• This Forum is for adults 18 years of age or over. By continuing to use this Forum you are confirming that you are 18 or older. No content shall be viewed by any person under 18 in California.

neck sizing vs FL sizing

I just recently got a neck sizer for my 243ai. I have a load worked up that shoots .4-.5 consistant on fl sized brass how much better or i should say will there be a big change if i just neck size? Meaning i have some brass that is fl sized and not loaded but dont have piles of brass to just set those aside and not use but i also have some fired stuff that needs to be sized . Is it going to change my load considerable? By the way when i full length size its absolute minimum shoulder set back just enough to close the bolt.
 
My .243 ack likes neck sized brass a bit better, it tightens my groups up like a tenth of an inch compared to full length siing so not really a big improvement, just a little less brass to move when I size. As far as loads go, it should not cause any noticeable amount of pressure increase or velocity. If it does you may have changed the nack tension. If your just bumping the shoulder anyways it might not really improve accuracy at all. Basically, as with everything in reloading, it really just depends what your rifle happens to like. Some like fl sized, some like neck sized. In general most rifles shoot better the closer the brass matches their chamber. Be careful about only nick sizing though as eventually the case will expand to the point that it needs to be FL sized.
 
Yeah i know i have a fl sizer too. Just thought id try the neck sizing out my 204 does better with neck sized brass.
 
bobcat30 said:
I just recently got a neck sizer for my 243ai. I have a load worked up that shoots .4-.5 consistant on fl sized brass how much better or i should say will there be a big change if i just neck size? Meaning i have some brass that is fl sized and not loaded but dont have piles of brass to just set those aside and not use but i also have some fired stuff that needs to be sized . Is it going to change my load considerable? By the way when i full length size its absolute minimum shoulder set back just enough to close the bolt.

Full length sizing each and every time will ensure longer case life. Push the shoulder back .001", (push in at the shoulder and in at the case head area .001" each, which should be built into the die itself) and you've got it. Some would say .0005" at each location, but that would be difficult to do, let alone measure.

At some point, after just neck sizing, your brass won't fit your chamber or it would be a struggle to do so. You'll eventually have to F/L size, and when you do, you're going to have to overwork your brass to get back to the F/L sized dimension. Besides, you'll save some money, by eliminating a die you could have done without in the first place.

TWO dies are all you'll ever need. A F/L Bushing Die and a Bullet Seating Die.

After minimum sizing of the shoulder, remove the firing pin and its spring. Close the bolt on a dummy round. After doing that, the bolt should not fall on its own. It should however require a slight effort, and I mean slight, to move it downward if the shoulder was dimensioned properly. By removing the firing pin and spring, you've removed the energy of the spring and will have a better feel for the .001" set back you may or may not have imparted to the case. .001" is infinitesimal!
 
I use neck size dies for my 'target' guns. I have noticed,(but can't explain why), that the first time neck sized brass is not as accurate as those neck sized and fired several times. Maybe it is because with each firing the brass grows slightly, thus creating less headspace. My guns prefer a 'crush' feel upon closing the bolt. I usually neck size untill the 'crush' feel is too great,,then I FL pushing the shoulder back just slightly.
 
260Ravage said:
I use neck size dies for my 'target' guns. I have noticed,(but can't explain why), that the first time neck sized brass is not as accurate as those neck sized and fired several times. Maybe it is because with each firing the brass grows slightly, thus creating less headspace. My guns prefer a 'crush' feel upon closing the bolt. I usually neck size untill the 'crush' feel is too great,,then I FL pushing the shoulder back just slightly.

You're wearing out you brass long before its time.
 
Outdoorsman said:
260Ravage said:
I use neck size dies for my 'target' guns. I have noticed,(but can't explain why), that the first time neck sized brass is not as accurate as those neck sized and fired several times. Maybe it is because with each firing the brass grows slightly, thus creating less headspace. My guns prefer a 'crush' feel upon closing the bolt. I usually neck size untill the 'crush' feel is too great,,then I FL pushing the shoulder back just slightly.

You're wearing out you brass long before its time.

Actually, I can't see how neck sizing as routine and occasional FL sizing is going to wear the brass out. It works the brass less than FL every time.
 
From: bartbob@aol.com (Bartbob)
Newsgroups: rec.guns
Subject: Re: Bottleneck Cases - Seating and headspace
Date: 11 Jan 1996 09:34:11 -0500

Your questions about reloading the .308 Winchester are good.

Headspace for the .308 Winchester, as well as other rimless, bottleneck cases, is measured from the closed bolt's face to a datum point on the shoulder. This datum point for the .308 Win. is .400-inch. Minimum .308 Win. chamber headspace is 1.630-inch. Maximum is about 1.650-inch. New cases typically measure about 1.628-inch from case head to the shoulder's datum point so they will easily fit in minimum-headspace chambers, yet not stretch in firing enough to cause head separation problems when fired in a maximum-headspace chamber. New cases typically end up with a fired-case headspace dimension of about .001-inch shorter than the chamber's actual headspace.

Headspace is measured with steel gages precision ground to specific dimensions. They are put in the rifle's chamber, then the bolt is gently closed. If the chamber is too short and a minimum gage is used, the bolt won't fully close; the chamber must be lengthened with a reamer to fix the problem as new cases may not allow the bolt to be closed. If the chamber headspace is between the minimum and maximum limits,then the minimum gage will let the bolt easily close. If a maximum gage is put in the chamber, the bolt should not be able to close which verifies the chamber headspace is within manufacturing limits for safe use with new cases. But if the bolt closes on a maximum gage, chamber headspace is too long and new cases may rupture if fired in such a chamber. Minimum gages are called "go" gages, maximum gages are called "no-go" gages based on the idea that a the bolt should "go" closed on a go-gage and "no-go" closed on a no-go gage.

Bottleneck sized- or new-case headspace can be measured with a gage such as the RCBS Precision Mic. A case is put head-down in the gage, then a micrometer thimble is screwed on and tightened until it stops against the shoulder. The gage is read in thousandths of an inch. Loaded rounds can also be measured with such gages.

Here's what was learned back in the 1960s about sizing cases. It applies to the .308 as well as other rounds of similar size. Tests were conducted with super-accurate .308 Win. match rifles. Chamber headspace was 1.630-inch,or minimum. Rifles were held in an unrestricted machine rest. An unrestricted machine rest clamps the rifle's forend and butt much like it would be held by someone. On firing, it moves with the same resistance for each shot. It slides on three steel rods riding in V-blocks and moves about 3 inches when fired. The upper cradle is moved back forward against a stop after each shot and repositions the rifle exactly the same for each shot. Such machine rests eliminates all human variables in holding and are commonly used by bullet making companies and military arsenals for accuracy testing. Sometimes only a barreled action is clamped in the rest; pictures of such machine rests are shown in Sierra's reloading manual. The US Olympic Shooting Team uses similar ones for testing .22 rimfire match rifles and ammunition as they know humans can't test them as well as the rest can.

Such tests are much, much better than shooting a highpowered rifle from a bench because of one important, but little known reason. The more recoil a rifle has, the more very, very slight changes in how it's held effect how it moves as the bullet goes down the barrel; very small changes cause the barrel axis to be different for each shot as the bullet leaves. Rifles used in 100 to 300 yard benchrest matches shoot mild cartridges with small powder charges and light bullets which are shot in virtually free-recoil conditions unimpeded by differences in holding which is near machine rest conditions. When held firmly like rifles shooting larger, more powerful cartridges have to be, they typically shoot much larger groups than the sub 1/4th-MOA ones they are famous for. Rifles tested in machine rests typically have groups with smaller spreads between largest and smallest ones than when conventionally benchrested. What this means is that most highpowered rifles actually shoot better than conventional benchrest techniques show.

The .308 rifles fired in a machine rest would shoot about 1/2-MOA test groups with cases sized correctly for best accuracy. Note that twenty or more shots were fired for each group. When hand-held and shouldered from a typical benchrest with the rifle's forend and stock toe on sand bags, the groups would be in the 1 MOA range. Here's a summary of what was learned from these tests.

When a full-length sizing die was set in the reloading press as instructions said, sized cases had a head-to-shoulder headspace typically shorter than a new case. When fired, these cases produced test groups about 1.5-MOA. Note that the die was set in the press such that its bottom just touched the shellholder as the ram was at the top of its movement. This caused the case shoulder to be set back so the sized-case headspace dimension was typically shorter than that of a new case. Such instructions supplied with reloading presses and dies are required for two reasons regarding chambers with minimum headspace dimensions. First, the great variety of chamber sizes for a given cartridge vary quite a bit and the manufacturer wants to be sure sized cases will chamber properly. Second, the amount of case lube applied causes sized-case headspace to vary several thousandths of an inch; lightly lubed cases will have a longer headspace and the manufacturer wants to be sure cases so sized will fit in minimum headspace chambers. Cases so sized could be reloaded about 10 times before their head separation became imminent.

Fired cases partially sized in a full-length sizing die with about three-fourths of the neck sized produced test groups about 1.5-MOA groups. Cases so sized had their body diameter's reduced a couple of thousandths of an inch which moved the shoulder forward several thousandths of an inch. These partially-sized cases were actually longer in head-to-shoulder datum point dimension than the chamber's headspace dimension. A slight binding was noted as the rounds were chambered. Case life of these cases was about 20 to 30 reloads.

Fired cases that were neck-only sized in dies that didn't have their body diameters reduced but their necks were sized down would shoot groups about 1-MOA groups. Subsequent firings of the same case resulted in its shoulder moving forward enough to cause very slight binding as the bolt was closed and groups opened up about 1/4th MOA with such cases. About 30 to 40 reloads per case was possible.

New, never fired cases produced test groups about 3/4ths-MOA even with all their irregularities from manufacturing. The smallest test groups came from cases full-length sized such as the shoulder was not set back from it fired position. Sized-case headspace was the same as, or not more than .001-inch shorter than fired-case headspace. Test groups were about 1/2 MOA. And cases could be reloaded 20 to 30 times.

This well explains why most folks get better accuracy with partial-sized cases using full-length sizing dies than by following press/die instructions for full-length sizing. It also explains why they get better accuracy with neck-only sized cases compared to conventional full-length sizing with the die set according to supplied instructions.

It should be mentioned that the machine-rest tests were made at 600 yards. Had the tests been done at 100 yards, the smallest groups would have been about 2/10ths-MOA and the largest ones about 3/4ths-MOA. In one test, 40 consecutive shots were fired into just under 2 inches at 600 yards. To do that well, the group at 100 yards would have to be about 1/10th MOA.

By using a sized-case headspace gage like the RCBS Precision Mic, you can set a full-length sizing die in a press such that it sizes the cases just enough to set the shoulder back no more than .001-inch. You'll probably get best accuracy this way as well as excellent case life.
 
Well, I think we have learned a tad bit more since those 50 year old 600 yard tests (Didn't say if they had a 600 yd tunnel or they measured conditions all along the way and plugged their effects against group size, either way we now know that even a tunnel has conditions that adversely affect the bullets flight).
Before everyone starts to think partial sizing is the new wave, read German Salizars, The Riflemans Journal, article titled "Basics- Resizing- Case Dimensional Changes" dated 6/9/10.......can be read on the website "Rifleman's Journal".
My answer to the OP's question would be Neck sizing may be more accurate, but if you're loading on the high end (and most with an AI do) you will probably get hard bolt lift every second firing or sooner, so it becomes a PIA to keep switching dies, and putting undue wear on your locking lugs.
 
Outdoorsman: "You're wearing out you brass long before its time."
I disagree. My 260rem with lapua brass has been reloaded 14 times and still going with no apparent faults lines. My .308 lapua has 12 loadings so far with no evedence of wear. Had I FL resized them,,,they'd all be in the bone pile.
 
Two additional explanations for FL vs NK sizing

Larry Willis' perspective on the same issue: http://www.larrywillis.com/resizing.html

"Full length sizing is the most commonly used form of resizing. Full length sizing dies reduce the neck and body dimensions of a fired case to allow free and easy chambering. In most instances, full length sizing will reduce the case dimensions enough to allow it to be used interchangeably in several different rifles chambered for the same cartridge. Contrary to popular opinion, full length resizing is commonly used by the vast majority of competitive shooters, especially in those disciplines where rapid-fire is involved. It should be clearly understood that full length sizing does not reduce a fired case to its original, unfired dimensions. The goal here is to bring the case dimensions down far enough to allow the reloaded case to be chambered without difficulty." (In doing so, it doesn't overwork the case. Reductions are minuscule) Source: ExteriorBallistics.com
 
I'm with Ravage here, I've reloaded Winchester brass in my 243AI until the primer pocket will no longer hold primers sufficiently, Necksizing the cases. Can't ask for better than that.
Outdoorsman said:
Two additional explanations for FL vs NK sizing

Larry Willis' perspective on the same issue: http://www.larrywillis.com/resizing.html

"Full length sizing is the most commonly used form of resizing. Full length sizing dies reduce the neck and body dimensions of a fired case to allow free and easy chambering. In most instances, full length sizing will reduce the case dimensions enough to allow it to be used interchangeably in several different rifles chambered for the same cartridge. Contrary to popular opinion, full length resizing is commonly used by the vast majority of competitive shooters, especially in those disciplines where rapid-fire is involved. It should be clearly understood that full length sizing does not reduce a fired case to its original, unfired dimensions. The goal here is to bring the case dimensions down far enough to allow the reloaded case to be chambered without difficulty." (In doing so, it doesn't overwork the case. Reductions are minuscule) Source: ExteriorBallistics.com
 
I love the exchanges on this forum to see all the different experiences and ideas other shooters have. I've been reloading since 1962 and have always been a varminter and target shooter and even with factory rifles have always been focused on getting the best possible accuracy. My range of rifles goes from a Savage Model 219 .22 Hornet through a full custom BR rifle built by Jim Borden (which cost more than my annual income in '62!) and I've never seen an experience where an FL sized load would shoot better than a neck-sized one. Most semi-autos and lever-actions require FL sizing to function properly but that's not an accuracy consideration.

Partially neck-sized cases, in my experience, are the best, especially in factory chambers. Sizing only the part of the neck that holds the bullet, keeps the case centered in the chamber and has a demonstrable improvement in accuracy.

After several to dozens of firings, a case will need to have the shoulder bumped back but I don't believe it will ever need FL sizing as long as it is used in the same chamber. FL sizing unnecessarily works the brass and -- other than fitting in semi-auto chambers -- has no benefit. There is no sizing process that stresses a case less than the Lee Collet die, but that's another subject.
 
Every one that I know, though a few may shoulder bump when they neck size. I don't even have an FL die for my 30 BR. Remember these are custom chambers with very little brass expansion during firing. Some of the shooters at my range, including a several-time National Champion, use loads so hot that I wouldn't even list them, and neck-size their cases in a 35-year-old Partner press, throw charges direct from a 35-year-old Redding measure, go to the line and shoot lights out.

I don't notice it so much with the 30BR, but some of the guys who have years of experience with the 6PPC will tell stories of actually breaking the bolt handle off the bolt trying to force a case into the chamber that had way too much expansion (kind of like using the chamber to resize!).

I'd like to see some comments from BR shooters, but I don't think many of them FL size their brass.
 
plus one on this

Outdoorsman said:
bobcat30 said:
I just recently got a neck sizer for my 243ai. I have a load worked up that shoots .4-.5 consistant on fl sized brass how much better or i should say will there be a big change if i just neck size? Meaning i have some brass that is fl sized and not loaded but dont have piles of brass to just set those aside and not use but i also have some fired stuff that needs to be sized . Is it going to change my load considerable? By the way when i full length size its absolute minimum shoulder set back just enough to close the bolt.

Full length sizing each and every time will ensure longer case life. Push the shoulder back .001", (push in at the shoulder and in at the case head area .001" each, which should be built into the die itself) and you've got it. Some would say .0005" at each location, but that would be difficult to do, let alone measure.

At some point, after just neck sizing, your brass won't fit your chamber or it would be a struggle to do so. You'll eventually have to F/L size, and when you do, you're going to have to overwork your brass to get back to the F/L sized dimension. Besides, you'll save some money, by eliminating a die you could have done without in the first place.

TWO dies are all you'll ever need. A F/L Bushing Die and a Bullet Seating Die.

After minimum sizing of the shoulder, remove the firing pin and its spring. Close the bolt on a dummy round. After doing that, the bolt should not fall on its own. It should however require a slight effort, and I mean slight, to move it downward if the shoulder was dimensioned properly. By removing the firing pin and spring, you've removed the energy of the spring and will have a better feel for the .001" set back you may or may not have imparted to the case. .001" is infinitesimal!
 

Upgrades & Donations

This Forum's expenses are primarily paid by member contributions. You can upgrade your Forum membership in seconds. Gold and Silver members get unlimited FREE classifieds for one year. Gold members can upload custom avatars.


Click Upgrade Membership Button ABOVE to get Gold or Silver Status.

You can also donate any amount, large or small, with the button below. Include your Forum Name in the PayPal Notes field.


To DONATE by CHECK, or make a recurring donation, CLICK HERE to learn how.

Forum statistics

Threads
166,284
Messages
2,215,513
Members
79,508
Latest member
Jsm4425
Back
Top