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 Sticky bolt at the beginning vs at the end of lift
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herbeapuce
Average Member

Canada
181 Posts

Posted - May 06 2017 :  23:00:54  Show Profile Send herbeapuce a Private Message  Reply with Quote
Hi.

Is there something to learn from a sticky bolt at the end of the bolt lift ? It opened easily first but then at the end it was hard to finally pull up ... Please note this action has a a COC (cock on closing) bolt ...

Very strange what happened today at the range: last week I was developing my load with 39 to 41.5g of H-4350 ( 6mm Rem, V-max 87) and I ended up with a sticky bolt only at 41.5g.. but a sticky bolt at the start of the bolt lift movement...seating depth was 2.830"

now today , I was playing with various seating depths at 39.5g H-4350
, same bullet, from 2.807" all the way to 2.852" and today I had a sticky bolt, but at the very end of the lift on every single bullet I shot ???
I didn't shoot the 2.852 string cause I was getting worried....

so to recap : this week sticky bolt with 39.5 at the end of bolt movement , on all seating depth (2.807, 2.820, 2.830, 2,840")
Last week all was fine until 41.5 ( stick bolt at beginning of lift...)

the only thing different that I did was annealing the brass.

-I heard one has to re-adjust his Full length die if one anneals, is this true?

- It there is anything to learn because of this, can you elaborate on the differences of a sticky bolt at first vs at the end please?

possibilities for today's high pressure: maybe I left a bit of oil/solvent in the chamber? maybe I left a tiny burr outside the neck of my brass? what else?

thanks for your help
stef




Onondaga
Advanced Member



USA
4017 Posts

Posted - May 07 2017 :  01:54:38  Show Profile Send Onondaga a Private Message  Reply with Quote
Stef, you said,
"-I heard one has to re-adjust his Full length die if one anneals, is this true?"

I see no logical reason to assume that is true, it contradicts the basics of die adjustment. Some loaders that set back shoulders substantially with their sizing die may have brass damage when their annealing was severely overdone. That damage is NOT the fault of die adjustment needing to be changed because brass was annealed. It is the fault of over softened brass giving way to the stress of being sized. That is normal and should be expected when brass has been over-annealed to weakness.
Over annealing is generally caused by incorrectly applying too much heat for too long to brass to the point where all work hardening of the brass is lost to heat and the brass loses it's spring back because it is dead or near dead soft.

Gary

Fine rifles are never really owned.
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Onondaga
Advanced Member



USA
4017 Posts

Posted - May 07 2017 :  02:12:30  Show Profile Send Onondaga a Private Message  Reply with Quote
Stef, you said,

"It there is anything to learn because of this, can you elaborate on the differences of a sticky bolt at first vs at the end please?"


The point in bolt rotation where lift force increases due to high pressure is usually associated with the rotation point where the initiation of extraction is timed in degrees of rotation in the bolt lift.

I don't know where the manufacturer puts that extraction point on your rifle, ask them. However if you get tight spots anywhere else, dirt or lack of proper lubrication is the cause. I know that on one of my rifles there is a particular spot that needs grease or I can feel it easily and it binds there, if there is clean metal there instead of greased metal. That could innocently be the problem too.

Gary

Fine rifles are never really owned.
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Shastaboat
Advanced Member



USA
9124 Posts

Posted - May 07 2017 :  05:19:45  Show Profile Send Shastaboat a Private Message  Reply with Quote
I would assume that you are getting signs of high pressure since there is no pressure to cock the bolt on the uplifting on your Swedish Mauser action in your 6mm Rem. When it was built the builder probably did not lap the lugs as is a custom to insure smooth consistent bolt operation. That being said the resistance is telling you something. You should back off your load to a smooth bolt lift.

But as you described, you backed your load off from 41.5 gr to 39.5 gr and are still experiencing sticky bolt lift but at the top of the lift. You describe that you annealed your brass? How far down did you anneal it? You may have annealed way below the shoulder and your brass is now stretching more if your sizing die is setting the brass shoulder back further from the previous firing. When you fire the brass again it is more ductile and stretching to fill the chamber.

I would re-evaluate the setting on the sizing die and readjust to just kiss the shoulder and not set the shoulder back. Do not set your die to full length size to the ram. This may cause bolt chambering to be snug but not hard. This procedure has been discussed many times on the forum. Your brass will last for 10 or more firings by not allowing it to stretch.

Also make sure you are trimming your bass to minimal size. Have you done a carosafe chamber cast of your rifle's chamber and throat?
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herbeapuce
Average Member

Canada
181 Posts

Posted - May 07 2017 :  16:42:21  Show Profile Send herbeapuce a Private Message  Reply with Quote
thank you guys.

Quote:" if there is clean metal there instead of greased metal. That could innocently be the problem too."

indeed this could be my problem! I forgot to tell but I also completely disassembled my bolt and thoroughly cleaned it with a toothbrush and brake cleaner, and lightly lubed it with oil... do I have to apply grease on the bolt itself, beside behind the lugs ? it's a mauser small ring bolt ( thanks Saska for letting me know)

I trim my brass religiously after each firing when a Lee case length gauge.

I haven't done a carosafe cast yet. I have some so will do this soon.

I do my annealing in a dark room with a propane torch and a gentle flame aiming at the shoulder of the cases. I shop at the exact moment when the first red apprears.


Edited by - herbeapuce on May 07 2017 17:29:20
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Onondaga
Advanced Member



USA
4017 Posts

Posted - May 07 2017 :  18:24:52  Show Profile Send Onondaga a Private Message  Reply with Quote
Steph,

Your color vision produces results similar to mine but I don't get color down the case body that far. The problem is that the ones you don't catch right and glow any color on you are over annealed. Your oxidation line from annealing is not consistent from case to case. Your annealing could be at fault. I aim to get the color line at the Datum Point. You aim your heat source farther from the case mouth than I do.

A practical way to check your annealing for the Reloader is going to cost you 2 of your brass cases, one you annealed versus one new factory. You use a needle nose and work the brass neck back and forth to ruin it and see if it gets brittle and cracks or it softens and tears as you keep it pinched and wiggle it's neck wall to death....Then just decide which you would rather shoot. Hint: both your annealed case a factory new case should feel exactly the same.

It is also useful for the Reloader to know over annealed brass sometimes re-work hardens from load cycles all by itself. Some cases will fail, some heal. This reflects margin of error. Life happens.

Gary

Fine rifles are never really owned.
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herbeapuce
Average Member

Canada
181 Posts

Posted - May 07 2017 :  19:43:08  Show Profile Send herbeapuce a Private Message  Reply with Quote
At the mouth this is how I used to do it, but after seeing so many pictures and videos of annealed brass, I was now aiming more at the shoulder.. ho well.... I even bought a themomelt pencil, a Markal 750F, but it doesn't work on brass. I should have bought the other brand ....
annealing without a machine is like doing sorcery... not easy to get everybody happy
but I agree my skill can be improved.
I like this guys setup, and it fits my bill : https://www.youtube.com/watch?v=yL0WnIip6VI

thanks for you output Gary.
stef


Edited by - herbeapuce on May 14 2017 23:24:12
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Onondaga
Advanced Member



USA
4017 Posts

Posted - May 07 2017 :  21:13:29  Show Profile Send Onondaga a Private Message  Reply with Quote
Stef, you are doing well. Some guys that try annealing shoot their case necks out the muzzle with the bullet and then blame Lee.

Gary

Fine rifles are never really owned.
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Zero333
Advanced Member



Canada
811 Posts

Posted - May 08 2017 :  03:19:45  Show Profile Send Zero333 a Private Message  Reply with Quote
If you don't know how far you're bumping the shoulders when FL sizing then you shouldn't worry about it being sized differently after annealing.

A headspace comparator is the only way to find out how far you're sizing. I use a HS comparator every time I FL size so I end up adjusting the die accordingly.

I did experience the same exact thing as you and with a 308win bolt gun using Lapua brass. First few firings I was loading 47.2gr Varget under a 155 scenar. Was getting 2,990fps from a 24"bbl. Then I decided to anneal the brass and all of the sudden 47.2 showed a sticky bolt life at the top of the stroke (during primary extraction).
So I dropped the load down to the next node at 45.2gr... It felt good and no sticky bolt lift until I sized them again, and had the odd sticky bolt during primary extraction at 45.2gr.

I assume that I over annealed it somehow. Even tho the brass is still safe to reload, it doesn't hold pressure as well.
I put this batch of 200 pcs of Lapua brass aside.
Not all brass anneals the same. I'm using Win. brass for the same 308win rifle, and I have annealed it 5 times thus far (every 5th reload). This win brass is on it's 27th reload and haven't scrapped a single piece from the beginning.


Treat that trigger like it’s your first date, not like you’ve been married to it for 20 years.
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