6BR is Siff in Rapid Fire; Resolved.

[Albany Mountain]

Re: 6BR is Siff in Rapid Fire

While you are swapping pins, carefully inspect the camming surface on the bolt. I have had issues with the bearing surface of the pin or striker, wearing a trough in the camming area leaving a slight burr the whole length. It is fricken amazing how much binding is created in this situation.

I have had about three bolts show this and had to polish out this area to fix. Most of these bolts did not have factory pins and springs, but speedlock advertized setups and heavier springs.

 

[Alex Wheeler]

Re: 6BR is Siff in Rapid Fire

If you are having an issue on initial rotation of the bolt this usually indicates a pressure issue, brass flow. It could also be caused by anything that will allow the brass to flow like oil in the chamber or a mirror polished chamber. If it is not pressure, I would suspect a bolt face that is not square.

 

[matorre]

Re: 6BR is Siff in Rapid Fire

Good idea, about the cam surface, but that's like a mirror , and doing its job.
Not really in the picture till the bolt handle is well under way.

The chamber got a mild polish lasting several seconds to check for any
irregularities, and that only after the symptom appeared.
.....and after backing the load down to minimum.
m.....

 

[Rtheurer]

Re: 6BR is Siff in Rapid Fire

Michael
Did you get a chance to run a couple sticky pieces of brass through a 308 or 243 FL Die to get that base of the case just above the Extractor groove pushed in a tad yet?

Had that issue just not so long ago and ran my Rapid fire brass through my Dillon to get that area reduced in size so that I had some flawless feeding again. I used a 308 Body die witch for what ever reason has a smaller clearance right there. Takes several firings before I have to get it back to the point that it needs to be done again.

Good luck. I see 10X cleans in your rapid fire future.
RussT

 

[dkhunt14]

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

What for video are you talking about?

 

[matorre]

Re: 6BR is Siff in Rapid Fire

15 posts back, include this one, Mr Tim Singleton
has a link in his post about a really good product called a ring die.

I my buy one just to found out my massive
6BR reloading accessories that I've accumulated
trying to squeeze this cartridge every which way
but function.

sigh..........maybe I should stuck with 308
M

 

[matorre]

Re: 6BR is Siff in Rapid Fire

What cartridge where you fixing with the
308 die ?

What is the diameter of your 308 base ?

If your were sizing 6BR, what diameter were you sizing the base down to ?

Were you experiencing the SAME symptom?

Thanks,
M-

 

[CatShooter]

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

I didn't think it was better - it looked like the same effort to me. Either he has to go down another 2 thou, or he needs to hit the shoulder a wee bit harder...

 

[Tim Singleton]

Re: 6BR is Siff in Rapid Fire

Michael you have a pm

 

[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

I didn't think it was better - it looked like the same effort to me. Either he has to go down another 2 thou, or he needs to hit the shoulder a wee bit harder...

Paul could have given a little more detail in his video. The whole purpose of the ring die is to leave the shoulder alone. You establish the head space for your self .001 or .002 what ever you want or like, me I do it by feel. Some of us like to feel a little resistance on the shoulder. We do not want resistance from the base of the case. That really shows up when it is sized just enough by the normal die to chamber but when fired that's when the problem shows up. Paul did adjust his shoulder so the slight resistance seen in the video is bolt close on shoulder. He could feel it was lees in the base.
Take a dummy round that has multiple firings set the shoulder back .015 so I know I can't feel it. Then chamber the fired piece, size with small base die and make adjustments as needed to get the base where you want it with an easy bolt fall. Look for .0015 smaller at the .200 line at base than the fired case was
Now your set up with both dies and ready to process the rest
Then run all brass through the small base die and the normal FL bump die to set your shoulder
Make up a few to test fire see how they extract. If still a little stiff grind the shell holder and run the base on up in the die
Good to go, no more extraction problems for 4-5 firings then repeat the above

Tim

 

[matorre]

Re: 6BR is Siff in Rapid Fire

Thanks for the idea Tim.

When your experiencing the symptom
is it bad " right away" meaning as soon as your
starting to move the bolt ?

Why would this do this with brand new brass ?
It fits the chamber with a stripped bolt.
Zero resistance.

It is made to correct dimensions.....have been
on the phone with Lapua to verify.

Are we are talking about identical symptoms ?

m

 

[Tim Singleton]

Re: 6BR is Siff in Rapid Fire

Thanks for the idea Tim.

When your experiencing the symptom
is it bad " right away" meaning as soon as your
starting to move the bolt ?

Why would this do this with brand new brass ?
It fits the chamber with a stripped bolt.
Zero resistance.

It is made to correct dimensions.....have been
on the phone with Lapua to verify.

Its important we are talking about identicle symptoms.

m

Sounds like Identical issues. Especially if you run a stiff load.
My Harrel Precision FL bump die does not size the base of my ppc cases enough. Most of the time it's 3-4 firings before it shows up. Different lots of brass or hotter loads it will show quicker.
There is adequate clearance for the round to chamber. Once fired the bolt is very stiff almost to the point of being stuck if you continue on firing and under sizing the same brass at the base it will get stuck on me and I have to take a dowel rod to get it out.
A small base ppc die fixed my problems

Tim

 

[BradY]

Re: 6BR is Siff in Rapid Fire

Might sound dumb but I had a dasher that was a bugger with a sticky bolt. Opening and closing and pulling the bolt back. I took out the front action screw and ground it down a bit shorter. Presto, no issue. Seems to be lots of technical recommendations but I for one am constantly guilty of overthinking things. Thought it might be a good suggestion.

 

[matorre]

Re: 6BR is Siff in Rapid Fire

Good idea but, thats one of the things checked early.

The thing that's important to remember is
once the gun is on the cam, the case pops out
with a two finger lift, and a flick to eject.

(and no click at the top, you at the back there)

Its the FIRST 1/8 of rotation that's the b-i - itch.

M

 

[Alex Wheeler]

Re: 6BR is Siff in Rapid Fire

Use a sharpie on the bolt face to see if you are getting even contact. Better yet use a depth mic and measure from the action face. Do this with the firing pin and ejector removed. Also check lug contact.

 

[gme]

Re: 6BR is Siff in Rapid Fire

Good idea but, thats one of the things checked early.

The thing that's important to remember is
once the gun is on the cam, the case pops out
with a two finger lift, and a flick to eject.

(and no click at the top, you at the back there)

Its the FIRST 1/8 of rotation that's the b-i - itch.

M

Have you checked that the bolt handle is not binding against the back of the notch in the action?

 

[matorre]

Re: 6BR is Siff in Rapid Fire

Yeah the bolt is silky smooth
normaly.
When I cycle my dummies its very slick.

Z-fast,
The blueing of the brass just showed me random contact,
nothing with any discernable pattern. Ditto for firing it
with coloured brass.
M

 

[matorre]

Re: 6BR is Siff in Rapid Fire

Gary
When you built that BRX, was the symptom like what I described here?

ie. Stiff bolt movement initially with fairly normal extraction?

Would it happen with new brass ?

M

 

[matorre]

Re: 6BR is Siff in Rapid Fire

I couldn't help but notice is that,
people who were prescribing small base dies
for my symptoms also prescribe small base dies
for a clicking at the top of the stroke.
Let me repeat that my problem is not clicking at the top
of the stroke of my problem............ is getting the bolt handle
to start to move initially.
- with new brass.-

M

 

[Erik Cortina]

Re: 6BR is Siff in Rapid Fire

Have you tried swapping firing pin mechanisms between both rifles?