Swapping out BCG

[qwkdrwmgw]

I was told that if I got a new upper and used my old BCG that I would have to have this guaged to the new upper, that I could just slap it in and go. My question is is this true and if so what is to guaging it?

Thanks Scott

 

[sloughfoot]

I have never heard of this. BCG's are interchangeable in every upper I own.

I own more uppers than I do BCG's. By several manufacturers.

 

[Jarhead1775]

Slap it in and go.

The AR platform is a go, no-go type setup in general.

 

[mvician]

How "old" is your old BCG?

If you don't have 1000's or rounds on it, everything should be OK.

Swap the carrier all you want, but it's a good idea to keep a bolt to one upper. The bolt wears to the barrel extension.

 

[sloughfoot]

How "old" is your old BCG?

If you don't have 1000's or rounds on it, everything should be OK.

Swap the carrier all you want, but it's a good idea to keep a bolt to one upper. The bolt wears to the barrel extension.

Maybe you have seen this, I haven't. I have one bolt that is on it's third barrel. And I usually change barrels at the 5,000 round, or so, point. Whenever 600 yard accuracy starts to go.

At this point, I'm not sure which BCG or upper it is in..The upper innards are all interchangeable no matter how old or how they have been shot.

In my experience anyway.

 

[Yeah]

If you like having use of your fingers it is a wise move to check that your setup won't close on a Field gauge.

AR construction being what it a bolt, extension, and chamber all in spec will give you in spec headspace.

 

[mvician]

In my experience anyway.

Run your riles how you want, but I'm not going to give advice to someone else telling them "ya, it's hunky dory, go ahead."

For the $40-60 it costs to have one bolt per barrel or about the same for a set of GO, NO-GO gauges to check and make sure you are safe and just not haphazardly switching a bolt from barrel to barrel, that is what I'll do and recommend.

 

[CountryBoy19]

Run your riles how you want, but I'm not going to give advice to someone else telling them "ya, it's hunky dory, go ahead."

For the $40-60 it costs to have one bolt per barrel or about the same for a set of GO, NO-GO gauges to check and make sure you are safe and just not haphazardly switching a bolt from barrel to barrel, that is what I'll do and recommend.

I agree... as rare as it may be for something to end up out of spec, I ALWAYS double-check with go/no-go gauges just to confirm that I'm GTG with a new barrel/bolt combo. An ounce of prevention is worth a pound of cure...

 

[bwframe]

You guys have a bit more info on the testing/checking procedures? When and how? Links to gauges you'd recommend?

 

[cosermann]

...The bolt wears to the barrel extension.

+1 The bolt and barrel extension wear together. If you have a high mileage/high wear barrel and swap in a new bolt or vice versa you can have issues.

New in spec parts should be interchangeable.

How many rounds through this barrel?

 

[XDLover]

Get the go, no-go gauge and check. Just picture a headspace that's wide open and you have issues. While they "should" be ok do you want to have that go boom in your face over a gauge not being used?

 

[Yeah]

The procedure runs along the lines of:

- Determine what chamber you have. 223 Rem; 5.56 NATO; Wylde; Noveske; DPMS; etc etc. Some headspace differently from the others, so at minimum you want gauges that headspace the same as your chamber.

- Buy gauge(s). Unless I was reaming my own chambers, for a non-adjustable setup like an AR I'd want a Field gauge. In order the gauge options are: Go = minimum headspace. If you can't close the bolt on a Go your headspace is too short. Note that you aren't in danger of blowing anything up, because you can't get the bolt into battery. You just won't be able to fire the thing; No-Go = maximum headspace. If you can close the bolt on a No-Go it might still be safe to fire, but the headspace is at least at the spec maximum. If you intend to reload your brass you'd be working it quite hard running through a gun that can close on a No-Go; Field = maximum safe headspace. If you can close the bolt on a Field the rifle isn't safe to fire and you'll be in danger of breaching the brass the first time it is fired, no reloading needed.

For an AR I like Bill Ricca's gauges as they are cut to miss the extractor and ejector so you don't need to take the bolt apart.

- Having sourced the appropriate gauges, pull your upper off your lower or pull the rear pin and hinge it up.

- Pull the bolt assembly out of the upper.

- Use your fingers to insert the gauge into the chamber. Gauges are precision instruments, don't fling the thing in there.

- Insert the bolt assembly, assembled, CH and BCG and al still in place, back into the receiver.

- Use your fingers to lightly push the assembly into battery. If you've a Field gauge in there, the bolt should not rotate into battery. If it does the headspace is dangerously long and you should not fire the thing.

A likely better description, with line drawings, using a 5.56 NATO Field gauge, starts on page 3-47 here.

If your rifle doesn't pass with your desired gauge you'd need to break out some measurement tools to determine the offending part(s), and replace as needed.

 

[Cerberus]

Maybe you have seen this, I haven't. I have one bolt that is on it's third barrel. And I usually change barrels at the 5,000 round, or so, point. Whenever 600 yard accuracy starts to go.

At this point, I'm not sure which BCG or upper it is in..The upper innards are all interchangeable no matter how old or how they have been shot.

In my experience anyway.

He said barrel extension, not barrel.