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Old December 3, 2019, 03:35 PM   #1
hounddawg
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Sticky bolt lift, how much to back off or not

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On my 6BR I am getting a bit of a sticky bolt lift. Nothing major but more than it should be. No flat primers, no dimpling, no ejector or extractor marks marks are present. Load is 30.0 Varget and 105 Berger seated .015 from lands with a 29 inch barrel.

Groups are great at 850. about .9 MOA for 10 shots from a bench which for me is outstanding, my rifles length of pull and scope are set up for prone shooting so my bench scores run a tad higher than prone.

Here is my quandary, I may have one, maybe two range sessions before my next match so not a lot of time to adjust. Would you shoot the match with the 30.0 or drop down to 29.8 (29.6) and rezero

edit - the 850 attachment was this mornings practice and the best I have ever shot which is why I am thinking of staying with the 30.0
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File Type: jpg 850.jpg (36.3 KB, 41 views)
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Old December 3, 2019, 04:11 PM   #2
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I can give you my opinion,and you will do whatever you will do.

Some folks will say "10 %" Some might suggest backing off in 1 gr increments till you like the results.

I'm sure you know how to research data. My Nosler book is handy.

The heaviest bullet they list for 6 mm BR is 80 gr. Varget is one of the recommended powders for an 80 gr bullet.max load 32.5 gr.

You are shooting a relatively heavy for caliber 105 gr bullet. You have a 29 in bbl.

IMO, the root cause of your problem might be Varget is too fast for what you are doing.

I might look toward a burn rate closer to (maybe) 4350, That's a seat of the pants guess.,but you get the idea. Probably does not fit your match schedule.though.

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Old December 3, 2019, 05:32 PM   #3
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Quote:
Originally Posted by hounddawg View Post
On my 6BR I am getting a bit of a sticky bolt lift. Nothing major but more than it should be. No flat primers, no dimpling, no ejector or extractor marks marks are present. Load is 30.0 Varget and 105 Berger seated .015 from lands with a 29 inch barrel.

Groups are great at 850. about .9 MOA for 10 shots from a bench which for me is outstanding, my rifles length of pull and scope are set up for prone shooting so my bench scores run a tad higher than prone.

Here is my quandary, I may have one, maybe two range sessions before my next match so not a lot of time to adjust. Would you shoot the match with the 30.0 or drop down to 29.8 (29.6) and rezero

edit - the 850 attachment was this mornings practice and the best I have ever shot which is why I am thinking of staying with the 30.0
Before adjusting charge, load identical load in a couple pieces of virgin brass just to be sure its not brass or sizing related. I have a 30 BR that starts to get sticky on the 5th or 6th shot. I shoulder bump full length size. When they begin to stick, I have to full length size them with a regular die, not my custom dies. They are only sticky on ooen, not close.
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Old December 3, 2019, 05:38 PM   #4
Jim Watson
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Speer, in the era of rule of thumb reloading, said that at any "pressure sign" including hard bolt lift, reduce the load 6%. I don't know anybody who has ever done that, most of them cut by half a grain and call it good.
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Old December 3, 2019, 06:16 PM   #5
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Thanks for the replies all. I am using FL resizing and using .002 shoulder bump and the neck expansion from loaded round to fired case is .003.

Duly noted on the Varget. Oddly enough 30.0 of Varget is considered a "mild" load, the Hogdon load data goes up to 32.5C in a 24 " barrel. But it is what it is and like I always say if it does not feel right then it probably is not right and that bolt lift just does not feel right

Other powders I have on hand that I found recipes for with 105's and 107's are CFE 223, 8208 XBR, RL 15, IMR 4350 and H 4350. Some data was found on the official powder/bullet manuals, some on the 6BR site

While eating dinner I pretty much decided to pull the bullets on the rest of those loads and drop off to 29.6, load another 25 and test Friday. If they shoot decently that is what I will shoot in the match and if not I will just use my 6CM and experiment with some different powders in th e6BR
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Old December 3, 2019, 11:57 PM   #6
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To go with Jim's 6%, I'd always heard 5% either for sticky bolt lift or for sticky extraction from a revolver. Trying it in QuickLOAD with common powders, depending on the powder, these changes land inside the range of 14% to 18% peak pressure reduction in rifle cartridges.
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Old December 4, 2019, 08:39 AM   #7
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pretty sure a couple of tenths will do it, it is not like I have to hammer the bolt open. Just a bit more effort than what I am used to on a Savage, which is not known for a smooth bolt at it's best. I had good numbers at 29.2. 5 ES and 3 SD @ 2750 with 29.2 so I will load up 15 each @ 29.2, and 29.6 and do a test run @ 300 yards tomorrow or Friday
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Old December 4, 2019, 06:52 PM   #8
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What action?
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Old December 4, 2019, 07:37 PM   #9
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Savage 12 with a bolt lift kit. Going back to range tomorrow starting at 28.8 and going up to 29.6 in .2 increments over chrono. By this time tomorrow I should have my answer
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Old December 4, 2019, 07:44 PM   #10
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I'm thinking HIBC, may be onto something.
With the long barrel, i'd try a slower burning powder.
Of the one you listed, i'd lean towards H4350.
Slower than Varget, but slightly faster than IMR4350.

Let me know if you need cases for that 6BR. I found a box of new Rem 6BR at a flea market.
Can't remember what grain bullet, but i can look at the box.
Picked it up for $15 or $20. Can't remember. Sticker still on the box.
I got it for someone on here looking for casings. They didn't want loaded ammo.
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Old December 4, 2019, 08:18 PM   #11
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Thanks std7mag but I have 300 cases right now, 100 unopened and anything with a neck over .012 thick has to be turned. I agree that the Varget just may be too fast but it seems to be the powder of choice for the LR benchrest crowd for this cartridge. I don't remember the bolt being this stiff during breakin or initial load testing but then I was having different issues then and needed to turn the necks on the Lapua to just get them to chamber.

Never had a issue like this come up before, I usually get flat primers some other signs when I push the max load data and here I am well below max and nothing except the bolt lift. I bought this action used, I may try a different bolt or swap out the bolt head if it still acts funky tomorrow. I have a spare bolt head in the parts drawer so that may be my next step, either that or swap the barrel to a different action
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Old December 4, 2019, 09:54 PM   #12
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Originally Posted by hounddawg View Post
Thanks std7mag but I have 300 cases right now, 100 unopened and anything with a neck over .012 thick has to be turned. I agree that the Varget just may be too fast but it seems to be the powder of choice for the LR benchrest crowd for this cartridge. I don't remember the bolt being this stiff during breakin or initial load testing but then I was having different issues then and needed to turn the necks on the Lapua to just get them to chamber.

Never had a issue like this come up before, I usually get flat primers some other signs when I push the max load data and here I am well below max and nothing except the bolt lift. I bought this action used, I may try a different bolt or swap out the bolt head if it still acts funky tomorrow. I have a spare bolt head in the parts drawer so that may be my next step, either that or swap the barrel to a different action
I dont know how old your varget is, but some guys I shoot with have been cussing some of the newer lots of it. The varget I am shooting is 7 or 8 years old so I have not loaded the newer lots.
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Old December 5, 2019, 06:24 PM   #13
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dropped down to 28.8 and worked my way back up to 29.6 @300 today. Stil had some sticky even at 28.8. I am going to rebuild bolt this weekend hoping to cure it. Most accurate shooting rifle I have ever shot though, broke through the half MOA barrier for ten shots at 300, a new personal record
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Old December 5, 2019, 08:32 PM   #14
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Originally Posted by hounddawg View Post
dropped down to 28.8 and worked my way back up to 29.6 @300 today. Stil had some sticky even at 28.8. I am going to rebuild bolt this weekend hoping to cure it. Most accurate shooting rifle I have ever shot though, broke through the half MOA barrier for ten shots at 300, a new personal record
Try a few pieces of new brass. Wont cost you anything.
I know it sounds stupid, but I have seen the problem in a lot of bench rest rifles.
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Old December 5, 2019, 08:51 PM   #15
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Try a few pieces of new brass. Wont cost you anything.
I know it sounds stupid, but I have seen the problem in a lot of bench rest rifles.
actually that sounds like a really good idea. I have 100 pieces of virgin Peterson.

There are absolutely no other pressure signs and the stickiness does not increase with powder charge at all, so I am down to the bolt, the receiver lugs or the brass. Using a bore scope the receiver looks good and the bolt lugs were polished and a bolt lift kit installed when I assembled it. I have two other bolts I can try both of which I know are fine. Also if I have to I will swap the barrel to a different receiver

I will try your suggestion next week, thanks
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Old December 8, 2019, 02:33 AM   #16
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Has your brass been annealed lately?
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Old December 8, 2019, 08:58 AM   #17
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Has your brass been annealed lately?
no but lets say I broke down and bought a AMP and annealed. What would that accomplish other than softening the neck and shoulder of the brass? The brass is sized properly already. I shoot and reload five other cartridges and none have problems with no annealing
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Old December 8, 2019, 09:31 AM   #18
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I looked at a few manuals and found you were probably about a grain over book. Not much, but I added the required warning the OP. If you know a published source with that load, I can pull it back out again.

It strikes me as odd the change did little to the stickiness. If you load the same brass down to, say 27.1 grains (the nearest bullet weight Sierra max) does it stop? If not, I'd be suspicious, as you are, the bolt has an issue or some debris got into it. Otherwise, I'd be looking for drag marks. Did you find any on the case head?
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Old December 8, 2019, 10:56 AM   #19
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Nick the Hogdon data site lists the 6BR Norma and Varget as 30.5 minimum 41,800 CUP and 32.5C 2,798 48,500 CUP. They list the 6BR Remington with Varget as 26.0 min 2,367 39,800 CUP and 29.0C 2,620 50,100 CUP.

http://www.hodgdonreloading.com/data/rifle

Strange since the Norma BR is just the Remington BR with a slightly longer neck from what I have read. I have had issues with the Hogdon site using too high a charge before with a .260 Rem load so I am not surprised that they are higher than Sierra. Some of the long range BR guys are going up a even higher so I was optimistic about the 30.0 charge and thought it was a good compromise

Next range session I am taking a extra bolt along, loading some new brass with the 29.2 load along with some that I have neck turned down to .010 thickness and doing some testing over the chrono. I will also load a few with 27.1 just to see how they behave

No drag marks on the brass. If I still have issues I will swap out the 6BR with the action I have on a .260. The action I am using now came on a 12 FV in .223 that looked like it had been used for prairie dogs, in other words a well worn barrel. I scoped it and the lands were well rounded and the grooves had a ton of copper. I shot a few rounds down it anyway just to see how the action behaved and had no extraction problems as I recall. Last resort will be swapping the 6BR onto another action.

Interesting problem, but I like challenges and I was planning on redoing the .260 with a short varmint taper 6BR putting it in a Shehane stock anyway and moving my .223 to the aluminum chassis. Fun times
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Old December 8, 2019, 11:49 AM   #20
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no but lets say I broke down and bought a AMP and annealed. What would that accomplish other than softening the neck and shoulder of the brass? The brass is sized properly already. I shoot and reload five other cartridges and none have problems with no annealing
It sounds like you are running this one pretty hot. You are likely sizing to the point that bolt close has light drag, if you are like me. As the brass hardens, it is my understanding that it doesn’t spring back much. Since factory actions usually stretch some, I think you are likely getting longer each firing and not able to bump it back much due to it getting harder.

The first thing I noticed when I got my Annealeez going was that I had by die set cranked down pretty hard to get any bump. After softening, this made the fl sizing setting way too short.

I would bet you are not to that point in the other rifles, or the case/die designs have slightly more leverage.

BTW, I’m not telling you to buy the AMP...my Annealeez works just fine.
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Old December 8, 2019, 12:35 PM   #21
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It sounds like you are running this one pretty hot. You are likely sizing to the point that bolt close has light drag, if you are like me. As the brass hardens, it is my understanding that it doesn’t spring back much. Since factory actions usually stretch some, I think you are likely getting longer each firing and not able to bump it back much due to it getting harder.
I check my sizing after firing, after sizing, and before loading. I was running .002 - .003 setback, bumped it down to .004 setback for after last resizing. I guess hot depends on which published load data to believe. I do tend to run close to the top of published data. Like I said in my last post I will go all the way down a couple of more gn's. At this point I am doubting it is rounds and am leaning more toward a receiver/ bolt issue. But am willing to shotgun my approach trying everything. I still have to find a slower powder that has had success in other peoples rifles, still researching that

Quote:
I would bet you are not to that point in the other rifles, or the case/die designs have slightly more leverage.
I have some Rem .260 that has over 15 firings, the 6BR brass last week was on it's 3rd

Quote:
BTW, I’m not telling you to buy the AMP...my Annealeez works just fine.
I have a Annealeeze sitting on my bench. Have not used it in a year but will give it a try on 5 rounds this afternoon just to see. If that cures the issue I will will go back to annealing after every firing and rethink my opinion on annealing, if it do I will go all the way and get a AMP. In my opinion it is the best design, but that is just my opinion and we all know the old saying about opinions and odor lol

thanks for the suggestions
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Old December 8, 2019, 12:58 PM   #22
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I’m looking at 3 data sources. The hottest I see is 29.4 gr....That is why I said kinda hot. Still, I can see how your rig may go over that safely, or it may not. Factory actions stretch more than the overbuilt custom benchrest actions....it just is what it is.


The problem you were trying to solve was higher than normal bolt lift, maybe due to high pressure. You identified you might be at max loads....seems like it.

I was just thinking the other side of heavy bolt lift....one side it all about the load, expansion, action stretch, etc, right? The other side is about springback, hardening of brass in loading process, maybe same die settings. IME, most guys get un fired bolt lift right on day one with new brass and kind of set/forget...me too...then brass hardens from firing and now bolt closing force is going up, but it is sneaky due to the caming action of the lugs. Now your max loads stretch the action the same amount, but the brass springs back less. It also sizes down less each sizing.

I have to admit, 3 firings is a super short time to see this issue in. Might help to try 20 new or anneal 20. You will have to reset your fl sizing die, just a bit as it will push the shoulder back more and be loose!

Do you have the newest Annealeez with the digital speed control? Wow! I love that thing! I know it is fire and that is kinda imprecise, but still cool. I just record, tip to case, inner flame length and speed. That seems repeatable to me for multiple setups..
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Old December 8, 2019, 01:41 PM   #23
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I linked the Hogdon load data a couple of posts back which shows a max of 32.5. With the loaded rounds having a shoulder setback of .003 - .004 I really don't see what annealing has to do with it but still I will give anything a try at this point. Just throwing mud against the wall seeing if something sticks. Seems to me as if it were a sizing problem it would show up when chambering, but I did read on another forum where going back another couple of thousanths of an inch cured the issue for them. I did have a tight neck problem which showed up when chambering on the Lapua brass but turning them down to .011 cured that. This one is a puzzler, I am leaning more and more toward it being a receiver/bolt issue
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Old December 8, 2019, 02:33 PM   #24
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Where are you finding the 6mm BR Norma on the Hodgdon website? I don’t see that.
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Old December 8, 2019, 03:18 PM   #25
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Good question, it won't show for me now either. That data in post 19 was cut and paste. I thought I may have confused it with dasher or other 6mm data but dasher is way higher and nothing else matches. I have no idea why it shows sometimes and then does not. I am starting to really mistrust the Hogdon load data now. I am dropping down to 27.0 - 28.0 and if the problem goes away I will never use the Hogdon load data site again. I just placed an order for a Berger load manual, something I should have done long ago
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