Compressd loads ??

[Goin'Hot]

I was loading some 223 AI's last night. In a formed case I can get about 26 grains of Varget in there with MINIMAL crunching when a 75 AMax is seated. COAL 2.425" (Lands at 2.507" w/ AMax)

My question is... How much kernel crunching is considered okay? I've loaded some 26.3, 26.6 & 26.9 as well that all had more crunching (in increasing amounts).

Technically, <span style="font-weight: bold">If</span> these show no signs of pressure, could I load the powder up into the neck and fully compress it with the bullet?

 

[Greg Langelius *]

Re: Compressd loads ??

Your primary concern is pressure.

Secondary concerns are accuracy and bullet creep.

It's not unheard of for bullets to slowly back out some under the pressure of a significantly compressed charge. What fits the mag when you put it together may not fit so well when you get it to the range.

It depends somewhat on neck tension.

Given the choice of increasing neck tension and decreasing the charge, I'd decrease the charge. My experience with unnecessarily high neck tension is that it doesn't go hand-in-hand with superior accuracy.

Greg

 

[kansas45]

Re: Compressd loads ??

Hey Greg, Not to change the sujbect, but, how do you determine neck pressure anyway?
Thanks
Sam

 

[Victor N TN]

Re: Compressd loads ??

I agree with Greg. Neck tension causes funny things when you mess with it.

One way to tell if you have too little neck tension is to stand a loaded round on the work bench or table top and try to push the bullet down with your fingers. If you can push it deeper in the case, you need to increase the neck tension a bit. If there is a noticeable bulge where the base of the bullet is located you may have too much neck tension.

Bushing type dies are a good way to control the neck tension.

There is nothing wrong with a compressed load. As long as it doesn't cause the bullet to creep or spring back out. That will cause the COAL cartridge over all length, to change.

 

[Greg Langelius *]

Re: Compressd loads ??

My neck tension requirements are minimal. I try for just enough tension to resist manually (forefinger and thumb) disturbing the bullet from its seated position. That's for single hand feeding into a bolt gun. Semis and mag fed bolt guns need more tension. IMHO, the goal is to resist unintentional setback.

I control tension a different way.

I use the .260 Rem chambering, in a SAAMI spec chamber.

I F/L resize with a .308 die (no decapper/sizer ball), which acts as a body die without touching the neck. I then neck size with the .260 F/L die (decapper/sizer ball inserted and functioning), but the die itself is backed off so it only touches the last 1/32-1/16" of the neck end. This does several things. It provides a minimal, and comparatively controllable neck tension, and it also leaves the rest of the neck expanded, to center the neck better in the chamber neck area. Finally, it confines the work hardening area to the very end of the neck, which might be expected to be trimmed off as case length grows, moving unworked brass into the sizing area. I find that such growth relates to load zip, and since I try to keep the zip down on my loads, growth is slow. I can use less zip because I use a longer barrel to get my velocity. It all adds up to longer life, barrel and brass both.

So why would a compressed load be my choice? Well, using a slower powder allows me to load the case to a higher capacity, bringing load compression to the table. I actually prefer mildly compressed loads, because there are no powder level discrepancies to deal with, which can cause ignition to be less consistent. I would rather waste a little powder than deal with this.

Greg

 

[jrob300]

Re: Compressd loads ??

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Greg Langelius *</div><div class="ubbcode-body">I find that such growth relates to load zip, and since I try to keep the zip down on my loads, growth is slow. I can use less zip because I use a longer barrel to get my velocity. </div></div>

Greg

What is "zip"?

Thanks

John

 

[bugman]

Re: Compressd loads ??

you have been given good advice by the previous posters. I can add a few things for you to consider.

1. if you are not showing any dangerous pressure signs, don't worry about the crunch. I have one rifle (6PPC) that I drop powder to within a few millimeters of top of neck. Of course this weapon has a custom bolt action that can handle the pressure and this is it's best node.

2. if you are going to be max compressing a load, you need to consider bullet creep. In my experience you can get away with .0015 to .002 neck tension with a bolt gun. Anything less than that and I have had OAL increase if I didn't shoot the ammo within a few days

3. also related to neck tension....if your OAL is jamming, then you better find a tension that won't result in further seating of the bullet upon bolt close (especially of this AE of yours is semi auto). With a jam above .010 or so, I have noted further bullet seating in bolt guns whenever I have used neck tension of .0015 or less. This can really be dangerous if you are on the ragged edge with your pressure curve. You better know your rifles true OAL.

4. none of this has considered your desires for barrel life, throat erosion, single feed vs. magzine, chrono numbers,etc.....but I guess that can be another topic

Jack

PS I think Greg uses the word "zip" for muzzle velocity

 

[ewoaf]

Re: Compressd loads ??

I'd load up a few to your OAL and measure them again after 24 hours or so, and if your OAL hasnt increased, you should be ok.

 

[Kinsman]

Re: Compressd loads ??

One way that I use to get more powder in the case without compressing the load is to use a drop tube. The powder may be considered compressed, but not by the bullet.
A 12" drop will cause the powder to settle in more closely, and can give a quarter inch or more empty neck area.
Try it by filling a case full of your powder, pour it into a container, then drop it back in the case through a drop tube. You will see the difference. Doesn't break kernels either.
You can make a workable tube with a piece of 1/4" copper tubing, flared at each end.
This does add a lot of time to your reloading process.

 

[Goin'Hot]

Re: Compressd loads ??

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: ewoaf</div><div class="ubbcode-body">I'd load up a few to your OAL and measure them again after 24 hours or so, and if your OAL hasnt increased, you should be ok. </div></div>

I'll give this a try. I am not jamming in the lands. It's mag fed through a Savage. Mag length is ~2.432, lands are 2.502". Pressure signs are JUST creeping in (slight cratering, no sharp edges) so as long as it still fits in the mag I SHOULD be fine. I'm neck sizing the entire neck (which as I read here may not lend to ultimate accuracy) which may be more than I need.

If I resize 1/2 of the neck and then use a LEE factory crimp die, would I be taking a step forward or backward in regards to accuracy?

Thanks for all the reply's.

 

[ChicSpandex]

Re: Compressd loads ??

I am going to try Retumbo in a 300WM, which is highly compressed. Even after vibrating the case, the powder is still in the neck, and the bullet goes below the bottom of the shoulder. I don't like the idea of pushing hard on the bullet (the seater really only contacts a ring on the bullet). Has anyone tried using a compressing rod? Black powder people do this. It sounds like smokeless has some springback, so it might be possible to slightly overcompress before bullet seating. I have also heard of bulging cases, which might require that the process be done in the sizing die. Does a long drop tube work better than vibrating? It doesn't seem like it should.

 

[kyreloader]

Re: Compressd loads ??

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Goin'Hot</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: ewoaf</div><div class="ubbcode-body">I'd load up a few to your OAL and measure them again after 24 hours or so, and if your OAL hasnt increased, you should be ok. </div></div>

If I resize 1/2 of the neck and then use a LEE factory crimp die, would I be taking a step forward or backward in regards to accuracy?

Thanks for all the reply's. </div></div>

I would not use the crimp die if you are after ultimate accuracy. The crimp die causes increased neck tension that in my experience does not lend itself to accuracy. Neck size only and you will get better accuracy.

 

[Victor Co Heather]

Re: Compressd loads ??

I compress a little bit with my .308 loads, never had a problem.

 

[Enios]

Re: Compressd loads ??

I compress some of my 308 loads and it's never been an issue.