243 AI vs 243 win improved 40°. Are they the same or what’s different?

[Mattd212]

Hey guys. I have wanted to rechamber my 243 win for quite some time now and was wanting to go to 243 ai but am having a pain trying to find dies. Have recently broke 4000fps out of the win and am wanting more.

 

[Bill Norris]

Hey guys. I have wanted to rechamber my 243 win for quite some time now and was wanting to go to 243 ai but am having a pain trying to find dies. Have recently broke 4000fps out of the win and am wanting more.

Yes Sir. They are the same. Go for it. You will like it alot.

 

[Bill K]

Back in the 60-70's when I was shooting the 243ai, my dies were from RCBS. One of the main makers should or could still have them.

 

[Bill Norris]

Yea Redding has them readily available.

 

[JLT]

Yea Redding has them readily available.

+1 for the Redding dies. I have them in .243 Ackley (Improved 40 degree) and I'm very happy with them.

 

[Mattd212]

+1 for the Redding dies. I have them in .243 Ackley (Improved 40 degree) and I'm very happy with them.

What kind of velocity are you getting from what bullets if ya don’t mind me asking

 

[ggshoots]

Bill, I have to disagree. finding a die set with 243AI actually on the box is kind of like finding hens teeth. I dont know if anyone is stocking them. The 243 Win 40deg Impr is not the same if my set is a good example. Those are the ones you commonly see and in the description says Ackley Improved but you will not find it on the box. My Redding body die actually oversizes the brass. Make sure you have the dies first. When I first got my 243AI dies and reamer, started shooting then reloading I had a terrible time trying to get things right. That was with the Redding Type S Neck die and body die. Finally figured out what was going on then read somewhere another guy was having the same problems as I was. I finally caught a set of RCBS 243 AI dies on Ebay and it took care of all my problems. Attached are a few pics.
My 2 sets of dies


Manson Reamer

Fired Brass Shoulder

Brass sized with RCBS 243 Ackley dies


Brass sized with Redding body die

Redding Bushing neck die and Body die

Bill maybe you can tell me if this body die is a custom. I called Redding and they were actually no help. I asked if they would send me a print of the die set and they would not. Not many sets of 243Ackley 40deg dies come up on eBay.

 

[JLT]

What kind of velocity are you getting from what bullets if ya don’t mind me asking

I'm sure Bill will chime in as well - he has a lot of experience with the .243 AI.

My applications for this round are medium game (mule deer and smaller), predator and LR varmint and an occasional F Class match.

My barrels are .237" bore, 1:8 twist, 28 inches. I tend to shoot 105 - 107 gr. class bullets almost exclusively, but I've recently started playing around with the 112 gr. Barnes in the .243 AI. The heavier bullet shows some real promise.

I use Berger 105 gr. Hybrids, 105 gr. VLDHs and 105 gr. VLDTs. When the Hybrids get scarce, I have no problem falling back on the VLDHs and the VLDTs. The VLDH actually has the best BC among the Berger 105s and they shoot just as tight as the Hybrids.

I've mostly used RL-26 (hunting) and RL-23 (target and hunting). RL-26 has been the speed king for me. My hunting load is any one of the mentioned 105s propelled by a pretty full case (Lapua) of RL-26 and a Fed 215/215M primer. I'm reluctant to post the exact charge but the load produces an average velocity just a hair under 3,400 fps with stellar precision. I mean tiny, itty-bitty little knots. Start at 47 grs. and work up. If your barrel likes RL-26, you should find a good spot in short order.

RL-23 will also produce speed, but not like RL-26. Much better manners for string fire, though. Mid 3,200s with a 105/107 are no problem for RL-23 in this case. Start around 45.7 grs. for your work up. Pressures are quite reasonable at this velocity.

Neither of these powders are easy to come by, and it would appear that a King's ransom is the going rate for an 8 lb. jug. I have a fair amount of both powders on hand and have been fortunate/lucky enough to maintain decent supply over the years. It will run out, though, and I'll be damned if I'm going to pay $500+ for 8 lbs of powder to replenish my supply. VV N-165, N-555 and N-560 are going to see some load development in the near future.

This is where the man with the Fender Jazz Bass can help you . . . .

 

[JLT]

Bill, I have to disagree. finding a die set with 243AI actually on the box is kind of like finding hens teeth. I dont know if anyone is stocking them. The 243 Win 40deg Impr is not the same if my set is a good example. Those are the ones you commonly see and in the description says Ackley Improved but you will not find it on the box. My Redding body die actually oversizes the brass. Make sure you have the dies first. When I first got my 243AI dies and reamer, started shooting then reloading I had a terrible time trying to get things right. That was with the Redding Type S Neck die and body die. Finally figured out what was going on then read somewhere another guy was having the same problems as I was. I finally caught a set of RCBS 243 AI dies on Ebay and it took care of all my problems. Attached are a few pics.
My 2 sets of dies
View attachment 1509489

Manson Reamer
View attachment 1509490
Fired Brass Shoulder
View attachment 1509492
Brass sized with RCBS 243 Ackley dies
View attachment 1509493

Brass sized with Redding body die
View attachment 1509494
Redding Bushing neck die and Body die
View attachment 1509495
Bill maybe you can tell me if this body die is a custom. I called Redding and they were actually no help. I asked if they would send me a print of the die set and they would not. Not many sets of 243Ackley 40deg dies come up on eBay.

What's the part number on the body die? I picked one of these up years ago and used it once. It was NOT a good match to my chamber. My FL sizing die was an excellent match, though.

 

[Mattd212]

So would going to a 243 win improved 40° yield the same results with just minor case dimension differences and far easier to be had supplies?

 

[Mattd212]

I'm sure Bill will chime in as well - he has a lot of experience with the .243 AI.

My applications for this round are medium game (mule deer and smaller), predator and LR varmint and an occasional F Class match.

My barrels are .237" bore, 1:8 twist, 28 inches. I tend to shoot 105 - 107 gr. class bullets almost exclusively, but I've recently started playing around with the 112 gr. Barnes in the .243 AI. The heavier bullet shows some real promise.

I use Berger 105 gr. Hybrids, 105 gr. VLDHs and 105 gr. VLDTs. When the Hybrids get scarce, I have no problem falling back on the VLDHs and the VLDTs. The VLDH actually has the best BC among the Berger 105s and they shoot just as tight as the Hybrids.

I've mostly used RL-26 (hunting) and RL-23 (target and hunting). RL-26 has been the speed king for me. My hunting load is any one of the mentioned 105s propelled by a pretty full case (Lapua) of RL-26 and a Fed 215/215M primer. I'm reluctant to post the exact charge but the load produces an average velocity just a hair under 3,400 fps with stellar precision. I mean tiny, itty-bitty little knots. Start at 47 grs. and work up. If your barrel likes RL-26, you should find a good spot in short order.

RL-23 will also produce speed, but not like RL-26. Much better manners for string fire, though. Mid 3,200s with a 105/107 are no problem for RL-23 in this case. Start around 45.7 grs. for your work up. Pressures are quite reasonable at this velocity.

Neither of these powders are easy to come by, and it would appear that a King's ransom is the going rate for an 8 lb. jug. I have a fair amount of both powders on hand and have been fortunate/lucky enough to maintain decent supply over the years. It will run out, though, and I'll be damned if I'm going to pay $500+ for 8 lbs of powder to replenish my supply. VV N-165, N-555 and N-560 are going to see some load development in the near future.

This is where the man with the Fender Jazz Bass can help you . . . .

I can’t wait to start acting playing with 105’s and bigger. One of the primary reasons I’m going to an ai/40°improved with a 1/8 twist. Also kinda wanna push a 55 nosler bt at absurd speeds

 

[Bill Norris]

Bill, I have to disagree. finding a die set with 243AI actually on the box is kind of like finding hens teeth. I dont know if anyone is stocking them. The 243 Win 40deg Impr is not the same if my set is a good example. Those are the ones you commonly see and in the description says Ackley Improved but you will not find it on the box. My Redding body die actually oversizes the brass. Make sure you have the dies first. When I first got my 243AI dies and reamer, started shooting then reloading I had a terrible time trying to get things right. That was with the Redding Type S Neck die and body die. Finally figured out what was going on then read somewhere another guy was having the same problems as I was. I finally caught a set of RCBS 243 AI dies on Ebay and it took care of all my problems. Attached are a few pics.
My 2 sets of dies
View attachment 1509489

Manson Reamer
View attachment 1509490
Fired Brass Shoulder
View attachment 1509492
Brass sized with RCBS 243 Ackley dies
View attachment 1509493

Brass sized with Redding body die
View attachment 1509494
Redding Bushing neck die and Body die
View attachment 1509495
Bill maybe you can tell me if this body die is a custom. I called Redding and they were actually no help. I asked if they would send me a print of the die set and they would not. Not many sets of 243Ackley 40deg dies come up on eBay.

O K I could be wrong. My Redding set says 243 40 Deg.

 

[JLT]

So would going to a 243 win improved 40° yield the same results with just minor case dimension differences and far easier to be had supplies?

The .243 AI/.243 Win Improved 40 degree (you can throw the 30-degree shoulder version on the pile, too) are wildcats. There are no standard dimensions, and the won't be until SAAMI says so. The best course of action is to spec a reamer to your liking and send a print off to the custom die maker of your choice for a set of custom dies that play very well with your chamber. I got lucky - my reamer and the Redding FL die were a very good match.

 

[Bill Norris]

Bill, I have to disagree. finding a die set with 243AI actually on the box is kind of like finding hens teeth. I dont know if anyone is stocking them. The 243 Win 40deg Impr is not the same if my set is a good example. Those are the ones you commonly see and in the description says Ackley Improved but you will not find it on the box. My Redding body die actually oversizes the brass. Make sure you have the dies first. When I first got my 243AI dies and reamer, started shooting then reloading I had a terrible time trying to get things right. That was with the Redding Type S Neck die and body die. Finally figured out what was going on then read somewhere another guy was having the same problems as I was. I finally caught a set of RCBS 243 AI dies on Ebay and it took care of all my problems. Attached are a few pics.
My 2 sets of dies
View attachment 1509489

Manson Reamer
View attachment 1509490
Fired Brass Shoulder
View attachment 1509492
Brass sized with RCBS 243 Ackley dies
View attachment 1509493

Brass sized with Redding body die
View attachment 1509494
Redding Bushing neck die and Body die
View attachment 1509495
Bill maybe you can tell me if this body die is a custom. I called Redding and they were actually no help. I asked if they would send me a print of the die set and they would not. Not many sets of 243Ackley 40deg dies come up on eBay.

Not real sure. I didnt get that set. Mine included the F/L and Neck bushing dies and a Comp. seater.

 

[Mattd212]

The .243 AI/.243 Win Improved 40 degree (you can throw the 30-degree shoulder version on the pile, too) are wildcats. There are no standard dimensions, and the won't be until SAAMI says so. The best course of action is to spec a reamer to your liking and send a print off to the custom die maker of your choice for a set of custom dies that play very well with your chamber. I got lucky - my reamer and the Redding FL die were a very good match. That, gentlemen, is like winning the lottery. Almost never happens.

As I am new to custom rifles. Where would a good place be to get a reamer

 

[JLT]

As I am new to custom rifles. Where would a good place be to get a reamer

Reamers - JGS, Manson, Clymer and Pacific Tool & Gauge. JGS and Manson are probably the top of the heap.

Whidden Gun Works, Warner Tool Company and Harrel's Precision are 'can't go wrong' sources for dies, although Hornady, RCBS and Redding offer custom die services as well. I don't know much about their process. I have several sets from Whidden and I love 'em.

 

[Bill Norris]

What kind of velocity are you getting from what bullets if ya don’t mind me asking

Im not pushing mine really hard at all and have not chronoed anything except the 105 gr. Bergers. Just over 3100 is where I stopped because the groups were really tiny. I am working with the 115 DTACs now and will chrono them soon.

 

[Mattd212]

Reamers - JGS, Manson, Clymer and Pacific Tool & Gauge. JGS and Manson are probably the top of the heap.

Whidden Gun Works, Warner Tool Company and Harrel's Precision are 'can't go wrong' sources for dies, although Hornady, RCBS and Redding offer custom die services as well. I don't know much about their process. I have several sets from Whidden and I love 'em.

Was gunna go Redding for dies but will look into whidden for sure.

 

[JLT]

I can’t wait to start acting playing with 105’s and bigger. One of the primary reasons I’m going to an ai/40°improved with a 1/8 twist. Also kinda wanna push a 55 nosler bt at absurd speeds

Out of a 1:8" twist the 55s might hang together long enough to get a read on the chronograph!

 

[JLT]

Im not pushing mine really hard at all and have not chronoed anything except the 105 gr. Bergers. Just over 3100 is where I stopped because the groups wre really tiny. I am working with the 115 DTACs now and will chrono them soon.

Your brass is going to last forever!