7mm-08 neck size problems.

[MondronT]

I've tried and tried to neck size 7mm-08 cases and they always stick in the chamber after firing. It happens with all the different brand cases I've used: Hornady,Remington; PPU; Federal and Winchester. I routinely neck size for both of my .223's without any problems. Is there something I'm missing or perhaps a bad die? They all chamber fine they just don't want to come out and I'm shooting a fairly moderate load of H4895. Any ideas?

 

[Bart B.]

Your cases have probably been neck sized and fired too many times and their body's are too big for the chamber. Or they're fired in another rifle before you got them. Full length size them then reload them and see how they function.

That's a common thing with neck sizing. Most benchrest folks quit neck sizing some years ago. They full length size their cases now and get better accuracy and long case life, too. Match rifle shooters using bullseye targets have been full length sizing for decades. So has Sierra Bullets getting sub 1/2 MOA test groups at 200 yards equalling benchrest aggregate group records.

Full length sizing makes case necks straighter on case shoulders and better aligns the bullet with the bore when they're fired. And keeps cases functioning properly.

 

[klausman]

Especially if you have formed your brass from .308, you should check the thickness of the brass in the neck. If the brass is too thick, the case won't fit after you have seated the bullet. If it just barely fits, you may have very high pressures because the neck doesn't have room to expand to release the bullet.

 

[MondronT]

Ok all cases have only been fired from this rifle since new factory ammo. This even happens with onced fired brass. I've experinced great improvement in group with my Savage and Weatherby 223 from neck sizing. Also during this last attempt I necked sized and FL'd the same loads otherwise. I only shot a group of three of the neck sized because the difficulty getting them out but the three shot group of necked sized was .378 and full was .524. Unfortunately I afraid of a full blown "STUCK" to shoot enough groups to be certain, but half inch at 100 yrds is pretty normal for this rifle with these loads.

 

[steve4102]

Chamber out of round?

 

[GooseGestapo]

Several things.
You might want to polish your chamber. Could be rough from reamer marks.
You didn't say what kind of rifle. I've seen this issue with Savage M110 and clones. They lack the camming during bolt opening/extraction of M98, Rem. M700, and Win. M70.
Check your load with 4895. It's on the fast side for the 7mm08. Even a starting load could be over the top with a tight chamber and short throat. Again, I had that problem with a Savage M110 LH in .30/06. 48.0gr of IMR4064 or 50.0gr of RL15 and a 150gr bullet would give sticky extraction and flattened primers. 52.0 (typical load, factory equivalent) would lock the bolt.

 

[MondronT]

Yes sir, this also is a Savage. It's an Edge (early Axis). I guess maybe I should just give up on the neck sizing. I've tried adjusting the loads up and down and have tried imr4895 and CFE223 with same effect. I've annealed the necks... i guess I have a hard time giving up. Otherwise this rifle shoots really well for a "cheap" gun.

 

[fguffey]

Also during this last attempt I necked sized and FL'd the same loads otherwise.

There is a difference between firing neck sized and full length sized, one should reduce pressure.

If you have experienced problems both ways it is time to check the diameter of the barrel or length of the case. I know you have trimmed the length of the cases from the end of the neck to the case head so we will eliminate that problem. Then there are 'artifacts', the case when fired mirrors the chamber.

Then there is the problem with chambers with tight necks. a reloader should know the diameter of the chamber neck after firing the first round. It helps if the reloader knows the outside diameter of the case neck before firing. It helps when the case neck can expand, expansion helps in releasing the bullet. A tight chamber neck will not allow the case neck to expand.

F. Guffey

 

[243winxb]

7mm-08 Neck Sizing

MondronT, What die is used to neck size? Lee Collet, standard neck die, or trying to neck size with a FL die? Added- Measure the head to datum of factory and reloaded fired brass. If firing a low pressure reload, the shoulder may get set back about .006" (223) from the firing pin strike.The low pressure round fires, but does not expand, or move the shoulder forward. On the next loading, the neck sized round is driven forward again in the chamber. The case body, having a taper, is jammed in the chamber from the firing pin strike, giving hard extraction. Increase the powder charge or use a faster powder. i do have an Axis in 223. You should not be "neck sizing" with a full length die. It can cause the problems your having. Thats my guess.

 

[MondronT]

I am using a RBCS N.S. 243winxb. But that makes good sense. I do get some soot around the neck shoulder area which may also indicate low pressure.

 

[fguffey]

the shoulder may get set back about .006" (223) from the firing pin strike.The low pressure round fires, but does not expand, or move the shoulder forward. On the next loading, the neck sized round is driven forward again in the chamber. The case body, having a taper, is jammed in the chamber from the firing pin strike, giving hard extraction. Increase the powder charge or use a faster powder. i do have an Axis in 223. You should not be "neck sizing" with a full length die. It can cause the problems your having.

I have seated primers without powder, without bullet. I have chambered primed cases with no bullet or powder and pulled the trigger. I measured the case length from the shoulder to the case head before and again after busting the primers. Results? I have cases that never make it to the shoulder of the chamber, and after ejecting the cases I did not find protruding primers.

F. Guffey

 

[243winxb]

Firing pin strike, setting the shoulder back - Savage Axis.

F. Guffey. Depends on the type and fit of the extractor. A Savage may let the case move forward off the bolt face as much as .017" from the firing pin strike. The first strike set the shoulder back .006" The 2nd strike (same dead primer) set the shoulder back even more. We never know, because the round fires and expands the brass. I learned this by accident with a bad primer that didnt fire. Rifle in 223rem.

 

[fguffey]

F. Guffey. Depends on the type and fit of the extractor. A Savage may let the case move forward off the bolt face as much as .017"

If there was any truth to that and of there is any truth to the case locking to the chamber and if the case head moves back to the face bolt the case will stretch .017" between the case body and case head. We should all know .017" stretch between the case body and case head renders the case scrap.

F. Guffey

 

[fguffey]

We never know, because the round fires and expands the brass.

There is stretch, there is flow and there is expand. "We will never know",

The low pressure round fires, but does not expand, or move the shoulder forward.

If the firing pin drives the shoulder forward to the front of the chamber the shoulder is already forward, firing the case locks the case to the chamber, in my opinion if any thing moves it is the case head.

Then there is that part reloaders always assume, the shoulder moves forward when the firing pin strikes the primer. I have case shoulders that do not move, they are erased and no longer exist, the shoulder on the fired case is a new shoulder that did not exist before I pulled the trigger.

We never know,

We with one exception, I have fired cases with .127" clearance between the shoulder of the case and the chamber shoulder.

F. Guffey

 

[243winxb]

The first strike set the shoulder back .006"

This amount is not a problem.

 

[WestKentucky]

I would look for burrs. Start with a mirror polished full length round. Carefully insert it without dragging it along anything sharp enough to mark it. Fire it, and check it over. If there are scratches on it that shouldn't be there then polish your chamber. If there are no scratches then look at your case and measure it about 100 ways and see where your big numbers are it will probably be either length from stretch (datum from base the shoulder, or shoulder to neck rim) or out of round.

 

[fguffey]

The first strike set the shoulder back .006"

This amount is not a problem.

Everyone except me is pretending they understand. The one amazing accomplishment mastered by reloaders is the .002" bump. If 'we' add the .002" bump to your .006" that does not matter I come up with .008", if we apply all of that to a 30/06 case we are .001" less than a no go-gage length chamber.

F. Guffey

 

[Bart B.]

I've shot several rounds of 308 Win ammo with 4895 powder under 165-gr bullets testing 4X-fired Federal brass case dimensional changes from minimally FL sized to fired. Started with 42-gr charges then in half-grain increment reduced charges. Federal 210 primers seated with cups bottomed in case pockets and a few thousandth below flush with case heads. All loaded rounds had about 002" head clearance and about 1.629" case headspace when chambered and fired in a SAAMI spec chamber with 1.631" headspace. Here's the dimensional changes after firing from a striker pin pushed with a 25-pound spring.

42.0 to 40.0-gr charges made their case headspace all about 1.630 and primers flush with case heads.

39.5 to 38.0-gr ones had 1.629" to 1.628" case headspace and primers backed out past case head.

37.5 to 36 gr loads had 1.626 to 1.627" case headspace and primers backed out .003" to .004".

Repeated the test with new Federal nickel-plated cases. Case headspace and primer cup protrusion changed about twice as much for each charge reduction below 40 grains.

Firing primed cases without powder or bullet set brass case shoulders back about .003"; nickel ones about .005".

The results with .30-06 cases starting with 48.0-gr loads showed about 15% to 20% more change.

Readers can form their opinions as to why that stuff happened.

 

[GLOOB]

It sure sounds like the firing pin might be able to jam the case in the chamber, somewhere. But if this is the case, you should be able to replicate that with an empty case with a dead primer (dented back out), no?

I wonder how you are neck sizing, and if you might be getting increased pressures, somehow, as a result. (Different neck tension, neck lube, crimp or whatnot). One thing you might try is to reduce the charge and see if the condition persists.

Also, someone needs to mention measuring and trimming.

 

[Vern Humphrey]

First of all, do factory loads extract normally?

If so, it is an ammo problem (proven by the fact factory ammo extracts normally.) If not, it is a rifle problem.

If it's an ammo problem, adjust your dies to kiss the shoulder, set it back just a bit and see how those cases extract.

 

[fguffey]

42.0 to 40.0-gr charges made their case headspace all about 1.630 and primers flush with case heads.

Head space on the case? SAAMI does not list case head space. SAAMI list chamber head space. Then there is that part where I said I have fired many rounds without the shoulder of the case making it to the shoulder of the chamber. I have had many primers crushed by the firing pin before the shoulder of the case made it to the shoulder of the chamber. I have had many case shoulders erased, I have fired many cases that had new shoulders that were formed from part of the neck and part of the shoulder became part of the case body, when fired.

F. Guffey

 

[243winxb]

Die and Powder Charge?

MondronT, The RCBS neck sizing die should only be making contact with the neck. You should be able to see on the neck where the die stops short of the shoulder, when sizing. What powder charge are you using, what make of bullet/weight . Its possible for a midrange load to produce to much pressure with some components. But strange that FL sizing doesnt act the same way.

 

[243winxb]

Brass

Using

Hornady,Remington; PPU; Federal and Winchester.

Does one brand of brass do it more than others? There was a post on PPU brass in 308 that made excessive high pressure with a midrange load. Different Component = Different pressure.

 

[MondronT]

Thanks guys for all of the ideas and suggestions... interesting reading. Factory loads and F.L. reloads extract fine. All of the before mentioned brand cases stick with neck sizing. The bullets I've tried are 120 gr. vmax; 120 Nosler BT; and 139 Hornady SP. I'm really more curious than anything. I've neck sized for both of my .223's (both bolt rifles) and have never had any issues with difficult extraction. My typical loads for 120 gr is 40 grains of H4895 and 41 of imr 4895. Not really sure off hand what I push the 139's with. I'd have to look in my notebook.

 

[Vern Humphrey]

Factory loads and F.L. reloads extract fine.

This tells me your rifle is borderline excessive headspace. That condition allows the cartridge cases to expand longitudinally in your chamber, making them a tad too long.

When you full length resize, you push the shoulder back where it belongs, and FL cases chamber as you say. I would experiment with die adjustments at this point. Start with just kissing the shoulder with the die. If a case sized that way won't chamber, turn the die down a quarter of a turn and try that. Keep trying until cases chamber freely and reliably.