02-05-2014, 08:45 PM
First let me say I enjoy watching what goes on within this site. I see a lot of very competent people discussing and helping each other towards a common goal focused around a love for 6.5 Grendel. Now I need some help or clarification from this community. I have only been dealing with AR's for a little over a year. I have developed a fast fondness of this weapon. I am a tinkerer by nature. I never can leave anything alone long. I seem to have always been a Tim Allen kinda guy, Grrr more power. 
Now to the point, I purchased one of the Lilja barrels in the A24 style. I had originally purchased a Vltor MUR-1 upper that needed a barrel. I was going to put the Lilja on that but listening to comments made felt that a heavier upper was in order for this barrel so I purchased a Mega billet to use. I didn't know that Mega machines their upper to be heat/chill fit to the barrel. I always put things together multiple times test fitting everything till I get it right. Might say I have a little OCD issue.
This is my problem, I chilled my barrel in my freezer which I keep at -10 (I'm an HVAC Contractor and do it because I can. :o ) When I tried to put it on the Mega upper it would only start maybe by about a 1/16 of an inch. If I heat the upper they will probably mate up but how will I ever get them apart.? I'm used to press fits but that's usually with steel parts that can take the force of pressing them on or off without damage. I'm concerned with this aluminum/steel situation though. As I have only changed barrels on my other factory built AR's with their much less precision fit. I'm apprehensive with this my first scratch build. Please anyone want to jump in on this and fill me in. Is there some trick I need to know, am I being overly cautious?
Now to the point, I purchased one of the Lilja barrels in the A24 style. I had originally purchased a Vltor MUR-1 upper that needed a barrel. I was going to put the Lilja on that but listening to comments made felt that a heavier upper was in order for this barrel so I purchased a Mega billet to use. I didn't know that Mega machines their upper to be heat/chill fit to the barrel. I always put things together multiple times test fitting everything till I get it right. Might say I have a little OCD issue. This is my problem, I chilled my barrel in my freezer which I keep at -10 (I'm an HVAC Contractor and do it because I can. :o ) When I tried to put it on the Mega upper it would only start maybe by about a 1/16 of an inch. If I heat the upper they will probably mate up but how will I ever get them apart.? I'm used to press fits but that's usually with steel parts that can take the force of pressing them on or off without damage. I'm concerned with this aluminum/steel situation though. As I have only changed barrels on my other factory built AR's with their much less precision fit. I'm apprehensive with this my first scratch build. Please anyone want to jump in on this and fill me in. Is there some trick I need to know, am I being overly cautious?