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Twud
Guest
How is the datum line established? Just half way down the shoulder?
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Dennis Sorensen
Guest
I believe it may vary according to the particular case...
for instance on a 30-06 it is located where a 3/8" diameter ring would contact the shoulder....
that would not work on a lot of other cases...
Unless you are manufacturing specific items why would you ever need that figure... I have been gunsmithing for 40 years and have never needed to know... ?
for instance on a 30-06 it is located where a 3/8" diameter ring would contact the shoulder....
that would not work on a lot of other cases...
Unless you are manufacturing specific items why would you ever need that figure... I have been gunsmithing for 40 years and have never needed to know... ?
J
Jay Idaho
Guest
I think that it is necessary if you are making a headspace gage.
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Twud
Guest
Datum
Mostly curiosity, but I have a new 6BR with a sticky bolt even with new unfired Lapua brass. With fired brass it's much worse. I ordered a head space guage as I think the cases might need to have the shoulders set back. Wouldn't a head space guage measure off the datum line?
It's a BAT action.
Another interesting thing, I use TM grease on the lugs. If I fire one round and pull the bolt all the grease has been wiped away, I assume by the the other lug. I've never seen this in any factory rifle I've ever owned.
Your help is appreciated.
Mostly curiosity, but I have a new 6BR with a sticky bolt even with new unfired Lapua brass. With fired brass it's much worse. I ordered a head space guage as I think the cases might need to have the shoulders set back. Wouldn't a head space guage measure off the datum line?
It's a BAT action.
Another interesting thing, I use TM grease on the lugs. If I fire one round and pull the bolt all the grease has been wiped away, I assume by the the other lug. I've never seen this in any factory rifle I've ever owned.
Your help is appreciated.
D
Dennis Sorensen
Guest
A sticky bolt on unfired brass... sounds like it is not chambered for Lapua brass which is slightly larger at the rear of the case...
If the headspace is a little tight, the bolt will be hard to close but it will not be sticky on extraction... it is when the rear of the case is tight in the chamber, you will get the sticky bolt opening as it is hard to extract that thick jammed in brass...
If the headspace is a little tight, the bolt will be hard to close but it will not be sticky on extraction... it is when the rear of the case is tight in the chamber, you will get the sticky bolt opening as it is hard to extract that thick jammed in brass...
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Larry Elliott
Guest
The only locking lug that's in contact with its receiver abutment is that one. The other lug couldn't wipe the grease away. If the lugs are making nearly 100% contact with the receiver the grease will mostly be wiped away when the bolt is opened after firing a round. On a factory rifle the locking lug contact is likely 60% or so at best so there will be more great left on the lugs.
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Twud
Guest
What is the solution to this problem? Tight base die? It's hard to open once fired and firm upon closing.
Mark
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Dennis Sorensen
Guest
You stated, ''I have a new 6BR with a sticky bolt even with new unfired Lapua brass.''
Can you inquire with the maker about the chambering?
Can you inquire with the maker about the chambering?
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Twud
Guest
Reamer
He used a reamer sized for the Lapua brass. He built a gun for himself right after mine using the same reamer. He shoots 34.5 gr. of Varget with his 68 gr. bullets without a hitch. I'm shoting the same bullet with 31 gr. of Varget and I'm getting a sticky bolt.
He used a reamer sized for the Lapua brass. He built a gun for himself right after mine using the same reamer. He shoots 34.5 gr. of Varget with his 68 gr. bullets without a hitch. I'm shoting the same bullet with 31 gr. of Varget and I'm getting a sticky bolt.
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Dennis Sorensen
Guest
If a piece of new unfired brass is sticking in the rear of the chamber, the rear of the chamber would appear to be too tight.
Your builder should be able to fix this.
Your builder should be able to fix this.
jackie schmidt
New member
Tough Call
If I had the Rifle, I could figure out what is wrong in a few minutes.
I suspect that Dennis has confirmed the real culprit.
If a chamber is cut correctly, with the correct reamer, and a case is tight going in, then you do indeed have a chamber that is too tight on the measurement you first inquired about. I will not call it headspace because I don't want to get into a discussion as to "what headspace really is??".
If the chamber is too tight at the web area, (wrong reamer for brass), then you will feel a tightness as you cam down the bolt, and it will probably come up ok upon extraction untill the top of the stroke, where you will feel a distinct "click", caused by the web of the case being too tight. You might also notice a distinct ring around the big end of the case.
You Gunsmith says that his reamer is indeed designed for Lapua Brass. Confirm this again.
It would be great if you could take the barrel off, and physically try a new case in the chamber.
When you say the lug gets the grease wiped away by the other lugg, I assume you are talking about the locking lugg, (the thing on the bolt), and the abutment, (the thing in the action). If you are getting that degree of contact on both luggs and abutments, feel fortunate........jackie
If I had the Rifle, I could figure out what is wrong in a few minutes.
I suspect that Dennis has confirmed the real culprit.
If a chamber is cut correctly, with the correct reamer, and a case is tight going in, then you do indeed have a chamber that is too tight on the measurement you first inquired about. I will not call it headspace because I don't want to get into a discussion as to "what headspace really is??".
If the chamber is too tight at the web area, (wrong reamer for brass), then you will feel a tightness as you cam down the bolt, and it will probably come up ok upon extraction untill the top of the stroke, where you will feel a distinct "click", caused by the web of the case being too tight. You might also notice a distinct ring around the big end of the case.
You Gunsmith says that his reamer is indeed designed for Lapua Brass. Confirm this again.
It would be great if you could take the barrel off, and physically try a new case in the chamber.
When you say the lug gets the grease wiped away by the other lugg, I assume you are talking about the locking lugg, (the thing on the bolt), and the abutment, (the thing in the action). If you are getting that degree of contact on both luggs and abutments, feel fortunate........jackie
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I think this opinion is correct...
Had the same symptom happen to me when I tried Lapua 6.5X47 brass in my 30HBR hunter rifle. The rifle was chambered with a reamer that was made prior to 1997 and the cases were to tight (about two thousands to big at the web). Even a small base die did not work. I didn't really want to re chamber because this Shilen barrel shoots so good; don't want to tempt fate. Soooo...back to my old standby, 300 Savage Remington and Winchester cases.
Virg
Had the same symptom happen to me when I tried Lapua 6.5X47 brass in my 30HBR hunter rifle. The rifle was chambered with a reamer that was made prior to 1997 and the cases were to tight (about two thousands to big at the web). Even a small base die did not work. I didn't really want to re chamber because this Shilen barrel shoots so good; don't want to tempt fate. Soooo...back to my old standby, 300 Savage Remington and Winchester cases.
Virg
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Larry Elliott
Guest
I've got a 6 BR live varmint rifle that's tight on fired cases with just about any load, and got a Redding small base die that seems to help some. I'm going to have someone look at it when I get to it. Too much stuff to fix all to once. 
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henrya
Guest
Chamber cutting technique? Brass or bore dimension differences?
Perhaps your chamber is cut close to size and the next one he did is a bit larger at the back?
In any event, your brand new brass should go in the chamber and the bolt should close without any effort, or maybe just the slightest feeling of something there. If its tight on new brass ask the gunsmith to correct it. A little polishing at the back might be all it needs to work with your brass.
And it might be you have a barrel that won't take as much powder as his barrel. Even good barrels vary in this regard, just as some are faster or slower than others of the same make.
Perhaps your chamber is cut close to size and the next one he did is a bit larger at the back?
In any event, your brand new brass should go in the chamber and the bolt should close without any effort, or maybe just the slightest feeling of something there. If its tight on new brass ask the gunsmith to correct it. A little polishing at the back might be all it needs to work with your brass.
And it might be you have a barrel that won't take as much powder as his barrel. Even good barrels vary in this regard, just as some are faster or slower than others of the same make.
C
chino69
Guest
Sticky bolt
Twud,
I use 34.5 grn. of Varget with 65 grn. V-Maxes as well as Berger, Hammonds, Fowler 68 grainers with no problem. This is out of a Hart 6mm BR 1:14" twist that was reamed with a different reamer.
If I'm not mistaken, the reamer used for your bore was a .265nd Henricksen? The same gunsmith, assuming it's who we've been trading e-mails back and forth about, chambered a Kreiger 1:7.5" twist using the same reamer your chamber was reamed with. I've had no problems with sticky bolt lift with my Kreiger and have been shooting the heavier 6mm bullets.
Just one item to consider that has worked for me in the past that may apply to your situation. I have found, in the past, that Redding body dies were not sufficient to squeeze the base when re-sizing, particularly with tight chambers. This was with significant over-cam leverage with the press. I took a skim cut of approx. .005 from the base of the die with a lathe. The die was then sent to Jim Carstensen (JLC Precision) to have it modified to accept a neck sizing bushing. The die was sent with five or six pieces of brass that had been fired in that chamber. The die that returned was a glove like fit for my chamber. Using die shims, I was able to set that die up to bump the shoulder exactly .001 each time and re-size the neck.
If I'm not mistaken, those reamers are ground to a nat's ass degree of accuracy and Redding body dies will need approx. .005 cut from the base, along with die shims, to properly size the brass. I had the same problem with a .22-250 A.I. chamber that I remedied with the above method.
Hope this helps.
Lou Baccino
Chino69
Twud,
I use 34.5 grn. of Varget with 65 grn. V-Maxes as well as Berger, Hammonds, Fowler 68 grainers with no problem. This is out of a Hart 6mm BR 1:14" twist that was reamed with a different reamer.
If I'm not mistaken, the reamer used for your bore was a .265nd Henricksen? The same gunsmith, assuming it's who we've been trading e-mails back and forth about, chambered a Kreiger 1:7.5" twist using the same reamer your chamber was reamed with. I've had no problems with sticky bolt lift with my Kreiger and have been shooting the heavier 6mm bullets.
Just one item to consider that has worked for me in the past that may apply to your situation. I have found, in the past, that Redding body dies were not sufficient to squeeze the base when re-sizing, particularly with tight chambers. This was with significant over-cam leverage with the press. I took a skim cut of approx. .005 from the base of the die with a lathe. The die was then sent to Jim Carstensen (JLC Precision) to have it modified to accept a neck sizing bushing. The die was sent with five or six pieces of brass that had been fired in that chamber. The die that returned was a glove like fit for my chamber. Using die shims, I was able to set that die up to bump the shoulder exactly .001 each time and re-size the neck.
If I'm not mistaken, those reamers are ground to a nat's ass degree of accuracy and Redding body dies will need approx. .005 cut from the base, along with die shims, to properly size the brass. I had the same problem with a .22-250 A.I. chamber that I remedied with the above method.
Hope this helps.
Lou Baccino
Chino69
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Twud
Guest
Body Die
I'm kinda' confused. Keeping spring back in consideration, don't we want a die that is smaller in the base than the fired rounds? Our builder friend dosen't want to seem to take this seriously. Should I say screw it and just shoot the gun this way?
I'm still waiting for my head space guage to show up as I want to rule out any head space issues.
I'm kinda' confused. Keeping spring back in consideration, don't we want a die that is smaller in the base than the fired rounds? Our builder friend dosen't want to seem to take this seriously. Should I say screw it and just shoot the gun this way?
I'm still waiting for my head space guage to show up as I want to rule out any head space issues.
C
chino69
Guest
Twud,
Everything you just said is true. What I perceived to be the problem is the case was not allowed to go far enough up into the die when re-sizing. When I first ran into the problem with my .22-250 A.I., I was resizing with a Redding body die cammed into the shell holder. The re-sized brass was still stiff to chamber but just a little better with a harder cam-over. That told me the case needed to go into the die a little more to properly squeeze the base and bump the shoulder. I had the firing pin removed from the bolt when I was working this problem out and was checking my headspace change constantly after every sizing . I took a skim cut of .005 from the base and used .004 of die shims, repeating the process and checking with headspace gauges. With around .003 of die shims under the die, my die bumped the shoulder back .001, squeezed the base and the brass chambered beautifully. I've done the same procedure with all of my Redding body dies, for chambers cut by our buddy, and have never had a problem since. See if that makes sense to you.
What I learned from the above and suspect, is that our buddy's reamers are tighter than others, as he orders to his specs. I believe that is why he favors using Henricksen reamers. As I explained, he takes a little patience to get to know but once you figure him out, he's a very cagey and experienced man who has adapted his own proprietary techniques that aren't readily shared. When I ran this scenario by him several years ago; explaining my hunches, he just smiled. Since that day, we've been very good friends.
Lou Baccino
Chino69
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Dennis Sorensen
Guest
You are correct in wanting to use a steel go gauge to determine if the headspace is set to a correct standard.
While you are waiting for it to show up, you can take one new fully sized brass that is sticky in your rifle, and file and polish the diameter of the case without changing the shoulder. Concentrate mostly towards the rear of the case. If it is the diameter of the case that needs sizing down more - this procedure is having the same effect and you should find this case stops being sticky. If the shoulder needs pushing back you will find this altered case hard to close the bolt on, but not sticky to remove.
There is a possibility your press is springing a bit and the case is not being sized because of that... but the headspace check with a steel go gauge will help determine the next step. It may be as simple as grinding a couple of thou off the bottom of your die.
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Twud
Guest
Got it. I'm not going to do anything until this shoulder guage shows up.
Mark