243 vs 243ai vs 6 creed

[satchamo]

Well I just saw McGowen is running a sale so you know, I “have” to take advantage.

I’m currently running a fast twist 243 tikka that I had lopped at 18”. I’m sitting around 500 rounds on that barrel and plan to shoot ALOT heading into an elk hunt this fall. So I wanna go ahead and have a barrel spun up to replace it when the time comes.

The barrel would be 1:8 twist/18 in running suppressed on a t3x that’s sitting in an Xlr element. So I’m stuck with 308 mags (don’t think this matters at all but throwing it out)

Initially I was thinking 6 creed for the factory options but at this point I’m fully kitted to reload 243 and actually have been enjoying it quite a bit. So now 243ai has entered the chat as a consideration since I’m comfortable reloading.

So obviously with anything other than 243 I’m buying new dies which is kind of a wash in my mind. Then there’s brass - with 243ai can you fire form fired 243 brass? I do have an annealer if that helps.

Right now I’m leaning heavily towards 243ai, then 243 then 6 creed. I honestly want the most speed I can get out of whatever which is why I’m leaning 243ai.

I was hoping to get some opinions from the folks here on which way to go having never fire formed or run a wildcat of any kind.

 

[il_cop]

I went through the same debate. Chose to stick with fast twist 243 for a few reasons.

I don't shoot factory ammo
Already have components
Aleady have loads developed
Fireforming takes time away from practice
I personally don't need anymore speed. The velocity window is already beyond my field capability.

 

[Pwb199]

For what it’s worth - I have a 260ai and while fire forming, the hand loads are incredibly accurate. No time wasted there. Yes you can fire-form fired brass.

 

[HandgunHTR]

I went through the same debate. Chose to stick with fast twist 243 for a few reasons.

I don't shoot factory ammo
Already have components
Aleady have loads developed
Fireforming takes time away from practice
I personally don't need anymore speed. The velocity window is already beyond my field capability.

If you want a bit more speed then go for the AI. That being said, it won't add as much as you might think. A lot of time people get big increases in speed because they are overpressure. You can overpressure an AI case and not see the traditional pressure signs due to the lower body taper (case holds to the wall better), so rearward thrust is reduced. Your primer pockets will often be the indicator that you are overpressure in that you will find them starting to loosen up after 2-3 firings.
That being said, I have 7 different "Improved" cartridges in my rifle stable currently. I like wildcats and they have their place. I would go AI just because it is something different.

As for the quoted above:
Already have components - the only thing different in components between a parent and an AI cartridge is the dies. Otherwise they are pretty much the same.
Already have loads developed - in my experience, a good load for a parent cartridge will be a good load for the AI, just with a bit more powder. Increase your accuracy load in the parent by 3-5% and a lot of times it is a good load for the AI.
Fireforming takes time away from practice - unless you are doing something like the COW fireforming, it isn't taking away from practice at all. Practice is about the fundamentals of shooting, not how big your groups are. You can focus on all of those things shooting fireforming loads. Plus, as Pwb199 pointed out, many times a fireforming load will also print small groups. All that is required when you start shooting full AI loads is an adjustment in zero.

 

[satchamo]

If you want a bit more speed then go for the AI. That being said, it won't add as much as you might think. A lot of time people get big increases in speed because they are overpressure. You can overpressure an AI case and not see the traditional pressure signs due to the lower body taper (case holds to the wall better), so rearward thrust is reduced. Your primer pockets will often be the indicator that you are overpressure in that you will find them starting to loosen up after 2-3 firings.
That being said, I have 7 different "Improved" cartridges in my rifle stable currently. I like wildcats and they have their place. I would go AI just because it is something different.

As for the quoted above:
Already have components - the only thing different in components between a parent and an AI cartridge is the dies. Otherwise they are pretty much the same.
Already have loads developed - in my experience, a good load for a parent cartridge will be a good load for the AI, just with a bit more powder. Increase your accuracy load in the parent by 3-5% and a lot of times it is a good load for the AI.
Fireforming takes time away from practice - unless you are doing something like the COW fireforming, it isn't taking away from practice at all. Practice is about the fundamentals of shooting, not how big your groups are. You can focus on all of those things shooting fireforming loads. Plus, as Pwb199 pointed out, many times a fireforming load will also print small groups. All that is required when you start shooting full AI loads is an adjustment in zero.

This might be a stupid question but running it at 18 - is that enough barrel to burn up additional powder with say 4350 if I go AI?

 

[TxLite]

I was looking at these 3 as well. I ended up on a 6mm creed and have no regrets. Factory Berger 108’s averaged 2700. Haven’t had a chance to proof my load yet but in initial testing, h4350 and the once fired Lapua brass is sending the Berger 108’s at an average 2943fps with a 3 shot sd of 3.4 and sub half minute (I know, 3 shot, don’t care).

Hoping to get out soon and proof it but so far really happy with the choice.

 

[satchamo]

I was looking at these 3 as well. I ended up on a 6mm creed and have no regrets. Factory Berger 108’s averaged 2700. Haven’t had a chance to proof my load yet but in initial testing, h4350 and the once fired Lapua brass is sending the Berger 108’s at an average 2943fps with a 3 shot sd of 3.4 and sub half minute (I know, 3 shot, don’t care).

Hoping to get out soon and proof it but so far really happy with the choice.

What length barrel?

 

[TxLite]

What length barrel?

18”

 

[satchamo]

18”

Ok you might have just made up my mind for me

 

[TxLite]

Ok you might have just made up my mind for me

I’d say it’s definitely on the upper end of what it should be doing so I wouldn’t use my number as a set in stone capability, but I have seen others in the same range

I have no doubt I’m over Saami pressures but in my rifle the primers look fine and no stiff bolt lift so I’ll continue to run it until it starts acting goofy

Even at the factory ammo velocity of 2700 it would do fine for what I personally was looking for out of the rifle

 

[HandgunHTR]

This might be a stupid question but running it at 18 - is that enough barrel to burn up additional powder with say 4350 if I go AI?

All the powder is being burnt in the first 8-10" of the barrel for that round. I have shot a standard .243 out of a 15" XP-100 with no issues. The "unburnt" powder thing is pretty much a wives tale to explain the large fireballs associated with large cartridges and short barrels.

I’d say it’s definitely on the upper end of what it should be doing so I wouldn’t use my number as a set in stone capability, but I have seen others in the same range

I have no doubt I’m over Saami pressures but in my rifle the primers look fine and no stiff bolt lift so I’ll continue to run it until it starts acting goofy

Even at the factory ammo velocity of 2700 it would do fine for what I personally was looking for out of the rifle

If factory ammo is giving you 2700 and you are getting 2950 with handloads, you are severely over-pressure. Lapua brass is hardy stuff, but I would be surprised if you get more than 2 loads out of it before your primer pockets give up the ghost.

 

[wpeach1912]

What kind of speeds are you currently getting in your 243?

 

[TxLite]

If factory ammo is giving you 2700 and you are getting 2950 with handloads, you are severely over-pressure. Lapua brass is hardy stuff, but I would be surprised if you get more than 2 loads out of it before your primer pockets give up the ghost.

I am at hodgdon max load (est. 60k psi) and .5gr over what Berger lists as max load. I’m not exactly going full pipe bomb, but yes, they are a little spicy.

 

[satchamo]

What kind of speeds are you currently getting in your 243?

2850 with 108s

 

[HandgunHTR]

I am at hodgdon max load (est. 60k psi) and .5gr over what Berger lists as max load. I’m not exactly going full pipe bomb, but yes, they are a little spicy.

Fair enough. Just keep an eye on your primer pockets. Remember, every barrel is different as is the pressure if you are using different brass and/or primers than the books.

 

[PistolPete]

How much slower would factory loads in 243 be when fired in a 243 AI chamber than in a regular 243 chamber, all else equal? I assume the larger chamber reduces pressures to some extent, but if the difference in insignificant, then your "fireforming" loads could likely be as useful for practice or hunting as any other, but with a small velocity penalty.

 

[Natebonebusta]

Out of my tikka 1/8 cut to 16.5”
108 eldm is 2560 at the muzzle with a .5gr less than max of SW Long Rifle

I did achieve 2670 out of the 108’s in the tikka with Superformance but SWLR produced a better group.

Out of my xbolt 1/10 cut to 18.5”
95gr Nos BT is 2995 at the muzzle with imr4350