Question regarding barrel fitting

[gaijin]

My preference when testing for mechanical accuracy with firearm (long gun)/ammo is “plenty of glass”; 2-10X minimum at 100 yds. A 1-4X at 100 yds, even 50 yds, isn’t enough magnification for me to begin to evaluate true potential of a gun/ammo combination.

[DG23]

I used hardened stainless shim stock purchased via Amazon, which is available in a variety of thicknesses. I had one upper which had a 0.002" variation between the inner bore of the receiver and the outer diameter of the barrel extension. I wrapped a 0.001" piece of shim stock around the extension and using heat on the upper and freezing of the barrel was able to get them fitted. Had another that had a 0.003 variance, and instead of buying 0.0015" shim stock, I opted to just wrap the 0.001 stuff one and half times around. With the extra half turn around the bottom of the extension.

Another reason every guy that does his pee while standing should have some Nitrous Oxide around somewhere.

A few seconds in front of that spray and that barrels extension (or whatever item you are trying to rapidly freeze) is frozen.

[WornOutGrunt]

I would concur with gaijin and the other poster that suggested better glass... I would have used that to T&E the barrel and the loads I just don't/ didn't have anything better..
(actually I do have a 1x6 but the center dot is 2moa and seems to cover the target more) the Vortex is 1moa dot.

I will continue on this quest and try some other loads.... Ballin on a Budget is tough...

I would certainly always welcome any advice and constructive criticism

I will post some additional test loads as soon as available

[georgeib]

Another reason every guy that does his pee while standing should have some Nitrous Oxide around somewhere.

A few seconds in front of that spray and that barrels extension (or whatever item you are trying to rapidly freeze) is frozen.

Wow, didn't think of that! I actually had the barrels in the freezer for a couple hours instead.

[gunnerblue]

As I mentioned this testing was done at 50yds... How much should I expect the groups to open at 100 yds ? ?

I can factor in elevation holds/ trajectory, but just wondering if it is accurate to assume the group size would double at 100 yds

Not necessarily, the only way to know for sure would be to shoot a group at 100 yards. I use no less than 10x magnification when shooting groups at that range as I would have trouble calling my shots otherwise.

[T2C]

Not necessarily, the only way to know for sure would be to shoot a group at 100 yards. I use no less than 10x magnification when shooting groups at that range as I would have trouble calling my shots otherwise.

I use the rule of three. Multiple the group size by three when doubling the distance fired. That should give you an honest expectation of accuracy.

[themonk]

We did this experiment a few years back. Stubborn Mule upper reciver with a Larue Stealth barrel. Receiver to barrel extension was fine but not tight and didnt need thermal fitting. Rail was a Geissele MK8 tightened to their spec. Upper was broken in and shot 100 rounds for a total of 125 rounds. Upper was accuracy tested with Fed GMM and shot average 1.2 moa with 10 rounds (two 5 shot groups). Upper was disassembled, trued in a lathe, add green loctite, rail tightened to spec. Upper shot .8 with same box FGGM. Accuracy was stellar out of that upper until the barrel was swapped to a V Seven. Now its a laser.

Constructor's post is spot on.

[Disciple]

Accuracy was stellar out of that upper until the barrel was swapped to a V Seven. Now its a laser.

Does that mean better or worse?

[themonk]

Better. I kind of always hated that Larue barrel. It was really finicky about it's level of cleanliness. The V seven is a much better barrel in my opinion with a lot less weight.

[vicious_cb]

Better. I kind of always hated that Larue barrel. It was really finicky about it's level of cleanliness. The V seven is a much better barrel in my opinion with a lot less weight.

Larue barrels were much better when they were made by Lothar-Walther. Definitely eyeing V-seven barrels if I ever shoot out my Noveske since V-seven seems to be the spiritual successor to the original John Noveske barrels.