I'm sure this question has been asked before but what do y'all use to secure your upper safely in a vise without a a vise block ?

Get a vise block (or like me keep on borrowing your friends block)

http://www.brownells.com/gunsmith-tools-supplies/rifle-tools/barrel-tools/ar-15-m16-reaction-rod-prod55168.aspx

http://www.ebay.com/itm/NO-M-A-R-223-556-WHT-Pin-Upper-Receiver-Vise-Block-4-15-Gunsmith-Barrel-Tool-/121511766984?pt=LH_DefaultDomain_0&hash=item1c4aaa6bc8

Reaction Rod by far is the best for mounting or removing barrels to the upper receiver.  But sometimes the vice block or delrin pin blocks are the ticket for small work. If you use a vice block make sure to put the replacement piece in for the bolt carrier or use a bolt carrier without the bolt in place.

Magpul BEV block.

 

http://www.ebay.com/itm/NO-M-A-R-223-556-WHT-Pin-Upper-Receiver-Vise-Block-4-15-Gunsmith-Barrel-Tool-/121511766984?pt=LH_DefaultDomain_0&hash=item1c4aaa6bc8

 

 

Just be careful with that. There is a reason for the design of the vise block - it supports most of the receiver. I know gunsmiths that have used that, but I wouldn't use it for barrel installs/changes. Flash hider? No problem.

Just used the Wheeler block..good to go

http://www.midwayusa.com/product/210021/wheeler-engineering-delta-series-upper-receiver-vise-block-clamp-ar-15?cm_vc=ProductFinding

I've used a similar no-mar style for 3 barrel installs....no problem yet...i see what your saying though

Geiselle rod or the brownells equivalent

http://www.midwayusa.com/product/210021/wheeler-engineering-delta-series-upper-receiver-vise-block-clamp-ar-15?cm_vc=ProductFinding

I've used the wheeler setup on three barrels, I like the part that slides in like the BCG , it has that pin for lining up the  gas tube  

I've used the wheeler setup on three barrels, I like the part that slides in like the BCG , it has that pin for lining up the  gas tube  

i didn't give that piece much thought until i was installing my barrel and used it to time/align the barrel nut with the gas tube pin.  took all the guess work out of getting it aligned just right