Case sizing for long range ammo and more

4399 Views 14 Replies 4 Participants Last post by jerrschmitt, Feb 19, 2010

thornblom

Discussion Starter · Feb 13, 2010

Gentlemen,

Here are some questions for ya'll. When loading you ammo for long range shooting, assuming you are using fired cases, do you full length resize your cases, partial resize by backing out your full length sizing die, or use a neck size only die?

Seating depth: Industry standard at 2.800" to 2.810", or magazine length at 2.825 to 2.830", or do you seat out to clear the lands by a nominal amount? The first 2 choices will let you load ammo into the magazine, the last choice will not in the short action 700.

Last, what is your favorite primer?

Sincerely,
Dave (Bubba) Thornblom

1 - 15 of 15 Posts

quaid

· #2 · Feb 13, 2010

I do long range shooting, Dave. This coming week I hope to receive,"Extreme Rifle Accuracy", by Mike Ratigan. The spread of muzzle velocity of my loads is too great for me to be really competitive at 1000 yards and I hope this book will help. According to those who (reckon) they know, the spread from highest to lowest velocity, must be no more than 35fps. At present, my spread is 50 fps. The elevation of the group will stay in the bull at 1000 but that isn't good enough to beat the hot shots.
This is going to be a long road for both of us, Dave. I am a novice at this kind of reloading. Benchrest.com is a very interesting site, if you're interested.
Good luck to us.

jerrschmitt

· #3 · Feb 14, 2010

As Quaid said, Extreme spread is king. I'm not up to his standards and probably never will be. For one thing, my Chrono sux. I'm also not a competator.

Now to answer your questions. I seldom full length size any of my brass except deer hunting rounds, Mostly I neck size to save money on brass. Full length sizing works the brass more than you need and you'll develope neck cracks. Brass for my 6BR (Norma) is close to a buck a round so I work it as little as I can. In the 6 BR I have a Redding bushing neck sizer and it only sizes it .003.

On my .223 I use an RCBS full length die and back it out so that only about half the neck is sized. Most of those cases have been reloaded 8-10 times and still don't need full length sizing. Same setup for the .243.

My .243 Ackley is proving to be a funny duck. Fired cases haven't needed to be resized at all. The smith that cut the chamber must have had the reamer cut to nearly "new brass" specs. The bolt closes smoothly on reloaded unsized brass and fired rounds. There is .0025 neck tension on my reloads. I've never run into this before but I'm happy with it. I do plan to pick up a sizing die in the near future.

As far as seating depth goes, forget industry standard. My rifles are all converted to single shot. (Except deer rifles) I measure the max length for each bullet then seat them to what ever they like. Each bullet will be different so you really need to do that measurement. Most of my rounds end up being .010 - .030 off the lands. In an AR I always seated at least .125 shorter than the max the mag would allow.

I use CCI primers in all my loads. Have for many years. Not sure that they are any better than other brands but it's what I've always used. You know what General Custer said, "Don't change nothing until I get back from the Little Big Horn.

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jerrschmitt

· #4 · Feb 14, 2010

This morning I found a great article on 6BR.com about neck tension and lower ES / SD. Here is the link:

http://accurateshooter.wordpress.com/2010/02/13/neck-tension-bullet-seating-and-the-time-factor/

El Chorizo

· #5 · Feb 14, 2010

I second what Jerrschmit said. My rifles are single loaders as well, and my AR I load to fit the magazines niceley.

thornblom

Discussion Starter · #6 · Feb 15, 2010

Gentlemen,

Here is why I asked. When using Federal Military .308 cases, once fired in my rifle, the fired cases will chamber with no problem. I tried partial resizing from 1 turn out, 3/4 turn out, 1/2 turn out, 1/4 turn out, 1/8 turn out and just touching the shell holder with the bottom of the die. None of those partial resized cases will chamber in my rifle. If I lower the ram and turn the die further in by 1/2 turn to 5/8 turn and resize, those cases will work great in my rifle. It seems that partial resizing does something to the shoulder of the cases and it won't chamber.

I use Hornady New Deminsion dies. I don't know if it is something wrong with the full length sizing die or the cases I am using.

Sincerely,
Dave (Bubba) Thornblom

jerrschmitt

· #7 · Feb 16, 2010

Boy. That's a mystery. Been thinking about it for more than an hour and it just don't make sense. I'd measure the fired case at the neck, shoulder and base as fired. Then measure again when necked sized to see where the change is taking place.

thornblom

Discussion Starter · #8 · Feb 16, 2010

OK, here goes:

Fired case: neck diameter .344", shoulder diameter .4585", base diameter .470"

Full length resized case: neck diameter .335", shoulder diameter .449", base diameter .469"

It seems that my chamber is minimum spec length from base to shoulder, but doesn't the fired neck and shoulder diameters seem a little large. .009" difference in the neck and shoulder diameters from fired cases to full length resized cases.

This rifle is a Remington VSF .308, 26" barrel, 1 turn in 12" twist and HS Precision stock. It shoots pretty good with 100 yard groups as small as .500" to .625".

Sincerely,
Dave (Bubba) Thornblom

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jerrschmitt

· #9 · Feb 17, 2010

What kind/brand of die are you using? It kind of looks like you have a minimum chamber and maximum die. .009 is a lot to work that neck but certainly not unheard of. I still don't understand why neck sizing didn't work unless your shoulder to rim dimension is off and you're setting the shoulder back when you full length resize.

http://www.6mmbr.com/308Win.html

quaid

· #10 · Feb 17, 2010

jerrschmitt said:
What kind/brand of die are you using? It kind of looks like you have a minimum chamber and maximum die. .009 is a lot to work that neck but certainly not unheard of. I still don't understand why neck sizing didn't work unless your shoulder to rim dimension is off and you're setting the shoulder back when you full length resize.

http://www.6mmbr.com/308Win.html

Hmmm. Very tricky, this one. When you FLS, not only is the shoulder set back but the neck is also FLS. It could be neck expansion impeding chambering. It could be the base to shoulder distance has increased too much. Could be those things separately or in combination. It is possible, according to Ratigan, to buy a shoulder gauge, to assist in avoiding over-sizing. After this step, he uses shims under a full length die. The full length die is only used to make the rifle easy to operate, when they have expanded too much for normal neck sizing to allow ease of chambering.
My gunsmith insisted on FLS. Apparently, it's easier on the locking lugs. Confused?
Good luck

thornblom

Discussion Starter · #11 · Feb 17, 2010

The dies I am using are Hornady New Deminsion .308.

I think that because the shoulder diameter is so large after firing that when the die starts squeezing the case at the shoulder the shoulder actually moves forward which causes the partial resized case not to chamber. Then it has to be full length resized to set the shoulder back to where it needs to be to chamber.

Just my thoughts.

Maybe I should send the die and some fired cases to Hornady and see what they can come up with.

Sincerely,
Dave (Bubba) Thornblom

jerrschmitt

· #12 · Feb 17, 2010

thornblom said:
The dies I am using are Hornady New Deminsion .308.

I think that because the should diameter is so large after firing that when the die starts squeezing the case at the shoulder the shoulder actually moves forward which causes the partial resized case not to chamber. Then it has to be full length resized to set the shoulder back to where it needs to be to chamber.

Just my thoughts.

Maybe I should send the die and some fired cases to Hornady and see what they can come up with.

Sincerely,
Dave (Bubba) Thornblom

You might be on to something there. Sure couldn't hurt.

El Chorizo

· #13 · Feb 18, 2010

That's interesting to say the least.

I use hte partial resize method on my fired cases just enough to bump that shoulder back a little. however, in my chamber the cases don't seem to expand all that much.

quaid

· #14 · Feb 18, 2010

thornblom said:
the shoulder actually moves forward which causes the partial resized case not to chamber.

Sincerely,
Dave (Bubba) Thornblom

I think you are right Dave. By chance, I was reading Precision Shooting Reloading Guide, edited by Dave Brennan. In the article,"Reloading For Highpower", p 99, the author, Dave Milosevich says, "At a certain point the shoulder starts to move forward toward the mouth. This is caused by the die reducing the diameter of the case, thereby extruding the shoulder forward before the die shoulder makes contact and pushes the case shoulder back".
I would never have thought of it.

jerrschmitt

· #15 · Feb 19, 2010

quaid said:
thornblom said:

the shoulder actually moves forward which causes the partial resized case not to chamber.

Sincerely,
Dave (Bubba) Thornblom

Click to expand...

I think you are right Dave. By chance, I was reading Precision Shooting Reloading Guide, edited by Dave Brennan. In the article,"Reloading For Highpower", p 99, the author, Dave Milosevich says, "At a certain point the shoulder starts to move forward toward the mouth. This is caused by the die reducing the diameter of the case, thereby extruding the shoulder forward before the die shoulder makes contact and pushes the case shoulder back".
I would never have thought of it.

I never would have thought of it either. That's why I love these forums. You learn something new every day.

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