What changes has the case went through that causes the bolt to stick in high preasure?

The case is telling you to back off a few grains ted.

The case head has expanded beyond elastic limits sufficiently that the bolt face and/or extractor are dragging. Ditto for the case in regards to difficult extraction. It is not good news BTW.

Ted the case has expanded but not contracted like it should, so it is still griping the chamber walls.

Yes but.....Something has to move to create the space for the brass to expand/grow into.

When the case is fired and pressure builds, it is contained within the chamber of the barrel, and the boltface. The bullet goes out the other end. The barrel won't expand enough to cause problems, but the boltface will.

Given that most bolt lugs are not making full contact on both lugs, (or multiple lugs) the bolt will set-back until it is retained. Even if the lugs are in full contact, the lugs do flex some.

So if the boltface sets back a thousand's or two, the brass will expand into that space. Once the pressure is off, then you have the sticky bolt lift.

Hey Ted, The previous answers might all be correct - for different causes.

1. Are you Neck Sizing?

2. If you are not Neck Sizing, describe how you set-up your Full Length Die in the press.

3. Does it happen on the First Shot from a new case or do you get a few reloads before you see it?

4. What load/cartridge are you shooting?

Thank you for all your comments I personaly have no problems yet with a sticky bolt but allways read about it in all load data I just wanted some points of view of what happens inside the chamber to cause this. Thanks again

quote:

Originally posted by ted thorn:
What changes has the case went through that causes the bolt to stick in high preasure?

The case has been stretched beyond its' elastic limit, and didn't spring back away from the chamber walls as it does if the pressures are not too high! When this happens, you are in effect breaking it loose from the chamber walls when you open the bolt. The better the bond between case and chamber wall, the harder it is to get the bolt handle up! If the case head has actually expanded in the bolt face as well, it may require the barrel to be removed from the action to get the deformed case out.

Just an interesting sidebar to the sticky bolt thing. I have a buddy who has had two Kimber's which had sticky bolts--had to pound open with our hand occassionally. The first was a 300 WSM, and when he talked to Kimber, they said they 'simply needed to polish the chamber'. We both looked at the chamber before he sent the gun back, and after they returned it, the chamber seemed to be just that--polished up and a bit shinier. The same factory loads (some from the same box) and never a problem again. The second one to stick was a 270 WSM and instead of sending it back to Kimber, I just took a 20 Gauge shotgun bore mop, daubed it up with some Flitz and chucked it up in one of my cordless drilss and gave the chamber a buff. It shined the chamber up nicely, and same rounds through this one as previous, and slick enough, no more sticky bolt!

I'm not sure of the technical dynamics in play here, but it made an unbelievable difference.

I have actually used an empty case and some polishing/lapping compound to do the same thing on a couple of other rifles, with the same result.

Just FWIW--Don