Full Length or Neck Only; What's Best Resizing for Accuracy?

[Edd]

I've been hoping someone would ask but since they haven't I'll have to do it myself.

bigedp51, have you ever kissed German Salazar's ring?

 

[birdiemc]

You have a soft annealed neck and case shoulder contacting the shoulder of the chamber with circular machining marks. And you are telling us the soft brass is going to smoothly center itself and center the bullet. Somehow I don't think the chamber surface is smooth enough and accurate enough to center the bullet with .00025 clearance on each side of the bullet.

I could do without all the bickering but this is a good point I've never considered. Looked at all my rifles since I got my cheapo borescope and I have to admit I've noticed these rings...even on the one I cut myself....gasp

 

[bigedp51]

I've been hoping someone would ask but since they haven't I'll have to do it myself.

bigedp51, have you ever kissed German Salazar's ring?

No, but I have read a lot of his articles and postings and he was well thought of and respected.

 

[bigedp51]

I could do without all the bickering but this is a good point I've never considered. Looked at ally rifles since I got my cheapo borescope and I have to admit I've noticed these rings...even on the one I cut myself....gasp

Once the firing pin kicks the case in the backside the soft annealed shoulder is stuck where it lands on those chambering rings. You could try putting Vasoline on the case shoulder and see if it slides.

 

[Bart B]

Once the firing pin kicks the case in the backside the soft annealed shoulder is stuck where it lands on those chambering rings.

That's when the case shoulder lands against the chamber shoulder. Oftentimes setting case shoulder back a couple thousandths or more.

Julian Hatcher wrote about this decades ago.

 

[bigedp51]

That's when the case shoulder lands against the chamber shoulder. Oftentimes setting case shoulder back a couple thousandths or more.

Julian Hatcher wrote about this decades ago.

Bart B

Julian Hatcher also wrote about reaming the chamber shoulder on a 30-06 M1917 further and further forward until it got too dark to see anymore. The case never ruptured and the chambered case shoulder wasn't even contacting the shoulder of the chamber. His point being the extractor was stoping forward movement of the case and the shoulder just formed to the longer chamber when fired. And nothing happened to the rifle or cartridge.

There are too many variations in chamber dimensions to make the blanket statement the shoulder of the chamber centers the bullet. And the vast majority here are not shooting military firearms with long, fat chambers with larger freebore diameters.

Below the top image is of a standard .223 chamber with a 1in12 or 1in14 twist that the vast majority reloading manuals use. The freebore diameter is .224 and the same as bullet diameter, and the 5.56 chamber has a .226 diameter freebore that puts .001 on each side of the bullet.

Below the same as above showing the actual chamber and chamber finnish. And the shoulder of these chambers are rough and I do not think of brass sliding across its surface. Meaning again the bullet is being centered in the freebore before the case shoulder contacts the shoulder of the chamber.

Bottom line, the entire case is tapered and has some aligning effect when chambering. BUT the cartridge is centered by the bullet in the freebore and held by the boltface in the rear 99% of the time.

"a full-length sized case in which the neck is also fully sized. There is clearance at the neck and in the body of the case, the closest fit anywhere is the bullet in the throat. If the neck to bullet concentricity is good (although it needn't be perfect), then the bullet will find good alignment in the throat and the case body and neck will have minimal influence. Let's not forget that the base of the case is supported by the bolt face or the extractor to a certain degree as well; this is yet another influence on alignment. As you can see, there are several points from base to bullet that can have an effect. My procedure is to minimize the influence of those that I can control, namely the case body and neck, and let the alignment be dictated by the fit of the bullet in the throat and to some extent by the bolt's support of the base. Barring a seriously out of square case head, I don't think the bolt can have a negative effect on alignment, only a slightly positive effect from minimizing "case droop" in the chamber. Given that a resized case will usually have a maximum of 0.001" diametrical clearance at the web, this isn't much of a factor anyway.

In conclusion, I believe that allowing the bullet to find a relatively stress-free alignment in the throat by full length sizing (including the neck) and turning necks to enhance concentricity gives the bullet the best probability of a well-aligned start into the rifling."

The Rifleman's Journal
Germán A. Salazar

 

[birdiemc]

Once the firing pin kicks the case in the backside the soft annealed shoulder is stuck where it lands on those chambering rings. You could try putting Vasoline on the case shoulder and see if it slides.

Anybody got some pictures of brass with Mark's left from the rings? While I agree they are in all the chambers I own, I also realized I've never seen an imprint left by those rings on the shoulder of a case. This seems odd if they are large enough to hold the case back from fully seating shouldn't they imprint into the soft brass?
I got no dog in this fight just thinking out loud here

 

[Rich Coyle]

We believe what we want because of facts or inspite of them.

Like you, I never saw them also.

 

[Bart B]

Bolt faces rarely have case heads held against them when the round fires as long as the case head to shoulder dimension is less then chamber shoulder to bolt face. Extractor claws have minimum clearance to bolt faces whose dimension is a few (several?) thousandths more than case rim thickness.

 

[Rich Coyle]

Bart B made me. If one neck sizes one has more than the shoulder holding the case. The whole taper of the case is preventing forward motion of the case.

 

[Bart B]

Bart B made me. If one neck sizes one has more than the shoulder holding the case. The whole taper of the case is preventing forward motion of the case.

Almost true. First fired case body diameters are not exactly the chamber body diameters. Nor is the case head to shoulder dimension exactly the same as chamber shoulder to bolt face. Maybe a thousandth or so less.

Neck sizing that case to reload it reduces its neck diameter and nothing else. Bolt closes easily on it. Firing it again ends up with body diameters a couple ten-thousandths bigger as well as its head to shoulder dimension.

Repeatedly neck sizing that case soon requires more force to chamber it as it's now too big to fit the chamber easily.

Time to full length size that case setting its shoulder back a couple thousandths and start the shoot - neck size cycles all over.

 

[Rich Coyle]

When I did the 2,000 round test with the .223 I could do seven neck sizes before I had to full length size them. I discovered an average of 44.5 feet per second higher velocity with the neck sized cases over the full length sized cases. They ran from 39 feet per second to 49 feet per second faster depending on powder. Never the less, all necked cases produced higher velocity than the full length cases.

 

[Mram10us]

When I did the 2,000 round test with the .223 I could do seven neck sizes before I had to full length size them. I discovered an average of 44.5 feet per second higher velocity with the neck sized cases over the full length sized cases. They ran from 39 feet per second to 49 feet per second faster depending on powder. Never the less, all necked cases produced higher velocity than the full length cases.

Man, I wish we had guys doing 1000 round tests on the rums, wsms, etc. Sure save us a lot of time

 

[Bart B]

When I did the 2,000 round test with the .223 I could do seven neck sizes before I had to full length size them. I discovered an average of 44.5 feet per second higher velocity with the neck sized cases over the full length sized cases. They ran from 39 feet per second to 49 feet per second faster depending on powder. Never the less, all necked cases produced higher velocity than the full length cases.

If the higher velocity loads had more neck grip on the bullets, that would make them shoot faster.