Bolt sticks on extraction - could it be carbon build-up?

[hawlejr]

I've been using some older 30-06 brass which I've reloaded several times without much cleaning. I use it for practice shooting rather than load development or hunting. The outside of the necks are black with carbon. They may be a little hard on the chambering part of the process, but they are really tough on extraction. After firing, I have to use some force to lift the bolt, but it's not excessive. After the bolt turns, however, pulling it back can be so tough that I sometimes have to hammer on a rod down the muzzle to move the bolt back. There are no signs of over pressure and the groups are running a little over 1 moa, with these practice loads. I'm wondering if it could be that the carbon is burning/melting almost like glue between the neck and the chamber. The carbon on the necks when they first come out is shiny. There is no lube on the cases as I use a collet neck sizer.

 

[marksman1941]

That still sounds like a pressure issue. Even if cases and primers look fine, you can still be overpressure. Sticky bolt lift is almost always over pressure, at least to my knowledge.

 

[Varmint Hunter]

Certainly sounds like over-pressure to me. Clean the black off the necks with a little steel wool and see if that changes anything. I doubt that it will but it's worth a try. I'd be concerned with any load that requires a rod to remove cases, regardless of the cause.

 

[Weaver93]

Why don't you clean, resize and trim? See what happens.

 

[The_Whitetail_kid]

Do you full size or neck size?

 

[hawlejr]

Cases are trimmed. I don't have a good case cleaner, and I'm trying not to put in too much work on these as they are practice rounds. I think I'll try reducing the loads (although in new bright shiny cases there is no problem), and see if that eliminates the problem. If it doesn't, it's definitely got something to do with the carbon build up. I have been using a rotary brush with carbon cleaner on the chamber throat, but, perhaps after a few rounds it has built up enough carbon in the chamber to form a bond with the carbon on the case neck. I'm using 57 grs. of Vihtavouri N160 in 30-06 165 gr bullets either Hornady spitzer flat base, or deep curl projectiles ( all 165 gr.) The max listed for these/similar 165 gr. bullets is 61 grs. I've also used the 165 gr. GMX bullet with 55 gr of N160. All of the loads can show very tough extraction once in a while to the point of needing to use a rod down the muzzle to break the case free.

 

[ResearchinStuff]

You probably ruined the throat and neck of your chamber with that rotary brush technique.

 

[The_Whitetail_kid]

I had an issue with brass feeling sticky when I used to just neck size, full sizing fixed that problem.

 

[hawlejr]

I use a collet neck sizer die. Again these are practice cases where I don't want to spend too much time and mess with lube and full length sizing. I'm really interested in knowing if anybody has had difficult extraction due to carbon buildup. Of course if I go to the trouble of obtaining a case tumbler or ultrasonic cleaner, and full length size the problem will go away, I'm sure. New brass doesn't exhibit the problem ....at least not on first firing. Again, I'll drop my charge by 4 grs of powder, and see if they still stick.

 

[The_Whitetail_kid]

I get that you don't "want" to but if you want consistency and top notch performance a lot goes in and you can't half way do it.

 

[hawlejr]

It's a nylon .338 brush in the 30-06 chamber. I use carbon out cleaner and spin it with my electric drill for 10 -15 seconds. Very mild. No damage.

 

[Koda_]

I use a collet neck sizer die.

If your only neck sizing you still have to full length size them every now and then or they will stick...

 

[hawlejr]

I appreciate all the inputs guys, and I normally would spend a lot more time on the brass if I was doing serious load development or going on a hunt. In fact I wouldn't use these cases at all. I'm practicing mounting the rifle and shooting quickly. I'm also practicing shooting off sticks. I'm practicing working the bold quickly and firing rapid follow up shots. I'm not trying for super tight groups off the bench. In fact, I'm not using a bench at all. I'm happy with rounds that give me better than 2 MOA. However, as you can imagine, the bolt sticking really impacts this type of practice. That's why I'm trying to determine if carbon build up is the answer. If it is, I'll go out and buy a tumbler. If nobody has had stickiness due to carbon build up, then I could waste a couple of hundred dollars, and a bunch of time on case cleaning, when it is not the answer. So far nobody has correlated carbon fouling to difficult extraction, so like I said, I'll drop the charge a bit and see if the carbon maybe was raising the pressure ( although there's no flattening of the primers nor extractor marks on the base), and secondly, take about 20 cases out and clean the hell out of them and load them up and see if any of those stick. I know that new cases do not stick with these loads. Thanks again for your comments.

 

[victor3ranger]

If these are stiff to lock down the bolt that sounds like the shoulders are up against the chamber