Prefit barrels, and how the barrels are indicated during manufacture

[Lennyk]

Hello to all! For my beginnings in the PRS world, I have noticed the rise of prefit/barrel nut barrels. I understand the ease, and simplicity of their installation on the actions. The question is, how well and accurate is the chambering done on their end (the specific manufacturers). Do they indicate the barrels to zero on the 10,000 scale? Just curious what you guys think. Bottom line is, what is their mastery in the gunsmithing world? Something tells me that there are a lot opinions

 

[Supersubes]

Hello to all! For my beginnings in the PRS world, I have noticed the rise of prefit/barrel nut barrels. I understand the ease, and simplicity of their installation on the actions. The question is, how well and accurate is the chambering done on their end (the specific manufacturers). Do they indicate the barrels to zero on the 10,000 scale? Just curious what you guys think. Bottom line is, what is their mastery in the gunsmithing world? Something tells me that there are a lot opinions

Nobody is guaranteeing dialed in to .0000”. You’ll find some claims of .0002”, which is totally doable. Lot of shops do prefits, some better than others, but its not a question of mastery imo. They all know how to do it well. Like any production item, there has to be a balancing of tolerances and productivity. Only question that matters is, do the barrels shoot?

 

[Lennyk]

Nobody is guaranteeing dialed in to .0000”. You’ll find some claims of .0002”, which is totally doable. Lot of shops do prefits, some better than others, but its not a question of mastery imo. They all know how to do it well. Like any production item, there has to be a balancing of tolerances and productivity. Only question that matters is, do the barrels shoot?

Thank you and agreed...but how do you know in advance?

 

[Supersubes]

Thank you and agreed...but how do you know in advance?

The reputable makers would exchange a barrel that didn’t shoot, so how they dial in doesn’t matter for the consumer.

What if I told you that just because the indicator runs on zeros that does not mean the bore is running on zeros? There are a number of ways to dial a barrel in, and all have drawbacks. Then add in crooked bores, non uniform land heights/groove depths, and you're just chasing ghosts. Its a series of trade-offs.

 

[aquasales]

I recently built a prefit with a barrel from a company I won't name. It didn't shoot.
I didn't gauge it before shooting, but finally did to check it out.
It would close on a no-go like it was an empty chamber.
One piece of tape on the gauge and it would close with slight resistance.
Two pieces wouldn't close at all.
I contacted the maker, they sent me a shipping label and are fixing it.
We'll see how it goes.

 

[Shanerbanner10]

How they indicate can depend on what kind of machine they are using. Example: CNC many indicate differently than one would on a manual machine lathe with a shorter headstock. There are many ways to skin that cat but at the end of the day most of the smiths will get it within .0002" or better. That can take more time than the actual machining in some cases.

 

[DeathBeforeDismount]

Not all prefits are the same. Buy from a top smith (LRI, SPR, Stuetsville, ICE, 5x5) or buy from one of the bargain houses and lessor joints and get those kinds of results.

Also most of the good, prefit actions are within .001". .0002 is a ridiculous target number. The headspace range is usually within .010"

 

[Supersubes]

Not all prefits are the same. Buy from a top smith (LRI, SPR, Stuetsville, ICE, 5x5) or buy from one of the bargain houses and lessor joints and get those kinds of results.

Also most of the good, prefit actions are within .001". .0002 is a ridiculous target number. The headspace range is usually within .010"

The .0002 being mentioned is in regards to dialing in the bore within .0002 of the lathe axis. Not related to headspace.

 

[DeathBeforeDismount]

The .0002 being mentioned is in regards to dialing in the bore within .0002 of the lathe axis. Not related to headspace.

Ah gotcha. I mean that kind of goes without saying. I guess I was wondering why that was unique to prefits? All barrels are going to be indicated to the bore.

 

[Supersubes]

Ah gotcha. I mean that kind of goes without saying. I guess I was wondering why that was unique to prefits? All barrels are going to be indicated to the bore.

Right, but the op wanted confirmation which specific prefit manf’s, if any, were dialing bores to .0000”. .0002” was mentioned after that, etc.

 

[hero's machine]

Once you've dialed a few to the tenths....you can appreciate the effort required. I'm curious how many cnc shops just touch off and let it eat without a fixture like the tbas.

 

[DeathBeforeDismount]

And who is going to know that besides the manufacture. And if they aren't, are they going to admit it? Its a silly question that is irrelevant.

 

[JBoomhauer]

And who is going to know that besides the manufacture. And if they aren't, are they going to admit it? Its a silly question that is irrelevant.

That last line sums it up.

 

[Supersubes]

And who is going to know that besides the manufacture. And if they aren't, are they going to admit it? Its a silly question that is irrelevant.

That last line sums it up.

Agreed. I was trying to walk him into that, but it looks like he’s disappeared.

 

[Rio Precision Gunworks]

You mentioned PRS. It's going be fairly hard to find any quality prefit that won't exceed the amount of precision needed for PRS.

 

[Lennyk]

You guys are awesome, and apologies for the absence. BTW, Happy Thanksgiving to all! In all, I guess it's just a matter of faith and trust. PRS and OCD seems to go hand in hand! In my perfect world, I would have a precision lathe, have the knowledge and experience to use it. Go to Gordi's course. Do my own barrels. I can only wish. I came across an amazing thread not long ago where a gunsmith from Pennsylvania (I'm out of Maryland) chimed in. He had very good insights. The prefits open the world to custom actions, and that's the super amazing stuff. I guess kudos to Savage to let us know that this is possible.

 

[Shanerbanner10]

You guys are awesome, and apologies for the absence. BTW, Happy Thanksgiving to all! In all, I guess it's just a matter of faith and trust. PRS and OCD seems to go hand in hand! In my perfect world, I would have a precision lathe, have the knowledge and experience to use it. Go to Gordi's course. Do my own barrels. I can only wish. I came across an amazing thread not long ago where a gunsmith from Pennsylvania (I'm out of Maryland) chimed in. He had very good insights. The prefits open the world to custom actions, and that's the super amazing stuff. I guess kudos to Savage to let us know that this is possible.

I wouldn't say kudos to savage. I'd say kudos to modern manufacturing processes making their way into precision rilfes. In my opinion it took too long. CNC machines have been able to hold these tolerances to produce receivers that accept shouldered prefits for quite sometime. There is quite literally nothing magical about turning a barrel. I started a business in my garage with a $2500 dollar lathe that I picked up in Detroit and brought back to Oklahoma. I knew nothing. I had talked to some people and gathered my knowledge from the good ole internet. Ran the business for 6 years on that lathe producing thousands of shouldered prefits. The machinery and tooling is not all that expensive. The "knowledge" is on the internet for anyone to learn without taking a course. The actual machining that takes place is not hard. Anyone that says that it is, is just silly. Its super basic turning, threading and reaming. Don't let the internet gunsmiths fool you, a monkey could spin a quality barrel with limited training.

 

[Lennyk]

a monkey could spin a quality barrel with limited training

You made my night! Here I am sitting at the keyboard with Stoli Elit, and I am laughing my brains out. What a wonderful community!

 

[Lennyk]

And my "kudos to Savage" is based in my belief that they were the 1st commercial "prefit." Am I wrong?

 

[Mike Casselton]

Savage barrels weren't actually "prefit."
They were made with a barrel nut to allow adjustable headspace.

It was all done to allow faster, cheaper production.


Just so you're aware, a true Prefit actually has a shoulder. A Remage/Savage/etc had the nut to allow for variances in receiver face to bolt face distance.

 

[Rubicon Precision]

If you find a builder to tell you how they hold a barrel, the maximum total indicator reading they will accept pre-machining, and where that reading is taken, how do you plan on verifying it once you get the barrel?

I know how I’m doing it. I know how some others are doing it. My method works great for me any my customers. I’d laugh if the internet said I was doing it wrong, because, well, the internet told them so…

 

[Rubicon Precision]

Once you've dialed a few to the tenths....you can appreciate the effort required. I'm curious how many cnc shops just touch off and let it eat without a fixture like the tbas.

I doubt any do that. You’d be crashing tools if you tried to rapid a bushing that is >.0002” smaller than the bore, if the bore was out more than that.

 

[Bigrederic]

I wouldn't say kudos to savage. I'd say kudos to modern manufacturing processes making their way into precision rilfes. In my opinion it took too long. CNC machines have been able to hold these tolerances to produce receivers that accept shouldered prefits for quite sometime. There is quite literally nothing magical about turning a barrel. I started a business in my garage with a $2500 dollar lathe that I picked up in Detroit and brought back to Oklahoma. I knew nothing. I had talked to some people and gathered my knowledge from the good ole internet. Ran the business for 6 years on that lathe producing thousands of shouldered prefits. The machinery and tooling is not all that expensive. The "knowledge" is on the internet for anyone to learn without taking a course. The actual machining that takes place is not hard. Anyone that says that it is, is just silly. Its super basic turning, threading and reaming. Don't let the internet gunsmiths fool you, a monkey could spin a quality barrel with limited training.

That is what I am working towards in my spare time... I like to tinker, and treated this like black magic for too long.