Barrel Extension Fit?

[Pugsbrew]

I have two Grendel barrels. One has the barrel extension finished/blued, the other one is not blued. When fitting in to an Aero Precision M4E1 upper, the blued one fits great. The un-blued goes in about 1/8 of the way and seems to stick.

I have measured the extensions, and they are they same. It seems that the blued extension is slicker, if you will, and slides in with hand pressure.

So, I'm concerned about FORCING the un-blued barrel in.

Any techniques of getting the barrel seated?

Thanks.

edit I should have included that both are from the same manufacturer. Both were purchased on a group buy here.

[depletedyourcranium]

Depends on how much forcing you have to do. A snug fit is a good thing IMO, and it's nothing to have to seat the barrel with a few taps of a rubber mallet. Now if you have to do much more than that I would stop, remeasure along different points of both barrel extensions and try to figure out whats going on.

[A5BLASTER]

Put the barrel in the freezer for a few hours and if you have a high heat hair dryer or heat gun, heat the upper good then get the barrel and slide it in for a nice tight compression fit.

Also if you have the tools wouldn't hurt to lap the receiver face before doing up the build.

[LRRPF52]

I don't know of anyone that blues their barrel extensions.

It's more likely nitrided.

A press or interference fit is more desirable for accuracy. When I get a match like that, it makes me happy.

[Kswhitetails]

^ This. Don't be afraid to use some elbow grease to get it together, it will help ensure a tight fit, and will reduce the potential for minute movement under recoil. This is the why behind it's being desirable.

[Sticks]

And wrap that barrel in a Towel before you freeze it, and keep it wrapped until it reaches ambient temps after install. Might want to run an oil patch down the bore first as well. Condensation sucks.