Need help with 7mm load

[Derek M.]

I don't think my 7MM magnum cases will hold 75 grains of Retumbo without serious compression. I was loading 71 grains yesterday and the powder level was half way up the shoulder. Hodgon lists 69.5 as a compressed charge but that isn't the case with my brass, at least with 160 grain Accubonds seated to fit the magazine box.

Bob

Bob you are correct. But Retumbo is so slow that you can seriously compress it in this caliber. Just like overflowing a 270 or 30.06 case with Re22 and compressing the heck out of it to seat a 180 bullet in the latter.

I've had as much as 74 gr of Retumbo but had to tap each case with a screwdriver to settle the powder.

Good Hunting

 

[astring]

7stw- Thanks for pointers on the brass. What neck die should I use? I have full set of RCBS dies that are probably at least 10 years old. Or should I invest into a neck die?

Derek- Where would I start if I wanted to load some 168's to get a compressed load then?

 

[7stw]

I would start with about 66.5grains of h1000. I had really good luck with the WLR Winchester primers. These are the hottest STD. Primer on the market. I was getting fliers with all the rest. My seating depth is 3.336. That puts me .about 35 thousandths off the riflings. You have headroom with the powder, and I think you can go to about 68 or 69 grains. My sweet spot is 67.5. Velocity is 2977. One thing about a 7mag is that you always do not have to use mag primers. The case size is on the edge of STD, and full blown size where you you NEED the magprimer. My 700p is very tight chambered. As far as the book goes, I have headroom on the charge amount, but my gun says no more. The gun is ALWAYS the deciding factor as to how much, or enough. Have fun, it is a great combo, BC, decent speed, downrange energy, etc. AIM SMALL,MISS SMALLlightbulbgun). 7STW

 

[rscott5028]

A lot of folks recommend mag primers with ball powders, or when you have more than 60gr of powder. This is to ensure good ignition under all conditions, especially sub-freezing.

That's just a rule of thumb that I pretty much adhere to it with hunting rifles.

Fed GM215M is a good one.

-- richard

 

[Derek M.]

Derek- Where would I start if I wanted to load some 168's to get a compressed load then?

I started at 71.0 gr Retumbo and kept adding .5 gr.

Keep in mind that any changes in seating depth can change pressures so make sure they are seated the SAME.

 

[Derek M.]

I will add that when I load Re22 in my beloved 30.06 the powder is at the top of the case or close and I compress it with a 180 bullet. AND use a magnum 215M primer too. No worries.