Hey Folks,
I was recently given a really nice 7400 in 30-06. Getting ready to buy a set of dies (old Lee 4 hole) and have a few questions before I make my choice. Up until this point, all my rifle loads have been worked up for bolt action milsurp rifles, 303 Brit, 7.5x55 Swiss, 7.7 Jap etc. For these I do not FL resize my fired brass, and use a collet die instead of a crimp die.
Being a semiauto, I'm assuming I'll need to use a crimp and FL size the brass each time. Correct?
The rifles are used primarily for deer hunting.
Thanks in advance!
For any and all gas guns, you need to full length resize and size to gage minimum,
That mechanism has a free floating firing pin and you are better off using CCI #34 mil spec primers to avoid slamfires. Which are rare, but do happen in semi autos with soft commercial primers. Always clean and ream your primer pockets to make sure the primer is below the case head when seated. You do not want a shallow pocket and a high primer!. That will cause slamfires.
For you mechanism I would recommend any of the 4895 series of powders, that is IMR 4895, H4895, and AA 2495. H4895 is supposed to be an improved "extreme" powder, less sensitive to temperature changes, if the price is the same, I would buy that.
IMR 4895 was the powder used in the WW2 Garand cartridges and in the National Match ammunition used in the Garands. It's pressure curve is appropriate for your mechanism. I would load a 150 anything, 47.0 to 47.5 grs IMR 4895, CCI #34 primer, any case. This load should be just at 2700 fps in your rifle, and that may seem slow, but that duplicates ball ammunition, and will not beat up your rifle. This series of rifles batters the rails less than the Rem 742 series, but it pays to be prudent
Remington 740/742/7400 Semi-Auto Rifles
Web posting From Wisner's Inc
The biggest changes made to make the 7400 were designed once again around an effort to resolve the bolt lug battering problem. The action arms were beefed up to both strengthen them and to increase weight. The bolt carrier was permanently fixed to the action arms to strengthen the connection. The inertial weight was made lighter, but longer in an effort to spread the operation over a longer period of time instead of a sharper snap that the 740 and 742 created. The cone in the front of the weight (action tube) was increased to allow the gas pulse to expand more and thus slow the operation of the weight a little. A "flex arm" part was added to help secure the action arms which allows the parts to flex a very small amount and thus slow the operation yet some more. All of these changes have managed to slow the cyclic rate enough to virtually end the bolt lug battering problem that plagued the 740/742, but the problem does still exist. On 7400s I have inspected, all that have seen more than a few rounds have shown shiny spots on the rail where the lug contacts the rail. However, Remington removed the 15 small lugs in favor 3 larger lugs. This change increased weight on the bolt a little which once again works to slow the cyclic rate, but also serves to make the contact with the rail one wider impact instead of 5 smaller impacts. The wider striking surface spreads that impact over a wider area, and serves to keep the rail from experiencing the amount of metal displacement that the earlier models showed. I have never seen a 7400 that had enough lug battering to create a problem. This is partly because hunting rifles do not normally experience the number of shots that it would require to cause this problem anyway, but mainly is a result of Big Green finally making enough changes to have slowed the process enough that the vast majority of 7400s will never see the number of shots it would require to damage the rail. In short, Remington fixed the problem for all intents and purposes.
Always keep your chamber clean, buy a chamber brush, run it through the chamber each time the rifle is fired, and wipe out any residue. A dirty rusted chamber will ruin the extractor. So keep the chamber and barrel clean.
