View Full Version : Rechambering 243Win to 234AI

August 19, 2006, 07:30 PM
Need some info from any Gunsmiths out there...........

I ordered a custom barrel in a 243 Ackley Improved for my T/C Encore from a very reputable custom shop.

Make a long story short..they messed up and chambered the barrel for the std...243Win.

In talking with the people on the phone, they said for me to send the barrel back in and they will rechamber it to the 243AI.

I have talked to a few people about this and they have told me that by rechambering from the std 243 to the Ackley Improved...I will not have the true diminsions of the 243AI because of having to clean the shoulder area from the rechambering.....that the barrel will have to be set back a tad.

I do not think there is be a problem with this.....but have some concerns

Could you all give me some info on this situation...

Thank you

August 20, 2006, 11:01 AM
Your friends are correct.You cannot simply run an AI reamer into the chamber. The barrel needs to be set back. To do the job properly, the lump would have to be un-brazed, rear of the chamber machined off, new chamber and extractor groove cut, lump re-brazed and barrel refinished. The repaired barrel would be short of the overall length you ordered by the amount they had to machine off the rear of the chamber. IMO, it would be cheaper for the barrel supplier to build you a new barrel.

Harry Bonar
August 20, 2006, 07:42 PM
Dear Shooter:
First, I know they are fine rifles but I simply hate Encores.
Now, if your bbl is properly chambered for the 243 ( the 308 necked down to 243 cal) and the headspace is O.K. you aren't lost!
Let me explain that most all of Ackleys "improved" chambers are made so that the standard case that it is improved for can be used in the improved chamber due to the fact that the only thing you've changed is the neck/sholder area. Now, "improved chambers" are cut just up to the neck/sholder junction. This means that "standard: 243 cartridges can still be fired because they still bear on that small area - the neck/sholder junction. Now, also, "improved chambers when you shoot your 243 cartridge is fired in it will expand to the "improved chamber - thus giving you your "improved case. The body in an improved chamber is wider so that makes no difference as long as 243 winchester cases headspace within specs.
You can, if these conditions are met, run (very carefully) a 243 AI reamer in and save tour rifle.
Hope this helps.
Harry B.

Harry Bonar
August 20, 2006, 08:00 PM
dear Shooter;
Let me be very plain - your 243 (call Clymer and ask them if they agree with me) IF YOUR PRESENT HEADSPACE IS NOMINAL. you can run an "improved" AI reamer in and have a 243AI chamber - correctly done by a professional it will be fine. After all, how will you get reloadable cases for reloading without firing 243 cartridges in the AI chamber?
Yes, I know that the cases headspace on the "datum line" and when you "improve" the chamber to AI specs you headspace at the neck/shoulder area.
This must be done very carefully by a professional and I imagine the Co. who wanted you to return your bbl. would do exactly what I'm saying.
I just want you to know that this is a very precise and delicate process - I want to advise you of this.
Finally, the 243 AI case is still a std. 243 case blown out to Ackleys dimensions.
Please realize that you're fiddling with a "wildcat" 243. Reloading should be carried out according to Clymer instructions and specificatins. The 243AI is a great cartridge. Harry B.
P.S. - I would also contact Thompson Center and advise them of your plan! I do not like the Encore action concept AND - BE CAREFUL OF CUSTOM GUN SHOPS! You will need some professional help in handloading your 243AI

August 20, 2006, 10:25 PM
Thanks so much for your alls info...I really apprecate it.......

Bullberry Barrels is who made my barrel....When I first got my barrel.....I loaded up 2 boxes of 243win to fireform the some brass....I then noticed that it was not the 243 Ackley but the std 243! Called bullberry....they said they made a mistake...send it in and he would rechamber to the 243 Ackley Improved.......I would assume they know what they are doing......I sent it in a couple weeks ago and just got it back Saturday.

I just heard the same info that DnPRK gave me about rechambering....that the barrel had to be set back and that concerned me that Bullberry did not do this.....I am going to fireform some brass this weekend......

I have some very experienced (encore) shooters and reloaders helping me out on this...they have great success with their Encores with these ackleys. I will have plenty of coaching........

By the way.........that 243Win bullberry barrel cut one jagged hole at 100yds...

Thanks again for the concerns and help.......

August 20, 2006, 10:31 PM
Harry....are you located just outside of Belpre, Ohio? If so...I am just a few miles from you.

I am located outside of Parkersburg......

Harry Bonar
August 21, 2006, 06:17 PM
Dear KLH8:
Yes, I am - let me know how I can get in touch with you!
Thanks for comeback.
Harry B.

August 21, 2006, 07:07 PM


September 1, 2006, 03:05 PM
I recieved my barrel after the rechambering job from the 243win to the 243AI.
It definatley is not right. Was fireforming in the presence of a gunsmith that is in your area and we came to the conclusion that he did not run the reamer in deep enough. The shoulder had what is best to decribe a second step halfway down and other measurments outside of the 243AI specs! We fired that case 3x's. I called the manufacture and requested a new barrel. Well he wants to try again.....he said he will send me a sample fired case that was fired out of the chamber..and if it does not meet my approval...he will then make me a new barrel......So I have sent it back to him for the second time.

I will let you know the out come of my unfortunate event.....

Bud Helms
September 1, 2006, 03:57 PM
... a very precise and delicate process ... I'll say! :D I ruined a .30-'06 barrel that way. Getting the AI chamber reamer aligned perfectly with the standard chamber is a real challenge. Going back in and trying to cleanup a second time is, well, ... good luck. I suppose it could happen.

Jim Watson
September 1, 2006, 04:25 PM
By the way.........that 243Win bullberry barrel cut one jagged hole at 100yds...

A sign to leave well enough alone. Pity you didn't.

September 1, 2006, 05:19 PM
Jim...I had my heart set on the Ackley Improved........but yes.....that 243Win shot wonderfully and I did have second thoughts to leave it alone and keep it......I am "hoping" this guy knows what he's doing......I am having second thoughts on that............:(

Harry Bonar
September 4, 2006, 07:49 PM
Dear Sir:
You see, it appears to me that the AI. reamer was not taken in far enough!
This is a very, very detailed process - it must be done in a lathe with frequent measurements for depth. It is a detailed job but can be done if done carefully.
Do you have the 243 Ackley Improved reamer?
If you do it might be possible still to rectify this.
One of the problems with the Encore bbl is the brazed (?) piece on the bottom of the bbl. breach.
To do this the breach must be locked solidly in a chuck as close to the breach as possible. A steady rest won't work nor will many of the jugs and fixtures they use.
The AI reamer should JUST CLEAN UP THE 243 CHAMBER TO THE NECK AREA so that 243 headspaces there.
The other thing, if they get the chamber slightly deep would be to reduce your normal load about a grain from max - seat your bullets to the lands and fire form cases that way.
The better way is to expand the neck area to a larger dia. and then size down to 243 dia and let that be tightly headspaced - after firing you'll have a perfect 243AI chamber slightly over length but for your gun only.
Hope this helps.
Harry B.

September 4, 2006, 09:22 PM
Thanks Harry.

My barrel is back at it's manufacturer....hopefully he is doing the job the way you explained.
Thanks for your call.
When I get the barrel back and see I still have problems...if you do not mind......I will give you call.

Harry....do you still work at Novak's?

I have a S&W 3913tsw that I may want the trigger tuned up in the future.

Thanks again....

Harry Bonar
September 5, 2006, 01:48 PM
Dear Sir:
No, no more Novaks. After my son, Joe Bonar was killed by a drunk driver in 03 the work fell off - we were the Colt division - there was very little work for me.
I did machine set-up, special projects, machine worl on 1911 and clones, etc.
I feel that, if you checked with Thompsom Center you might be better off just to acquire another bb'.
Changing from 243 to the Ackley Improved will not result in more pressure. I simply give you more case capacity to drive it faster at the same pressure.
I would tell you that, yes, Ackleys Improvements are good, but not good enough to really justify the cost. As a matter of fact I did a 6.5-06 and learned that the std. 6.5X06 is faster!
Over-bore cartridges don't make good "improvement" models sometimes - but - with our modern slow burning powders this is changed slightly1 But, know this - the game will not know whether it is hit with a 243 or243AI!
Harry b.

September 5, 2006, 08:02 PM
Harry ios correct. AS long as the original chamber is not at max, you actually can make an AI without setting back.
I use a dial indicator on the reamer depth and go slow.
If the original chamber is at max, then setting back is going to be required.
I am sure PO new this, but given the machining skills of the average gunsmith, setting back is safer and works every time.
Unless you run the reamer in too far...

September 5, 2006, 09:23 PM
Let us know what happens when you get the barrel back the second time.

I had a Ruger #1 converted from 243 to 243AI at the Colorado Gunsmithing School. I only did it because they charged about 20 dollars, had the reamer on hand and they did set the barrel back a thread, recut the extractor notch and re set the headspace. Mine works great.

September 5, 2006, 09:59 PM
Thank you Gents...I did request a new barrel after I sent it the 2nd time. Will let you know what happens...

Harry....I do remembering of hearing about the tradgic death of your son......very sorry...

Thanks again...I will keep you guys posted....