Still cant figure out my headspace.....FL sizing Die Set-up

[MoneyWaster]

I have a blueprinted Remington 700 action with a M24 Bartlein barrel chambered in 223. I had it rechambered after shooting about 500 rounds through it because I was experiencing case/head separation on brass after about 3 reloads. My measurements on fired brass indicated excessive headspace/an excessively deep chamber. I took it back to the gunsmith who originally chambered it, and he cut a new chamber (although he said it was in range).

After getting the gun back I proceeded to workup a ladder firing 75 gn Hornady Match BTHPs over loads of Varget. I used new/unfired Lapua brass for this. I determined that 23.5 gn of Varget produced the best accuracy with an average muzzle velocity of 2845 fps out of a 26" barrel. There were no pressure signs.

Measuring the case length from the base to shoulder (using a Hornady comparator) on the once fired brass I found a range of lengths. I started a thread here to discuss this and was informed that many of the cases may not have been fully expanded/stretched upon firing because of some of the light loads in the ladder. It was suggested that I neck size only for the next reloads and see what measurements I get after the second firing. Taking that advice I loaded up 50 neck sized cases to find what jump the bullet liked, and I headed to the range.

When I fired the neck sized cases I immediately found some difficulty closing the bolt on a few cases, and extraction on several cases was very difficult. I literally had to hit the bolt rearward with a strike from the palm of my hand to get the cases out. The primers on these cases looked fine (still rounded at the edge) and there was no evidence of extractor marks. Looking at some of the cases I can see what appears to be a fine line in about the same location where I experienced case/head separation previously with the old chamber. Again, this is on the second reload of new Lapua brass that was neck sized only.

Measuring case length from the base to the shoulder on 10 of the twice fired cases I get an average length of 1.560", with a maximum length measurement of 1.565"

Measuring case length from the base to the shoulder on 10 of the once fired neck sized cases I get an average of 1.551" with a maximum length measurement of 1.553".

Based on those measurements I increased the average base to shoulder measurement by 0.009" with the second firing of neck sized cases. This seems excessive to me.

I want to full-length size the 50 remaining neck sized cases to avoid the extraction issues that I experienced. However, I have no idea what my target base to shoulder target length should be based on the variance between the once fired and twice fired cases. Should I set up my FL die to bump the shoulder on the maximum length case 0.001", or should I target bumping the average length by 0.001"?

Should I be concerned about the difference in measurements between the once fired and twice fired cases? The appearance of the faint line near the case web has me worried.

Any opinions and guidance here is appreciated. For what its worth, the dies are Redding and the press is a Forester Co-Ax. Powder charges are thrown with an A&D scale accurate to 0.02 gn.

 

[FeMan]

I would suggest using the longest brass from the second firing as the guide. I would fl size that to bump the shoulder (I suggest two thousandths). Then chamber the empty case and make sure the bolt closes with no bind (remove the firing pin for this). If there is any bond, resize bumping it back a thousandth or two. Once you get that squared away it should be your target for all cases.

Nothing is impossible but having head separation with new Lapua brass based on what you describe is pretty close to it. Died often leave a shiney ring near the base that can look like separation.

My 6.5x47 Lapua brass has shoulders that are about 10 thousandths short when new. Unless the loafs are stout it can take 2 to 4 loadings before they fully stretch out and get consistent. I fire form and load as you described. I got 14 reloads on my last batch before giving them to a buddy and starting new. He is still hammering away with them.

Hope that helps.

 

[SheepDog]

Let's let go of past history here and look at the evidence:
On your first firing you notice no problems with pressure or impending case failure.
You neck size the case - are you using a neck sizing die? If not how do you neck size?
On the second firing you experience hard extraction and a noticeable ring on the brass at the web, which is NOT in the area of case head separation.
Difficulty chambering a round that extracted easily from the same chamber, points to a problem in your reloading procedure.
Case head separation happens above the web between 1/16" and 1/8".
Is the chamber rough?
Were the bullets seated to the same depth as before?
Are you sure that the powder levels were the same?
Was there a difference in the ambient temperatures?
The SAAMI standard maximum case length is 1.760", what is your case length?

My thinking is that you need to ignore your comparator and go back to basics.
Using the same powder charge reload your ammo. Full length resize the brass, trim to the proper length (1.75") and seat the bullet to the listed length from the bullet manufacturer. (or to the SAAMI maximum COAL)
Do that with ten cases a total of three times. If the problems you are having don't reappear then back your sizing die out a half turn and repeat the process. Do that until you have difficulty chambering the brass. When you run into difficulty chambering screw the dies in 1/2 turn and reload.

 

[Prose]

Have you put a headspace gauge in or caste the chamber?

 

[CharlieNC]

In one of your shortest hs brass, partially seat a primer. Insert into the chamber and bolt it in to finish seating the primer. Remove and measure to obtain your zero headspace chamber dimension. Size brass .002 to .003 shorter. Until you know your chamber your pissin into the wind.

 

[MoneyWaster]

Let's let go of past history here and look at the evidence:
On your first firing you notice no problems with pressure or impending case failure.
You neck size the case - are you using a neck sizing die? If not how do you neck size?
On the second firing you experience hard extraction and a noticeable ring on the brass at the web, which is NOT in the area of case head separation.
Difficulty chambering a round that extracted easily from the same chamber, points to a problem in your reloading procedure.
Case head separation happens above the web between 1/16" and 1/8".
Is the chamber rough?
Were the bullets seated to the same depth as before?
Are you sure that the powder levels were the same?
Was there a difference in the ambient temperatures?
The SAAMI standard maximum case length is 1.760", what is your case length?

My thinking is that you need to ignore your comparator and go back to basics.
Using the same powder charge reload your ammo. Full length resize the brass, trim to the proper length (1.75") and seat the bullet to the listed length from the bullet manufacturer. (or to the SAAMI maximum COAL)
Do that with ten cases a total of three times. If the problems you are having don't reappear then back your sizing die out a half turn and repeat the process. Do that until you have difficulty chambering the brass. When you run into difficulty chambering screw the dies in 1/2 turn and reload.

SheepDog,

I neck sized with a Redding neck sizing die (bushing die). Because I was searching for the most accurate jump for the accurate charge (23.5 gn), I loaded 10 rounds each at that charge for jumps to the lands beginning at 0.005" jump and ending at 0.025" jump. I measured velocity to attain statistics and all SDs were 12 or less, so I know that charge variance was minimal. Again, Vavg was 2845 fps out of a 26" barrel, which is in the range of published velocities for this bullet being pushed by Varget (but in a 24" barrel).

 

[T-shooter]

My method is like the picture below. I use a cleaning rod just a little smaller then the bore. Don't try this with a .22 diameter rod in a larger .308 bore, it will bend and flex. I use drill bit stops on the rod. I also have a plastic flat tip that screws into the end. You could probably make one or take the tip of a rod segment and fill the end with epoxy making it flat. You also have to be certain the rod fits under the ejector pin, if not your measurements will be way off. You can measure outside to outside on the stops and subtract the thickness of one of them. Set the first stop firmly against a closed bolt, then remove and put the second stop on. I put the bullet (seated way too long) in the chamber and (very lightly) allow the bolt to seat it into the lands. If you get any engraving marks on the bullet or it sticks, it went in too hard. A rubber band will keep enough tension to hold the bolt against the case. Lock the second stop and then measure. This will be your distance to the lands. I can pull everything out and reset up and stay under .001".

Using the exact same bullet, seat it exactly to the same installed length as you measured (tip to base), minus whatever jump you want to have. Once that is done, you can measure it with a bullet comparator. Mine for a .308 measures .298" inside. After getting the measurement here, use the same measurements when seating your bullets, never from the tip. You should do this with each different lot of bullets even though they may be the same part number.

For instance, these are 2 different lots of the same Hornady 168g Match BTHP measured with the tool above from both ends. There is at least .015" difference in the overall lengths. But seating either of these with the tool produced within .002" of the same jump distance.

 

[MoneyWaster]

SheepDog,

Also, the ring that I see measures 0.375" from the base of the case.

 

[MoneyWaster]

Have you put a headspace gauge in or caste the chamber?

I have not.

 

[jdj71]

I'm with FeMan. Striped bolt method works well. Start w/ longest cases (be prepared to sacrifice some brass) reduce length 1 or 2 thou at a time.When bolt closes w/ little or no effort you are close to chamber size, maybe 1 thou more +/- .BTW if you don't see flat primers on first fire you are probably not fully forming cases. My 2 cents. Good luck with project.

 

[FeMan]

... If the problems you are having don't reappear then back your sizing die out a half turn and repeat the process. Do that until you have difficulty chambering the brass. When you run into difficulty chambering screw the dies in 1/2 turn and reload.

A half-turn of a sizing die is over 30-thousandths of an inch. That'll get you to head separation real quick!

 

[T-shooter]

Sorry, I missed the point of the post. It was a brass headspace issue. Try loading a few rounds a little warm for maximum expansion. After firing them measure with your Hornady case insert. Try the longest case just as it is and see it it will chamber without any problems. If it's ok, keep that measurement and set your brass headspace about .001" shorter. With a semi-auto, I usually go .004" shorter. You may have to check several as you resize them to be sure your press and die are getting everything to the proper length. Some presses flex and will change the size based on how hard you press on the handle. Also, lube the cases and lube the inside of the necks. Had it happen only once, but on an un-lubed case, the expander ball must have pulled the neck and/or shoulder out and it wouldn't chamber. It may have been an annealed case, I don't remember.​

 

[MoneyWaster]

Thanks for all the guidance guys. I ended up taking the FL Type "S" die and bumped the shoulder of the longest case by 0.001". It chambered and ejected without any issue. I think I'll FL size the remaining 50 neck sized pieces, load them and see how they do at the next range session.

 

[Brians356]

For instance, these are 2 different lots of the same Hornady 168g Match BTHP measured with the tool above from both ends. There is at least .015" difference in the overall lengths.

On your two drawn bullets, what do these measurements denote?

Upper Bullet: .377 and .538
Lower Bullet: .401 and .574
-

 

[fguffey]

Sorry, I missed the point of the post. It was a brass headspace issue.

The case does not have head space, I wonder what it is reloaders do not understand about the chamber, when I cut a chamber I know the length of the chamber from the datum/shoulder to the bolt face. A reloader with a good understanding of reloading should know the length of the chamber from the datum/shoulder to the bolt face before they leave for the range. And then there are fire formers, I form first then fire.

F. Guffey

 

[hogpatrol]

To me, this appears to be a dog chasing it's tail. Buy, or borrow a headspace gauge. Remove the firing pin and ejector pin & spring and check it OR take it to another gunsmith and have him check it.

 

[Richard Coody]

To me, this appears to be a dog chasing it's tail. Buy, or borrow a headspace gauge. Remove the firing pin and ejector pin & spring and check it OR take it to another gunsmith and have him check it.

Fully fireformed.brass will certainly tell you what the headspace is. Headspace is kind of a mute point with experienced reloaders. As long as it isn't so excessive that it causes case head separation on the first firing. Saami specs no longer have any validity once you have fully fireformed brass.

You use a headspace gauge on fully fireformed brass, and it isn't fully fireformed until all the cases in that group have the same measurement, and bump that shoulder no more than 1 or 2 thousands. If you size to saami or some case gauge your brass won't last for $&!.

As for OAL. Use your stoney point and find the lands. That is.your max unless you are limited to mag. Length. Just remember you must measure with each bullet type you use with the stoney point. No two bullet types will have the same measurement

SAAMI is about as meaningless as MIL SPEC.

 

[ireload2]

I bet you do not know the exact length of any of your chambers to 4 decimal places.

The case does not have head space, I wonder what it is reloaders do not understand about the chamber, when I cut a chamber I know the length of the chamber from the datum/shoulder to the bolt face. A reloader with a good understanding of reloading should know the length of the chamber from the datum/shoulder to the bolt face before they leave for the range. And then there are fire formers, I form first then fire.

F. Guffey

 

[Ggmac]

For all the time , money and gadgets you have ,dig a little deeper and buy a headspace gauge . Stop chasing your tail , I'd full length size all brass or resize enough to close easily . Trust your smith . If he said it was within specs and you didn't specify that you wanted a min chamber , he did you a big favor by redoing his work .
Your reloading procedures need some guidance and I don't mean via Internet videos or answers .

 

[Richard Coody]

I bet you do not know the exact length of any of your chambers to 4 decimal places.

I don't really care!