Used bolt, new upper

[urbankaos04]

Based on my search, it appears that this is not a major issue; however, I have two questions.

1) Would you guys use a FIELD GAUGE to "check" headspace if using a BCM BCG, with about 500 rounds on it, in a new Noveske N4 Light upper?

2) What advantage is there to "fitting" a bolt to a new upper? Does it really improve accuracy any?

[Packman73]

I wouldn't bother with checking head-spacing if it was me with those two companies' parts. And I don't think you can 'fit' a bolt; the head-spacing is either correct or it's not. But you don't need to worry with those manufacturers, at least I wouldn't.

[urbankaos04]

I figured as much. And the reason I asked question #2 is that in ordering an upper for my buddy today, the Noveske rep cited that they would be "fitting" the BCG he was also ordering from them. I thought they would slap any one of the BCGs they have on hand and not go to any extra lengths to ensure fit of any kind.

[Packman73]

Huh, that's cool. I'd just throw one in lol. They make a great product.:cool:

[mhanna91]

I was going to start a thread on this last week because I just got a new BCM upper and had a previously used (1200-1500 rounds) BCM BCG. I didn't figure this would be a problem though, especially given the amount of uppers for sale in the equipment exchange with no BCG.

[GTifosi]

the Noveske rep cited that they would be "fitting" the BCG he was also ordering from them

A car is fitted with tires when you pick it up from the dealership.
A living room is fitted with furniture.
Them 'fitting' a BCG could very easily mean they'll drop it in the upper so it ships as a unit.

Likely it is going to be one of the many they've got around as you surmise, and someone will drop it in and hopefully do a quick go no-go headspace check on it (if its a barreled upper anyway) before sending it out the door.

'We're going to fit it with handguards and a stock', as in handguards and a stock will be installed. :shrug:

What it may 'seem' like it might mean is that they'll take a BCG and an upper and have some $70 an hour specialist journeyman tool and die maker with hones, stones, cutters and micro files custom fit that BCG specifically to that upper. But that is exceedingly unlikely to occur in any shop that has even moderate volume to get out the door.

[a0cake]

A car is fitted with tires when you pick it up from the dealership.
A living room is fitted with furniture.
Them 'fitting' a BCG could very easily mean they'll drop it in the upper so it ships as a unit.

Likely it is going to be one of the many they've got around as you surmise, and someone will drop it in and hopefully do a quick go no-go headspace check on it (if its a barreled upper anyway) before sending it out the door.

'We're going to fit it with handguards and a stock', as in handguards and a stock will be installed. :shrug:

What it may 'seem' like it might mean is that they'll take a BCG and an upper and have some $70 an hour specialist journeyman tool and die maker with hones, stones, cutters and micro files custom fit that BCG specifically to that upper. But that is exceedingly unlikely to occur in any shop that has even moderate volume to get out the door.

Noveske has a proprietary standard for headspace that is more stringent than commonly accepted standards.

[GTifosi]

Noveske has a proprietary standard for headspace that is more stringent than commonly accepted standards.

Do they juggle parts to get a spec between bolt and chamber with a tweak of the barrel extension if neccisary, or is it more a case of literally modifying parts to fit together?

The former I could see happening, but the latter would be excessively time consuming and leave the parts in a position where they really 'shouldn't' be used with any other parts than what they were mated to.
Of course you likely could swap certain things around successfully, but I imagine the bolt and barrel would have to be mated for life.

I ask because I'd like to know, not because I'm trying to pick holes.

[a0cake]

Do they juggle parts to get a spec between bolt and chamber with a tweak of the barrel extension if neccisary, or is it more a case of literally modifying parts to fit together?

The former I could see happening, but the latter would be excessively time consuming and leave the parts in a position where they really 'shouldn't' be used with any other parts than what they were mated to.
Of course you likely could swap certain things around successfully, but I imagine the bolt and barrel would have to be mated for life.

I ask because I'd like to know, not because I'm trying to pick holes.

If standard "new rifle headspace" is 1.4646" to 1.4706'', which equates to a tolerance of 6 thousandths, then Noveske's tolerance is simply less than that. I think they hold theirs to a 3 thousandth's window but don't quote me on that. It's not a case of modifying parts, matching or pairing would be better terminology. I don't work for Noveske so please don't take my numbers as gospel. I'm just saying that you shouldn't assume "fitting" to mean them simply dropping a BCG into the upper.

[Iraqgunz]

I agree with a0cake.

Anytime I swap bolts (except in an emergency) I always check the headspace with a MILSPEC gage. I also gage the firing pin hole and protrusion on all new parts I buy.

[big b]

My understanding is;
Used bolt + new barrel extension = good to go
New bolt + new barrel extension = good to go
New bolt + used barrel extension = good to go
Used bolt + used barrel extension = no go

This is assuming all parts are still in good working order and not beat to shit. Someone with more knowledge may be along to correct me if I'm wrong.