300BlkTalk

Hi all,

I have a new build that I'm attempting to break in and cycling is not happening at all. When I say not happening I'm saying I have not experienced a single cartridge ejection over about 80 total rounds. In taking the gas block off I can see the carbon ring is concentric with the barrel's port. There is no sign of any blockage in the tube...

I'm running a carbine length gas Wilson Combat 18 inch at 1:8 with Wilson Combat gas block, Wilson Combat gas tube and Wilson Combat full auto BCG. The existing gas port measures about .097

My buffer and spring are carbine also, the actual weight of my buffer is 2.95 ounces. I run new builds a little on the wet side with Frog Lube. I've tried 15 escalating load combos, these 3 are the high end of each two tenth grain increment charge ladder I tested:

H110/Sierra 125
17.7gr produced 2101 FPS avg

H110/Sierra 155
16.6gr produced 2004 FPS avg

H110/Nosler 155
16.6gr produced 2002 FPS avg

My chrono was at 10 feet from the muzzle. I'm in the People's Republik of Kalifornia so this rifle won't see a suppressor. I plan to shoot bullet weights from 110 to 155.

SO - it appears to me that I need to enlarge the port. Question is, what should it be? Thanks in advance for any and all advice -

XXXXXXXXXXXXXXXXXXXX

Updated After Range Report - Everybody was right... except me! LOL

I made up some hotter loads, tried a couple of rounds at each tier of powder drop. No change, the bolt still didn't cycle. I pulled the full auto BCG out of my .223 and dropped it in my 300 Blk... And it suddenly cycled, ejected. The lighter loads didn't lock back at empty but the load suggested by Outsydlooknin did.

Range results:

H110/Sierra 125 (2.23 COL, CCI MAG Primers)
18.5 gr produced 2250 FPS avg

H110/Sierra 155 (2.23 COL, CCI MAG Primers)
17.8 gr produced 2097 FPS avg

The gun still won't rapid fire but I figure that's something I can work on over time. This is my first 300 and I have to say I'm pretty happy with the hurt the heavier bullets put on steel at a distance.

I pulled the Wilson Combat BCG apart when I got home and found that the ears on top gas ring were bent like the bolt had been dropped and the gaps in rings 2 and 3 were aligned. I'm feeling pretty stupid for not catching this when I lubed the bolt for assembly.

Thanks for all the advice... I can now say I drank the 300 BLK Kool-Aid and I'm glad that I did.

The 125smk's can probably go hotter.....I'm loading 18.5 of h110

Outsydlooknin wrote:The 125smk's can probably go hotter.....I'm loading 18.5 of h110

Thanks, good to know -

Looks like its time to start swapping BCG's from another rifle as well as trying the upper on a different lower, etc.

Good luck and report back with what you have done and the results

tallburnedmidget wrote:Looks like its time to start swapping BCG's from another rifle as well as trying the upper on a different lower, etc.

Good luck and report back with what you have done and the results

You're right, I just need to get one of my buddies to cough up a lighter BCG because the Wilson full auto I have is lighter than the other four I have on hand. Thanks for the advice and I'll keep the thread updated with my results.

conejo_guy wrote:

tallburnedmidget wrote:Looks like its time to start swapping BCG's from another rifle as well as trying the upper on a different lower, etc.

Good luck and report back with what you have done and the results

You're right, I just need to get one of my buddies to cough up a lighter BCG because the Wilson full auto I have is lighter than the other four I have on hand. Thanks for the advice and I'll keep the thread updated with my results.

You can always try one or all of your other 4 BCG's just to get an initial idea that you have something going on with your current BCG. The BCG weight is usually not the issue.

What you might have is an issue extracting. You may also want to simply switch bolts and see if that helps. Thoroughly inspect the current bolt to see if there is any issue with the extractor, springs, rings, bolt face, etc. I believe one guy recently had a similar issue where all he did was switch the spring and everything worked like a charm and another guy recently found a burr on is bolt face that was causing issues.

This should give you something to do other than weight and give you some more trigger time to test. Good luck

I think you have a gas leak somewhere in your BCG.

However-we have found that the 18" barrels really need a hot load for best functioning.
Like a factory supersonic or other hot loading.

Customers have reported using lightweight action springs with good results and plying with buffers but honestly I think it just boils down to load development.

Try some new BCG's and report back. Thanks

WCR

Outsydlooknin wrote:The 125smk's can probably go hotter.....I'm loading 18.5 of h110

Just got my copy of QuickLoad, what is the overall case length you're using from the 18.5 gr powder drop?

Thanks -

Screw all the swapping parts and crap. Pay a gun smith $25 and have the gas port opened to .125" and it will run like a sewing machine.....a sewing machine that sounds like a rifle that is. Your loads are fine. I run similar 125 SMK velocities than you with no problems while running H2 buffer. You don't have to take my advice, but swapping parts is not really solving a problem, just working around it. I also run subsonics with a can and have no issues either. I ran some subs without the can and it cycles sometimes, but that is expected with carbine gas length.

+1 on the .125.