Accuracy on necksized rounds is getting worse

[bayjoe]

I have a pet load for my rifle. The gun shoots less than half inch at 100 yds and yesterday that same load shot over 3 inches at 100 yds.
So here is what I have
Rem 700 VS bull barrel in 308
F C nickel case same lot Case Wt. 176.5 plus or minus .3
Trimmed to 2.005
Primer Win LR
44.2 gr IMR-4064
Bullet is Hornady 155 gr. AMAX
Case overall length is 2.800
Load developed over last fall and winter. Average temperature 40 to 50 degrees and elevation is 7938 feet.
Yesterday temp was 45 degrees and no wind.
Casings have been reloaded twice. I partial resize the case. I size the case neck to within 30 thousandths of touching the shoulder. Rounds are a little stiff when chambered.
So that is what I have and now I don't know why accuracy fell off so drastically.
Could it be that I need to full length resize cases.
And my scope is tight and all other screws are tight.
So any opinions on what is going wrong.

 

[46and2]

I have shot neck sized and full length sized loads side by side more than a couple of times. The fl sized won every time.
When I say fl sized I mean bumping the shoulders .002-.003".
The name of the game is consistency. So even if you had a load that shot better neck sized you eventually WILL have to fl size. So you'll have to fire the whole damn lot again. Why risk galling lugs and barrel life on fire forming again so you can neck size???

 

[F Class John]

Can I recommend some light viewing?
Eric honestly spells it out the best.

 

[Oleg S]

^^^^^^ this

 

[dolek]

Neck sizing is great ... but lets beat that dead horse ...

 

[dolek]

Can I recommend some light viewing?
Eric honestly spells it out the best.

Fake news !

 

[Doug Beach]

I’m all in favor of full length sizing, but I don’t think neck sizing makes a 1/2” load into a 3” load. Something else has gone wrong.

 

[B23]

Casings have been reloaded twice. I partial resize the case. I size the case neck to within 30 thousandths of touching the shoulder. Rounds are a little stiff when chambered.
So that is what I have and now I don't know why accuracy fell off so drastically.
Could it be that I need to full length resize cases.

Am I understanding you correctly that you are trying to neck size with a full length sizing die. What, specifically, die are you using?

 

[bayjoe]

I use a RCBS FL die
But you are correct. I get that neck sizing is wrong. I want to know what is going on that makes the accuracy go sideways.
Cases are trimmed so it's not the bullet getting over crimped. Cases are basically fire formed to the chamber, even though they are a little stiff to extract.

 

[Straightshooter1]

I have a pet load for my rifle. The gun shoots less than half inch at 100 yds and yesterday that same load shot over 3 inches at 100 yds.
So here is what I have
Rem 700 VS bull barrel in 308
F C nickel case same lot Case Wt. 176.5 plus or minus .3
Trimmed to 2.005
Primer Win LR
44.2 gr IMR-4064
Bullet is Hornady 155 gr. AMAX
Case overall length is 2.800
Load developed over last fall and winter. Average temperature 40 to 50 degrees and elevation is 7938 feet.
Yesterday temp was 45 degrees and no wind.
Casings have been reloaded twice. I partial resize the case. I size the case neck to within 30 thousandths of touching the shoulder. Rounds are a little stiff when chambered.
So that is what I have and now I don't know why accuracy fell off so drastically.
Could it be that I need to full length resize cases.
And my scope is tight and all other screws are tight.
So any opinions on what is going wrong.

The fact that they're neck sized isn't the issue as neck sizing works just fine. I do it mostly and will FL size after f 4 or 5 firings as a matter of procedure to make sure the case body and neck remain aligned. I use a Lee collet die to size the necks then bump the shoulder with a Forester Neck Sizing die, but without the bushing so that I'm doing nothing more than bumping the shoulders with that die. I get in the 3's and 4's with my .308 and today was in the low 4's using a mild load of 40.9 gr of 4064 behind 168 SMK's @ .020 off the lands.

Sounds like your sizing is to create a false shoulder??? Which would explain the stiffness when chambering. But being over 3 inches from your normal, maybe there's a concentricity issue there along with some other issues.

If it were me, I'd probably check out the scope in detail as very often that much of a change happens there.

 

[Joe Salt]

How many rounds before cleaning?

Joe Salt

 

[B23]

Your stiff chambering is because you're trying to use a FL die to neck size and the die isn't screwed down properly. A FL die that isn't screwed down enough for the shoulder of your brass to come in contact with the inside of the die will result in the shoulder actually being pushed forward.

The first thing a FL die does, as you run a piece of brass up into the die, is size/squeeze the body and as it squeezes the sides of your brass the brass flows up which lengthens it until the should comes in contact with the upper inside of the die then it squishes it back down. If the shoulder of the brass doesn't come in contact with the top of the die you will be left with a longer, from base to shoulder, piece of brass.

Take lid off of a plastic bottle of water and watch how the water level goes up as you gently squeeze the middle of the water bottle with you hand, that's exactly what is happening with your brass, until it comes in contact with the top of the die.

No disrespect, but you're kind of halfassing the process. If you want to neck size, get a bushing neck sizing only die.

 

[K22]

The top shooter's that I know all full size with a .001 to 002" shoulder bump (bolt rifles)

I shot neck size cases for many years believing the myth of the 60's that neck sizing produces more accurate reloads and longer case life. While my neck sized reloads all shot very well they did not shoot better than properly full sized cases and did not last any longer that properly full size cases.

The problem with only neck sizing is that eventually you may have to full size so that the cases will chamber or chamber without galling the bolt lugs. If you're a hunter like me, functionality is just as important as accuracy. I have to know that a round will chamber and extract without problems. Properly full size cases does that for me without reducing accuracy or case life.

I'm not a "expert" or claim to be but I've reloaded literally thousands of bottle neck rifle cartridges since the late 60's and this has been my experience. I now only full size all cases for all rifle using a .001 to .002" shoulder set back.

Also using a FL sizing die to "neck size" is partial sizing. Since you are not contacting the shoulder you could actually be making the case longer but extruding it. If you want to neck size only then purchase a neck sizing die.

 

[chkunz]

The change that you are seeing is significant and not some small thing. Look for something MAJOR to be causing such a drastic change. Something this big should not be hard to find.

 

[bayjoe]

Thank you very much for explaining what I did wrong.
So if I understand correctly by sizing the lower part of the case and not pushing back the shoulder is one part of my mistake. Would the other be that the concentricity of the case be bad by not having my die properly adjusted.
I will see if this is my problem
Many thanks gentlemen

 

[B23]

Thank you very much for explaining what I did wrong.
So if I understand correctly by sizing the lower part of the case and not pushing back the shoulder is one part of my mistake. Would the other be that the concentricity of the case be bad by not having my die properly adjusted.
I will see if this is my problem
Many thanks gentlemen

Improperly sizing your cases shouldn't make a sub .5 gun all of a sudden start shooting 3+ inch groups. As was already mentioned, you've likely got something else going on causing that.

 

[Oleg S]

Thank you very much for explaining what I did wrong.
So if I understand correctly by sizing the lower part of the case and not pushing back the shoulder is one part of my mistake. Would the other be that the concentricity of the case be bad by not having my die properly adjusted.
I will see if this is my problem
Many thanks gentlemen

How many rounds on your barrel?

 

[bayjoe]

I cleaned my barrel really good after the last shooting lesson. Cleaned the copper fouling made it supper clean.
Barrel has 500 to 600 rounds.
I disassembled the few remaining rounds, soaked the primers and then full length resizing. And I had to cam over just a little bit to size the cases down .002. I used the 45acp round to measure the amount of shoulder push back to .002 and then double checked the cases that they cycle thru the action smoothly.
So I am going to put the rifle in a HS precision stock, load some more rounds and go see if the problem persists. I think if it still shoots large groups then i'll change scopes and see if that is the problem.
Many thanks gentlemen for your help

 

[Liven The Dream]

Have for sale a RCBS .308 Neck Die ?

 

[Jet]

I would look beyond how you size your cases. Check your action screws and scope rings. Once that’s done listen to Mr Cortina and start FL sizing.
Good shooting.

Rich