Body sizing? A necessary step?

[pyroducksx3]

I am reloading my 7 rem mag for the first time. I am shooting some factory loaded RWS brass and using the cases for reloads. I was going through my brass prep steps today. I am using redding competition sizing dies. So first I deprimed and neck sized the cases. Next I was going to bump the shoulder .02 back with the redding competition shell holder set. Now when I reload for my 300 wsm and I chamber fired cases there is resistance closing the bolt until I bump the shoulder but in this 7 mag after neck sizing there is no difficulty chambering a once fired piece of brass. So I am wondering if bumping the shoulder is necessary. I'm thinking to maintain concentricity I would want to work the brass as little as possible, right? So I skipped resizing/bumping the shoulder and I moved on making my dummy round trimmed the brass and seated a bullet .010 off the lands for a OAL of the ogive of 2.644. It fits in the magwell fine and cycles easily, so I'm thinking I will skip bumping the shoulder and just check it after every firing and when I notice difficulty chambering the fired case to bump that group of cases. Is this an appropriate line of thought? Or should I just resize the cases every time by bumping the shoulder as I'm not going to full length resize? I guess I was thinking the only reason to bump the shoulder is so it chambers easily, so if its already chambering easily why bump the shoulder at all. I appreciate your thoughts, thank you.

 

[J E Custom]

I am reloading my 7 rem mag for the first time. I am shooting some factory loaded RWS brass and using the cases for reloads. I was going through my brass prep steps today. I am using redding competition sizing dies. So first I deprimed and neck sized the cases. Next I was going to bump the shoulder .02 back with the redding competition shell holder set. Now when I reload for my 300 wsm and I chamber fired cases there is resistance closing the bolt until I bump the shoulder but in this 7 mag after neck sizing there is no difficulty chambering a once fired piece of brass. So I am wondering if bumping the shoulder is necessary. I'm thinking to maintain concentricity I would want to work the brass as little as possible, right? So I skipped resizing/bumping the shoulder and I moved on making my dummy round trimmed the brass and seated a bullet .010 off the lands for a OAL of the ogive of 2.644. It fits in the magwell fine and cycles easily, so I'm thinking I will skip bumping the shoulder and just check it after every firing and when I notice difficulty chambering the fired case to bump that group of cases. Is this an appropriate line of thought? Or should I just resize the cases every time by bumping the shoulder as I'm not going to full length resize?

I think you are on the right track.

I don't recomend bumping the shoulder unless it is hard to close the bolt on it.

Bumping is nessary sometimes but it is better not to as long as you can get by with it.

When I do bump the shoulder I only size it enough to ease closing the bolt. (If it only takes
.0005 to do it, that's all I size) It keeps from working the brass any more than necessary.

Bumping more than that only increases head space. and the only time that I size smaller is
on dangerous game rifles where you want them to chamber easy and under all conditions.

J E CUSTOM

 

[pyroducksx3]

I missed a zero, I meant bump the shoulder back a couple thousandths so 0.002. Thanks J E, I appreciate your reply

 

[Bart B]

The most accurate fired belted cases I know of are those full length resized setting the shoulder back a couple thousandths then body sized again with a second "body die" that sizes the fired case all the way to the shoulder getting rid of that "step" in front of the belt on fired cases. This body die is made by cuttiing off the bottom of a regular full length sizing die just above the belt relief and a little below the shoulder. It's set in the press such that the die barely touches the belt when the case is all the way up into the die.

What this method does is get rid of the ridge in front of the belt on fired cases that interferes with how the back end of the case fits the chamber. New cases also shoot just as accurate and that's because they don't have that step. A commercial version is available at Innovative Technologies - Reloading Equipment and it works wonders.

I've fired 15-shot test groups at 1000 yards with both new cases and double sized fired ones. Both groups were about 6 inches. I doubt any benchrest rifle's shot that well with belted cases for 15 shots in a row. Sierra Bullets full length sizes their belted cases using Redding full bushing dies or standard full length dies for testing loads in rifles and rail guns for quality control. I doubt anyone shoots their bullets as accurate as they do.

When belted cases were favored for shoulder fired rifles in prone matches, new cases or fired ones double sized shot the best scores. New belted cases headspace on their belt and even if this leaves 5 or 6 thousandths clearance between case shoulder to the chamber shoulder when the round fires, it doesn't cause accuracy problems. The idea that belted cases have to headspace on their shoulder for best accuracy is a popular myth. Latest evidence of this is a year or so ago when new .300 Weatherby cases were used to set a benchrest record at 1000 yards.

 

[J E Custom]

I missed a zero, I meant bump the shoulder back a couple thousandths so 0.002. Thanks J E, I appreciate your reply

What I ment was 0.0005 (1/2 thousandths).

I like a case to fit the chamber with no chance of movement.

A very tight chamber and no head space will accomplish this.

I have seen the ridge/bulge that Bart B was talking about and this is caused by a lose chamber
and must be addressed by body sizing as he stated. also it can be caused by the bolt face being
to large allowing the case head to lay in the chamber off center.

If this problem does not exist then the chamber, bolt face and head space is good and minimal
sizing is recommended for maximum brass life and consistant accuracy.

Just my opinion.

J E CUSTOM

 

[Bart B]

I have seen the ridge/bulge that Bart B was talking about and this is caused by a lose chamber and must be addressed by body sizing as he stated. also it can be caused by the bolt face being to large allowing the case head to lay in the chamber off center.

That ridge is caused by any case whose diameter in front of the belt is smaller than the chamber at that point. What happens is the case is pushed back against the bolt face when its fired leaving a gap between the front of the case belt and the front edge of the headspace ridge in the chamber. When pressure peaks, it pushes the case out as far as it will go between its belt's front edge and the headspace ridge in the chamber. this may be one to several thousandths of an inch depending on the chamber headspace dimension and the head to belt front on the case.

My belted case rifle has its bolt face quite large. All my 30 caliber magnum chambers have been at SAAMI specs and therefore larger than new or full length sized cases. But the belted cases get pushed off center at the back end of the chamber from the extractor pushing them there. How much depends on how much clearance there is between the chamber and case at the case pressure ring. When the fired case belt clears the chamber as its extracted, the extractor pushes its rim against the bolt face walls. All chambered cases have their back end pushed against the chamber which puts the case center a bit off the chamber center. Doesn't hurt accuracy at all.

 

[Kevin Thomas]

Bart,

actually, most anyone should be able to get just as good accuracy as Sierra does in their testing, at least based on the reloading processes involved. They do nothing special, don't sort cases, don't turn necks and don't develop tuned loads for each individual rifle. It's all very straight-forward and done in the most timely manner possible. Yes, they do Full Length size, but they use very few belted cases, where ever they can get away from them. Like I said, nothing special, and I suspect that almost any serious competitor is far more discriminating about their brass prep and handloading operations.

 

[Bart B]

Bart, actually, most anyone should be able to get just as good accuracy as Sierra does in their testing, at least based on the reloading processes involved. They do nothing special, don't sort cases, don't turn necks and don't develop tuned loads for each individual rifle. It's all very straight-forward and done in the most timely manner possible. Yes, they do Full Length size, but they use very few belted cases, where ever they can get away from them. Like I said, nothing special, and I suspect that almost any serious competitor is far more discriminating about their brass prep and handloading operations.

Kevin, you're right. I should have said that few folks will shoot Sierra's bullets more accurate than they do using their full length sizing. Yes, they don't test many bullets with belted cases. Their best match bullets have shot in the ones with unprepped cases properly full length sized.

But I'll stand by my suggestion that double sizing belted cases the way I mentioned can't be beat for accuracy. And it's equalled with new cases. I've shot enough ammo wearing out barrels with cases of both types. Won my share of the matches doing so, too.

 

[pyroducksx3]

Man just when I thought it figured out! I'm not sure I want to full length size with just my body die but I'm going to look into this innovative die that sizes the base and if that works out I will start double sizing possibly. I would love to hear more about this though so keep the info coming.
Bart B, is this the typical argument "full length vs. Neck sizing only" or is this a belted mag prep step? In other words do you feel it's best to full length resize non belted cases as well as belted or just belted cases?

 

[Kevin Thomas]

Bart,

no problem at all, and no offense intended. Besides, we're in complete agreement on the F/L vs. N/S issue. Just wanted to make clear that Sierra doesn't do anything that most serious reloaders do in turning out ammo. In fact, they do less. Simply don't have the time to do the painstaking work it takes to produce serious match quality ammo when you're doing 500-600 rounds a day, plus case prep work, plus cleaning, plus target measuring, plus data entry, etc.. Frankly, I'm glad to be off that particular hamster wheel! It was driving me nuts and I'd gotten to the point of hating the very thought of going in every morning.

But no, there was nothing even remotely close to match techniques used in doing day to day accuracy QC testing there. You just don't have time for that sort of thing when you have a limited amount time (complete with endless interruptions) and a mountian of test samples every single day.

 

[Kevin Thomas]

pyroducksx3,

Don't know if Bart's still around, but I'll drop two cents in here. Yes, F/L sizing is the way to go. There's no loss of accuracy and you'll sidestep the inevitable chambering problems that go hand in hand with N/S only. Be smart about it, and don't move the brass any more than you need to to facilitate free and easy chambering. But yes, they should (must) chamber without resistance. Use gages, and know what sort of movement you're affecting on the shoulder. Adjust your dies accordingly an you're in business.

 

[pyroducksx3]

I looked at the innovative technologies body die, is it possible to use my redding competition neck sizer only and this die? Or do I neck size, use the body die to bump the shoulder no more than .002 (does the redding body die size anything if I set it short so that it doesn't even bump the shoulder?) and then use this innovative die? I have the Sinclair head spaces gauges/collets and comparators and also use the redding competition case holder set.

 

[Kevin Thomas]

Sorry, had to duck out for dinner! Yes, you should be fine with those if I'm understanding what I've heard about the Innovative Tech dies is correct. Personally, I don't own any belted case rifles and tend to avoid them. But that should take care of both necks and bodies. I'm not sure about bumping the shoulder back and whether these dies will do that. If not, another die is in order. Stick with the gages though, and use them. Frankly, not enough reloaders do, and that's the source for a lot of headaches out there.

 

[Bart B]

Bart B, is this the typical argument "full length vs. Neck sizing only" or is this a belted mag prep step? In other words do you feel it's best to full length resize non belted cases as well as belted or just belted cases?

Yes, this is another chapter in the comparison titled "Full Length vs Neck Sizing Only." I think it applies to rimless bottleneck cases, too. The most accurate ammo I know of has all been properly full length sized, both rimless and belted bottleneck cases. Be sure to set the fired case shoulder back no more than a couple thousandths. And don't use an expander ball; RCBS or Redding full bushing dies are excellent. Use a bushing with it's diameter about 2 to 3 thousandths smaller than a loaded round's neck diameter. This virtually eliminates bent case necks often caused by expander balls.

Here's an example of what new, unprepped cases and neck turned, weight sorted and flash hole uniformed fired cases will do. .30-.338 Keele cases are made from .300 Win. Mag. cases, looks like a .308 Norma Mag. with a 1/10th inch longer neck. These groups were shot at 1000 yards shooting prone slung up with the fore hand/end on a rice bag and another rice bag under the toe of the stock. My wobble area on the target was a bit less than an inch in diameter from heartbeat bouncing the rifle.

The Sierra 190's were shot from twice fired cases, double sized as I mentioned, neck turned, flash hole uniformed and sorted to a 1-grain weight spread. The Sierra 200's were shot from new, unprepped virgin brass ran through a standard RCBS full length sizing die with its neck lapped out to 2.5 thousandths smaller than a loaded round to set the .300 Win. Mag. shoulder back about a tenth of an inch so the case body's the size of a .338 Win. Mag. Both ammo types had bullet runout of no more than 2 thousandths. The mildest large rifle primer made was used; RWS 5341's. Two sighters were fired, one with each load to center the groups on the target. Then a 190 was fired for its 15-shot group followed by a 200 to its 15-shot group, then back and forth between the two loads for 28 more shots so I could see how each load performed after up to about 30 rounds of each. Note each load's group center is separated by a few inches vertically; the difference between 65 grains under a 190 and 64 under a 200. Compare this test from an old Winchester post '64 Mod. 70 conventionally epoxy bedded in a solid wood stock to the latest whiz-bang pillar bedded wonder used in current day benchrest matches' 15-shot aggregates.

Both groups, both with new cases and totally prepped full length sized ones, are about the same size. The chamber is a standard .338 Win. SAAMI speck for case body and shoulder dimensions, but just using a neck long enough for this round. Chamber neck is .344-inch and loaded round neck diameter's .336 for prepped cases, .338 for new ones; lots of clearance around a loaded round's neck. Long live new cases and proper full length sizing. That X-ring's 10 inches in diameter.