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Resizing only part of the neck??

DngBat7

Silver $$ Contributor
When I bought my Forster shoulder bump die/ neck die, in the instructions it says that you can loosely fit the bushing. This will cause you to only size about 2 thirds the neck. Leaving the bottle third to the fired dimension. Basically leaving a big external donut on the neck. They say this will center the bullet in the throat when chambered. In theory, this sounds like it would work and make since to do. Does this actually work and improve accuracy? I have never seen this talked about here, may be because it is a waste???
 
That's done routinely in BR shooting. Whether it helps or not depends on a lot of factors....throat, chamber dimension vs. sized case dimension, etc, etc. It's something that you have to try both ways.
 
dkhunt14 said:
I feel the pressue ring should not be pushed through and into the unsized part. The bullet needs the right freebore to allow this. Matt
Click to expand...
Yes. I would think that his seating depth is taking that into consideration. It is a good point to mention it though.
 
Don't do it. It doesn't make the ammo better for most applications, and there is a chance you will get a loaded round stuck in the chamber, but unable to fully close the bolt, or extract the round. Probably won't happen, I know, but I have seen it, and it's unsafe when that happens. The rifle has to be taken to a gunsmith as is - that is, with a loaded round almost fully chambered, but clearly not in battery. What would you do if you were the gunsmith? I've seen them work on it, and I've heard of them whipping out the hacksaw.
 
jim_k said:
Don't do it. It doesn't make the ammo better for most applications, and there is a chance you will get a loaded round stuck in the chamber, but unable to fully close the bolt, or extract the round. Probably won't happen, I know, but I have seen it, and it's unsafe when that happens. The rifle has to be taken to a gunsmith as is - that is, with a loaded round almost fully chambered, but clearly not in battery. What would you do if you were the gunsmith? I've seen them work on it, and I've heard of them whipping out the hacksaw.
Click to expand...

Hacksaw?:eek:
 
Dan S said:
When I bought my Forster shoulder bump die/ neck die, in the instructions it says that you can loosely fit the bushing. This will cause you to only size about 2 thirds the neck. Leaving the bottle third to the fired dimension. Basically leaving a big external donut on the neck. They say this will center the bullet in the throat when chambered. In theory, this sounds like it would work and make since to do. Does this actually work and improve accuracy? I have never seen this talked about here, may be because it is a waste???
Click to expand...

You can use a false shoulder to fireform cases which is a oversized version of only sizing 1/2 to 3/4 of the neck. And in another posting here someone asked if neck turning more than once was necessary. And he asked this because he turned his necks a second time and removed more brass.

So my thoughts are if the case necks do not have uniform neck thickness why use part of the neck to misalign the bullet and the bore.

In a .308 chamber the throat opening is .310 and the .308 bullet has .001 clearance around its circumference.

So what happens if you have .002 to .003 case neck thickness variations and the base of the neck holds the bullet off center with the throat and axis of the bore. Meaning to only size 1/2 to 3/4 of the case necks you must turn your necks. And then keep on turning the necks to keep ahead of brass flow into the neck.

RDNXFbN.png


Life was much simpler in 1973 when I bought my Rockchucker press and the only gauge I had was a green plastic Lyman vernier caliper.
 
Last edited:
JohnKielly said:
Get your chambers cut to .3085 like I do
Click to expand...

And if the case necks are not turned your .0005 extra clearance will not help.

On top of this neck sizing dies can create more neck runout because the case body is not full supported like a FL die.

And a neck sizing bushing die can even add more neck runout.

I love my Forster full length benchrest dies, "BUT" my .223 Forster bushing bump die produces more neck runout than my RCBS or Redding non-bushing .223 neck sizing die.

So I'm wondering if the OP has a off the shelf factory rifle and if he is neck turning. The Forster bushing bump die does not come with a expander like Redding dies. I also wonder if the OP has a runout gauge, a neck thickness gauge and a neck turning tool.
 
I've been using this technique lately with no problems, and very good accuracy. I just don't see a downside to it. This is a small caliber cartridge (20) and I'm absolutely not anal about my brass history. I shoot them till they fail, and routinely get sub .5 MOA, and frequently in the twos.

My chamber neck is fairly roomy, and I just don't think I need to full size the neck completely. been doing 50%, and then a mandril to final size. jd
 
Back when I started shooting in IHMSA production and unlimited classes with a TC Contender (10" and 14" bull barrels, respectively), the barrels were both chambered for 30-30 Winchester, and the TC 30-30 barrels of that period had liberal chamber dimensions. We got better accuracy and shot to shot consistancy by setting an full length sizing die to size the cartridge half way down the neck, creating 2 rings to help center the bullet in the chamber, one at the unsized portion of the neck and one near the base of the cartridge. Worked great for us in the TC; YMMV.
 
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