Moopey's LR-308 Build Thread

I sent an email to 762 to see what they suggest. I doubt we have 2 bad barrels from 2 different companies. By the sounds of it the bolts are just to tight for the headspace gauges. I might try running a couple mags through by hand and see if it loosens up some like one of the guys did in one of the links posted.
 
The MEGA barrel claims sub MOA so its chamber is CRAZY tight. The 762 Industries BCG claims to be National Match so its
tolerances are CRAZY tight. For example, a DPMS barrel and bolt face combo are .002" longer. The bolt face on my DPMS BCG is 0.124"
deep while the bolt face on my 762I bolt is 0.125 (I measure 0.126" but manu. says 0.125).

The result was that I couldn't close the BCG on a Forster 308 1.630" GO gauge, at least no without pushing hard and having no way to get it apart again.

Interestingly the bolt WOULD close on a Federal M80 7.62x51 cartridge. According to the specs 7.62x51 has a rim that is just a tiny bit thinner than .308 Win.
I filled a magazine with rounds and hand-cycled them through, letting the BCG slam home each time.

After I did that a couple times I WAS able to get the BCG to seat on a GO gauge but it was T-I-G-H-T!!

I did some test shooting. I had on big gardening gloves and looked away for that first shot!
Everything worked fine. The gun shoots beautifully and had no problems with 762 or a couple of AE 308s I tried. I can see little bits of NiB coating flecking off the
back sides of the bolt teeth but I image that is to be expected. Out of 40 rounds fired I had 2 failures to eject. Dunno why.

Spoke to both MEGA and 7.62 Industries and both seemed to think the above is normal. I told them both the story and they seemed to think just putting lead
downrange would cure the issues. Basically they just need to wear each other in (the bolt and barrel extension). The guy at MEGA said 500 rounds.

FYI, it is definitely the 762I bolt that is tight. If I put a DPMS bolt in the 762I carrier it seats easily over a GO gauge. Amazing what 1/1000" will do!

Curious to know other people's experiences! Also curious to know if people think it's a waste to have a NM BCG in a 16" CQB/medium range MATEN. I could
put it in my Fulton Armory FA-10 22" Critereon instead and put the DPMS bolt in the MEGA.
Click to expand...

From ar15.com,
 
I cycled some dummy rounds with mixed results. I had a couple of the brass kind with plastic rounds. After a few cycles I started to notice some scratches down the length of the brass. I borrowed the dummy rounds so they were used. The brass wasn't blemish free when I got them but I'm pretty sure the marks are from my rifle.

The only plus side was that the chamber did close on the dummy rounds but only if the bolt really slammed it in.

Then after all that I put an empty shell stuck in the chamber. woops.
 
I had a round finally close in the chamber slamming the bolt shut. Then after being fired the round didn't eject and was stuck in the chamber.
 
i should clarify, i took the upper off and put an empty round in the chamber by hand trying closing the bolt. that's when it got stuck.
 
ImageUploadedByTapatalk1373124766.180601.jpg

If you look, just behind the teeth of the bolt, there isn't material milled out, unlike some others that have a 'half moon' tooling mark behind the teeth of the bolt. Obviously this shouldn't have an effect on whether or not the bolt will close on a gauge, but it leads me to believe there could be more than one bolt 'style' floating around.



-------------
Excuse the brevity, I'm mobile.
 
I tried chinalfrs on saturday and couldnt even get it to lock in without anything in the chamber. Got my replacement bolt today from 762 and pulled the ejector and extractor and now it will close on the go gauge. It's still a little tight with a round in the chamber but i think it will loosen up.

Sent from my rotary phone
 
dropride said:
I tried chinalfrs on saturday and couldnt even get it to lock in without anything in the chamber. Got my replacement bolt today from 762 and pulled the ejector and extractor and now it will close on the go gauge. It's still a little tight with a round in the chamber but i think it will loosen up.

Sent from my rotary phone
Click to expand...

was Chinalfr's bolt also a 7.62 Industries?
 
moopey said:
i should clarify, i took the upper off and put an empty round in the chamber by hand trying closing the bolt. that's when it got stuck.
Click to expand...

this could be the brass. i did this last night with brass fired from my r700. could not close the bolt all the way and was a pita to pull the bolt out.

the brass gets fire formed to the chamber it was fired from. using a live round, the bolt would close fully but it is damn tight.
 
johnN said:
this could be the brass. i did this last night with brass fired from my r700. could not close the bolt all the way and was a pita to pull the bolt out.

the brass gets fire formed to the chamber it was fired from. using a live round, the bolt would close fully but it is damn tight.
Click to expand...

that's what I figured. That's why I wanted to clarify.
 
Just got back from the gunsmith. After his initial inspection he believes the barrel needs to be reamed a bit. I left the rifle so he can look into it further.

- - - Updated - - -

Just got back from the gunsmith. After his initial inspection he believes the barrel needs to be reamed a bit. I left the rifle so he can look into it further.
 
The gunsmith called me today to let me know the rifle is all set. He went to the range and put a few magazines through it and said it's now working fine. I'll get complete details of what he needed to do to the barrel tomorrow. The total was only $125 and that included pinning the muzzle break. Not too shabby. I can't wait to get to the range now!
 
moopey said:
The gunsmith called me today to let me know the rifle is all set. He went to the range and put a few magazines through it and said it's now working fine. I'll get complete details of what he needed to do to the barrel tomorrow. The total was only $125 and that included pinning the muzzle break. Not too shabby. I can't wait to get to the range now!
Click to expand...

Excellent news! This has been quite the epic saga, so I'm glad it's turning out all right in the end.
 
moopey said:
The gunsmith called me today to let me know the rifle is all set. He went to the range and put a few magazines through it and said it's now working fine. I'll get complete details of what he needed to do to the barrel tomorrow. The total was only $125 and that included pinning the muzzle break. Not too shabby. I can't wait to get to the range now!
Click to expand...

Glad to hear it!
 
Went to the range this morning. I took my magpul flip up sights off of my AR and put them on the .308 temporarily. I had a small window of time at the range so I couldn't zero them in. A buddy of mine brought a bolt action .308 so I could compare. I think it was a Ruger.

I didn't hit many targets with my rifle, but it ran well. I put about 30 rounds through it. No failures to feed or extract. I was originally worried about the phase 5 bolt catch but it worked fine. Recoil wasn't as bad as I thought it might be. The thing is friggin loud though, which put a smile on my face. After shooting my rifle a few times I then tried my friends bolt action. It definitely had more recoil. It didn't really hurt my shoulder but I could feel it more through my head since I had my cheek resting on the stock....if that makes sense. His bolt action was dead nuts accurate with just iron sights which was pretty cool.

All in all I'm happy with the way my .308 turned out. I have a new low profile hand guard coming in next week and that should take care of the only outstanding issue.

Now I need to decide If I want to invest in better iron sights or just get a scope. Part of me would rather just keep the magpuls as backup and take the $200 I would spend on irons and put it towards a scope.

I took some video on my phone. I just need to figure out how to get it online.
 
Evadd said:
Any update? Did the low-profile handguard work out? Which did you go with?
Click to expand...

Ah yes....I stayed with the Troy TRX-308 13.8" model, just swapped out the hi profile for the low profile. I bought the hi profile from Brownells but they didn't have the low profile in stock. I ended up getting the low profile one from DPMS. Thankfully even though a few weeks had gone by, Brownells accepted the return of the old one.

The low profile rail lines up perfectly. I really like that the end of the rail lines up perfectly with the end of the gas block and conceals it nicely.

I haven't been back to the range yet though.
 
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