Need help with 6mm BRA

[MTB doc]

Hoping to get advice for my next build. I'm planning on doing a 6mm BRA barreled action which I will drop into a MPA Matrix chassis. I have a few questions which I am sure will be basic for some of you but I appreciate any advice/help.

1. Action- I was thinking Bighorn TL3. I would like to be able to use pre-fits. Is there an advantage to going with the TL3 (integral lug) over an Origin given I plan on using pre-fits? Any other action(s) suited better for pre-fits? Any reason to NOT use prefits?

2. Barreled Action- since I plan on using pre-fits, do I need to make sure the original barreled action has a pre-fit barrel on it? Do I order the action and barrel separate since I think I want a pre-fit?

3. Freebore/who to get the barrel/action from. Is there anyone in particular who has a known reamer that I should get the action/barrel from? Like @Alex Wheeler?


Any help/advice greatly appreciated. Thanks.

 

[Dthomas3523]

Several actions have the ability to use prefits. Though IMO, the only reason to use them is if you can get them cheaper than what it would cost to buy a blank and have your Smith chamber it. Once your Smith has your receiver dimensions, the rest are essentially pre fits. I run lone peak Fuzions, but haven’t used a “prefit” as none of them I’ve seen would save me enough money to care.

Wheeler 6bra is always a good choice. I can’t remember what the neck size is, but I prefer a .275 neck on any 6mm. That gives .006 clearance on any brass that is .013 thick and .004 on brass that is .014. If you go with something like a .272 neck and get ahold if something like Peterson brass that’s .014, you might end up with issues or turning necks. So, I would personally order a reamer such as wheeler‘s, but have the neck spec’d at .275

Freebore is fairly easy. Do something like a .104 or .120. If you decide after doing some dummy rounds you want more, your smith can run a throater. You can always throat out more freebore. You can’t put any back.

 

[King_beardsly]

I did something similar last year, but went with a dasher instead with a TL3 and prefits after running an origin the year before. The differences between the origin and TL go a lot deep then just the pinned lug and integrated lug. The have different cocking ramp profiles, bolt handle angles, and receiver materials. That being said I feel that the TL feels leaps and bounds better if you run them side by side.

You can purchase the action and barrel separately if your doing a prefit, just need the small investment in the proper tool for the install and to check headspace just to air on the side of caution. As for reamers that one area that I haven’t really gotten to deep into but I will say .104 freebore has worked great for me.

 

[Sheldon N]

1. Action- I was thinking Bighorn TL3. I would like to be able to use pre-fits. Is there an advantage to going with the TL3 (integral lug) over an Origin given I plan on using pre-fits? Any other action(s) suited better for pre-fits? Any reason to NOT use prefits?

2. Barreled Action- since I plan on using pre-fits, do I need to make sure the original barreled action has a pre-fit barrel on it? Do I order the action and barrel separate since I think I want a pre-fit?

3. Freebore/who to get the barrel/action from. Is there anyone in particular who has a known reamer that I should get the action/barrel from? Like @Alex Wheeler?

Both the Origin and the TL3 will work fine with prefits, I do think having an integral lug is nice when switching barrels as there are less parts involved. Lots of other actions out there suited for prefits, Lone Peak and Impact are two common ones.

You can order the action and barrel separately, provided you have tools to assemble them yourself (action wrench, barrel vise, torque wrench). A set of go/no-go gauges is optional, I've never bought them. Just put a piece of 6BR brass in the chamber and see if you get slight resistance on bolt close. If you buy the barrel/action together they are likely to be sold as a "barreled action" rather than a prefit. Just semantics, as the resulting product will be the same thing either way.

For freebore I've shot both .104 and .135 freebore barrels, both shot great. It seems like most 6BRA reamers out there are based on the successful Alex Wheeler print, but with a neck diameter between .272-274. Many capable gunsmiths out there who can either make you a prefit or who sell them off the shelf.

 

[MTB doc]

Several actions have the ability to use prefits. Though IMO, the only reason to use them is if you can get them cheaper than what it would cost to buy a blank and have your Smith chamber it. Once your Smith has your receiver dimensions, the rest are essentially pre fits. I run lone peak Fuzions, but haven’t used a “prefit” as none of them I’ve seen would save me enough money to care.

Wheeler 6bra is always a good choice. I can’t remember what the neck size is, but I prefer a .275 neck on any 6mm. That gives .006 clearance on any brass that is .013 thick and .004 on brass that is .014. If you go with something like a .272 neck and get ahold if something like Peterson brass that’s .014, you might end up with issues or turning necks. So, I would personally order a reamer such as wheeler‘s, but have the neck spec’d at .275

Freebore is fairly easy. Do something like a .104 or .120. If you decide after doing some dummy rounds you want more, your smith can run a throater. You can always throat out more freebore. You can’t put any back.

Thanks so much, this is exactly the type of info that I need to be educated on. Appreciate it.

 

[MTB doc]

I did something similar last year, but went with a dasher instead with a TL3 and prefits after running an origin the year before. The differences between the origin and TL go a lot deep then just the pinned lug and integrated lug. The have different cocking ramp profiles, bolt handle angles, and receiver materials. That being said I feel that the TL feels leaps and bounds better if you run them side by side.

You can purchase the action and barrel separately if your doing a prefit, just need the small investment in the proper tool for the install and to check headspace just to air on the side of caution. As for reamers that one area that I haven’t really gotten to deep into but I will say .104 freebore has worked great for me.

Thanks, the comparison on the actions helps a lot.

 

[King_beardsly]

Thanks, the comparison on the actions helps a lot.

You’re welcome, figured I’d chime in since I have experience with both, you can’t really go wrong with either just ones a fair bit more polished and refined in my eyes.

 

[MTB doc]

Both the Origin and the TL3 will work fine with prefits, I do think having an integral lug is nice when switching barrels as there are less parts involved. Lots of other actions out there suited for prefits, Lone Peak and Impact are two common ones.

You can order the action and barrel separately, provided you have tools to assemble them yourself (action wrench, barrel vise, torque wrench). A set of go/no-go gauges is optional, I've never bought them. Just put a piece of 6BR brass in the chamber and see if you get slight resistance on bolt close. If you buy the barrel/action together they are likely to be sold as a "barreled action" rather than a prefit. Just semantics, as the resulting product will be the same thing either way.

For freebore I've shot both .104 and .135 freebore barrels, both shot great. It seems like most 6BRA reamers out there are based on the successful Alex Wheeler print, but with a neck diameter between .272-274. Many capable gunsmiths out there who can either make you a prefit or who sell them off the shelf.

Thanks. My whole reason for wanting to go the prefit route is because I don't really have a smith nearby that I know/trust. Also, I like to work on my own stuff when possible. Based on what you were saying, it does sound like it's not hard to do the pre-fits if you have the right tools. Like most guys, I enjoy getting new tools and I have no issue with buying exactly what is needed.

 

[MTB doc]

I second a .274-.275 neck. No need to neck turn Lapua 6BR brass unless you're a hermit.

Yes, I should have mentioned that, I have no interest in neck turning.

 

[King_beardsly]

Thanks. My whole reason for wanting to go the prefit route is because I don't really have a smith nearby that I know/trust. Also, I like to work on my own stuff when possible. Based on what you were saying, it does sound like it's not hard to do the pre-fits if you have the right tools. Like most guys, I enjoy getting new tools and I have no issue with buying exactly what is needed.

It’s super easy with the proper tools, just need a barrel vice, action wrench and torque wrench with the appropriate socket for the action wrench. I actually bolted my barrel vice to stacked 2x4’s and stood on it to torque down the action since my work bench wasn’t finished.

 

[King_beardsly]

The sac vice is pretty awesome and now with them releasing the bravo version for a better price point it’s hard to argue with them.

 

[Forward543]

JGS BRA #1 with .272 neck runs Lapua Brass well. Don't get too tied up in the freebore, unless you are trying to build a 30" barrel and trying to get it to run super fast. This cartridge does well running controlled speeds. So I don't think there is a reason to push too hard. Mine is in nucleus, I have a reamer, and have used prefits. Either way is fine.

 

[MTB doc]

JGS BRA #1 with .272 neck runs Lapua Brass well. Don't get too tied up in the freebore, unless you are trying to build a 30" barrel and trying to get it to run super fast. This cartridge does well running controlled speeds. So I don't think there is a reason to push too hard. Mine is in nucleus, I have a reamer, and have used prefits. Either way is fine.

Thanks, I was considering getting that reamer but wasn't sure if whomever is selling the prefit (Keystone, PVA, etc) already has that exact one and that is what they use.

 

[Forward543]

Thanks, I was considering getting that reamer but wasn't sure if whomever is selling the prefit (Keystone, PVA, etc) already has that exact one and that is what they use.

If you buy a reamer, do not run pre fits. Buy a barrel and have a smith cut the chamber with that reamer. If you don't want to send the action, you can have the smith cut a "pre fit" for your action. The advantage is you won't have to change much between barrels. Or you can send a hand full of barrels to your smith with the reamer, and have them all cut at once. Then you are done for a minute.

 

[jmw]

Buy a lone peak fuzion or a impact, call TS customs, have them spin up a barrel, screw it on action and shoot. It is just that easy

 

[B-P-UU]

Buy a lone peak fuzion or a impact, call TS customs, have them spin up a barrel, screw it on action and shoot. It is just that easy

This is the correct answer