets. Weatherby uses long throats. Benchrest shooters want bullet close to lands to eliminate bullet jump mis-alignment with bore whether long, standard or short throat. Let your rifle tell you what the "sweet spot seating depth" is.

Your rifle will likely be diff, but before I rechambered my #1 7rm to 7mm Dakota, I would run 64gr of RL22 or 65gr of IMR7828 under the 160grNP for 3100fps. Bullets were seated to 3.30" & well off the lands. Accuracy was right at 1moa. I prefer IMR7828, it seems more stable from lot to lot. The RL22 hasen't proven to me it's temp. sensitive, but just too much variation from lot to lot for me.