Headspace guage

[CKshooter]

Hello folks,
I got a good friend that has a 6.5 Creedmoor and is having flattened primer issues. We are thinking its because he is pushing his shoulders back a little too far when resizing. There are different opinions on which headspace gauge to use from a set of hornady headspace set. Some say use the 400, some the 375, another says he should get a Sinclair as they are the only company that makes the correct one for his rifle.
To refute any thoughts that he may have pressure issues he is loading at minimum charge according to Hodgdon reloading manual for H4350 with 140gr pills, so high pressure shouldn't be an issue.
Thanks in advance for any advice.

 

[Milo 2.0]

These case gauges worth their weight in gold.
http://www.whiddengunworks.com/product/case-gauge/

 

[K22]

He can do a quick check of proper shoulder set back by setting the ram at zero cam, size the FIRED case and check the ease of chambering. If stiff resistance is met, increase cam in slight increments until the case chambers with slight resistance. This should give you an custom fit for that specific rifle.

Don't force the case into the chamber if stiff resistance is met. If possible remove the firing pin to get a better feel of chambering resistance cause by the case.

 

[ireload2]

SAAMI says .400 on the drawings for both chamber and cartridge.

It does not make a lot of difference if you compare fired cases from that rifle with a sized case. Just be sure to use the same bushing all the time - preferably the .400.
However the Hornady tool will not give you the SAAMI number for the length because they break the edge of the bushing bore. That creates a few thousandths error.

If you have a 6.5 Creedmoor gunsmith headspace gauge you can zero the Hornady tool to the number on the gauge and you will get a very close to the exact SAAMI dimensions. The reason you will not get the exact number is the lack of resolution with calipers.

http://www.saami.org/specifications_and_information/publications/download/206.pdf

Hello folks,
I got a good friend that has a 6.5 Creedmoor and is having flattened primer issues. We are thinking its because he is pushing his shoulders back a little too far when resizing. There are different opinions on which headspace gauge to use from a set of hornady headspace set. Some say use the 400, some the 375, another says he should get a Sinclair as they are the only company that makes the correct one for his rifle.
To refute any thoughts that he may have pressure issues he is loading at minimum charge according to Hodgdon reloading manual for H4350 with 140gr pills, so high pressure shouldn't be an issue.
Thanks in advance for any advice.

 

[lawman29]

Get a decapping die to remove primers from fired cases without sizing the case (you cannot accurately measure without removing the fired primers first). Use a bump gauge to measure the length of the fired case with the primer removed (Whidden & Harrell dies come with the gauge). Take same case, resize and re-measure. You want .001-.002 difference between sized and un-sized. Adjust die accordingly.
http://bulletin.accurateshooter.com/2015/08/measuring-shoulder-bump-harrells-tool/

 

[Steve Ladino]

Get a decapping die to remove primers from fired cases without sizing the case (you cannot accurately measure without removing the fired primers first). Use a bump gauge to measure the length of the fired case with the primer removed (Whidden & Harrell dies come with the gauge). Take same case, resize and re-measure. You want .001-.002 difference between sized and un-sized. Adjust die accordingly.
http://bulletin.accurateshooter.com/2015/08/measuring-shoulder-bump-harrells-tool/

Easy to make with a lathe.

 

[CKshooter]

thanks everyone for your input on this topic. Always grateful for the folks on accurate shooter.

 

[butchlambert]

He can do a quick check of proper shoulder set back by setting the ram at zero cam, size the FIRED case and check the ease of chambering. If stiff resistance is met, increase cam in slight increments until the case chambers with slight resistance. This should give you an custom fit for that specific rifle.

Don't force the case into the chamber if stiff resistance is met. If possible remove the firing pin to get a better feel of chambering resistance cause by the case.

You need to rethink this method. Could give excess headspace. How do I know? Been there. If you want I will type a response to this later today.
Basically, if you have brass that is too large in front of the rim, it will chamber hard. If you screw your die down you are squeezing or resizing the base to fit your chamber. Butt!!! you maybe be bumping the shoulder back while you are doing this.

 

[CharlieNC]

Using your .400 comparator take a measurement. Partially seat a primer, chamber and slowly bolt it in to finish seating the primer. Remove and measure again, and the difference from the first measure is the HS. Now you have a reference to adjust your die to get .002-.003in clearance. No more guessing or arbitrary bumping.

 

[Zero333]

He can also check the cases he's already sized by putting a layer of masking tape on the head and see if it chamber's.

1 layer of masking tape extends the working headspace of the case by 0.004"

If the bolt closes on a case with 1 layer on the head that's too much shoulder bump but not dangerous. If the bolt closes with 2 layers of masking tape on the head, it means he's got at least 0.008" working headspace which is far too much.

Best to remove the ejector to do this, but not critically necessary to remove it.

 

[jdh47]

Is he reloading for an AR? Could the bullets be seated too long? That will cause pressures to spike. How does it compare to factory ammo?

If he is using an AR it could need a body die. What Butch said is correct it could be the base.

From Wm. Hamby Clark's book "Center Fire Rifle Accuracy" you can take a dial caliper and measure a fired case at the shoulder and lock it. Then measure a resized case with the same caliper and if it slips down the case more than about 1/8" you are resizing too much.

Just some thoughts.

Joe

 

[K22]

You need to rethink this method. Could give excess headspace. How do I know? Been there. If you want I will type a response to this later today.
Basically, if you have brass that is too large in front of the rim, it will chamber hard. If you screw your die down you are squeezing or resizing the base to fit your chamber. Butt!!! you maybe be bumping the shoulder back while you are doing this.

I get that - would like to see more.

I used this method in the "old days" 60's and 70's before I had gauges to set up full sizing dies. I found out that if I followed the instructions with the die and turner the sizer as they instructed I got way too much cam over and sizing. So I began to experimenting "custom fitting" the cam over, i.e. sizing to a specific rifle and cases restricting those cases to that rifle. It seem to work. I would also mark the shoulder area with a black marker to get a sense of shoulder contact something I should have mentioned but didn't want to get too complicated.

I was only offering this as a quick check not a substitute for proper gauges but your point is well taken. Well I became affluent I went to Wilson headspace gauges which gave an approximation of sizing which sort of validated my old procedure, somewhat. Eventually I entered the 21th century and began using the Hornady headspace gauge to more precisely measure shoulder set back. I have to say the "old method" was fairly consistent with a .002 shoulder bump on bolt rifles.

No way I want to mislead the orginal poster so thanks for your input. I didn't take into what I think your referring to is bulges in the head area of the case that might contribute to stiff chamber aside from headspace. I guess that could lead to oversizing but the excessive cam over or variation in chambering between difference cases at the same cam over setting would raise a question, at least to me that something is awry and require a recheck.

Bottom Line - Use the Hornday Headspace gauge to eliminate any confusion. Wasn't sure if he could get the proper fixture for this caliber so using a quick check might reveal if he sizing too much.

 

[Mtstalker]

I use the bolt method and a hornady gauge. I do use a 0-1" .0001" mik to check the base when i screw my die out to start to see how far it is sizing down the case( just check between a fired and the sized). So far on every rifle that i own ( all factory) the bolt method is confirmed with the hornady guage. Now with that being said i have been told that you should neck size for 2 firings to let the case grow to max headspace, i font know if this is true but i just set my die off of one firing. When you screw your die out a turn or two and then size you will notice the headspace measurment will actually get longer if the die is sizing the body down. Once that stripped bolt closes about half way on its own ill measure ut again and its usually .001" less than the fired case. But still mark the body in sharpie and check to make sure your body isnt hanging up any where.