Bullet Seating Depth 7mm STW

[rb85cj7]

okay I am trying to develop a load for my STW and can't quiet figure out what the seating depth should be. I am shooting 160 grain accubonds in a custom 700 action.

Here is my process:
1. make sure the bullet will slide into the case with enough pressure to keep it in place but still be able to slide it in and out.
2. push the bullet in just past the boat tails and chamber the round
3. Pull the round and measure the overall length.

I used 5 different cases and 2 different bullets and these are the numbers I came up with.

3.807
3.798
3.802
3.843
3.831
3.798
3.803
3.805

For an average of 3.810 at the lands. if i subtract .02" than that give me 3.790 at .020" off the lands.

The Nosler reloading manual says they that the SAAMI cartridge length is max 3.600" Could I really be that much larger then the SAAMI cartridge? Does this sound right?

 

[627PCFan]

Your guns max cartridge length doesnt equate to SAAMI max cartridge Length. Manufacturers never recommend seating that close to the lands for fear of overpressure. Now your problem is will those cartridges fit in your magazine?

Your measurements look good.

 

[rb85cj7]

No they won't so what do I need to do now? I guess there are two options. Load one shot at a time or seat the bullet deeper and load from the magazine.

 

[edelbrock]

My STW loads won't fit in the magazine either. If it shoots better then load one at a time. You should only need one shot anyway.

 

[NCsmitty]

If you are only going to shoot paper, use the .020 of the lands, one at a time.
If these are going to eventually be used in a hunting situation, (i would suspect) then select the COAL that functions through the magazine. Develop the powder load based on your use.

NCsmitty

 

[loadedround]

All I can offer is some information on my experiences with the 7mm STW. When this cartridge was first announced I became rather intrigued with it and wanted one. Since it was a Wildcat Round at that time, and I just happened to have a rather new Ruger 1B in 7mm RM available and it also just happened that there was an old time retired gunsmith around who had a shop in his basement and this fine gentleman rechambered my Ruger 1B to a STW. Using the little loading information around and not having a cartridge magazine to worry about, I found that I could achieve excellent accuracy by seating bullets out as far as possible and still have a stable round. Considering he tuned and bedded my rifle at the same time, I could shoot 100 yd groups of less than 1/2'' at 100 yards. All shooting was done with the Sierra 160 gr bullets and H4831, IMR7828,and H1000 powders . At the time I didn't realize that these powders were basically the same powder. I still have this rifle and it's not for sale!

 

[rb85cj7]

I am going to load some that will fit my mag and see what I get. If i am not happy with that then I will look at the longer COAL.