Bolt cam over

[klemm]

What causes the bolt to have that click at the top of the throw when ejecting a spent cartridge? Some times I have to give it a slight tap with the palm of my hand. Am I over pressure? I have a slight Plunger mark on the brass, but I have to look hard to find it.

 

[918v]

Yes, you're over pressure.

 

[klemm]

Why does it not happen on all the cartridges?

 

[918v]

Because the pressure is not uniform in all your cartridges. Because case volume varies within your lot if cartridges.

 

[ShtrRdy]

I've experience this too on one of my rifles. It's a 300 Win Mag. I'm thinking it's something other than strictly pressure. Some loads are at max and driving the bullet fast yet I don't experience this "click"

 

[Lefty7mmstw]

you are developing over pressure in the loads that are causing the "cam over" but not in the other loads. Some powder/bullet combinations will produce differing pressures in your rifle than the test rifle. You are working your rifle and brass unnecessarily ( and it is rather dangerous) with over pressure loads when you let the bolt hitch over and you have marks on your brass. Even one casing showing this is enough that you should reduce your load 5%.

 

[bigedp51]

Lifting the bolt straight up is called primary extraction and it is to break the case free of the chamber before pulling the bolt straight back or secondary extraction.

The main cause of the "click" is the base of the case has expanded to the point it does not spring back from the chamber walls and binds and drags.

It can be cause by high chamber pressure, soft brass or a bolt timing issue that is a frequent problem on Savage rifles.

If you measure just above the extractor groove of the case and it has expanded .001 over a new unfired case it is over pressure. If you have brass flow into the ejector it is over pressure. (this happens at aproximatly 70,000 psi) If you do not have the pressure signs above then chances are you need a small base die.

Since you have brass flow into the ejector, your loads are over pressure and the brass was stretched past its elastic limits.

Also remember that different manufactures of cartridge cases have varying hardness in the base of the case. I have a scrap brass bucket full of factory loaded once fired Federal .223 cases dated between 2005 to 2009 with over sized primer pockets.


Simple Trick for Monitoring Pressure of Your Rifle Reloads | Hodgdon Reloading


How Hard is Your Brass? 5.56 and .223 Rem Base Hardness Tests

TEST RESULTS
Using Rockwell hardness standards (.062″x100kg, Rockwell "B"), the brass measured as follows:
LC 2008 = 96
Lapua 223 Match = 86
Winchester 223 = 69
Remington "R-P" = 49

http://bulletin.accurateshooter.com...r-brass-5-56-and-223-rem-base-hardness-tests/

(as you can see above Lake City and Lapua have the hardest brass and would show pressure signs much later than Remington and Federal)

 

[Gene]

Lifting the bolt straight up is called primary extraction and it is to break the case free of the chamber before pulling the bolt straight back or secondary extraction.

The main cause of the "click" is the base of the case has expanded to the point it does not spring back from the chamber walls and binds and drags.



]

Just encountered same problem this past week in a rechambered 6mm Dasher, while trying to resize old brass to fit a new chamber. It drove me crazy until I found the problem was even with die set fully down tight against the shell holder, to cam over, I could not size fully to the bottom of the previously fired cases. I need to buy a small base die. You need to do the same.

 

[AZShooter]

I agree with Gene. Some of the thicker cases like WSM, RUM and RCM don't spring back as they should and hang up, even with loads that are not over pressure. At least that is what I have encountered.

The RCM gave me fits till I had Whidden make me the correct sized FL bushing die. I Tried Hornady's die first, then RCBS and even Redding before I got the Whidden. Now that click is gone.


If you cannot get a small base die you can make one. After several firings my 300 RUM just wouldn't work well with same click described by the OP. I used a carbide tool bit and cut off both ends of a RCBS FL die, leaving the center so I could lower it to properly size down the web area. Issue solved.
(you should see the beautiful orange sparks as the cutter goes through the case hardening! After that it cuts like regular steel)

 

[bigedp51]

We live in a plus and minus manufacturing world and no two dies and chambers are the same. Example I have a standard Lee full length .223 die that reduces the case diameter more than my RCBS small base die does. This same RCBS small base die only sizes the case .0005 smaller than my standard FL RCBS die "BUT" the small base die sizes further down the case.

On semi-auto rifles the sized case should be .003 to .005 smaller in diameter than the chamber. This insures that the brass will spring back from the chamber walls and extract.

And again the brass hardness in the base has a big effect so a different brand of brass like Lapua or Winchester might fix the issue.

 

[BountyHunter]

Just encountered same problem this past week in a rechambered 6mm Dasher, while trying to resize old brass to fit a new chamber. It drove me crazy until I found the problem was even with die set fully down tight against the shell holder, to cam over, I could not size fully to the bottom of the previously fired cases. I need to buy a small base die. You need to do the same.

Before you spend the money on a small base die, contact Harrells Precision. They make Dasher dies in .001 increments to exactly size what you need. They will you require you to send them the brass so they can measure and they will swap to a smaller die if it does not work. They are one of the best in the business.


Full Length Die

 

[BountyHunter]

A fix is to buy a redding body die and see if it works and much cheaper.

If it sizes, then send it to JLC Precision in Iowa and for $85 he will custom hone it to the exact dimensions you need so you do not size too much and convert it to a FL bushing die. Turn around is about 3 weeks normally.

Too many guys do not understand that the key is getting a die that matches your chamber. Not all dies will work for the same caliber in every gun. Whidden and Redding dies very closely match a standard chamber cut with a PTG reamer. PTG provides the resize reamers to Redding and they can match your reamer to an existing set of dies very easily.

I have always found that Whidden dies normally work also, so would imagine he uses PTG reamers. I always use PTG reamers so I know I can find a set of dies normally or have JLC hone one for me.