243 AI-Any Input?

[Colorado Cowboy]

I am a big fan of PO Ackley, definately a man before his time. He would go nuts with all the new slow burning powders we have today. I have a .220 AI Swift that shoots lights out!. The .220's had a bad reputation of low barrel life when they first came out. Mine is a custom build with over 2000 rounds thru it. Still shooting fantastic groups.

 

[PathFinder]

H1000 in the .243 case is magic. I've considered 6 creedmoor before but can't come up for a valid reason being a handloader.

Different but similar, I recently did a 6x284 on a factory 8tw tikka barrel and the false shoulder is more consistent for forming than just jamming the bullets. At least it has been for me. With jamming I always got some pieces that didn't fully form vs the false shoulder that all came out perfect. Good luck on your project. I've got a set of .243ai dies on the bench that have been staring me in the face for years now that I probably need to put into use at some point. Looking forward to seeing your results.

What has your experience been with the standard 243 and H1000? I've read anything from 45-48 grains from max in the standard case.

 

[satchamo]

What has your experience been with the standard 243 and H1000? I've read anything from 45-48 grains from max in the standard case.

I tried it with 46 gr and it was pretty compressed and slow for me seating out to 2.8 with 108 eldms in SL brass. Small sample size. I will say it was very accurate tho.

Edit: big detail missed, only an 18” barrel so not ideal for h1000

 

[pods8 (Rugged Stitching)]

Different but similar, I recently did a 6x284 on a factory 8tw tikka barrel

Don't be a tease... lets hear some details / performance. Limited chatter on the 6x284 here so far but I've tried to keep an eye out for folks playing with this one. Which brass you necking down? Power / bullets tried?

 

[Karl B]

What has your experience been with the standard 243 and H1000? I've read anything from 45-48 grains from max in the standard case.

22" tikka 8tw with lapua brass and 108 eldm. Got me a nice bump over h4350. Accuracy is fantastic. Its a full case for sure though!

 

[Karl B]

Don't be a tease... lets hear some details / performance. Limited chatter on the 6x284 here so far but I've tried to keep an eye out for folks playing with this one. Which brass you necking down? Power / bullets tried?

Didnt mean to hijack the thread but 6.5x284 lapua brass. Settled on n570 and 105 target hybrids. Wasn't positive i would love it so just re-chambered a tikka .243 barrel as kind of a test dummy. Cut to 19". Tried some 115 hybrids and they shot decent but the 105's and 108 eldm both shot very well.

I tried h1000, n565, and n570. 570 was the clear speed winner with h1000, and n565 being about 75fps slower.

These were the ladders for the 3 powders and 115's. N570 was at that 3,100fps at pressure and horrible accuracy. H1000 and n565 both hit pressure at that 3,070fps mark. Id want to be down around 3,025 to feel good. H1000 was the winner for accuracy with the 115's.

 

[Karl B]

105 hybrids will be my go to for now though. Ive killed a bunch of stuff with them and like all bergers they just shoot. 30 shot group just to pull some more data. New jug of n570 was a bit slower. 30 shot average was 3,185fps

 

[Bater]

Have you had any issues in cold temps with the SRP? Seem to recall a few folks have.

Do it for science! Report back.

None, CCI450’s

 

[PathFinder]

Anyone have an idea what the standard freebore on a typical 243 AI reamer is? The throat in my Tikka is pretty short, and I assume a 243 AI is going to be roughly the same. For now the plan is to run a throater in it after doing the chamber. It's only an extra $30, so that brings the total rental to $120 with shipping.

Sent from my Pixel 6 using Tapatalk

 

[HandgunHTR]

Anyone have an idea what the standard freebore on a typical 243 AI reamer is? The throat in my Tikka is pretty short, and I assume a 243 AI is going to be roughly the same. For now the plan is to run a throater in it after doing the chamber. It's only an extra $30, so that brings the total rental to $120 with shipping.

Sent from my Pixel 6 using Tapatalk

Not sure there is a standard for the AIs (other than the 280AI). If you are renting from 4D, they can tell you who made the reamer and you can reach out them to find out. 4D may have the reamer print as well. Most likely PTG, JGS, or Manson.

 

[CJ_BG]

Anyone have an idea what the standard freebore on a typical 243 AI reamer is? The throat in my Tikka is pretty short, and I assume a 243 AI is going to be roughly the same. For now the plan is to run a throater in it after doing the chamber. It's only an extra $30, so that brings the total rental to $120 with shipping.

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No saami spec means no "standard". I would just load the bullet to the length you want and then chamber it for that setup. That's what I did with mine and what I will do again moving forward

If you do it post what you're getting with the 112s or 115s with the shorter barrel. I'm heavily debating a 7.5 or 8tw with a 18 or 20 inch barrel.

 

[Castle Rock]

I'm currently working on putting a 243 AI together on a Tikka. The plan is to hand ream a factory Tikka 243 20" threaded 1:8 barrel (already on hand) to 243 AI. It won't have the slightly shorter chamber of a typical AI, but I'll be starting with Alpha 260 brass so using a false shoulder to fireform will be pretty easy. Is it completely unreasonable to go to the 243 AI with the added cost of a reamer rental, fire forming, and more expensive dies? My reasoning for going to the AI is:

• Better brass life with little to no trimming. I despise trimming.
• ~10% capacity increase
  • Pushes it farther into slow powder territory (more on that below)
  • Velocity increase
• Use of H1000
  • Extended barrel life. Same idea as the 6 Comp Match and 6 SLR.
• The chamber needs more free bore anyways, may as well do both.
• The Alpha brass benefits from a fire form anyways, so that doesn't change much. I have lots of extra bullets and powder to do that with.

Basically the idea is to exceed 6 Creedmoor performance, but keep excellent long term barrel life. Even if I stick with the standard chamber, H1000 is going to be the powder of choice. Is the gain worth the time to ream the chamber, reamer rental, and more expensive dies?

You seem to have a good handle on the job, don’t be put off by hand reaming with mechanical assistance, ie a drill.
I have done this a few times with complete success.
A high quality cutting fluid is a must and blow the chips out very regularly from the reamer and barrel.

You can guide the shaft of the driver with a pair of split bushings in the rear receiver bridge , a long 3/8 socket extension makes a good driver, the little bit of slop at the connection allows the reamer to follow the existing chamber.
Mane up a couple of cases with the necked down brass and use them to set the headspace, then use the throating reamer once you have a fire formed case to make a dummy off.
Also make sure you strike out the 243 markings on the barrel

 

[PathFinder]

You seem to have a good handle on the job, don’t be put off by hand reaming with mechanical assistance, ie a drill.
I have done this a few times with complete success.
A high quality cutting fluid is a must and blow the chips out very regularly from the reamer and barrel.

You can guide the shaft of the driver with a pair of split bushings in the rear receiver bridge , a long 3/8 socket extension makes a good driver, the little bit of slop at the connection allows the reamer to follow the existing chamber.
Mane up a couple of cases with the necked down brass and use them to set the headspace, then use the throating reamer once you have a fire formed case to make a dummy off.
Also make sure you strike out the 243 markings on the barrel

Thanks for the input! I've been trying to decide if it's a bad idea to start with the drill. Sounds like it's worth a shot, so as long as it feels ok I'll probably run the drill really slowly until it gets partway down the shoulder. Reamers just use a 3/8" square drive correct? I've got one with a semi-ball end so that sounds like it will be good for the application.