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Neck sizing v full-length sizing

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This is a topic we occasionally discuss on UKV. There is a great article on 6mmBR.com at the moment by Erik Cortina, one of the USA's top F Class shooters.

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He is 100% correct, too. Many of us gave up on neck sizing years ago opting for a fitted FL sized case or return to factory spec for ammo to be used across several rifles of the same chambering such as the four .223 varmint rifles I use. My Tikka Creedmoor gets a full length fitted case, as does my RPR 308. The rounds cycle effortlessly and are superbly accurate.~Andrew

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I full length size all my F class loads. I feel it's more consistent and I like easy bolt closure as it disturbs the gun in the bags far less.

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One thing to note is if you are just starting to fl your brass and you have had a drop in accuracy , just tweak the seating depth to get it back . Probably by the same amount you have bumped the shoulder back so your bullet is abit futher out but technically at the same point at the lands ' area ' ( same COL ) atb..

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I now FL size everything and have seen no decrease in brass life (I anneal every firing) and like the consistency.

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I have the best of both worlds (insert smug face)

 

Whidden F/L bushing dies size the entire case as well as giving you the ability to control neck tension.

 

I love them!

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One thing to note is if you are just starting to fl your brass and you have had a drop in accuracy , just tweak the seating depth to get it back . Probably by the same amount you have bumped the shoulder back so your bullet is abit futher out but technically at the same point at the lands ' area ' ( same COL ) atb..

 

 

I dont entirely get your drift here gunner?

 

Are you saying that by moving the shoulder it has an effect of COAL?

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I dont entirely get your drift here gunner?

 

Are you saying that by moving the shoulder it has an effect of COAL?

 

 

I thought the same. Surely, even if COAL was affected by say, 2 thou, that's unlikely to affect accuracy as barrel time differences are next to nothing for a few thou. The only real difference that I can envisage between neck sizing and FL might be minutely reduced case capacity for FL sized cases compared with fire formed neck sized ones.

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I bought neck sizing dies for my .260 Valkyrie.

 

Now I find that I neck size, then bump the shoulder back in a separate die each reloading anyway...

 

*sigh*

 

maximus otter

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Although I do use competition shell holders to partially FLS on my 22PPC and 6BR I saved the expense of these with my 223 by just using a spacer between a standard shell holder and where it contacts the bottom of the die when mounted in the press.Arriving at the ideal amount of "sizing" is easily done by using a comparator bushing that I made up on the lathe.The bushing[fits a stony point body] you can see is in the picture along with three spacers made from shim steel.The spacers were made by placing shim steel between two pieces of ply then clamped together tightly and then drilled in a drill press.Nice neat holes are made in this way and easily trimmed out of the shim steel sheet.For my 223 the ideal sizing is done by using the 10 thou spacer and this bumps the shoulder back from a reading of 1.472[fresh fired case] to 1.468 wheras full FLS without the spacer gives huge bumping back to 1.460,,,,thats a huge amount of sizing and unnecessary.These reading are using my home made bushing of course and only serve as a reference in my set up.Even partial FLS can move/lengthen cases so always check case length after such operations,,,,many of you will already know all this,,apologies ,,just a heads up for all reading.So you can see I bump my shoulders back about 4 thou and this gives a good feel on the 223 closing bolt,,well almost no feel and I reckon the case is now snug but not being pressured in any way in the chamber and provide for minimal amounts of resizing over and over again.I do understand many of you size tighter and looser than this and I do in fact run my PPC and BR to less tolerance than 4 thou,,,,its an individual thing I guess and a lot to do with feel on the bolt.Here are a couple of pics and hope this helps someone that may want to have a go at a cheap trick,,,,,,,O

post-41-0-41759800-1508583129_thumb.jpg

post-41-0-04262600-1508583164_thumb.jpg

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Interesting, thanks onehole. I don't use bushing dies, but have a mix of Redding, RCBS and Lee dies. Using a comparator for brass which has been fired several times (neck sized in between) I take a measurement for the head to shoulder point where the comparator body meets the shoulder and use this as my fire-formed reference. I then adjust my FL die(s) out a little at a time until I get to this same dimension or a max of 2 thou shorter, no more. I'm unsure just how accurate or reliable using a comparator is in this way, but it seems to work, with no bolt closure problems and no over-bumping of the shoulders which tends to happen with the dies adjusted to the recommended settings.

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Interesting, thanks onehole. I don't use bushing dies, but have a mix of Redding, RCBS and Lee dies. Using a comparator for brass which has been fired several times (neck sized in between) I take a measurement for the head to shoulder point where the comparator body meets the shoulder and use this as my fire-formed reference. I then adjust my FL die(s) out a little at a time until I get to this same dimension or a max of 2 thou greater, no more. I'm unsure just how accurate or reliable using a comparator is in this way, but it seems to work, with no bolt closure problems and no over-bumping of the shoulders which tends to happen with the dies adjusted to the recommended settings.

Hi,,thanks,,,,,you could incorporate a spacer if you can make one or two up and experiment with your FLS die,,,,,,,,,,I know you can achieve same thing by adjusting die but you are then tied to working with your press at full sroke/over centre position?,,,,,,,with the spacer system you can work with the die and press ram set anywhere as it will only size the same everytime,,,,no faffing with setting the die??,,,,,,,,,regds,,,,,,O

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Although I do use competition shell holders to partially FLS on my 22PPC and 6BR I saved the expense of these with my 223 by just using a spacer between a standard shell holder and where it contacts the bottom of the die when mounted in the press.Arriving at the ideal amount of "sizing" is easily done by using a comparator bushing that I made up on the lathe.The bushing[fits a stony point body] you can see is in the picture along with three spacers made from shim steel.The spacers were made by placing shim steel between two pieces of ply then clamped together tightly and then drilled in a drill press.Nice neat holes are made in this way and easily trimmed out of the shim steel sheet.For my 223 the ideal sizing is done by using the 10 thou spacer and this bumps the shoulder back from a reading of 1.472[fresh fired case] to 1.468 wheras full FLS without the spacer gives huge bumping back to 1.460,,,,thats a huge amount of sizing and unnecessary.These reading are using my home made bushing of course and only serve as a reference in my set up.Even partial FLS can move/lengthen cases so always check case length after such operations,,,,many of you will already know all this,,apologies ,,just a heads up for all reading.So you can see I bump my shoulders back about 4 thou and this gives a good feel on the 223 closing bolt,,well almost no feel and I reckon the case is now snug but not being pressured in any way in the chamber and provide for minimal amounts of resizing over and over again.I do understand many of you size tighter and looser than this and I do in fact run my PPC and BR to less tolerance than 4 thou,,,,its an individual thing I guess and a lot to do with feel on the bolt.Here are a couple of pics and hope this helps someone that may want to have a go at a cheap trick,,,,,,,O

attachicon.gifIMG_0457.JPG

attachicon.gifIMG_0463.JPG

I like that idea with the spacer, when I've done it in the past I had the spacer between the die and the press, I think your idea is probably easier to set up

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Hi,,thanks,,,,,you could incorporate a spacer if you can make one or two up and experiment with your FLS die,,,,,,,,,,I know you can achieve same thing by adjusting die but you are then tied to working with your press at full sroke/over centre position?,,,,,,,with the spacer system you can work with the die and press ram set anywhere as it will only size the same everytime,,,,no faffing with setting the die??,,,,,,,,,regds,,,,,,O

 

Yes, I see what you mean. I may just try that out.

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I always resize using a Lee Collet Die, sometimes I have to run them through a Body Die to bump the shoulder a tad

I thought I would try FL sizing a bit back and the grouping went all to hell & back!

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On October 21, 2017 at 8:42 AM, Big Al said:

 

 

I dont entirely get your drift here gunner?

 

Are you saying that by moving the shoulder it has an effect of COAL?

Go to the link in post #3 that jcambellsmith has kindly posted and wath the short vid from the guy called eric something ? It made instant sence to me!!  He basically says that try your fl sized against nk sized and if fl doesn't group as tight - adjust your seating depth to bring it back . If yo have moved your shoulder back by say 5 thou maybe more if its an std cheap die 'fits all' sizer. If your previous nk load sat 15 thou off lands , then the fl sized with bumped shoulder could have the bullet sat around 5 thou closer to the lands . Affecting accuracy . Make abit more sence ? Probably not 

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3 hours ago, gunner said:

Go to the link in post #3 that jcambellsmith has kindly posted and wath the short vid from the guy called eric something ? It made instant sence to me!!  He basically says that try your fl sized against nk sized and if fl doesn't group as tight - adjust your seating depth to bring it back . If yo have moved your shoulder back by say 5 thou maybe more if its an std cheap die 'fits all' sizer. If your previous nk load sat 15 thou off lands , then the fl sized with bumped shoulder could have the bullet sat around 5 thou closer to the lands . Affecting accuracy . Make abit more sence ? Probably not 

OK, I thought that was what you were saying, now have a think about it.

Your COAL or CBTO measurement is taken from the base of the case to either the end of the bullet or the ogive, this measurement will remain the same regardless of where the shoulder is. :)

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31 minutes ago, Big Al said:

OK, I thought that was what you were saying, now have a think about it.

Your COAL or CBTO measurement is taken from the base of the case to either the end of the bullet or the ogive, this measurement will remain the same regardless of where the shoulder is. :)

Just throwing this one out there Alan. Will the amount of shank held by the case not be altered even if the cbto or coal remains the same? Could this have an effect on accuracy?

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Regardless of what sizing method you use, if your seating die is set up with a lock ring, then it can only seat that bullet to the same depth as the die bottoms out. Where the shoulder has been sized to, is irrelevant.

Full length sizing cases can affect different calibre in different ways. On some, it can lengthen the necks, on others, it can shorten them.

The reason the groups change is because the internal volume of the case has been changed, and will give a different pressure.

To get the most from f/l sizing, you want the bolt dropping with minimum resistance on a newly sized case. That way, you are not overworking the brass. Also, you are as close to minimum headspace as possible. Thats where the accuracy is. You don't want the case growing 0.004" every time its fired.

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12 hours ago, Panda said:

Just throwing this one out there Alan. Will the amount of shank held by the case not be altered even if the cbto or coal remains the same? Could this have an effect on accuracy?

Yes, the bullet could be held in the neck over a different length depending on how much the shoulder was bumped while the CAOL and CBTO would remain the same. Typically we are talking here about bumping a shoulder a couple of thou so thats how much different the hold would be.

I can't say as Ive not tested this but I would be surprised if having a couple of thou more or less bearing surface to neck contact mattered. Its hard enough to really see a meaningful difference when adjusting seating depth by so little although some would argue that point.

 

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7 hours ago, Catch-22 said:

An excellent video that runs through how to F/L size and measure properly.

 

Spot on this vid , interesting that he bumps back 4 thou so the shoulder has no influence on the centering of the bullet in the lands , to where a nk sized ( tight bolt ) could affect accuracy , such a fine art and sweet spot , atb. 

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I have a question, if you full length all your brass as I have always done, what would cause the slight stiffness on closing the bolt? It only happens now and again.

i am prity  methodical in reloading for 7mm .

 Cheers Nick 

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It's likely in that event that it's due to brass migration from the case head to the shoulder and neck area.  Have you checked the brass thickness on the necks for the stiff to load cases and the overall diameter compared to SAAMI?

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