Stumped

[FlSportsman]

I have been reloading for a few years. I have loaded 30-06, 270 and 308 with great success and speed. But I just loaded my 7mag with 150g NBT from CT. The powder I am using is 65 grains of IMR 4831, a Federal 215 Mag primer new winchester brass trimmed under 2.500 and col of 3.290. My rifle is a Rem mod 700 adl with a 24" barrel. What suprised me was I was only getting 2850 fps on the crono consistantly. This is the max load and no sign of pressure. The book shows 3240 fps and I have been getting usually 100 to 200 fps slower than the book on all other loads. What is my next steps to get at least 3000 fps? or what can be causing the difference in speed. I have run a bore snake through the barrel and have kept the barrel clean.Thanks in advance

 

[bowhuntrrl]

I would try to see if you can find a load for Magrpro for your 7mm. The case capacity is just a bit less than a WSM and Magpro is one of the powders used to attain high velocities. I know of several people getting 3400 with 140 Accubonds in .270 WSM. My accurate load (.5 MOA) is a 140 AccuBond over 70 grains of Magpro with a regular Federal large rifle primer. This gives me 3200 fps. I just looked it up on Accurate's page a 140 gr will give about 3200 with a max load in your 7mm Mag, and a 160 gr shows just about 3000 with a max load of Magpro. It seems feasible to attain 3000 with a 150, maybe even a little better. Of course with high velocity, there is no guaranty you will get accuracy. Good luck!!

 

[WHELENATOR]

Sportsman, your using the wrong powder. Simple math. Try 72.0 gr. of RL-25, 66.0 gr- IMR 7828, 70.0 gr-H-1000, or 63.0 gr-RL-22 with a 160 AccuBond.
You could also tey 63.0 gr-IMR 4350 behind your 150 BT...half inch in my rifle.
That 72 gr of Rl-25 and 160 AccuBond runs 3090 out of my Colt Light Rifle..it only has 24 inches of barrel too.

 

[fjlee]

I just loaded my 7mag with 150g NBT from CT. The powder I am using is 65 grains of IMR 4831, My rifle is a Rem mod 700 adl with a 24" barrel. What suprised me was I was only getting 2850 fps on the crono consistantly. The book shows 3240 fps and I have been getting usually 100 to 200 fps slower than the book on all other loads. What is my next steps to get at least 3000 fps? or what can be causing the difference in speed.

A velocity of 2850 cfps under the condition you describe might seem a little slow, yes. But there are so many variables that can affect results.

Double and triple check your powder scales and your chronograph. Were the chronograph screens set up the correct distance from muzzle?

You have a book that shows 3240 fps with 24 inch barrel, 150 grain bullet, and 65 grains of IMR 4831? What book is that, if I may ask?

In my opinion IMR 4831 is a bit "fast-burning" for your situation. I think a 'slower' powder with a burning rate similar to IMR 7828 might be better.

It should be possible to get 3000 fps from 7 mag with 24 inch barrel, and 150 grain bullet......yes. With safe pressure.

Lee Carkenord (fjlee) Denver CO

 

[Eagleye]

I have a 700 "Classic" in 7mm Rem Mag, and use the standard 150 Ballistic Tip in Competition in a class where we must use a "hunting" bullet. My pet load is 64.5 Grains of IMR4831 fired by a WLRM primer in WW cases. I have chronographed this load many times, and the average in my 24" barrel is 2970 fps. This load is very accurate, and will group ½" or better if I do my part. This is not a max load in my rifle, but it is the most accurate. It is easy to break 3000 with a 150 in most 24" 7 Mags. Regards, Eagleye.

 

[FlSportsman]

Thanks for the feedback. I have been using my 30-06 so far this year. Eagleye what is your COL and would shortning or lengthing the COL speed it up?

 

[Eagleye]

FISportsman; My Remington has a fairly long throat, and since the magazines on those 700's are plenty long, My COL is 3.380" I do believe that it has some effect on velocity, but not a large amount. If I were you, I would measure how long your rifles throat is and seat to within .020" of the lands. You might try sneaking up .5 grains at a time till you reach 67 grains. I would not go higher than 67. Keep an eye out for any signs of excess pressure. Regards, Eagleye.