6.5 Creedmoor head space issues

[swd]

I've built 2 6.5 Creedmoor's for clients over the last few months. Today we put about 10 rounds through one I just finished and I noticed the primers were flat as a pancake with new Winchester 140gr ammo. I ran a couple through the chrono and they were 2750ish, nothing hot there. Then I checked them in the chamber, .006"-.007" headspace. I checked 1 Hornady I had on hand and it was .006". The chamber on a PTG go gage is .0015". Has any one else noticed this? Either my Go gage is long or the ammo is short....

 

[SHootSTraight22]

I've built 2 6.5 Creedmoor's for clients over the last few months. Today we put about 10 rounds through one I just finished and I noticed the primers were flat as a pancake with new Winchester 140gr ammo. I ran a couple through the chrono and they were 2750ish, nothing hot there. Then I checked them in the chamber, .006"-.007" headspace. I checked 1 Hornady I had on hand and it was .006". The chamber on a PTG go gage is .0015". Has any one else noticed this? Either my Go gage is long or the ammo is short....

I would check on the reamer specs...

 

[Dusty Stevens]

Did you try any other ammo to see if its different?

 

[swd]

I have 1 round of boutique loaded ammo on a Hornady case that's about 6-8 months old and the client had brand new Winchester. From what I can find the Winchester may be made by Hornady for them. Both had similar head space.

Anyone have a Creedmoor headspace gage I can borrow that's not a PTG?

 

[KMart]

My best guess is short Hornady cases. I have seen several different factory loaded Hornady rounds give very flat primers and in some cases, ejector marks. 308 as well as 223

 

[Deton8tor]

When I started shooting a 6.5 Cm, I used WW ammo. It would do just what you describe. I think it was a bit too warm. I tried Hornady and had no issues. I needed brass is the only reason I was going the factory ammo route.

 

[Jhayesvw]

My factory Hornady brass is about 0.006" shorter in headspace than my Hornady die will bump back to.
I thought it was just me. It appears this Hornady brass is just very short.

 

[swd]

I'm glad to know its not just me. I chambered another one a few weeks ago and was tempted to cut the chamber a little short but ended up setting it up to just barely drag on the go gage. Some day brass will probably be in spec, hopefully...

 

[brian427cobra]

I push 140 Hybrids out of my 6.5 Creed at 2840, virgin brass always looks overpressured, at first I was extremely concerned, now its just part of the fire forming process.

 

[DHD]

In my experience, the factory new brass runs about .005" - .006" shorter than my fired brass (and I have snug chambers).

Also, the little bit of factory ammo I have fired, I have noticed the same thing. Flattened primers with relatively low muzzle velocity and no signs of pressure except for the primers.

Edit: I just noticed this was an old thread. Somebody resurrected it.

 

[WSnyder]

6.5 Creedmoor

SAAMI chamber bolt face to .400 datum is 1.541" min.

Your HS gauge +.0015+1.541"=1.5425". So your chamber bolt face to datum may be 1.5425".

SAAMI cartridge base to datum is 1.5438" -.007. So minimum cartridge base to datum can be 1.5368".

Your chamber minus min SAAMI brass:

1.5425"-1.5368"=.0057" pretty darn close to what you say you have. If so it's right at min SAAMI spec. So is it short or just at min SAAMI spec?

I generally have brass that's somewhat less than max. Rarely have I had brass that chambers tight out of the box even with min chambers.

 

[Jhayesvw]

Great explanation.
Thank you.

 

[Puzzaz01]

I chambered mine with a Manson Reamer a little on the short side, where the bolt face just rubbed the go gauge going down and its still a little loose on the factory rounds and on the new Hornady brass. I believe the factory rounds are a little short.

 

[WSnyder]

It is possible (and common) to have a minimum spec chamber and for minimum spec brass to be shorter than that minimum chamber. The brass may be "short" but it's likely not shorter than min SAAMI spec. Some have been known to chamber to a specific lot of brass instead of a gauge because of this. I'm sure it has happened but I have never had brass shorter than min SAAMI.