Just got my 7mm-300 win mag reamer

[Badgerclaw]

Well, shot 75.5 gr loads again with the brass prepped the right way. The cases came out of the chamber easier but still can't fit a bullet in the fired case without pushing a little. What thickness do you guys turn your necks to? If you turn your necks

 

[louis f]

You said in your original post that you had the reamer, Call the company that made your reamer and ask them for a reamer print. If not you can make a chamber cast. I just clean up the necks on my cases about 3/4 around. But for what its worth the necks measure 0.014 thickness measured with a ball mic.

 

[FURMAN]

Well, shot 75.5 gr loads again with the brass prepped the right way. The cases came out of the chamber easier but still can't fit a bullet in the fired case without pushing a little. What thickness do you guys turn your necks to? If you turn your necks

My loaded rounds, as I believe I have stated before, are .313 in a .316 chamber. I can not drop a bullet into the case of a fired round from either barrel and have zero pressure problems. My custom 300 win chamber is the same way. You can not drop a bullet in a fired case. The only time I have personally been able to do that is with a sloppy SAAMI chamber. In a chamber on the tight side there is enough spring back to preclude the ability to drop bullets into the fired case. When you have chambers set up this way it is important to pay attention to what brass you are using.

 

[louis f]

The thing I forgot to mention on my tight neck chambered rifles I allow 0.004 clearance. when you fire the cartridge it has plenty of room for clearance. As the brass cools the neck will then shrink down, there will be a little resistance if you try to put a bullet in the case. With that said I don't have any noticeable high pressure. But they shoot really good groups with that amount of bore aliment. But I am sure someone will find fault with what I say.

 

[BJH]

BJH,

Which bushings do you use to step down?

I'm curious as to why you step down in three steps, I could be doing something wrong, but my smith told me one step was all I need and have not had any problems.

Have you run into problems using one step?


Sorry about the delay, I have been hunting the last couple weeks. But, yes, I ran into problems trying to step down all at once. My gunsmith also told me that all i needed to do was run the case through a sizing die and load. But I tried that on the first case and the neck ended up inside the body. It crushed it and shoved it down inside the case. I do not remember which bushing I use off the top of my head. But I have found that small steps to get to where I want it to be is the easiest and cleanest way. It only takes a few seconds to switch the bushing in the die, and having to run them through it a couple extra times is not too much trouble to save the headache ruining some or all of the cases by trying it all at once.

 

[Clucknmoan]

BJH,

Which bushings do you use to step down?

I'm curious as to why you step down in three steps, I could be doing something wrong, but my smith told me one step was all I need and have not had any problems.

Have you run into problems using one step?

Badgerclaw,

Is it possible that you had the head space messed up on that case? Maybe when you were setting up the die, you bumped the shoulder back too far on one case? You shouldn't be seeing pressure there, and obviously your not if you could go 2.5 gr higher without problems. Excessive head space can look like high pressure.

See post #18. Bushing sizes are there. If you don't want to expand up just change that last bushing size to whatever you want your tension to be.

 

[BJH]

It looks like i forgot how to add a quote in my last post. It has been a couple days. You are correct about your info on Post #18. I end up using a .311 bushing for my final step. I do not turn the necks or anneal or do any of that stuff. I just size them down and shoot. It is pretty simple to step the necks down and get to shooting. I have really enjoyed shooting my rifle in this chamber configuration so far.

 

[nmbarta]

I'm also using a a .311 bushing.
With norma brass and a 175 eldx my neck tension is .002.
Runout is typically less than .001, but have seen .002 on a couple.
It's an impressive little round.

 

[Timnterra]

Nathan Foster's information on the 7mm practical which is basically a 7-300 has been helpful to me. In his write up he mentions that the 1-9 twist works for everything other than the 195s and the 1-8 doesn't work as well with the lighter bullets. If you are going to shoot 195s then a 1-8 will be the best choice but the 1-9 would be a better choice for everything else.

 

[BJH]

This round would be a great one for the 180 grain class. I ended up going with the 195 due to the ES and SD on the load i got running with it. I had to use Winchester brass because the Norma and Nosler Brass was a 1 and done situation. After firing once the primer pockets were very loose and would not hold a primer anymore. I also got a lot more consistency with my velocity out of the Winchester brass. Mine runs the 195 Berger at 2862 fps with an ES of 6 and SD of 3. It has been a lot of fun to shoot and we found out that the combo works really well on elk.