This is just a "FYI" to those concerned.
Is something going on with LRB or the machine shop they use ?

I can not & will not recommend LRB receivers because of the numerous problems that still persist.
I still maintain my personal standards, that a receiver must pass inspection before the build can proceed.
If the receiver doesn't pass inspection, I will not build on it.
To the owners who bought a LRB receiver within the last year I suggest you measure the thickness of the receiver safety bridge.
If it's way under spec., you should consider replacing the receiver.

Just a few notes regarding serious problems with the LRB receivers I've seen in the last 6-9 months.
The main problem is the receiver safety bridge being so far out of spec, that the receivers in question
are rejects (per GI drawing) or scrap or unservicable or whatever you want to call them.
Simply put, "not safe to build on" due to safety concerns.

I have 2 more here that are rejects or scrap because the receiver safety bridge is very thin.
I know of 2 so called M-14 smiths who have built rifles on LRB receivers with these very serious problems described here.
If you had rifles built by some other builder (not me) on LRB receivers in the last 6-12 months, check the safety bridge.
If the receiver safety bridge measures between .120-.160 you should take the matter up with your builder.
Most of the newer builders are not gauging or checking receivers before doing the build.

The receiver safety bridge should be .170 +or- .005 per GI drawing.
The measurement from the front of the receiver ring to the rear of the safety bridge should be 3.935
I have seen many LRB receiver safety bridges that measured between .120-.140 (thousandths).
That's .030-.050 under GI spec.
In laymans terms, I'll say it easier for you to understand.
.031 = 1/32", .062 = 1/16"

Some of the problems associated with the out of spec. receiver safety bridge is that the firing pin retraction is delayed.
The firing pin retracts late which causes the bolt timing to be wrong.
Meaning the bolt is moving farther faster, before it slows down.
This condition can also cause the firing pin tang to stick or bind during the bolt opening phase of the rearward travel.

The top of the safety bridge also supports the bolt when the bolt is closed & during cycling (firing the rifle).
A thinner safety bridge is also prone to more stress because of less bearing surface & could crack or break.

Some other things to note.
The op-rod support rail on the right side of LRB receivers are now .225 wide.
Standard is about .300 wide on USGI receiver print.
Also, the op-rod dismount notch now has a square undercut about .003-.005 deep.

LRB says their receivers are made to USGI specs but, they're not close to GI spec. at all.
Everyone knows what LRB receivers cost.
I suggest the Fulton or 7.62mm receivers for those wanting a quality receiver to build a rifle on.
The following pics show what I'm refering to in my post here.











Warbird

Good info, would be neat if you had a rack grade springer receiver in those photo's.

I did some checking:

Make and serial number / Bridge Thickness / Op Rod Rail Thickness

Poly Technologies 00074 0.155 " 0.275 "
Armscorp 17XXX 0.185 " 0.325 "
Federal Ordnance 60223 0.182 " 0.262 "
Springfield Armory, Inc. 002XXX 0.215 " 0.268 "
Springfield Armory, Inc. 134XXX 0.215 " 0.276 "

Here are my observations between my LRB and my Norinco. The thickness of the safety bridge on the Norinco is the same thickness vertically to the point where the bolt rides on it. My LRB has a taper to it where it is thin at the bottom and it thickens to where the bolt rides on it. Here are my measurements: my Norinco measured in at .174" from top to bottom, and my LRB measured in at .156" at the thinnest point and .173" at the thickest point. Here are some pictures.

First 2 is the LRB:

Bottom of oprod rail.


Norinco:

Bottom of oprod rail.

No he hasn't, he was banned from there some time ago.

I just got thru measureing my 2 LRB receivers. 1 is from about August of 2007 and I just received the 2nd .

The measurements are identical minus the op rod dismount notch.

The top of the receiver bridge width is .173 and tappers to the bottom width of .145

distance from front of barrel ring to rear of receiver bridge is right on target at 3.935

I see you're trolling again (as usual).
You never add any constructive comments anywhere at anytime.



Hey Lee
Blooper time.........

I gave measurements for the "WIDTH" not the thickness of the right rail.
Measurement is from the receiver leg outward (on the bottom of the rail).
Now we know how misunderstandings are created......



Corrected to include truthful content.



Only a matter of time before a LRB defender comes along.
You're the one known for "shitting" on someone for personal gain.
You proved it here.
People like you must be a shill for LRB or else your comments would be much different.
If not, prove it by not making personal attacks without proof to back it up.
Otherwise you're just trolling.

I gave proof then, that some barrels wouldn't headspace correctly to "some" Armscorp receivers.
Some of the members on that "other" forum backed me up on it but, people like you still sling mud in the wrong direction.
The last time this came up it didn't bode well for the "other" forum.
Looks like you never learn from history..................................
You should take good advice & let it rest.

I gave facts here about problems I've seen with "some" LRB receivers to educate customers.
Customers deserve to know about things that affect a safe build.
I have given info. regarding "all" makers, not just LRB.
Those other makers include SAI, Fulton, Armscorp. 7.62mm, Enterprise, etc.
LRB was told at shot show 2010 last January of some of these serious issues.
Soooooooo I'm not the 1rst to bring it up.
They still fail to correct problems after 10 years of production time, go figure.

I have "NO" financial gain from any maker of receivers, including 7.62mm firearms.
I will say that 7.62mm has done what no other receiver maker has done before.
They had less problems in shorter time & have corrected most if not all of them.

I totally agree 100%.
The last time it came up, my inbox maxed out with "I want rifle work done" emails.
Took me almost 2 weeks to catch up on emails.

I'm a big man & I have thick skin to boot.
Some people don't understand that I can take criticism & keep on movin.
I moved on long ago.
I'm still here, and will be here for anyone who needs me for years to come.



Warbird

I'am the one known for shitting on someone for personal gain? How so? i am not a site sponsor , i am not a vendor i have nothing to gain by voiceing my opinion on any subject on this forum or any other. You want to throw rocks at me , that fine but remember you were the one that was baned from the TFL forum, not me. No one gets kicked off of that site for no good reason, but you managed to, i wonder why? AFWIW i do not own an LRB nor do i plan on buying one in the near future. I have more that enough rifles to feed as it is.

Given the timing of my reply above, and this post, I'll give you the benefit of the doubt––this time.
ANY personal comments by ANYONE in Tech fora may be subject to sanctions. Consider yourself warned. raf

If you do not own or have a interest in a LRB receiver then you should not be commenting on Warbird's post. He is not a politically correct person, thank god, and calls it like he sees it. His expertise on the M14/M1A platform is well known and so is the quality of his work on many different types of firearms. I know this because he has done work for me. If he says there are inconsistencies in what LRB sells you compared to what they claim then it is so. He does not produce receivers himself so there is no financial gain for him to educate people on this subject.

The safety bridge is supposed to be tapered. It is not one thickness. Your measurement shows nothing and is pretty misleading. LRB receivers are accurately machined to the small details that other manufacturers neglect.

And I have no dog in this fight. I'm simply a consumer. I don't sell, market, manufacture or build anything, before anyone starts throwing accusations.

Plastic calipers?