[JBelk]

when it comes to the assembly of the trigger mechanism of the Model 77 Ruger's

Remember, it was the assembly of the X Mark Pro Remington triggers that caused a recall due to improperly applied LocTite. The trigger was brand new and supposed to cure the problems with the Walker but it was defeated by assembly mistakes and badly made Mexican parts.
ECONOMY is number one in mass market firearms. You have to pay for quality.

 

[MikeG]

Let's get back to the AR in question.

There is a spec on EVERYTHING. Min/max on: firing pin diameter, firing pin hole diameter, firing pin protrusion, as well as headspace. Location of the gas port and diameter of the port are important. In addition, the firing pin nose is supposed to have a radius (rounded) and not be pitted, scarred, or chipped.

From my understanding of the AR platform, the key to headspace is the barrel extension (because that's where the bolt locks up). Probably some specialized tools - certainly for assembly. Pin gages to measure hole diameters, and a decent caliper to check outside dimensions (check the caliper against the pin gages). Loupe or magnifying glass to inspect firing pin nose.

Last, double-check the bore diameter and make sure it's actually what it is supposed to be.

Get some numbers and this will start to make sense. No numbers = guessing, and guessing is what we are doing. Slapping a new set of heads on an engine with bearings that knock doesn't solve much of anything.......

Good luck

 

[Darkker]

If that was true we should never see a defective firearm.

Because it is true, is exactly why we see defective guns....


Headspace is measured the same as regular rifles Mike, but you'll need more than "Armorer's" tools to change the barrel extension once it's been pinned. A lot of times a simple bolt swap can correct headspace. Given the firing pin/bolt face is supposedly worn, and I'm betting a box of donuts so are the rings; probably need to change parts and remeasure headspace soon anyway.

Cheers

 

[Usmcpmi]

Hey, FWIW, I've noticed a major decrease in the quality of AR parts over the last several years.
I bought a new bcg, only to find that the carrier was so far out of spec you could hardly operate the charging handle. Poor bolts and other carrier parts are definitely out there.

Big G

 

[Msalm]

So the AR10 platform has no ‘standard’ spec unfortunately. Barrel extensions/bolts typically are close but the issue I see here is a cheap bolt with larger fp hole. The blanked primer is an indicator. I would look at replacing with a high pressure bolt, JP used to offer them. Smaller fp hole and fp tip. I ran into this when building a 6.5x47 Lapua that uses sr primers. This was on a FN SPR, and even mild loads blanked every primer. Swap the bolt and fp out for a higher quality one with a smaller hole and tip, should fix your issue.

 

[JDinFbg]

[Exactly what is the “deformity” that the OP is “trying to show]”?
That picture was suppose to be showing a deformity and I struggle to say bulge because I didn't see it but that's how he tried to explain it.

Check the spring tension on the ejector pin. My Remington 700 has that type of spring-loaded ejector, and as it came from the factory, and that thing would practically eject cases into the next county. I ground some coils off the spring to reduce the force the ejector put on the case. With this type of ejector, the case always has spring pressure on it that works to push the cartridge away from the bolt face. If the extractor has any slop in holding the cartridge and if there is generous headspace in the chamber, these factors will all work to allow the case head to sit away from the bolt face when a round is chambered. To test this theory, remove the ejector, single-shot load a cartridge and fire (you'll need to fire several to have a representative sample), and see if the condition still exists. This will give you one indication of where to start to fix the problem. If the rifle has generous headspace, it may be a handloading proposition only where ammo can be made to fit the chamber.

 

[gbro]

Check the spring tension on the ejector pin. My Remington 700 has that type of spring-loaded ejector, and as it came from the factory, and that thing would practically eject cases into the next county. I ground some coils off the spring to reduce the force the ejector put on the case. With this type of ejector, the case always has spring pressure on it that works to push the cartridge away from the bolt face. If the extractor has any slop in holding the cartridge and if there is generous headspace in the chamber, these factors will all work to allow the case head to sit away from the bolt face when a round is chambered. To test this theory, remove the ejector, single-shot load a cartridge and fire (you'll need to fire several to have a representative sample), and see if the condition still exists. This will give you one indication of where to start to fix the problem. If the rifle has generous headspace, it may be a handloading proposition only where ammo can be made to fit the chamber.

I think what you are saying could be the issue with the Remington 788 .30-30 that I just put in a replacement Bolt.
Firing it a couple days ago i found 4 out of the 5 rounds had significant set back primers.
I posted about that on my 788 thread and Jack opined that I need to increase the load pressure and had also made reference to the .009" of headspace I found with this replacement bolt acceptable in that many Model 94 Winchesters have that much headspace.
So I took my 1894 out and checked out the ejector and found a very strong ejector that is 180 deg away from a very tight extractor so the case is held tight to bolt face just like you posted. This 788 Remington has a very sloppy extractor and a strong ejector. I am not going to remove the ejector to prove this but will neck size for this rifle and see if that makes a difference and check for comparability with my 1894 Winchester.
Thanks so much for your insights/
Gregor
CGVS

 

[Harry Knutz]

AR10 bolts are known to have firing pins that are too large, For some reason 6.5 cartridges seem to have more trouble with pierced primers. I know, I have had it happen on bolt guns that were fine with 308, When I changed the barrel and chambered it to 6.5x54R, Light loads would pierce the primers, I bushed the bolt and turned the firing pin down and I could run high pressure loads. The primer backing out is an indication of excessive headspace, Normally from what I have seen the amount that is protruding above the head is the amount of excessive headspace. Also had the same problem with 6.5 PRC, I now bush all my bolts and true them.

 

[Harry Knutz]

If you continue to shoot it like that, Bare minimum you will get those little primer blanks inside of the bolt and it will stop working, I experienced a broken firing pin spring. And erosion can also take place. Sounds like 2 separate problems. 1: excessive headspace 2: firing pin and hole too big.