Problem with light strikes

[chromatica]

Measuring from bolt face to the chamber’s shoulder datum any length at or between a minimum of 1.630” to 1.640” maximum is within SAAMI’s chamber specs.


SAAMI’s cartridge length specs measuring from case head to shoulder datum is 1.634” -.007”, or a minimum of 1.627” up to a 1.634” maximum.


If the chamber was cut to the SAAMI maximum length of 1.640” and a cartridge sized to the SAAMI minimum length of 1.627” gets chambered, then the resulting clearance between bolt face to case head is .013” (headspace), and all’s still within SAAMI’s specs, der …


Need to first find what’s your chamber’s length and then size cases to a thousandth or so shorter.

Freak,

I settled on the lower side of this range because I wanted to be able to use factory ammo if necessary. When I first started this build five years ago, I measured some Remington factory ammo and found the shoulder height to be closer to the 1.630 than the 1.640 end of the range.

 

[chromatica]

You shoukd have a Hornady headspace tool and a set of calipers. Then you can measure a fired case and a sized case to see how much you are bumping them. Go to You Tube and look up video of Hornady headspace tool. Matt

Hi Matt,

Hornady doesn't have a corner on the case gauge market. I have an RCBS case gauge with fewer moving parts. I "calibrated" it using a known reference case. My no-Go gauge is marked 1.634. When I place it in my RCBS case gauge, the micrometer drum reads + .001. So the reference case height for my case gauge must be 1.633. I sent a query off to RCBS to verify this, but it seems likely.

 

[chromatica]

I have an RCBS case gauge. You put the round inside and screw down the top until it reaches the shoulder. There is a micrometer drum readout. My fired cases are coming out of the chamber at SAAMI - .003 or -.0035. I bump them in my sizer die 1 thou so they measure SAAMI -.004.

My fired cases measure 1.633 - .003 = 1.630 reflecting the length of my chamber. My sized cases measure 1.633 - .004 = 1.629. My Forster Go gauge marked 1.630 measures 1.633 - .004 = 1.629. When I re-headspaced after replacing the Savage bolt head with a PTG bolt head, I screwed the barrel into the receiver (before installing the ejector) until it met the Go gauge. Then I adjusted the barrel, and the barrel nut until the bolt just closed smoothly over the Go gauge, but would not close over the No-Go gauge. These numbers are all beginning to make sense.

 

[chromatica]

chromatica,

Most likely cause is the shoulder was set back a tad to far and the firing pin could not make a firm hit on the primer. Only a few thousandths forward movement of the case can make a difference - especially if you are using primers with harder than usual cups like CCI BR primers.

I've had this happen before then I got a little to over-zealous for silky smooth bolt closure and lift. Check the fired case shoulder datum to base dimension with the Hornady tool if you have one and try not to move the shoulder back any more than 0.003" from this point - or, if the case will fit the chamber after firing - neck size only and drive on.

Ken

Hi Ken,

I am using CCI #200 primers. Are those known to be “hard”?

 

[dkhunt14]

Hi Matt,

Hornady doesn't have a corner on the case gauge market. I have an RCBS case gauge with fewer moving parts. I "calibrated" it using a known reference case. My no-Go gauge is marked 1.634. When I place it in my RCBS case gauge, the micrometer drum reads + .001. So the reference case height for my case gauge must be 1.633. I sent a query off to RCBS to verify this, but it seems likely.

Just because your no go gauge says 1.634, a fired case could be a lot bigger and you are bumping them to much. Read post 31. You need the fired case length. Matt

 

[Webster]

My fired cases measure 1.633 - .003 = 1.630 reflecting the length of my chamber. My sized cases measure 1.633 - .004 = 1.629. My Forster Go gauge marked 1.630 measures 1.633 - .004 = 1.629. When I re-headspaced after replacing the Savage bolt head with a PTG bolt head, I screwed the barrel into the receiver (before installing the ejector) until it met the Go gauge. Then I adjusted the barrel, and the barrel nut until the bolt just closed smoothly over the Go gauge, but would not close over the No-Go gauge. These numbers are all beginning to make sense.

Don't all factory loaded rounds have excess headspace so they will chamber in any rifle? They always go off.

 

[kvd]

Hi Ken,

I am using CCI #200 primers. Are those known to be “hard”?

My experience with failure-to-fire was with CCI BR-4 primers. Not sure if the same would apply to CCI 200's but they may use the same cups.

Ken

 

[Ringostar]

My fired cases measure 1.633 - .003 = 1.630 reflecting the length of my chamber. My sized cases measure 1.633 - .004 = 1.629. My Forster Go gauge marked 1.630 measures 1.633 - .004 = 1.629. When I re-headspaced after replacing the Savage bolt head with a PTG bolt head, I screwed the barrel into the receiver (before installing the ejector) until it met the Go gauge. Then I adjusted the barrel, and the barrel nut until the bolt just closed smoothly over the Go gauge, but would not close over the No-Go gauge. These numbers are all beginning to make sense.

I'm not sure what your saying here with all the -.004 stuff. If you set your barrel to just close on your go gauge, then that is your true chamber size. Not all measuring tools necessarily measure equally. Just put your go gauge into your case length gauge. Take the reading for what it is. Then size your fired cases 1-2 thousandths less than that.

 

[Richard Coody]

My experience with failure-to-fire was with CCI BR-4 primers. Not sure if the same would apply to CCI 200's but they may use the same cups.

Ken

200's have a thinner cup

i have used.BR4's exclusively for.years. never had a primer.failure but there always is a first time.

don't know why all this discussion about headspace. to do it.right is so simple. measure your fired brass with the hornady headspace gauge. with a bolt.gun set the shoulder.back 1 to two thousandths. with an AR 3 to 5 thousandths. if you don't know how to set up your sizing die to do this then learn how.

one caveat to this. first.firing may not fully fireform your brass. you need to check that fired brass every firing until it is consistent.

 

[JRS]

200's have a thinner cup

i have used.BR4's exclusively for.years. never had a primer.failure but there always is a first time.

don't know why all this discussion about headspace. to do it.right is so simple. measure your fired brass with the hornady headspace gauge. with a bolt.gun set the shoulder.back 1 to two thousandths. with an AR 3 to 5 thousandths. if you don't know how to set up your sizing die to do this then learn how.

one caveat to this. first.firing may not fully fireform your brass. you need to check that fired brass every firing until it is consistent.

The only difference between the "BR" primers and the standard primer is the designation and additional price for the "BR" primer.

 

[dkhunt14]

The only difference between the "BR" primers and the standard primer is the designation and additional price for the "BR" primer.

This is not true. The BR4 has a thicker tougher cup to take higher pressure without blanking. I believe they are .005 thicker. Matt

 

[hogpatrol]

 

[hogpatrol]

Don't all factory loaded rounds have excess headspace so they will chamber in any rifle? They always go off.

I doubt it. The lawyers would have a field day with that condition. To answer your questioin about chambering in any rifle, not in my experience. I have friends that bought import ammo that would not chamber in Remingtons or Savages.

 

[JRS]

This is not true. The BR4 has a thicker tougher cup to take higher pressure without blanking. I believe they are .005 thicker. Matt

The same thing was said when BR shooters switched to the 205 when the 205M was unavailable. Once reality set in, they found no difference whatsoever between the two.

A person with a different idea or or view is a crank until the view or idea succeeds. German Salazar and the late John Adams performed a substantial amount of testing with the primers. Different name with a higher price tag.

 

[dkhunt14]

The same thing was said when BR shooters switched to the 205 when the 205M was unavailable. Once reality set in, they found no difference whatsoever between the two.

A person with a different idea or or view is a crank until the view or idea succeeds. German Salazar and the late John Adams performed a substantial amount of testing with the primers. Different name with a higher price tag.

In Federal the only different between 205 and 205M is the Match goes through a visual inspection and are made by the higher paid, more experienced workers. They believe this makes a more consistent primer.

The BR and regular primers are different. The cups are not the same. They made them thicker to not blank as quick with the higher pressures shot with the PPC and 6BR cases. Matt

 

[JRS]

"The CCI BR2 is the ballistic equivalent of the CCI 200 and both are interchangeable. Use the same data as CCI Standard (non-magnum) primers".

I suppose the difference in price is due to the extra step when stamping the B on the primer Do you really believe (the rumor) someone is visually inspecting and individually packaging hundreds of thousands of primers everyday Other than the application of the compound, it's an automated process.

 

[dmoran]

As Matt stated, the real reality is there's obvious difference between BR4 and a 400 (in cup hardness). And to the 450's in thickness/height. But to some, if they read it on the internet, it has to be true...

 

[JRS]

Reality is there's obvious difference between BR4 and a 400 in cup hardness. And in thickness/height verses the 450. But to some, if they read it on the internet, it has to be true.....

"(non-magnum) primers" The quote is from CCI. Hardness is dependent on thickness with material greater than 0.250.

 

[dkhunt14]

"(non-magnum) primers" The quote is from CCI. Hardness is dependent on thickness with material greater than 0.250.

I would like to see that quote from CCI. The primers can vary form cup thickness, diameter and even total thickness. I am sure CCI isnt going to tell what hardness their primers are. I bet it is an industry secret. According to tests, different companies and different sizes or styles, vary in hardness and thickness of sheet material ordered. Matt

 

[JRS]

I would like to see that quote from CCI. The primers can vary form cup thickness, diameter and even total thickness. I am sure CCI isnt going to tell what hardness their primers are. I bet it is an industry secret. According to tests, different companies and different sizes or styles, vary in hardness and thickness of sheet material ordered. Matt

As with all equipment, as tooling wears, product dimensions change.