Crowning a c'bored barrel? Remington VTR

[jtnf]

I've got a Remmie 700 VTR in .223 that I can't seem to get to perform better than about 1.5 minutes at 100 yards, even on sandbags. It's been driving me nuts, so I decided to take some photomicrographs before returning a borrowed USB 'scope.

I've abandoned the ultralight VTR stock and replaced it with a Choate, and ground away a contact point where the stock was touching the barrel. It SHOULD be full floated at this point, standard paper-strip-as-feeler-gage all the way to the receiver.

Obviously, re-barreling is on my list of things to do BUT, I'm wondering if the burr I think I see could be the reason for the performance? (Pics below.)
The odd counter-bored integral comp looks like it was blind cut with a flush end mill. There appears to be somewhat of a countersink also.






Am I seeing a burr at the bottom of the flush cut? If so would some kind of crowning be warranted before writing off this barrel? I was thinking of abrasive crowning, as I don't think any real piloted crowning tool will be small enough in diameter to fit down that hole (.346 diameter FWIW.)

 

[Mountain]

Sorry no expertise in corrective measures, but I agree that there could be something going on at the barrel crown. Bottom of the comp does not look clean and does not look totally clear of the rifling if I am looking at this correctly. Maybe recovered bullets would show something going on? Compare w/ rifling marks from a known good barrel? Good luck- that must be frustrating to get groups ~1 MOA more than you should.

 

[mac1911]

Crown or lack of it from what it looks like.
So discounting you sending it back to remington a few things you could try.
I have had very good results using a ball bearing glued to a small piece of rod then with some fine lapping compound lightly kiss the crown with the bearing in a slow speed drill.
I would imagine you have nothing to loose if your considering a re barrel anyway.
I,have used this method on crusty 22s and air guns with more than happy results.
Other than that I can't see why a good Smith or machinist can't make a crown cutter fit the muzzle brake area. Maybe take a 11' crown cutter from brownells and machine the cutter body till it fits inside the muzzle device?
charliedatuna.com/airgun.../Barrel%20Muzzle%20Crown%20Procedure.do...

 

[jtnf]

Ball bearing is certainly a possibility... I have a selection of them available at the office.
I've also seen people using brass panhead bolts with lapping compound for the same effect.

 

[mac1911]

Ball bearing is certainly a possibility... I have a selection of them available at the office.
I've also seen people using brass panhead bolts with lapping compound for the same effect.

I use the brass to dress up a crown. The steal bearing will help actually cut into the steel vs polishing with the brass.

Go to praticalmachinest.com I get great ideas from there and apply them the best I can to DIY technology and tools.

 

[mac1911]

Ball bearing is certainly a possibility... I have a selection of them available at the office.
I've also seen people using brass panhead bolts with lapping compound for the same effect.

I use the brass to dress up a crown. The steal bearing will help actually cut into the steel vs polishing with the brass.

 

[jasons]

I'd lop of the whole thing and put a target crown on it.

 

[jtnf]

I'd lop of the whole thing and put a target crown on it.

That is a possibility. I'll ask the machine shop supervisor if I can get some lathe time. Off the action most people would not recognize it for what it is.

 

[mac1911]

I'd lop of the whole thing and put a target crown on it.

I assumed he wanted to keep the brake? Would make things easier for sure.

 

[jtnf]

Keeping the brake is certainly optional. The asymmetrical brake on the VTR is said to cause trouble with boat tail projjies.

 

[mac1911]

Keeping the brake is certainly optional. The asymmetrical brake on the VTR is said to cause trouble with boat tail projjies.

Geez, combine tactical with varmint and try to make it look cool too.....no wonder it don't shoot so did remington put out any recommendations or accuracy reports with this rifle?
Not good with boat tails so I assume the recommend varmint loads with -60 grain flat base bullets?

Maybe some flat base bullet test before you mess with the barrel?

 

[jtnf]

Geez, combine tactical with varmint and try to make it look cool too.....no wonder it don't shoot so did remington put out any recommendations or accuracy reports with this rifle?
Not good with boat tails so I assume the recommend varmint loads with -60 grain flat base bullets?

Maybe some flat base bullet test before you mess with the barrel?

Some early reviews were generally positive, especially of the odd tri-lobe barrel: Reportedly it is stiffer than a bull barrel of equivalent outside diameter.
I'll fabricate a brass ball tip abrasive tool and try that as a first step, then consider the more radical circumcision.