I made some 338 whisper brass from 30-06 partly because the 7mm bench rest brass I normally make it from costs about $80 per hundred and I wanted slightly thicker necks that would fit the chamber better. The 7mm BR brass necked up to about .007”. I found that the thickest neck I could make that would allow chambering was about .009”. Brass with a .009” chambers without resistance. Brass with a neck .010” thick would not fit in the SSK 338 whisper chamber. The necks of the expended brass were too tight to push a bullet into them.

If the expended necks are still tight, does this mean they are not opening enough to ensure consistent release? Do I need to turn the necks down a bit so that expended brass necks are loose enough to push a bullet into? Thanks.

Ranb

Do you know the chamber neck dimension?? From your experiment with the .009 and .010" neck wall dimensions, it sounds like your chamber dimension is somewhere in between the neck diameters of these two case dimensions.

You need a chamber neck diameter which is about .002" larger than your loaded case dimension.

If you have brass fired in your chamber, measure neck diameter of that fired brass - call this Dim-1.

Now size that brass and seat a bullet. Measure neck diameter of the loaded brass, call this Dim-2.

Dim-1 - Dim-2 >= .002" to ensure proper bullet release.

Much below that, and you are into "fitted" necks, where you don't really have to resize brass to seat bullets. But this is a BR technique, and whether you want to get into this, I'll let you decide.

- mike

quote:

If the expended necks are still tight, does this mean they are not opening enough to ensure consistent release? Do I need to turn the necks down a bit so that expended brass necks are loose enough to push a bullet into?

If you are using a maximum load, the necks should let a bullet drop into the fired case. But a light load at times will not expand the neck, as the brass springs back after firing, the neck will not except a bullet easly. A donut may have formed when sizing down your brass. This donut at the neck/shoulder junction may keep a bullet from fully entering the case neck after firing. Be safe, go with a .0085"

quote:

If you are using a maximum load, the necks should let a bullet drop into the fired case. But a light load at times will not expand the neck, as the brass springs back after firing, the neck will not except a bullet easly. A donut may have formed when sizing down your brass. This donut at the neck/shoulder junction may keep a bullet from fully entering the case neck after firing. Be safe, go with a .0085"

I`d have a cast made of the neck/throat area of your chamber and decide where to go from there. Measuring fired brass is not the way to find this. The spring back of the case will skew the results, and depending on the work hardening of the case will vary every time you try to read it.

Bench shooters do keep neck fit snug in their rifles, but still try for 0.0015"/side or ~0.002"/0.003" clearance. This is a very small amount, and any dirt or slightly over sized bullet can cause a pressure problem. I personally in a non bench type chambered gun want a hair more play.
I`ve a 270 Win with min SAAMI spec chamber and a neck clearance on thick Remington or Norma brass of ~ 0.003". I can load a fired case with out resizing the necks, and the case will hold the bullet. The case doesn`t open enough to remain at a ID large enough after firing to allow a bullet fully enter without effort

They are light subsonic loads, only 8 grains of bullseye or 12 grains of H110.

Ranb

quote:

only 8 grains of bullseye or 12 grains of H110.

A fast burning powder like Bullseye can produce high pressure really fast. If the bullet gets crimped into the chamber a little with your tight neck, things could go wrong very fast. As for H110, it may not be safe to use that powder. You may know more about this then i. Hodgdon warning > "). H110 and Winchester 296 loads should not be reduced more than 3%.

Reduce H110 and Winchester 296 loads 3% and work up from there. H110 and Winchester 296 if reduced too much will cause inconsistent ignition. In some cases it will lodge a bullet in the barrel, causing a hazardous situation (Barrel Obstruction). This may cause severe personal injury or death to users or bystanders. DO NOT REDUCE H110 LOADS BY MORE THAN 3%."

I am actually using surplus NM04 in place of bullseye and WC820 in place of H110. Both look and perform like their commercial counterparts.

I have also never had a problem with lightly loading H110 in the past. H110 and WC820 meter and burn very consistantly, even with light loads. The light H110 loads are recommended by SSK for their subsonic Whisper cartridges.

Ranb

quote:

Originally posted by ranb40:
I made some 338 whisper brass from 30-06 partly because the 7mm bench rest brass I normally make it from costs about $80 per hundred and I wanted slightly thicker necks that would fit the chamber better. The 7mm BR brass necked up to about .007”. I found that the thickest neck I could make that would allow chambering was about .009”. Brass with a .009” chambers without resistance. Brass with a neck .010” thick would not fit in the SSK 338 whisper chamber. The necks of the expended brass were too tight to push a bullet into them.

If the expended necks are still tight, does this mean they are not opening enough to ensure consistent release? Do I need to turn the necks down a bit so that expended brass necks are loose enough to push a bullet into? Thanks.

Ranb

Your cases sound like they are either hard from the forming process or your loads are light or both. Try annealing the necks of a few cases and firing them. They will blow out straight and not spring back.

Your loaded rounds should chamber without binding in the neck area. Unless you are shooting bench rest or just want to experiment keep your neck clearance at least .002 to .003.