Re-barreled my .270 to 25-06 and set Headspace like I usually do(Go gauge closes smoothy with no resistance, but won't close all the way with .001 shim added between bolt face and Go gauge). No Go stops at 2 o'clock position. When test chambering live factory rounds(Federal 100gr BT) the bolt requires more resistance to close than my other others. This happens with all of the rounds in the box, but some are almost normal and some require actually pushing on the bolt a little to close. I covered the worst one in Sharpie and chambered to look for contact points. What I noticed is there is a prominent scuff proportional to bolt throw right in front of the case. I cleaned the chamber thoroughly and checked again...Same thing. I do not feel or see any burrs.
I've measured the COAL and case length and they are all less than what Nosler indicates for Load data and this bullet, however I'm nervous to pull the trigger.
FWIW this action has had a few hotter .270 rounds(Hornady Superformance) require force to open bolt, and my gunsmith polished the chamber, and backed headspace off a bit on that barrel. Following that, it never happened again.
I have since adjusted headspace another .0005(bolt closes barely on .001 shim and Go gauge)and it closes a little better but still firmer than my other action/barrels.
Any ideas? Why would the scuff be only on one side? Is it possible that the action needs trued?
A couple of things: There is an established tolerance on headspace and headspace gauges and a tolerance of headspace length on the ammo. It is possible to get ammo that is longer than the headspace of the chamber and still be in in tolerance. I would adjust the headspace to fit the ammo.
The scuff on one side is caused by the ejector pushing the cartridge to the right before it finally chambers.
"As long as there's lead in the air....there's still hope.."
No-Go gauges are typically 0.004" longer than a Go gauge, so if you're using a 0.001" shim you're creating a really tight headspace which is part of the problem.
Have you checked with any other types of ammo? This will help determine if it's an issue with that Federal ammo or the gun itself.
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I just pulled the very same bullet from the case in the picture and tried it. Same amount of resistance so this reinforces what you guys have said, and it's probably having too tight of headspace for this load. I'm heading to LGS to pick up another box of something else( I need brass anyways) to see how it chambers. If it too is tight, I will back off the headspace a little more to headspace it on this case with light resistance. My guess is I will wind up with .0015-.002 shim above Go gauge and the bolt at the 3-4 o'clock position on No Go gauge.
Makes sense about the ejector and the bullet scuff, especially now that I know its a case/headspace issue.
Thanks guys!
Bought some PPU 100gr SP's. They closed with only slight resistance. I backed off my headspace to .0015 above Go gauge(Go + .001 shim closes freely and .002 won't close). I wind up w/ bolt at the 3 o'clock position on No Go gauge. The Federals still encounter some resistance the last 1/4 of bolt closure, The PPU's you can feel just making slight contact but no resistance.
In most calibers/barrel switches I've found best accuracy setting them right at .001 above the Go Gauge. I don't have dies yet for this caliber as I bought the barrel on a whim, having always wanted one. I'm an avid fan of .270 and .243 and load for them. I do a lot of coyote & some deer hunting and wanted to see how if the 25-06 is all that Ive heard and read over the years as a dual caliber and how much more recoil it has over the .243
The first barrels I installed I put on with very tight headspace.... and now I don't. Very tight headspaced barrels are more of a pain than they are worth. In my opinion you are better off to give yourself a little extra room (as long as it wont fully chamber a no-go gauge.) I had barrels that would chamber a go gauge- but my full length sizer die was not able to size the brass enough that it would easily chamber. Brass will have some spring back- so if it is difficult to chamber factory ammo right now it could be worse trying to use reloads. Then you have to have your die ground....
Also- if you use correct reloading techniques you are not working your brass anymore in a chamber with a little more room vs a very tight one.
It may be something very simple but most likely you have already checked. In the past I had a front action screw that when properly torqued it barely rubbed against the bolt head. You couldn't feel it on an empty chamber but had noticeable drag with a case in the chamber.
I headspace all mine on the tight side of go-gauge and factory brass (saami) is always loose.
Might be worth looking at that screw if you haven't already. I color it with a Sharpie on the side of the bolt head.
Hope you get it figured out.
Randy
Thanks. I’ e backed off the headspace a notch and switched ammo.
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Factory ammo-especially across manufacturers, but within the same as well- will have dimensional variations within tolerances as mentioned.
One can run with tight headspace with handloads because consistent shoulder datums can be obtained- but this isn't so with factory ammunition.
As an additional point, there's really no reason to strive for minimal headspace with a rifle that's going to shoot factory ammunition. There's no concern about brass stretching/brass life, having 2-3 thou of headspace ensures all factory ammo will chamber- and also provides a nice buffer in case any dirt, grit etc. finds it's way into the chamber which is good to have with a rifle that's used in the field. Why risk creating a problem, when it's unnecessary...
Im sitting about .002 above go gauge now.
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