I have necked sized piles of brass, but have admittedly done the entire neck, be sure to avoid the shoulders. I was wondering if there is anything to resizing only part of the neck. How much of the neck? Any general rules to this?
Neck sizing - how much neck?
- Thread starter schick
- Start date
saskgunowner101
CGN Ultra frequent flyer
- Location
- near Prince Albert
You might not get good neck tension if most of the neck isn't sized. Just a guess though. I'm new to reloading for rifle cartridges, so take my thought for what it's worth.
My Forster bushing bump dies had a mention in there about partially sizing the neck, its hard to explain so here is a link to the diagram....
http://www.forsterproducts.com/Pages/precision_dies.htm
I suppose it might help with case alignment if the size of the chamber neck is on the far end of SAAMI spec. So far I have not experimented with it myself but it seems to make sense.
http://www.forsterproducts.com/Pages/precision_dies.htm
I suppose it might help with case alignment if the size of the chamber neck is on the far end of SAAMI spec. So far I have not experimented with it myself but it seems to make sense.
I size my necks from case mouth to about .005-.010 above the shoulder (whatever my Redding Comp Die will size to).
I asked the same question a few moons ago and decided that full sizing would be the best way to go. I have yet to have an issue doing it this way and have even won a few competitions.
I asked the same question a few moons ago and decided that full sizing would be the best way to go. I have yet to have an issue doing it this way and have even won a few competitions.
- Location
- The Conservative part of Ontario
I had a 303 some time back that had a very sloppy chamber worst neck I've ever seen.
For it, I didn't size the entire neck, I left quite a bit of visibly un-sized neck.
My feeling was that the un-sized portion would help align the case to the bore.
The bore was so bad it didn't make a visible difference for me, but, I felt better doing it.
For it, I didn't size the entire neck, I left quite a bit of visibly un-sized neck.
My feeling was that the un-sized portion would help align the case to the bore.
The bore was so bad it didn't make a visible difference for me, but, I felt better doing it
.
I asked a similar question a week ago. The post will be further down.
I ended up setting my redding die, to about 20 thou off the shoulder. Just so it was visible that I had not reached the base of the neck.
I shot some 100 yard groups in the high 0.4s and 0.6s at the weekend so I think it worked. Surprised me anyway.
I ended up setting my redding die, to about 20 thou off the shoulder. Just so it was visible that I had not reached the base of the neck.
I shot some 100 yard groups in the high 0.4s and 0.6s at the weekend so I think it worked. Surprised me anyway.
If it's a cartridge with a lot of taper, I usually size about 90% of the neck, until I feel the increased effort when the case body gets involved. With straighter sided cases, that resistance can happen 1/2 of the way down the neck and in those cases I use a dedicated neck-sizer.
Just to be that guy for better results you should not size the entire neck.
the theroy goes in order to better align the bullet with the bore you leave a portion of the neck unsized. The unsized portion will closely fit the neck of the chamber and thus bring the bullet in straighter alignment.
The interesting point about this idea is, it would seem, to work better if you are jumping your bullet. If you seat bullets into the land this may take away the affects of only sizing a portion of the neck. By seating so the bullet starts engaging the lands the alignment may already be set prior to the neck aligning with the chamber.
I learned of this technique from Mike Ratigan's book Extreme rifle accuracy.
Please note it is most likely he is shooting a tigh chamber and neck turns his brass.
Trevor
the theroy goes in order to better align the bullet with the bore you leave a portion of the neck unsized. The unsized portion will closely fit the neck of the chamber and thus bring the bullet in straighter alignment.
The interesting point about this idea is, it would seem, to work better if you are jumping your bullet. If you seat bullets into the land this may take away the affects of only sizing a portion of the neck. By seating so the bullet starts engaging the lands the alignment may already be set prior to the neck aligning with the chamber.
I learned of this technique from Mike Ratigan's book Extreme rifle accuracy.
Please note it is most likely he is shooting a tigh chamber and neck turns his brass.
Trevor
I disagree with the alignment theory... That additional un-sized portion on the neck isn't going to improve the alignment of an already fire-formed case. I don't buy it.
I believe that what it does is negate the neck tension variation caused by donuts. They are much more common than many would believe. I've found them in many cases, even 308 Win.:
http://www.canadiangunnutz.com/forum/showthread.php?t=330018
I've been using gage pins for checking neck tension and for probing for donuts. They're pretty cheap; $2.50 each @ http://www.meyergage.com/products/individual_class_z_pins.htm in 0.0005" increments, $25 dollars got me a set from 0.304" to 0.308". Get some of those (the '-' ones) and you'll likely find some surprises in cases that have had the neck fully re-sized. I can often feel them even after using a Lee collet die... Even when a 0.0005-0.001" smaller gage can pass through them, they still affect my traces and make groups grow. Leaving the bottom 1/16" of the neck un-sized seems to negate them...
I believe that what it does is negate the neck tension variation caused by donuts. They are much more common than many would believe. I've found them in many cases, even 308 Win.:
http://www.canadiangunnutz.com/forum/showthread.php?t=330018
I've been using gage pins for checking neck tension and for probing for donuts. They're pretty cheap; $2.50 each @ http://www.meyergage.com/products/individual_class_z_pins.htm in 0.0005" increments, $25 dollars got me a set from 0.304" to 0.308". Get some of those (the '-' ones) and you'll likely find some surprises in cases that have had the neck fully re-sized. I can often feel them even after using a Lee collet die... Even when a 0.0005-0.001" smaller gage can pass through them, they still affect my traces and make groups grow. Leaving the bottom 1/16" of the neck un-sized seems to negate them...
Hi Kombayotch
I am not sure why you would disagree with the alignment theory if you leave a portion of the neck unsized it should have a tighter fit then a full length neck sizing, this should bring you in to better alignment with the bore. see Forster pic.
As to the donut you experienced with busing dies I think that the removal of the donut by partial sizing of the neck might be a side benefit and may be away to avoid neck turning. Using of bushing dies squeezes any imperfection to the inside causing the donut. I have not experienced the dreaded donut and am suprised that you have with the Lee dies as I also use Lee collet dies which squeeze the brass around a mandrel pushing the donut to the outside of the neck.
I think there was a good discussion over on the long range board about using a mandrel after neck sizing with a bushing die I will see if I can find it and paste it here if I recall Kodiak here on CGN explained it pretty well.
I am not sure why you would disagree with the alignment theory if you leave a portion of the neck unsized it should have a tighter fit then a full length neck sizing, this should bring you in to better alignment with the bore. see Forster pic.
As to the donut you experienced with busing dies I think that the removal of the donut by partial sizing of the neck might be a side benefit and may be away to avoid neck turning. Using of bushing dies squeezes any imperfection to the inside causing the donut. I have not experienced the dreaded donut and am suprised that you have with the Lee dies as I also use Lee collet dies which squeeze the brass around a mandrel pushing the donut to the outside of the neck.
I think there was a good discussion over on the long range board about using a mandrel after neck sizing with a bushing die I will see if I can find it and paste it here if I recall Kodiak here on CGN explained it pretty well.
In neck
sizing, looking from the benchrest perspective, the custom dies that most benchrest shooters use size the entire length of the neck to just above the neck shoulder junction. There is no option when using a custom Harrel die to size it partially. The dies VERY CLOSELY match the dimensions of the chamber and size the entire case by about .002.
One does NOT want to have the pressure ring (base of the bullet) go below the sized portion of the neck. Boat tail bullets are a different animal as they do not have a pressure ring at the base like a flat base bullet does.
CBY
sizing, looking from the benchrest perspective, the custom dies that most benchrest shooters use size the entire length of the neck to just above the neck shoulder junction. There is no option when using a custom Harrel die to size it partially. The dies VERY CLOSELY match the dimensions of the chamber and size the entire case by about .002.
One does NOT want to have the pressure ring (base of the bullet) go below the sized portion of the neck. Boat tail bullets are a different animal as they do not have a pressure ring at the base like a flat base bullet does.
CBY
Trevor,
I disagree because a fire formed case is already tight in your chamber. We aren't talking about a two point alignment here, it's aligned along the full body of the case. For the neck to have any influence in alignment, the case body would have to be loose enough in the chamber to allow for some movement and you would have to have a second alignment point at the back of the case that is also snug and concentric to the bore. That would have to be the bolt face which is neither snug or concentric to the bore. The bolt face may be perfectly perpendicular to the axis of the bore (trued), but that is not the same as concentric.
I've also done the experiment with a slight twist: I sized the entire neck down to a diameter just above where the donut would contact the bullet with a larger bushing, and then partially with a smaller bushing to only give neck tension to the top 3/4 of the neck. It improved results with both FL and neck-only sized cases. In both cases, no portion of the neck was contacting the chamber. Further, in the absense of donuts, I don't see any improvement in groups between FL and neck-only sized brass in my tight Palma chamber, which also makes me doubt the improvment is due to alignment.
I disagree because a fire formed case is already tight in your chamber. We aren't talking about a two point alignment here, it's aligned along the full body of the case. For the neck to have any influence in alignment, the case body would have to be loose enough in the chamber to allow for some movement and you would have to have a second alignment point at the back of the case that is also snug and concentric to the bore. That would have to be the bolt face which is neither snug or concentric to the bore. The bolt face may be perfectly perpendicular to the axis of the bore (trued), but that is not the same as concentric.
I've also done the experiment with a slight twist: I sized the entire neck down to a diameter just above where the donut would contact the bullet with a larger bushing, and then partially with a smaller bushing to only give neck tension to the top 3/4 of the neck. It improved results with both FL and neck-only sized cases. In both cases, no portion of the neck was contacting the chamber. Further, in the absense of donuts, I don't see any improvement in groups between FL and neck-only sized brass in my tight Palma chamber, which also makes me doubt the improvment is due to alignment.
I can not confirm or deny yours or Ratigan's statements as I have not tested both models to have conclusive evidence that one works better then the other. When I use the lee die i try and leave a portion of the neck unsized/less sized then the other and the results have been consistant for me.
I have created a new post about the mandrel so as to not throw this one off topic.
Thank sfor your imput CBY i gess there is more then one way to get the results we are after.
Trevor
I have created a new post about the mandrel so as to not throw this one off topic.
Thank sfor your imput CBY i gess there is more then one way to get the results we are after.
Trevor
What I found when I partial neck sized as described above is that the cases got tighter in the chamber after a few loadings. I'm not sure why the neck was moving forward but it was.
What I do not is lube the case, smoke the shoulder with a candle, adjust the die down until it is just barely touching the shoulder. Then I test the case for feel in the chamber, in other words the bolt closes easily but with just a bit more resistance than full length sized. This seems to give me the best combination of easy of chambering, long case life and accurcy.
What I do not is lube the case, smoke the shoulder with a candle, adjust the die down until it is just barely touching the shoulder. Then I test the case for feel in the chamber, in other words the bolt closes easily but with just a bit more resistance than full length sized. This seems to give me the best combination of easy of chambering, long case life and accurcy.
- Location
- Vancouver Island BC
Neck sizer dies are larger internally to avoid the shoulder, so even doing the whole neck the shoulder won't be touched anyway.
