6BR is Siff in Rapid Fire; Resolved.

[matorre]

Re: 6BR is Siff in Rapid Fire

Why do you suspect the bolt ?

GME.... I have a Herrells die.

I just threw the statement about my ground base in, cause some people
like to bump the shoulders back .030
and call it good. ( mi-spec ?) :- )

308 die ? This is a 6BR . Is that part of the program now ?

M-

 

[John from MN]

Re: 6BR is Siff in Rapid Fire

Neither your primary extraction or your case dimensions are going to vary when going from slow fire to rapid fire.

The variable is the amount of force you are using while manipulating the bolt.

 

[jonbearman]

Re: 6BR is Siff in Rapid Fire

One thing popped up in this discussion. If you gunsmith did the fitting work,I would say to take it back or send it to someone like bob green,sid Goodling or whomever with the experience and maybe once they see it ,it will be apparent to them.

My gunsmith built me two guns with a new reamer.
One is single shot. It cycles fine and dandy with all loads.

Both Krieger Light Palma barrels

The other is a five shot used to shoot three position.

The Problem..............................
In the rapid fire stage 3 out of 5 cases feel like they have glue on them
and I must yank fiercely on the bolt handle. No signs of pressure.
Random cases, not the same ones, second time around.............

Case loads easily after its been fired.

Even though its new, soak with "Wipe Out" , and "Butches" reapetedly.

Reamed with a no turn neck. Both guns got .001 for head space, but after
trying every easy fix, we sent back in and gave it .0025 head space on the
gauge.
Chamber has been polished. Load has been back down to minimum and back again.
The single shot gun fires max loads fine.
The extractor cam is doing its job.
Bothe R-700 receivers tuned by the same machinist.
Load is new Lapua brass.
CCI450s
Varget. 27.5g to 31gr.
107SMK
Swapped out fireing pin springs, tried Harrells dies, Forster dies,
Redding dies,.....polish,polish,polish.

I'm looosing the will to shoot over this. Been trying to solve to two years.
I would throw more money at it but, where ?
Regards
Michael

 

[matorre]

Re: 6BR is Siff in Rapid Fire

The variable is the amount of force
I MUST use to move the bolt.

I wish to eliminate that VARIABLE because its
gotten yo be a pain in the brass.

M

 

[gme]

Re: 6BR is Siff in Rapid Fire

Michael,
Many custom reamers are made to minimum dimensional specs, because of this standard dimension dies will not always reduce the base of the case, it dosent matter who's die your using, I've seen it many times, small base dies do the same thing but usually overwork the brass, the method I referred to allows you to control how much base sizing, the best way to tell if that's your problem is to just measure your fired vs resize brass.

 

[LHSmith]

Re: 6BR is Siff in Rapid Fire

Did the smith use a Kiff bolt or sleeve the bolt? Does the bolt work freely when cycling without cartridges?

 

[matorre]

Re: 6BR is Siff in Rapid Fire

The reamer is a " generous" reamer.
Not the benchrest reamers of old, with tight dimensions.

No,the bolt is not sleeved.

75% of the time the gun cycles like an old Mauser.

Empty of cases, or when I am cycling dummies, (like I'm doing now),
.......the gun cycles like a new Mauser.

M

 

[dkhunt14]

Re: 6BR is Siff in Rapid Fire

Take your fire control out of the bolt and see if bolt shuts fairly easy on a fired case. Then size a case and see if the bolt falls shut. I adjust my dies till it falls shut. You might need two different die settings for your two guns. How much are you bumping them? Is the case getting smaller in front of the extractor groove after sizing? Read your PM. It doesn't matter what the reamer is; if the die doesn't size at the back end they get tight. Especially if they are close to max loads. Matt

 

[matorre]

Re: 6BR is Siff in Rapid Fire

The base gets .0005 smaller.
The bolt, stripped will fall closed on an empty case.
or, on an empty dummy, similar to what's happening now.

m-

 

[Alex Wheeler]

Re: 6BR is Siff in Rapid Fire

Are you having a hard time rotating the bolt also or just pulling it back? Sounds like the chamber may be polished too much in the middle, which will make the brass bigger in the middle than the base. Use a marker a color up one of the problem cases (not resized) and chamber it and see where the color rubs off.

 

[matorre]

Re: 6BR is Siff in Rapid Fire

Problem is initiating the rotation.

It did it from day 1, before I polished.

If it wasn't broken I sure was not going to fix it
by lathering it up with grit.

I polish things for a living.

m...

 

[Tim Singleton]

Re: 6BR is Siff in Rapid Fire

How many firings on this set of brass? If it's more than 4-5 stiff loads. You really need to at least try a small base die and size the base back down. They will feel fine with normal sizing on bolt close maybe a slight resistance.
But as you are finding its opening where the problem is.
The reason other guys have suggested a small base 308 is so you want mess up your head space by moving your shoulder back. It won't hurt anything to give it a go. Pretty sure it will cure your problems

I shoot a ppc after 4-5 hot loads the brass feels fine sized with a Harrel die, just right on bolt close. When im in the middle of trying to run 5 shots in a condition and the heavy bolt lift and extraction is upsetting my rig. That won't do, its time to run them thru a small base die. Good as new for another 4-5 loadings

Again it won't cost you anything but a little time if you don't have a small base 308 or 243 surely a buddy has one you can borrow

Pbike257 makes custom ring dies just for this problem. https://m.youtube.com/watch?v=-QW-5npXJKs

Tim

 

[Tim Singleton]

Re: 6BR is Siff in Rapid Fire

The base gets .0005 smaller.
The bolt, stripped will fall closed on an empty case.
or, on an empty dummy, similar to what's happening now.

m-

.0005 total is not enough it's just not. As other have said you need at least .001 maybe more then you will have at least .0005 all around clearance. Not .00025 clearance all around

 

[matorre]

Re: 6BR is Siff in Rapid Fire

I bought 500 rounds of new brass, for
This rifle.
300 rounds for the other rifle.

It started from the first rapid string.

All the brass hasn't gone through the rifle yet.
Some brass has been through twice.

That's all. Some 2 fired.
respectfully submitted....(mentioned in first post)

I -have- a small base die.
I have gone to extremes and put
.0015 on it.

I can't close the logic loop on new brass being oversized,
when its already rattling around in the chamber.

m

 

[matorre]

Re: 6BR is Siff in Rapid Fire

In the video he still had to push the bolt
closed. It didn't clank shut like it was generously clearanced.
Better, but still interference.
M

 

[Tim Singleton]

Re: 6BR is Siff in Rapid Fire

I think that's the first mention of new brass or that you sized it more than the .0005 you mentioned earlier

I will back out of the way

 

[Tim Singleton]

Re: 6BR is Siff in Rapid Fire

In the video he still had to push the bolt
closed. It didn't clank shut like it was generously clearanced.
Better, but still interference.
M

Shooting ppc we want a slight amount of interference in head space. We want the bolt to have slight resistance to the shoulder not tight at the web.

 

[matorre]

Re: 6BR is Siff in Rapid Fire

All good info that re-enforces good loading
practices, but I have yet to nail it.

m

 

[Erik Cortina]

Re: 6BR is Siff in Rapid Fire

All good info that re-enforces good loading
practices, but I have yet to nail it.

m

Swap firing pin assemblies and see if it makes a difference.

 

[matorre]

Re: 6BR is Siff in Rapid Fire

Ok.
m