A Real Head Scratcher-30-06 Headspace Issue

[59FLH]

Yes, just as a test

OK, interesting, I have no problem with that as its not much different then pushing with a press. But how is it factored into a head space measurement?

Help me follow along. You want to know why your brass with 49.0 gr of IMR 4064 is not expanding to SAAMI chamber dimensions after firing, correct? And if it is expanding to your chamber why the dimensions are inconsistent and all below SAMMI minimum, correct?

 

[Chas1]

Correct. Getting back to the primer test. Since my cases seem to be all shorter than my chamber I figured right or wrong that id I barely seated a primer and then inserted them into my gun and closed the bolt that the bolt would only seat the primers further once case shoulder is up against chamber and stop seating them any deeper once bolt was fully closed. Then I could measure using Hornady comparator to base of primer and got 2.045. Now I know comparator isn't an exact measurement but is does at least let me compare to other fired cases. Now if I take a go gauge at 2.0487 and put it in my comparator take a reading then I'll know how many thousands + or - my comparator is off and either add or subtract from the 2.045 measurement and that should give me a pretty good idea on actual headspace...well at least in theory IMO.

 

[59FLH]

Ok, and all the cases being discussed here have been fired and NOT run through a resizing die of any sort?

What bullet, and COAL?

Using SAAMI (default) COAL and a generic 150gr spitzer your 49.0g of 4064 calculates to aprox 42,000 psi chamber. I cant imagine that's not enough to fire form.

I'm fine with the -.003" that can be uncertainty from the chamfer they put on the tool for deburring and you could have a chamber at or close to SAAMI minimum, its the -.017" that's got my interest up.

 

[243winxb]

Try f/l sizing a couple of fired cases with the f/l die backed out a half of a turn( about .035) and see what kind of measurement you come up with

A little neck sizing will take place. The tapered case body may not be sized. Shoulder not moved. Depends on the diameter of the fired brass and the ID of the FL die.
(tolerances))

My General rule- Don't neck size with a FL die.

 

[Chas1]

Ok, and all the cases being discussed here have been fired and NOT run through a resizing die of any sort?

what bullet, and COAL?

Using SAAMI (default) COAL and a generic 150gr spitzer your 49.0g of 4064 calculates to aprox 42,000 psi chamber. I cant imagine that's not enough to fire form.

I'm fine with the -.003" that can be uncertainty from the chamfer they put on the tool for deburring and you could have a chamber at or close to SAAMI minimum, its the -.017" that's got my interest up.

All fired not resized, Sierra 150gr FMJBT, don't measure COAL instead measure to ogive when seating and measures 2.632 (.011 of lands). I'm leaning towards 49.0grs probably isn't enough. I'm also thinking cases at -.017 may have been form early load development when I started out at 45, 46 and 47grs so you could be right on not enough pressure...and so the reverse , they shrink.

 

[7stw]

I think I'm going to take cases that are .003 - .007 below max headspace and step the load up gradually and see if at some point they start to stretch.

I would do that also, but as mentioned above, I'd suggest neck size only, until you get full contact, shoulder to rim. Lapua brass is firm. Sometimes it takes two firings to get it to fully come up to , and fill shoulder . I see that when fireforming 25.06ai from Lapua 30.06 brass. Good luck.

 

[wnc-coyote]

Not sure if it has been asked yet but what is your neck tension. If your neck tension is super light maybe that could be playing into your problem

 

[Chas1]

Not sure if it has been asked yet but what is your neck tension. If your neck tension is super light maybe that could be playing into your problem

All necks trimmed to .012 thickness

 

[philipbrousseau]

If you have protruding primers in fired cases your load pressure is low and the case is shorter than your chamber. Not enough pressure to expand the case.

 

[JemezDave]

If you're worried about head space check the chamber with a go and no go gauge. If that's good I wouldn't worry about it. Neck size 3-4 times, anneal, and FL as needed. You can have a gunsmith check your chamber if you're worried. If your chamber is good I don't see how your brass measurements can be wonky unless it's bad brass. Your charge is not low so that's out. How old is your powder-did you buy that from someone? I store mine at a pretty constant 70 degrees but left in garage it can see wide temp swings. If you keep powder for many years this can take a toll. A chrony would bear that out though. 4064 is good powder for 06. Sorry to ramble just throwing out some ideas

 

[JemezDave]

Also, 1/4 to 3/4" groups are pretty good for a hunting rifle. What new scope did you put on the rifle and what are your velocity strings like(parallax/SD) If you don't have a chrony your chasing the wind. Wind conditions during your shoot? I'm sort of doubting your case measuring no offense but a case gauge you drop the case in and it's go or no go for size and length/shoulder

 

[Chas1]

4064 powder came out of same 8lb jug which I had shipped to me recently. Scope is Vortex Strike Eagle 4-24X50. At 49.0grs average velocity is 2816fps, can't remember spread. No offense taken on case measuring, I'm not confident either. Hopefully we'll get closer to an answer once factory ammo arrives along with go gauge.

 

[Chas1]

UPDATE : Received Go Cage and Remington Factory 30-06 ammo. Here are the results so far. I used the go gauge which measures 2.0487 and it measured in my Hornady gauge 2.0415 so now I now my Hornady case gauge is showing cases .0062 shorter than they actually are. Just for shi?s & grins I took 4 factory rounds before firing and on the Hornady they measure as follows: 2.040, 2.040, 2.039 & 2.041 or average 2.040 net net can't imagine Remington would produce ammo .005 below SAMMI cartridge spec-2.052 -.007 or 2.045 BUT, if I add the .0062 to 2.040 average I then get factory cases on average measured 2.0462 and walla within SAMMI spec. I then went to range and fired 4 factory cases and 4 reloads at 49grs IMR 4064 and then measured all cases and they all grew in length by .002. At this point my conclusion is that the cases I originally reported at .017 below max are really .011 or .004 shorter than minimum which I think I can safely reload and check to see how much they stretch.

 

[slikmrc]

Looks like your chamber is in spec, seems it will take a few firings to get your brass formed with the 4064 load. Was there a reason you turned down the necks for the factory chamber?