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Discussion Starter #1
I've recently started reloading .308 Winchester for my Savage 10 bolt-action rifle. I am aware that when loading for the same bolt-action rifle a case was fired in, that you can neck-size only, avoiding the hassle of full-length resizing, lube, etc. This is because the case is fire-formed to the chamber of the rifle it was fired in.

However, I've noticed that when I full-length resize, the level of the powder in the case is much lower than if I only neck size. In fact, the powder is so high when I don't full-length resize, that it gets pushed down when seating the bullet! I hear a distinct (crunch) when seating the bullet. I've also found I have to use a lot of force to extract loaded ammunition when only the neck was sized, but that full-length resized ammunition seems to chamber and extract a lot more smoothly.

The pictures below are of the same brand .308 case, loaded with 44 grains of Varget. The one on the left was neck-sized, and the one on the right was full-length sized. I am seating to an OAL of exactly 2.800".





Needless to say, I've been full-length sizing all of my ammunition, as it chambers better, extracts better, and the powder level is lower with the same amount of powder and OAL. But I'm confused why I am experiencing these issues with neck-sizing. Wouldn't accuracy be affected as well since the powder levels are different?

Curious how you guys size your cases and if you have experienced any of this before.
 

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Your observations are correct, full length sizing reduces volume of the case which in turn causes higher chamber pressures as compared to neck sizing. Your chamber dimensions are larger than the dimensions of the sizing die. Did you ever chrono the two rounds? How close are you to the max load when using 44 gr of Varget? Do the full sized cases show any signs of high pressure? Compressing a load could cause the case pressure to build too high. Drop down .5 gr on the full sized cases.
 

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Discussion Starter #3
I haven't chronoed anything, I am still working on getting loads that chamber and extract properly. Just observed this, and found it strange since everything I've read has been that you can more or less use the two sizing methods interchangeably.

I think I'm going to stick with full-length. I prefer the ability to use the ammo in different guns if needed too.
 

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What brand dies are you useing? I have reloaded alot of 308 and have only FL resized the first time i load and neck size after that. I find your problem odd. FL resizing will strech your case making it longer thats why i neck size, you get very little case growth.(kinda lazy hate trimming brass) I am wondering if your neck sizing die might be turned in to far and you are crushing the case alittle, this would make your case shorter and if this is happening you would have trouble with chambering and extracting. If you can mic your cases where the shoulder of the case meets the body of the case and see if there is a diffrence between a FL case and a Neck sized one. This could also cause the diffrence in powder hight due to one case being made longer and one case being crushed a little. Let me know what you find out.
 

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I would have thought that a full length sized cartrige would have LESS volume since it is being squeezed back down to factory dinensions where a fire formed case is expanded to the chamber and would have a greater volume (the powder would sit lower). I am confused. from what I have read I would not use a compressed powder charge unless the loading data calls for it. The loads I have worked up for the 308---270 win---and 30-06 have all had the best accuracy in the lower third of load ranges.
 

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I was getting all set to type 8 inches. Then I saw this was about reloading which I am totally ignorant of. Good luck with your reloads.
 

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All depends on what the rifle likes I use 130 nosler ballistic tip out of my Browning A bolt I think i load 58 or 59 grains of IMR 4831 it's compressed and my rifle loves them. But I only use that rifle to hunt with I wouldent use compressed loads for something that i was going to shoot alot hard on you and hard on the equipment. And as far as FL resized brass it does get skinnier but it also gets longer. Like i said i've loaded alot of 308 stuff and have never run into anything like this before. Weird.
 

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All depends on what the rifle likes I use 130 nosler ballistic tip out of my Browning A bolt I think i load 58 or 59 grains of IMR 4831 it's compressed and my rifle loves them. But I only use that rifle to hunt with I wouldent use compressed loads for something that i was going to shoot alot hard on you and hard on the equipment. And as far as FL resized brass it does get skinnier but it also gets longer. Like i said i've loaded alot of 308 stuff and have never run into anything like this before. Weird.
I have not been reloading for that long but the case doesn't grow with full length sizing except at the neck....right? That is why we trim. the overall case dimensions of a full length sized case is to spec. the neck length is what grows...right?
 

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But to Scotchman's initial description, he fire forms the cases (which should really expand the case a bit as it fits the chamber) he then goes and neck sizes and then finds that a load that should not be compressed is.

That feels like something isn't going right with the neck sizing.
 

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But to Scotchman's initial description, he fire forms the cases (which should really expand the case a bit as it fits the chamber) he then goes and neck sizes and then finds that a load that should not be compressed is.

That feels like something isn't going right with the neck sizing.
That is what I was trying to say...and probably no well..lol. comparing an equally length trimmed neck sized and full sized case neck sized case should have a greater volume. the powder should be sitting lower. Is the shoulder looking crushed or pushed in?
 

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Man looking at the pics that is a lot of diffrence in powder levels. I dont think you would see that much diffrence in the powder level from a fire formed case to a FL sized one. That looks like several grains diffrence to me. Wonder how he measures his powder?
 

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I was wondering if there was any bridging of the powder going on. I think that podwer ia a long cylinder type. It can bridge. For my rifles I scale every charge.
 

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Discussion Starter #16
But to Scotchman's initial description, he fire forms the cases (which should really expand the case a bit as it fits the chamber) he then goes and neck sizes and then finds that a load that should not be compressed is.

That feels like something isn't going right with the neck sizing.
I'll measure the length of just the cases next time.

I am using Hornady Match brass, 44 grains of Varget (46 is max load, 44 seemed to give the best accuracy in the limited testing I've been able to do), and Hornady 168gr HPBT bullets. Lee reloading dies in a Classic Turret press.
 

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Discussion Starter #17
Man looking at the pics that is a lot of diffrence in powder levels. I dont think you would see that much diffrence in the powder level from a fire formed case to a FL sized one. That looks like several grains diffrence to me. Wonder how he measures his powder?
Powder is being thrown with a Lee Perfect Powder measure. I have weighed multiple throws and always get exactly the same to 0.1 grain accuracy. I measured the two throws in that picture as well, both are exactly 44 grains.
 

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Discussion Starter #18
What brand dies are you useing? I have reloaded alot of 308 and have only FL resized the first time i load and neck size after that. I find your problem odd. FL resizing will strech your case making it longer thats why i neck size, you get very little case growth.(kinda lazy hate trimming brass) I am wondering if your neck sizing die might be turned in to far and you are crushing the case alittle, this would make your case shorter and if this is happening you would have trouble with chambering and extracting. If you can mic your cases where the shoulder of the case meets the body of the case and see if there is a diffrence between a FL case and a Neck sized one. This could also cause the diffrence in powder hight due to one case being made longer and one case being crushed a little. Let me know what you find out.
Good point. If the case is getting crushed, that would explain some of my difficulties with extraction. I will measure as you say next time I am at my bench.
 
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