Heavy bolt lift??

[wisconsinteacher]

Hey guys, I am stuck and need some help. The rifle is a 6BR on a Savage action. I used go/no-go gauges to set the headspace on the Criterion barrel. I am using virgin Lapua brass with 29gr of Varget and 107 Sierra bullets with CCI 450 primers. I have the bullets .012 into the lands.

Before I loaded the ammo, I ran the virgin brass through the rifle and the bolt closed with ease. When I fired the ammo, I got a heavy bolt lift but the primers are not flat, they look like new primers except for the primer strike in the middle. I took 5 fired pieces and tried to chamber them, but they do not chamber unless I took a hammer to the bolt.(I did not do that) I then sized them in a Redding die in a Lee press with a Lee shell holder. I started at 1/4 turn out all the way to touching the shell holder and the brass will still not chamber.

So my two questions are, why the heavy bolt lift and what do I need to do in order to get the fired brass sized so it fits in the chamber?

 

[wildgene]

...have you checked the case length???

 

[kraky]

This is where I beg people to spend $35 on a hornady head space checking kit. You'll know the dimensions of your brass before firing, after firing, after sizing.
For now my recommendation would be to use a rcbs press that can toggle over or shave about. 004 off the top of your current shell holder.

Looks like that is a Max charge according to hogdon...perhaps jambing the bullet is giving you a pressure spike. Some lots of varget are pretty warm.

 

[wisconsinteacher]

Case length is good and I have the Hornady head space kit. I was not able to move the shoulder as I turned the die down. I check every piece several times.

 

[kraky]

Hey Rice Lake...what are the dimensions to mid shoulder on other once fired brass that does chamber...this is where you need to get the shoulders on the offending brass.
You may have to sand/grind the top of a shellholder so you can continue the quest adjusting your die downward. I have several shellholders here I use for these situations.

 

[SJB358]

I am with Kraky here, you will need to bump the shoulders back some to get them to chamber. Something seems odd that you cannot rechamber a once fired piece of brass though? Until you get the shoulder to move a little, easy chambering isn't going to happen. Probably just needs a .001 or maybe .002 and it should chamber very nice.

 

[wisconsinteacher]

Well after some measuring and looking, I need to bump the shoulder at least .02" more to get them to chamber. 2.662" will not chamber but 2.660" will. (measured with Hornady head space gauge)

Now onto the heavy bolt lift issue. The brass shows no pressure signs and the primers are nice and round. I guess all I can do it drop back in charge weight.

 

[Dwh7271]

FWIW, you're entering multiple variables into the equation.
i.e. Both moving the shoulder back and changing powder charge.
My thought is if it works, which one fixed it?
Up to you. Just a thought.

 

[wisconsinteacher]

I get what you are saying Dwh. I still have some virgin brass so I could use those with reduced loads to see if that fixes the issue.

What I am not understanding is how some guys are shooting 30.5gr of Varget with the same bullet and not having any issues.

I did some measuring with the Hornady tool and came up with this.

There are some numbers that I cam up with.

Virgin brass-1.158"

Fired brass that will fit-1.160"

Fired brass that will not fit-1.163"

 

[Darkhorse]

Heavy bolt lift is just one sign of excessive pressure. One is all it takes to stop you in your tracks. You don't need to see flattened primers or anything else.
I measure my brass when working up loads with a .0001 micrometer. You can get a 10'th caliper but I use my calipers for other things. I use a mic. when it's critical. When case expansion begins to increase past a certain point that is my indicator that I'm approaching high pressure and I stop there. By the time you start seeing those visual pressure indicators your pressures already too high.
I measure the belt on a magnum case and the rim on a beltless. Some people measure the case head but if the case is tapered at all it's hard to get the same reading each time. Which negates measuring in the first place.
It doesn't sound like high pressure is your only problem but that sticky bolt would certainly give me pause.

 

[dubyam]

I'm not looking at load data, but if that's a max charge, and you're jammed into the lands, heavy bolt lift is all I need to know that load is over. What other guys get is irrelevant. What your rifle is telling you is to drop back to a start charge and work up. Seating into the lands can dramatically increase start pressure and thus overall pressure as the combustion chamber is smaller at any given point in the burn cycle.

What you should do is a work up in brass which fits, and find max charge for that COL for your rifle.

As for the brass you have which won't chamber, try turning the die in another quarter turn at a time and cramming the press into it (unless you're using a Co-ax or some such) and it should fix the issue. You might have to turn it in more than one quarter turn but go in quarters.

 

[kraky]

A quarter turn on a sizing die is an awful lot. I think a full turn is about .072"?
I put witness marks on my die threads and the lock ring w/a marker or dab of paint.
Start with the marks lined up on ea.
Move them about 1/4" and you'll have a change of about .004" which should be perfect for your needs.

 

[Oldtrader3]

Good idea Kraky! This 1/4 turn business scares the heck out of me!

 

[dubyam]

It's been my experience that brass as long as WT's will require more die movement. I believe it is due to the change in sizing depth penetrated due to the contact of the shellholder and die. You are no longer sizing just brass but now having to compress the steel of the die/shellholder (or deform it, if compress is not the right term) so the amount of die movement required is more than when the die is not touching the shellholder. Everybody does it their own way. I have yet to separate a casehead with my method so it's not scary to me.

 

[skidmark]

Heavy bolt lift is just one sign of excessive pressure. One is all it takes to stop you in your tracks. You don't need to see flattened primers or anything else.
I measure my brass when working up loads with a .0001 micrometer. You can get a 10'th caliper but I use my calipers for other things. I use a mic. when it's critical. When case expansion begins to increase past a certain point that is my indicator that I'm approaching high pressure and I stop there. By the time you start seeing those visual pressure indicators your pressures already too high.
I measure the belt on a magnum case and the rim on a beltless. Some people measure the case head but if the case is tapered at all it's hard to get the same reading each time. Which negates measuring in the first place.
It doesn't sound like high pressure is your only problem but that sticky bolt would certainly give me pause.

This is also they way I do it. If I want to work to a max load I use case head measurements
to tell me when to stop. And use a mic not calipers unless you got good ones. Heavy lift means you got problems that are dangerous. It aint worth it. Start over. Measure for COAL with your chosen bullet and try it again. The satisifaction of knowing your load and rifle will make you smile. :wink:

 

[DrMike]

Assume that when you have heavy bolt lift, you are tickling the dragon's tail.

 

[kraky]

Dubyam....I see what you mean but would still rather see him making small adjudtments.
The manufacturers of dies and shellholders make them so that beginners can't get themselves in too much trouble pushing shoulders back too far.
The problem like we have here is that a few thousands change on dimensions here and there get us to the point we need just a smidge more travel to make things work. .003" is about all he needs for now...just the thickness of a piece of paper.
WT is probably gonna need the ability to dial his die down just a little more as the brass work hardens too.
He's gonna like the guidance that hornady tool gives him as he proceeds!

 

[dubyam]

To be sure, I'm a 100% advocate of the Hornady tool. I've even worked hard to find which bushing works with my Weatherbys, which is no small task with the double radius shoulder. I'm okay with the concept of turning in slowly, but in my experience, if you have .003" to move, you're going to turn in more than one quarter turn. Heck, start with 1/16 turns if you can visualize it. Safety first, for sure.