Thread: Sticky bolt?

Hey team. I have a 308 Win that I'm running 150NBTs in Lapua brass using AR2208 and CCI BR2 primers. The load shoots very well in my little Forbes at 2750fps and should be a pretty sedate load. I think 2208 is not the ideal powder but is good enough.
I have had a run of occasional very tight bolt lift though on the occasional load. I thought I may have had the headspace a little too long so I have measured across a number of fires cases with a Hornady comparator and bumped the shoulder back another 0.002" from fired brass. Everything chambers easy. I have one piece of brass that jammed on me last night that measures 2.006" long. I think this is well undersize at 2.015" so unlikely it's not too long. I have a base of 0.4721 which is about 0.0011" over CIP so I'm not picking that's too bad. 2208 is nearly impossible to overload so I doubt I'm too hot. The primer tells the same story. The only thing I can find in this one piece of brass is a mark across the base. I'll have to take a look at the bolt when I get home but its the only thing I can see wrong. I'm scratching for ideas. I was planning to use some CFE223 in this but I would really like to get to the bottom of this first problem before I get any further down the track.

Carbon ring in the throat


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Originally Posted by MSL

Carbon ring in the throat


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How do I check for that?

How many brass are tight

Put them aside and monitor the rest

I ran my Forbes with the same projectile at 2900 FPS with 2208 and lapua brass

Originally Posted by 7mmsaum

How many brass are tight

Put them aside and monitor the rest

I ran my Forbes with the same projectile at 2900 FPS with 2208 and lapua brass

They're only tight after shooting. Everything chambers mint. Not all are tight either, on average I'd say one in 6. I can't be fucked risking a missed chance with a gammy bolt. I'd rather just chuck everything out and start again but that's assuming its the brass and not the rifle. I may just buy some fresh brass and try that.

It’s the brass for sure

My Forbes used to do that but not on bolt lift it was on bolt extraction.
And was only caused by loads being too warm.

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Have had the same thing in my tight chambered 280 with neck sized brass. So watching this with interest.

The Forbes has no primary extraction which is a bit sucky. I don’t see anything in the bolt that looks bad. The brass still measures fine for headspace but won’t extract even when rechambered. I’ll give it a neck size to remove the carbon ring idea and if that goes then I’ll FL size it and see.

Greetings Kiwijames,
Looks to me as though the case has been scored on something before or while it is being chambered. There may be a raised ridge on one side of the score which would have chambered OK but would have been hard to extract. It would be worth looking at your mag and bolt face for any rough bits as well as your reloading gear. Brass particles on anything other than your trimmer should be regarded with some suspicion. Also you could check all the other cases for score marks. It would also be interesting to know if the tight rounds chronographed any faster than their mates.
Regards Grandpamac.

Originally Posted by grandpamac

Greetings Kiwijames,
Looks to me as though the case has been scored on something before or while it is being chambered. There may be a raised ridge on one side of the score which would have chambered OK but would have been hard to extract. It would be worth looking at your mag and bolt face for any rough bits as well as your reloading gear. Brass particles on anything other than your trimmer should be regarded with some suspicion. Also you could check all the other cases for score marks. It would also be interesting to know if the tight rounds chronographed any faster than their mates.
Regards Grandpamac.

Cheers. I don’t have a chronograph and prefer to validate at range. This load was very consistent and the deer I shot last night was bang on for elevation with 3.25MOA dialled in.

I’m thinking the score on the base may be a red herring. I’ve checked it for length and it’s well inside others that chamber and extract fine. I’ve neck sized it and it is still sticky, only after I FL size does it go back to behaving itself. I think I’m going to chuck the brass and try some fresh stuff. I’ll also go to a different powder but I really don’t see the load ever getting warm. 2208 is just too bulky to make the 308 overloaded.

Originally Posted by kiwijames

2208 is just too bulky to make the 308 overloaded.

Not correct- can easily be done esp with a combo of high neck tension/ fouling/ heavy brass/ hot primers/...

2208 is in fact an ideal powder for 150 class projectiles in a .308- ask any fullbore shooter

Originally Posted by 6x47

Not correct- can easily be done esp with a combo of high neck tension/ fouling/ heavy brass/ hot primers/...

2208 is in fact an ideal powder for 150 class projectiles in a .308- ask any fullbore shooter

I'd agree with this 100%. There are many loads out there that are way over normal limits. I often run the loads people on here "mention" on Quickload and while there are a lot of variables in the estimates it gives, its a great tool.

Recently I was in the LGS and he hand me a Tikka T3 action. It had enormous setback on the locking lugs, something like 8 thou as I recall (so much its a wonder it was still firing). I'm no fan of Tikka's bu they are very strong actions . . . . for one to have that much setback it must have been operating at truly horrific pressures. The thought occurred to me looking at this action was "how the hell did the brass stand the pressure without a failure".

I'd say brass is very much better than it was 10 or 20 years ago and reloads of 70,000 psi are not uncommon - they go ok in modern rifles in good condition but its a game of chance.

The SAAMI max pressure for 308 is 62,000 psi. You don't give the barrel length of your Forbes but to get 2750 from an 18" barrel with a 150 in a 308 and 2208 you'll be running at 65,000 psi - not way outside the limit but getting close to "tolerance" if there is something not normal with your rifle or brass etc.

Originally Posted by 6x47

Not correct- can easily be done esp with a combo of high neck tension/ fouling/ heavy brass/ hot primers/...

2208 is in fact an ideal powder for 150 class projectiles in a .308- ask any fullbore shooter

Or you can try plugging the barrel with dirt too if you really want to be silly, ask any halfwit.
I have 0.003" neck tension, low fouling and standard CCI BR2 primers in Lapua ex military brass.

My charge is 46.0g 2208.
Hogdons has 47.0C g Varget only reaching 50K CUP. I'm not totally discounting it but it is also not going to be on my most likely list.
My reloading is quite consistent so I will also discount error as a probable cause.
The fact that it is an inconsistent problem has me scratching my head. Most scenarios offered should be more repeatable.
I have inspected both the bolt and the chamber. Neither appear to have blemishes or other errors that stand out.