Help Needed for Custom "Tikka T3x Tac A1" Build in 6.5 PRC

[Eamonn100]

Hi, it my first time posting and I've just got my first gun licence. (I am posting from New Zealand).

I hope everyone's doing well. I've been contemplating a custom rifle build for a while now and I'm seeking your expertise to help me select the best components based on my requirements. I'm essentially aiming to create a lightweight version of the Tikka T3x Tac A1, but chambered in 6.5 PRC, for long-range target shooting and future hunting endeavors once I've gained some experience.

Here are my specific requirements:

1. 2 Stage Trigger: I prefer a 2-stage trigger for the precision it offers. Any recommendations for a reliable, crisp 2-stage trigger?
2. Tikka Bolt Action: I've always been a fan of Tikka actions for their smoothness and reliability. Should I go for the Tikka T3x action, or are there any other Tikka actions I should consider?
3. 26 to 28" Barrel: I'm looking for a longer barrel to maximize the potential of the 6.5 PRC cartridge for long-range accuracy. Any suggestions for high-quality barrels in this length range?
4. 6.5 PRC Cartridge: This cartridge seems to strike a great balance between velocity, ballistic performance, and manageable recoil for my purposes. Any thoughts on the best 6.5 PRC loads or any special considerations I should keep in mind?
5. A BLK Bi-pod: I'd like the ability to mount A BLK Bi-pod. Are there any specific bipod mounting options or adapters I should consider for the Tikka platform?
6. Folding Stock: Lastly, I'd love a folding stock for ease of transport and storage. Do you know of any folding stock options compatible with the Tikka T3x action that would work well for this build.

I'm grateful for any guidance, recommendations, or personal experiences you can share regarding these components. I want this custom build to be a precision tool that I can enjoy for both long-range target shooting and eventually hunting, so your insights mean a lot to me.

Thanks in advance for your help, and I look forward to hearing your thoughts and suggestions!

 

[Okie_Poke]

Welcome to the forum. I'm mostly chiming in here to follow along to see what others are going to recommend to you. But I'll provide a little bit of feedback on a few items. I'm speaking from a daydreaming perspective more than an experience perspective with respect to most of the below, so take my thoughts with a grain of salt.

I have a Tikka rifle and I'm a fan. I will likely own another one at some point. I'm only aware of their T3x centerfire and T1x rimfire actions, so I don't know of any Tikka action that would work for you other than the T3x (or older T3 if you find a used one).

The 6.5 PRC seems to be a fine cartridge choice. I don't have one, but if it meets your needs/wants and you can get ammo for it where you live, I say go for it. Anything potentially negative I have to say about the cartridge is based only on internet rumors, so I'll defer to the folks who actually shoot and reload for that cartridge.

I'm not sure if you're starting from a bare action and building completely up from there, or if you are buying a rifle and then upgrading things as you go. If the latter, Tikka's T3x Super Varmint model comes in 6.5 PRC and has a two-stage trigger from the factory. It's only a 24" barrel, but it would check several boxes to get you started.

I'm not familiar with the BLK bipod. A little google-fu makes it look like that is a replacement forend with an integrated bipod for a few rifles, including the Tikka T3x TAC 1. I don't have any idea how it attaches or if it would work with any other Tikka model or any other chassis. I also don't know if you can put the 6.5 PRC in Tikka's TAC chassis---I presume, but do not know, that there is a reason Tikka doesn't offer that model in 6.5 PRC.

Among my current daydream projects is a Tikka T3x sitting in an MDT HNT26 chassis with a folding stock and an ARCA forend. I don't own one (yet), but it's something I'm considering for a similar project at some point.

 

[Eamonn100]

Welcome to the forum. I'm mostly chiming in here to follow along to see what others are going to recommend to you. But I'll provide a little bit of feedback on a few items. I'm speaking from a daydreaming perspective more than an experience perspective with respect to most of the below, so take my thoughts with a grain of salt.

I have a Tikka rifle and I'm a fan. I will likely own another one at some point. I'm only aware of their T3x centerfire and T1x rimfire actions, so I don't know of any Tikka action that would work for you other than the T3x (or older T3 if you find a used one).

The 6.5 PRC seems to be a fine cartridge choice. I don't have one, but if it meets your needs/wants and you can get ammo for it where you live, I say go for it. Anything potentially negative I have to say about the cartridge is based only on internet rumors, so I'll defer to the folks who actually shoot and reload for that cartridge.

I'm not sure if you're starting from a bare action and building completely up from there, or if you are buying a rifle and then upgrading things as you go. If the latter, Tikka's T3x Super Varmint model comes in 6.5 PRC and has a two-stage trigger from the factory. It's only a 24" barrel, but it would check several boxes to get you started.

I'm not familiar with the BLK bipod. A little google-fu makes it look like that is a replacement forend with an integrated bipod for a few rifles, including the Tikka T3x TAC 1. I don't have any idea how it attaches or if it would work with any other Tikka model or any other chassis. I also don't know if you can put the 6.5 PRC in Tikka's TAC chassis---I presume, but do not know, that there is a reason Tikka doesn't offer that model in 6.5 PRC.

Among my current daydream projects is a Tikka T3x sitting in an MDT HNT26 chassis with a folding stock and an ARCA forend. I don't own one (yet), but it's something I'm considering for a similar project at some point.

Thank you for your reply...

mostly my post is to make sure what parts actually fit to what other parts... as I'm new to gun ownership/components and don't really know what's even possible with custom/modifications, etc...

" Tikka's T3x Super Varmint model comes in 6.5 PRC and has a two-stage trigger"... yes I am aware of that... but how possible is it to get that same barrel in a 26"-28" barrel? Can that be ordered or is it not possible? Also, does the Tikka's T3x Super Varmint barrel shoot the same as (for example) the T3x Tac A1 barrel, in regards to accuracy/repeatability? If not, what custom options are available?


"I'm not sure if you're starting from a bare action and building completely up from there, or if you are buying a rifle and then upgrading things as you go." ...Well, I'm not sure as I don't know what's even possible. I wouldn't mind just buying the barrel and action, if possible, then a folding stock, etc... if that a good way to proceed?


"I don't have any idea how it attaches or if it would work with any other Tikka model or any other chassis. I also don't know if you can put the 6.5 PRC in Tikka's TAC chassis"... Yes as a beginner, I am wondering things like this. How difficult is it... or is it even possible to put a 6.5 PRC barrel on a Tikka's TAC chassis?


"Tikka T3x sitting in an MDT HNT26 chassis"... Something like the MDT HNT26 chassis is what I have in mind, but with just a BLK bipod forend attached to it. Like I say, I'm not even sure what can be screwed to what. I guess I don't mind taking the difficult parts to a gunsmith.


"I presume, but do not know, that there is a reason Tikka doesn't offer that model in 6.5 PRC."... If they did it in a 6.5 PRC I'd be a happy man.

Thanks.

 

[thump_rrr]

A few things I'm not sure that you're aware of.
The Tikka T3X Tac A1 is available in .308 Winchester and 6.5 Creedmoor.
Barrel length is 20" or 24" for the .308 and 24" for the 6.5 Creedmoor
The Bolt face diameter of both of these cartridges is 0.473"

The 6.5PRC has a .532" or Magnum bolt face diameter.
6.5 PRC has a barrel life of between 1,000 and 2,000 rounds.
Many say that peak accuracy is around 1,000 rounds.
I don't own one so I can't talk from personal experience.
Also if you are going to reload 6.5 PRC takes about 30% more powder than 6.5 Creedmoor.

If I were a new shooter I would purchase the Tikka T3X Tac A1 if you like the feel of that rifle in 6.5 Creedmoor and I'd go out and shoot it, a lot.
Barrel life on the 6.5 Creedmoor should be about double than that of the 6.5 PRC.

Once you get proficient with it if you want to go to 6.5 PRC all you need to do is order a Magnum bolt and a prefit 6.5 PRC barrel in the length of your choice from someone like Proof Research.
EDIT: As mentioned by Okie_Poke you may also need to find a magazine that fits the T3X Tac A1 for 6.5 PRC.

I've never shot PRS but I've held the Tikka T3X Tac A1 and the barrel even at 24" feels quite heavy.
If I were going into PRS I'd look at what the competitors are using and go with that.

Another option is to get the T3X Super Varmint and put it in a KRG or MDT chassis.
I wouldn't get too caught up in a 24" VS a 26" barrel.
My 24" 6.5 Creedmoor shoots very well out to 1,000y even with a 24" barrel.
This is with Hornady Match 147gr ammo and Sierra Custom Competition 140gr ammo.

 

[Okie_Poke]

Lots of good info in @thump_rrr's post and a sound recommendation. There's one thing I'm not sure about, though:

Once you get proficient with it if you want to go to 6.5 PRC all you need to do is order a Magnum bolt and a prefit 6.5 PRC barrel in the length of your choic from someone like Proof Research.

Usually you can do this with a Tikka T3x action. My hesitation is whether that holds true when the action is sitting in the TAC A1 chassis. I just can't tell if there is a magazine that will work with the 6.5 PRC and that chassis together. The TAC A1 appears to use a different magazine than most T3x models. There very well may be, and @thump_rrr may know there is, but I just can't tell from what I've read.

" Tikka's T3x Super Varmint model comes in 6.5 PRC and has a two-stage trigger"... yes I am aware of that... but how possible is it to get that same barrel in a 26"-28" barrel? Can that be ordered or is it not possible? Also, does the Tikka's T3x Super Varmint barrel shoot the same as (for example) the T3x Tac A1 barrel, in regards to accuracy/repeatability? If not, what custom options are available?

From the factory, no. But you can order a prefit barrel from Proof and several others as thump_rrr mentioned. If you can't find a prefit in the configuration you want, you can order a barrel and have a gunsmith cut it to length and chamber it for you. All it costs is money.

"I'm not sure if you're starting from a bare action and building completely up from there, or if you are buying a rifle and then upgrading things as you go." ...Well, I'm not sure as I don't know what's even possible. I wouldn't mind just buying the barrel and action, if possible, then a folding stock, etc... if that a good way to proceed?

I have seen Tikka actions and semi-custom barreled actions for sale in some places. https://jaoutdoors.com/product/tikka-steel-barreled-action-builder-copy/. I haven't seen it be super cost-effective to go that route, however. If it were me, I would buy a factory rifle that got me started and then upgrade it after I shot it a while and determined what I liked and didn't like, which is why I mentioned the Super Varmint. If you are flexible on the cartridge, then thump_rrr's recommendation may be better than mine. My target rifle is in 6.5 Creedmoor instead of a 6.5 PRC for many of the reasons he mentioned.

"Tikka T3x sitting in an MDT HNT26 chassis"... Something like the MDT HNT26 chassis is what I have in mind, but with just a BLK bipod forend attached to it. Like I say, I'm not even sure what can be screwed to what. I guess I don't mind taking the difficult parts to a gunsmith.

Someone on the forum may be familiar with that forend/bipod and how it attaches. Short of that, I think you'd just have to email the manufacturer and ask them to what chasses that forend will attach.

 

[thump_rrr]

Lots of good info in @thump_rrr's post and a sound recommendation. There's one thing I'm not sure about, though:



Usually you can do this with a Tikka T3x action. My hesitation is whether that holds true when the action is sitting in the TAC A1 chassis. I just can't tell if there is a magazine that will work with the 6.5 PRC and that chassis together. The TAC A1 appears to use a different magazine than most T3x models. There very well may be, and @thump_rrr may know there is, but I just can't tell from what I've read.

I believe that you're correct.
I never thought of the Tikka proprietary magazines.
All of my rifles are setup for AICS magazines.

 

[Eamonn100]

A few things I'm not sure that you're aware of.
The Tikka T3X Tac A1 is available in .308 Winchester and 6.5 Creedmoor.
Barrel length is 20" or 24" for the .308 and 24" for the 6.5 Creedmoor
The Bolt face diameter of both of these cartridges is 0.473"

The 6.5PRC has a .532" or Magnum bolt face diameter.
6.5 PRC has a barrel life of between 1,000 and 2,000 rounds.
Many say that peak accuracy is around 1,000 rounds.
I don't own one so I can't talk from personal experience.
Also if you are going to reload 6.5 PRC takes about 30% more powder than 6.5 Creedmoor.

If I were a new shooter I would purchase the Tikka T3X Tac A1 if you like the feel of that rifle in 6.5 Creedmoor and I'd go out and shoot it, a lot.
Barrel life on the 6.5 Creedmoor should be about double than that of the 6.5 PRC.

Once you get proficient with it if you want to go to 6.5 PRC all you need to do is order a Magnum bolt and a prefit 6.5 PRC barrel in the length of your choice from someone like Proof Research.
EDIT: As mentioned by Okie_Poke you may also need to find a magazine that fits the T3X Tac A1 for 6.5 PRC.

I've never shot PRS but I've held the Tikka T3X Tac A1 and the barrel even at 24" feels quite heavy.
If I were going into PRS I'd look at what the competitors are using and go with that.

Another option is to get the T3X Super Varmint and put it in a KRG or MDT chassis.
I wouldn't get too caught up in a 24" VS a 26" barrel.
My 24" 6.5 Creedmoor shoots very well out to 1,000y even with a 24" barrel.
This is with Hornady Match 147gr ammo and Sierra Custom Competition 140gr ammo.

Thank you for your reply...

"Another option is to get the T3X Super Varmint and put it in a KRG or MDT chassis.".. yes I am thinking of this.

Is it possible just to buy the barrel and bolt action of a T3X Super Varmint? Rather than buying the stock as well? ie... just the parts I need?

 

[Eamonn100]

A few things I'm not sure that you're aware of.
The Tikka T3X Tac A1 is available in .308 Winchester and 6.5 Creedmoor.
Barrel length is 20" or 24" for the .308 and 24" for the 6.5 Creedmoor
The Bolt face diameter of both of these cartridges is 0.473"

The 6.5PRC has a .532" or Magnum bolt face diameter.
6.5 PRC has a barrel life of between 1,000 and 2,000 rounds.
Many say that peak accuracy is around 1,000 rounds.
I don't own one so I can't talk from personal experience.
Also if you are going to reload 6.5 PRC takes about 30% more powder than 6.5 Creedmoor.

If I were a new shooter I would purchase the Tikka T3X Tac A1 if you like the feel of that rifle in 6.5 Creedmoor and I'd go out and shoot it, a lot.
Barrel life on the 6.5 Creedmoor should be about double than that of the 6.5 PRC.

Once you get proficient with it if you want to go to 6.5 PRC all you need to do is order a Magnum bolt and a prefit 6.5 PRC barrel in the length of your choice from someone like Proof Research.
EDIT: As mentioned by Okie_Poke you may also need to find a magazine that fits the T3X Tac A1 for 6.5 PRC.

I've never shot PRS but I've held the Tikka T3X Tac A1 and the barrel even at 24" feels quite heavy.
If I were going into PRS I'd look at what the competitors are using and go with that.

Another option is to get the T3X Super Varmint and put it in a KRG or MDT chassis.
I wouldn't get too caught up in a 24" VS a 26" barrel.
My 24" 6.5 Creedmoor shoots very well out to 1,000y even with a 24" barrel.
This is with Hornady Match 147gr ammo and Sierra Custom Competition 140gr ammo.

That's interesting about the barrel life. What does a .308 have over a 6.5 Creedmoor?

 

[Eamonn100]

Lots of good info in @thump_rrr's post and a sound recommendation. There's one thing I'm not sure about, though:



Usually you can do this with a Tikka T3x action. My hesitation is whether that holds true when the action is sitting in the TAC A1 chassis. I just can't tell if there is a magazine that will work with the 6.5 PRC and that chassis together. The TAC A1 appears to use a different magazine than most T3x models. There very well may be, and @thump_rrr may know there is, but I just can't tell from what I've read.



From the factory, no. But you can order a prefit barrel from Proof and several others as thump_rrr mentioned. If you can't find a prefit in the configuration you want, you can order a barrel and have a gunsmith cut it to length and chamber it for you. All it costs is money.



I have seen Tikka actions and semi-custom barreled actions for sale in some places. https://jaoutdoors.com/product/tikka-steel-barreled-action-builder-copy/. I haven't seen it be super cost-effective to go that route, however. If it were me, I would buy a factory rifle that got me started and then upgrade it after I shot it a while and determined what I liked and didn't like, which is why I mentioned the Super Varmint. If you are flexible on the cartridge, then thump_rrr's recommendation may be better than mine. My target rifle is in 6.5 Creedmoor instead of a 6.5 PRC for many of the reasons he mentioned.



Someone on the forum may be familiar with that forend/bipod and how it attaches. Short of that, I think you'd just have to email the manufacturer and ask them to what chasses that forend will attach.

"From the factory, no. But you can order a prefit barrel from Proof and several others as thump_rrr mentioned. If you can't find a prefit in the configuration you want, you can order a barrel and have a gunsmith cut it to length and chamber it for you. All it costs is money."

Yes a prefit barrel... but what about getting a Tikka T3X Super Varmint bolt and chamber on their own... and then get a 26" custom barrel to add to them. That would do the trick. But from reading your post... A Tikka bolt and chamber isn't easy to get? Parts from the factory aren't easy come by?

 

[thump_rrr]

That's interesting about the barrel life. What does a .308 have over a 6.5 Creedmoor?

Barrel life of a .308 is about 4,000 - 5,000 rounds before accuracy begins to drop off.

You can cut in half the barrel life of the exact same barrel by loading different powders or very hot loads of even the same powder.

You can also cut the barrel life in about half again by shooting very rapidly. There are calculators out there which suggest how much time you should give between shots.
Obviously during competition you cannot wait 90 seconds between rounds but when sitting at the bench practicing you can.

Here is a link that I found very helpful.
https://www.darkearthtactical.co.za/blog/what-is-my-rifles-accurate-barrel-life-expectancy/

Here is an example of 3 different loads for a 300 Win Mag with the predicted barrel life of each which are discussed in the link I provided

Load #1​

• Bullet: Hornady 195gr ELD Match
• Propellant Load: 75.5gr of Vihtavuori N560
• Muzzle Velocity: 3025fps
• Muzzle Energy: 3975ft-lbs
• Effective Range at Sea-Level Pressure: 1440 meters
• Accurate Barrel Life: 1003 Rounds

Load #2​

• Bullet: Hornady 195gr ELD Match
• Propellant Load: 75.5gr of Vihtavuori N165
• Muzzle Velocity: 2932fps
• Muzzle Energy: 3738ft-lbs
• Effective Range at Sea-Level Pressure: 1390 meters
• Accurate Barrel Life: 1895 Rounds

Load #3​

• Bullet: Hornady 195gr ELD Match
• Propellant Load: 70.5gr of Vihtavuori N165
• Muzzle Velocity: 2748fps
• Muzzle Energy: 3284ft-lbs
• Effective Range at Sea-Level Pressure: 1280 meters
• Accurate Barrel Life: 2705 Rounds

As you can see just by using a different powder and reducing the velocity by only 4% between loads #1 and #2 the barrel life increased by 89%.

Between examples #2 and #3 velocity was reduced by less than 7% and barrel life increased by over 40%.

This is a perfect example of why you don’t always need to use the highest accuracy node in load development if the lower node will do what you want it to do.

On my 6.5 Creedmoor my low node is only 2633 ft/s but it has no problem reaching 1,000m accurately.

I know guys shooting to a maximum of 500M running close to 2,800 ft/s.

 

[thump_rrr]

"From the factory, no. But you can order a prefit barrel from Proof and several others as thump_rrr mentioned. If you can't find a prefit in the configuration you want, you can order a barrel and have a gunsmith cut it to length and chamber it for you. All it costs is money."

Yes a prefit barrel... but what about getting a Tikka T3X Super Varmint bolt and chamber on their own... and then get a 26" custom barrel to add to them. That would do the trick. But from reading your post... A Tikka bolt and chamber isn't easy to get? Parts from the factory aren't easy come by?

Tikka T3X magnum bolts are around $370usd when they can be found.
I spent the last 20 minutes trying to find one in stock and I couldn’t.

When you add their proprietary magazine which sells for 2x the price of an AICS magazine the desire for me to purchase a Tikka drops down to where I don’t even consider them anymore.

They are fine rifles but they offer nothing more to me than other rifles.

I went with an Ultimatum Deadline action which takes Savage small shank prefit barrels in a Remington footprint. The Big Horn Origin action also takes Savage small shank barrels. The beauty of that design is that with a few simple tools you can replace barrels at home without a need for a gunsmith.

As for the barrels, an aftermarket barrel is probably of better quality than factory.

 

[Eamonn100]

A few things I'm not sure that you're aware of.
The Tikka T3X Tac A1 is available in .308 Winchester and 6.5 Creedmoor.
Barrel length is 20" or 24" for the .308 and 24" for the 6.5 Creedmoor
The Bolt face diameter of both of these cartridges is 0.473"

The 6.5PRC has a .532" or Magnum bolt face diameter.
6.5 PRC has a barrel life of between 1,000 and 2,000 rounds.
Many say that peak accuracy is around 1,000 rounds.
I don't own one so I can't talk from personal experience.
Also if you are going to reload 6.5 PRC takes about 30% more powder than 6.5 Creedmoor.

If I were a new shooter I would purchase the Tikka T3X Tac A1 if you like the feel of that rifle in 6.5 Creedmoor and I'd go out and shoot it, a lot.
Barrel life on the 6.5 Creedmoor should be about double than that of the 6.5 PRC.

Once you get proficient with it if you want to go to 6.5 PRC all you need to do is order a Magnum bolt and a prefit 6.5 PRC barrel in the length of your choice from someone like Proof Research.
EDIT: As mentioned by Okie_Poke you may also need to find a magazine that fits the T3X Tac A1 for 6.5 PRC.

I've never shot PRS but I've held the Tikka T3X Tac A1 and the barrel even at 24" feels quite heavy.
If I were going into PRS I'd look at what the competitors are using and go with that.

Another option is to get the T3X Super Varmint and put it in a KRG or MDT chassis.
I wouldn't get too caught up in a 24" VS a 26" barrel.
My 24" 6.5 Creedmoor shoots very well out to 1,000y even with a 24" barrel.
This is with Hornady Match 147gr ammo and Sierra Custom Competition 140gr ammo.

"Once you get proficient with it if you want to go to 6.5 PRC all you need to do is order a Magnum bolt and a prefit 6.5 PRC barrel in the length of your choice from someone like Proof Research."

How hard is it to change a tikka t3x tac a1 in 6.5 Creedmoor to 6.5PRC?

(1). I mean... are the barrel's threading the same?

(2). Changing the bolt to the bigger Magnum bolt? What does that entail? Drilling out the action??

(3). Could you put a T3X Super Varmint 6.5 PRC bolt/action into a tikka t3x tac a1 chassis?

 

[thump_rrr]

"Once you get proficient with it if you want to go to 6.5 PRC all you need to do is order a Magnum bolt and a prefit 6.5 PRC barrel in the length of your choice from someone like Proof Research."

How hard is it to change a tikka t3x tac a1 in 6.5 Creedmoor to 6.5PRC?

(1). I mean... are the barrel's threading the same?

(2). Changing the bolt to the bigger Magnum bolt? What does that entail? Drilling out the action??

(3). Could you put a T3X Super Varmint 6.5 PRC bolt/action into a tikka t3x tac a1 chassis?

1) There are prefit barrels out there that are made to fit the T3 action.
Google is your friend.

2) No work or permnent alterations are required.
You just slide out 1 bolt and install the other one.
Finding one is the issue but if you buy a super varmint in 6.5 PRC you will have a magnum bolt.

3) The more I look at the 2 cartridges the more doubtful I am that this is doable.
The cartridge length of the 6.5 PRC is 2.955"
Most magazines for 308 and 6.5 Creedmoor which are the calibers that the T3X Tac A1 is sold in only hold cartridges that are 2.870" long.
There is also the issue that the 6.5 PRC is a magnum cartridge that has fatter rounds than the 308 or 6.5 Creedmoor.

I think your best course of action is to buy the Super Varmint and go with a different chassis.
I don't have time right now but I will do some research and come up with some chassis suggestions.

Edit: After a quick search the 6.5 PRC is designed around the short action, the same as 308, and 6.5 Creedmoor.

The only issue is the magazine length which is why I think you’ll have to abandon using the T3X Tax A1 chassis.

MDT has a variety of chassis at every price point that will fit the T3 action.
In the drop down menu’s look for Tikka T3 SA (Short Action).
You can also see that they sell 6.5 PRC magazines.

Masterpiece Arms also makes the BA Competition chassis to fit the Tikka T3 short action

 

[Eamonn100]

1) There are prefit barrels out there that are made to fit the T3 action.
Google is your friend.

2) No work or permnent alterations are required.
You just slide out 1 bolt and install the other one.
Finding one is the issue but if you buy a super varmint in 6.5 PRC you will have a magnum bolt.

3) The more I look at the 2 cartridges the more doubtful I am that this is doable.
The cartridge length of the 6.5 PRC is 2.955"
Most magazines for 308 and 6.5 Creedmoor which are the calibers that the T3X Tac A1 is sold in only hold cartridges that are 2.870" long.
There is also the issue that the 6.5 PRC is a magnum cartridge that has fatter rounds than the 308 or 6.5 Creedmoor.

I think your best course of action is to buy the Super Varmint and go with a different chassis.
I don't have time right now but I will do some research and come up with some chassis suggestions.

Edit: After a quick search the 6.5 PRC is designed around the short action, the same as 308, and 6.5 Creedmoor.

The only issue is the magazine length which is why I think you’ll have to abandon using the T3X Tax A1 chassis.

MDT has a variety of chassis at every price point that will fit the T3 action.
In the drop down menu’s look for Tikka T3 SA (Short Action).
You can also see that they sell 6.5 PRC magazines.

Masterpiece Arms also makes the BA Competition chassis to fit the Tikka T3 short action

" I think you’ll have to abandon using the T3X Tax A1 chassis."... Roger that... thanks.

I have been Googling all this alot... but I like to ask actual humans who are in the know. Incase I misread something or, even through inexperience, read and run with dodgy internet info.

I was just trying to make the TAC A1 chassis work because it is compatible with the integrated bipod I'm wanting.