Is my headspace too tight?

[pho3n1x]

Ok, to start off with, I have a Remington 700 that was put together by a local custom builder. It has an AAC .260 Rem barrel. I went to shoot it for the first time yesterday to get a rough zero (all I had on hand was some fudd soft points, waiting on an order from Southwest Ammo for the good stuff).

I had Remington Premier Core Lokt Ultras and Federal Premium Sierra Gameking BTSP. The Remingtons had no issue (other than not being terribly accurate) but the Federals had some serious problems - I should have known something was up when the bolt required a lot of additional force to unlock than with the Remingtons. Out of 5 rounds I had two blown primers, and all five show severe flattening from the ejector. Needless to say after round 5, which was blown primer #2, I quit shooting it. It also shot way worse than the RP - maybe 3-4 moa versus 1.5 moa. Went home and measured the fired cases and the live ones, and here's the problem:

With a .308 headspace gauge on electronic calipers, the fired cases measure 1.622 (FC and RP)

Live rounds out of the Remington box were 1.621 - 1.625
Live rounds out of the Federal box were 1.625 - 1.630

Again, these were factory rounds, not reloads, so I assume the problem is with the rifle. So am I correct in guessing the headspace is too tight? Or is something else the problem?

Here's some pics:

The FC cases:

RP cases for reference:

TONS of brass on the bolt face, only 25 rounds fired - I don't know if this is normal as this is my first precision bolt gun, but even after putting 800 rounds through my AK in one day, the bolt face wasn't this covered in brass:

Thanks in advance for any help.

 

[JSF]

Re: Is my headspace too tight?

Take one of the loaded federals and color the bullet with a sharpie. Chamber it and then eject it. See if there are any marks through the sharpie. If there are you have an issue. Factory rounds should not be touching the lands.

 

[bodywerks]

Re: Is my headspace too tight?

Seems like a headspace issue, or a bad rifling job causing excess pressure.

 

[JSF]

Re: Is my headspace too tight?

You may also order a go-no-go gauge and check it yourself. Also, take the evidence to the guy that built it and have him check if you still trust him.

 

[MTETM]

Re: Is my headspace too tight?

Here are the SAAMI specs for a 260. http://www.saami.org/PubResources/CC_Drawings/Rifle/260%20Remington.pdf
Note the minimum headspace is 1.630

If your measurements are of the proper diameter at the correct location, than your chamber is short.

Evan if the chamber is .008 short, I find it interesting that the loads are that far into the lands...and creating the kind of pressure the Federal load is showing.

I would simply call the Gunsmith and visit with him.

 

[Bill Larson]

Re: Is my headspace too tight?

I would take gun back to guy who built it and ask him to check headspace.
here`s how to check "approx" headspace w/o a gauge.
disassemble bolt..( pull firing pin assy.)
cut some small pices of paper.
with a dab of grease put 1 paper piece onto BF
with new piece of brass in chamber...close bolt
keep adding paper pieces til you feel the case when closing bolt.
measure paper thickness.

 

[1911fan]

Re: Is my headspace too tight?

Easier redneck way, I don't even pull the firing pin. Put a small piece of electrical tape on the base of the case and trim it so nothing hangs over the edge of the case. Chamber and eject. You might or might not feel any resistance. Now look at the tape. You may have faint marks of the ejector, or not. Put another piece of tape on, chamber and eject. This time, you should feel some resistance as the case chambers, and you should have visible impressions on the tape. This is good and indicates headspace is redneck close enough.
You should not be able to put three pieces of tape on the case and chamber it without effort.


1911fan

 

[Turk]

Re: Is my headspace too tight?

I've had issues w/ FGMM on a rifle built by one of the premier builders. I was pissed at the builder at first for making the chamber so tight; as it turns out it wasn't the builder's fault. Federal seems to have increased their tolerances. If you want to reliably feed FGMM; chances are you're gonna need a slightly looser chamber. In the field it won't matter much, if any at all. My chamber ended up being +.0035 in order to feed the Federal stuff reliably.