RMW Extreme Build. It has begun.

[mrpipesmkr]

  I'm wondering if you need a new bolt carrier, is it smooth inside where the rings run?

It looks smooth, and moves as smooth as my 6.8 bolt assembly that is on my bench. It certain moves with less force than the 6.8.

Your carrier should be OK then.
  On my previous post I forgot to mention my thinking on the hotter loads.  With slow burning powders typically used in 10mm running them at lower pressure does not give a complete burn and usually means a dirtier chamber and gun.  With slow powders upping the pressure promotes a more complete, cleaner burn.
  You may just be fighting the partially burnt powder clogging your bolt and rings. I have no doubt a hotter round will create less unburnrd powder. I suggest Longshot only because it does well in 10 mm and has been working for me in my build.
  I just saw your post that you do reload. Great! Work up some Longshot loads and see if they make a difference.

[Pablo]

I have shot Underwood, Buffalo Bore and Double Tap.

They all shot fine.

Then I cooled the rifle down, came back to shooting and jammomatic.

I have shot medium home loads, and yes the whimpy commercial stuff. Sometimes it works, sometimes not.

The best luck I had was with the new Sig 10mm. 180 grain. Then I switched to some other ammo, ran fine, cooled down and ran like junk again.

I think you are very close, it builds up and when cooled, really cokes up and can't unfowl.

[mrpipesmkr]

Pablo,
  Sorry you are having problems with your 10mm build. Keep working at it, I think you have shot it enough to know the 10mm carbine is just a real hoot to shoot!
  As near as I can tell, our to builds are the same except fo 3 differences. 1. Mine is a 16 barrel, yours is, I believe 11 inches.  2. I am using Glock 20 mags and you are using Greese gun mags. 3. I use hand loads exclusively, no factory ammo. You have used a mix of different Ammos.
  Considering the location of the port in our rifles, barrel length should not be an issue. The system is pressurized in both our carbines well before the bullet exits the bore.
  The "stiffness" of the Greese gun mags could be contributing to the problem but this should be avoidable by partially loading the mags, rather than fully loading them. As I have mentioned, I have had a few partial feeds from new Glock mags but as I've worked with the piece it has loosened up and this problem is going away.
  So, it appears to me that the biggest difference might be the ammo we are using. You problems seem to be centered around carbon fouling rapidly building up on the bolt and rings slowing the action down until it quits working. I have not had this problem and I've shot as many as 50 rounds from mine in one setting. I do have carbon build up as al DI weapons will, but it does not jam the action. I can't say that I have conscientiously let the weapon cool as you have but my feeling is this would not make a difference on my piece, it just seems to run ok even after letting it sit for 15 minutes or so between strings.
  My suggestion then is that you load up some 180 grain Longshot loads working up to 9.6 grains with standard primer. Clean the carbine thoroughly before testing and do not mix any other types of ammo in with the Longshot loads. It's just possible that some of the ammo you are using is only getting a partial burn on the powder creating lots of fowling that you system cannot handle.  My Longshot loads burn pretty clean and the carbon they do create is very fine and not too sooty. The carbon builds up to a certain extent but does seem to self clean a little bit as the fine particles are blown out the vents on the side of the bolt carrier through the ejection hatch.
  The load I use, 9.6 grains Longshot under a 180 gr. Hornady  HAP  billet is  .1 gr. above max in the Hodgdons reloading data, but I consider it to be a medium hot load. The Hodgdons top load of 9.5 grs. Only gives , if I remember correctly, about 33-34000 pounds of pressure. This is way below the 37500 max pressure for the round. Even my 9.6 load does not hit full pressure and I have worked up as high as ( if I remember correctly, don't have my notes available)10.4 grains with a standard primer. At that level I had significant signs of pressure and feel that load is too hot.  9.6 grains with a magnum primer is very hot also, more than I want to run consistently, although Double Tap sells a 180 gr load of 9.5 with a magnum primer .
  The whole point of all this is that getting good pressure in the correct curve Is essential for the DI system. What works in my build may not work in yours. You must have enough powder in the case to create sufficient gas to run the gun. If my 9.6 load doesn't run yours you might try changing the curve by lowering the charge slightly but switching to a magnum primer, thus speeding up the burn and changing the curve.
  Hope I havnt bored you with all this but sometimes listening to another person air out their thoughts will help stimulate yours. I know you are pulling your hair out over your build and hope I am helping. I think when you get it figured out you will be surprised at how simple the solution was!
  Oh, let me throw in a Merry Christmas and a Happy New Year !!

   

[Pablo]

Extremely helpful. I won't have time until maybe next week to load. I may just do 50 with 9.5 and 50 with 10 gr. of Longshot. I have plenty of clean 10mm brass, so that's a bonus. I just need to re-setup my press.

Also, absolutely the GG mags never work when I jam 32 into them. I gave up on that long ago.

I think I have the bolt assembly about perfect. One last tweek. I also want to wait for the Militec to arrive.

Thanks a ton!

[Pablo]

The last difference I had in the 10mm in the bolt carrier group (from my 6.8 and 5.56) was the very tight, say sticky, firing pin.

First let me say I have spare bolts and firing pins and other parts for my other AR's. So I have parts to try things out. That said I took my known well functioning BCG's apart one at a time and brake cleaner degreased them, twice. Zero lube. Then reassembled. Somewhat key when comparing the feel. The 10mm is now the smoothest, but when the firepin was manual pushed into fire mode, it would hang and not fall back as the other two would. And only would retract with some level of effort, which I found disturbing. All parts are very clean. I know this shouldn't have any real effect on my issues, but it was different. So a grabbed a known good spare (like new) firing pin and now the 10mm BCG is essentially the same as my other two.

I will Militec all three when the lube arrives. I just think this variable should be somewhat in control.

[sstewart]

I am getting good but not 100% perfect results with PC 180gr Bullets. Using only 9.1 gr of longshot.
I am using quarter circle lower. Dremeled the Glock mags out a little to give bolt space to feed.
Getting an occasional FTF on KCI 45 long mag. 0 to 1 per mag. Mostly 0 on 15 round Glock mags

[mrpipesmkr]

Extremely helpful. I won't have time until maybe next week to load. I may just do 50 with 9.5 and 50 with 10 gr. of Longshot. I have plenty of clean 10mm brass, so that's a bonus. I just need to re-setup my press.

Also, absolutely the GG mags never work when I jam 32 into them. I gave up on that long ago.

I think I have the bolt assembly about perfect. One last tweek. I also want to wait for the Militec to arrive.

Thanks a ton!

Pablo,
  Sounds like a plan!  The only thing I would emphasize is, work up to the 10gr load. That is pretty hot and each chamber is different so make a ladder in.1 or .2 grain increments to be safe.
  Also if you have magnum primers, drop down a few tents of a grain and load with the hotter primers to speed the burn. This woul create more pressure at the port given that it is close to the chamber.
  The situation with your original firing pin is unusual.  I wonder if you had debris blow into the firing pin tunnel from the bolt? Something has to be causing the obstruction. You might use a pick to see if you can scrape anything out from behind the bolt face. While this may not be the cause of your problem it may contribute to it. I would also be worried about slam-fires if the pin does not retract. Also, is it possible the pin is bent? This may cause it to bind.
  Let us know how the new loads work!
 

[mrpipesmkr]

I am getting good but not 100% perfect results with PC 180gr Bullets. Using only 9.1 gr of longshot.
I am using quarter circle lower. Dremeled the Glock mags out a little to give bolt space to feed.
Getting an occasional FTF on KCI 45 long mag. 0 to 1 per mag. Mostly 0 on 15 round Glock mags

Stewart,
   Thanks for the feedback on your build. It sounds like it is very similar to mine in terms of running without problems. I have not run mine as low as 9.1 grains behind the 180 bullet but feel it might possibly run with that load, especially with a mag primer. Have you tried a hotter loading in yours? It might  help eliminate the FTF problems you are having since they are minimal at most. Also the bolt and barrel are built to handle higher pressures and those higher pressures might promote a cleaner system.  Remember, some .556 military loads generate in excess of 60,000 pounds of pressure.
  I trimmed the lower bolt lugs on my bolt to make them thinner so they clear the metal at the rear of the Glock mags. Still enough lug there to strip the round and lock the bolt without having to alter each mag.
   When you squeeze the KCI mag lips together to hold the 10mm round it lowers the position of the first round enough to cause problems. I gave up on mine, using them on my first QC10 lower they were very problematic. Now that QC10 has replaced my original lower with one that holds the magazine in a higher position I will have to re-visit the KCI mags.  My real hope is that Glock will offer a 30!rounder at some point.  Really, I don't mind the 15 rounders as they are less awkward than the longer mags, especially when firing from the prone position.  I would try the Kriss extensions but find it hard to pay 70.00 for a magazine!
   One last question, do you find your Longshot load is burning clean?.  How bad is the build up in the bolt area?

[Pablo]

Pablo,
  Sounds like a plan!  The only thing I would emphasize is, work up to the 10gr load. That is pretty hot and each chamber is different so make a ladder in.1 or .2 grain increments to be safe.
  Also if you have magnum primers, drop down a few tents of a grain and load with the hotter primers to speed the burn. This woul create more pressure at the port given that it is close to the chamber.
  The situation with your original firing pin is unusual.  I wonder if you had debris blow into the firing pin tunnel from the bolt? Something has to be causing the obstruction. You might use a pick to see if you can scrape anything out from behind the bolt face. While this may not be the cause of your problem it may contribute to it. I would also be worried about slam-fires if the pin does not retract. Also, is it possible the pin is bent? This may cause it to bind.
  Let us know how the new loads work!

I have shot super hot ammo in the gun with no issues with overpressure, but working up to it makes sense. It's the right thing to do.

I don't have magnum primers. I'll add them to the to do list.

The firing pin thing was resolved by putting a spare pin in - nice and loose like my other bolts. The bolt is exceedingly clean. Trust me on that one. Eventually I will measure the pin I took out, but it did not appear be bent with a simple roll test.

[mrpipesmkr]

Pablo,
  Merry Christmas !  I hope Santa brings you a cure to your FTF problems for your present!
  Working up to hot loads is always the best idea. I think 10grs with a standard primer and correct COL wil not be a problem for you but you never can tell.
  The reason for the mag primers is just to change the pressure curve to something that peaks quicker. You may find that the standard loads work fine and won't need to mess with the mag primers.
  I'm curious about your firing pin situation. Something has to be different with the old pin versus the new one or they would both run the same. Since you found plenty of evidence of debris build up in your bolt and carrier it seems logical that could cause the firing pin to begin to jam. Scraping a little to see what's in there makes since because some fouling won't be removed with solvents and has to be scraped. With what you've been going through taking a few minutes to be sure there is no build up is just good insurance.  I know you want to cover all the bases.
  I've followed your problems with the build so closely that I think I will be as excited as you when you get it running !  In a way, your problems have been a good "school" for me and I've learned a few things along the way. I appreciate you sharing your problems with the board for that reason!

[Pablo]

The bolt is clean. I took it all apart and even scraped inside with a right angle pick that will reach all the way through when the extractor is removed. It's clean.

And I whipped out my micrometer. The replacement pin actually is (slightly) larger OD than the stock pin............so I am baffled.......The replacement pin goes in loosely and rotates freely.

Wait, but the original pin is loose sometimes, tight others........it is indeed ever so slightly bent! I can see it when I clamp the bolt and rotate the pin fully depressed. Nice. Very, very subtle. Does the same thing in my other bolts. Never had a bent AR firing pin before.

[mrpipesmkr]

  It was just logical that there had to be some difference between the old firing pin and the new one you installed. 
  I have never seen a bent AR pin also. Strange, I wonder what caused it?  Anyway, replacing it has to be a plus.  Hopefully the gun will run a little better with the new pin. I don't think it was your whole problem but it had to contribute to it.

[Pablo]

I just started wishing I had a dial indicator, v- blocks, something.........then it hit me, the top my little precision vise jaws. The pin is ridiculously bent! I thought it was subtle because I was mentally canceling out any methods I was using to spin it, chuck it up, etc. It's actually embarrassing now - that I didn't notice this from day one! Trust me, I did nothing to bend this pin (well unless it was ancillary jam damage) . I agree, this wasn't the sole problem, but yet another symptom of this crap bolt assembly.

[undeRGRound]

I really wanna see them argue in court that a you become a felon based on how you hold a gun.

            
It's an unconstitutional agency, in needs disbanded. 
I think some of the agents are honestly trying to do
a good job, like the original writer of the opinion that
allowed shouldering the Sig Brace.  Even an "SBR"
needing a tax stamp is ludicrous IMO... among
other things that they base their jobs on  :'(

HI PABLO!!!  <RGR goes back to reading thread>   

[sqlbullet]

In most countries in europe a suppressor is about as regulated as bubble gum.  It is a safety device in their mind.  As it should be in ours.