Any experence / recommnedations on using the platic "insert" that goes inside the upper with two pins vs. the clam shell type clam (both are plastic).

While asking about re-barreling, any preference for the aluminum barrel clamp (less stree on the receiver, more marks on barrel ...)?

Thanks
John

The "insert" that attaches to the upper reciever with two pins is used only as a holder for cleaning, etc.  The upper "reciever block" (clamshell) also has an insert that replaces the carrier to properly support and hold the upper for re-barreling.  Using a set of barrel vise jaw inserts for re-barreling sometimes causes the barrel locating pin to twist in the upper reciever notch, distorting it and causing front sight housing to cant to the side.

JT
I have used both clam shell and jaw inserts for changing barrels. I prefer the clam shell.
I've had some barrels rotate in the jaws causing finish damage. The clam hold it with no chance of rotating.

Thanks for the inputs, in the process of moving the HBAR upper for the M16 over to a Colt flattop upper to use with the Aimpoint (plus future home of an ACOG TA11/TA31 ...)




The "insert" is different than a lower receiver top that can be placed in a vise and is used for cleaning (like the idea of using an old lower just as a mounting fixture [:)].

The "insert" (which will try to post pictures, however, son has the digitial camera at school ... in part because it is his ;-) can not be used for cleaning as all the room inside the upper is taken up by plastic that is milled to nearly fill the inside the of the upper and make contact at multiple points (nearly all surfaces).  New product from one fo the dealers.

yep, dpms has the insert with pins and is designed for barrel installation.  I would consider them a credible source of info.

I can't remember who, but someone "in the biz" so to speak, highly recommeded the white delrin insert as well.  I got the clamshell type that did not come with the little plastic handle part...so I'm considering getting the while delrin one myself.  

My appologies for relaying information about the "insert" with the two pins.  The one that I am familiar with is nothing more than a substitute lower reciever that mounts in a vise and did not seem very supportive of the upper reciever.  My assumtion was that it would be useful for holding the upper for cleaning, removing handguards, etc.

Harry

Appreciate the warning, with out my posting a photo is hard to know exactly what I am using.  
Like the idea of a "artifical lower" to hold the upper while cleaning (the old standby oak gun vise does not really work well for black guns).

Yes, the insert you speak of uses pins which I think go in the receiver and pivot pin holes IIRC?  I haven't used this insert since I have the lower insert and clamshell.

The regular lower insert is nice cause you can access the inside of the receiver, upside up or upside down, for uses other than barrel installation (I used it to hold my lower while I cranked off the Colt staked telestock castle nut).  I am assuming this is white delrin insert mentioned - the one that goes in the magwell (not the ones with pins).  Very handy, but I would use the clamshell for barrel work.  They come in black too I think.  There is someone on eBay or Gunbroker or such that is selling solid aluminum lower receiver inserts, supposedly much tougher and coated to prevent scratches.  They list it as "Receiver Block from Hell" or something like that.  I want one!

The insert has both pins and fits the inside of the receiver.  

One friend has the clamp type and the other a barrel clamp, so can swap as needed.

Changing the subject slightly, has anyone used any for the gas tube pliers?

Do you mean this ?

[img]http://www.bushmaster.com/shopping/gunsmith/Images/gastubewrench-small.gif[/img]

If so - I have one, and I like it.  Kinda expensive for something that is optional (you could use pliers).  But, if you have the bucks to spare, and appreciate proper tools for the job at-hand, I recommend it highly.  It is a high quality little gizmo.

That is the one ....

Was thinking this makes taking the gas tube in and out a little easier (I am assuming primarly out, however, like you said can always use pliers and at worst trash the tube).

Thanks
John

The clamshell is great for barrel scrubbing. Put it in the vise upside down, with the muzzle lower than the upper. Very secure. Spoo oozes out the muzzle.