Just wandering what kind of Vel this round gets and how hard cases are to form.

In my testing in the same barrel loaded to same pressures you see a gain of 10-15fps over a factory 243. As to forming if the chamber is cut correctly take a 243 med heavy load of a med to fast powder with cheapest bullet you can find and fire.

what would you like to know ?? I have used one for the past 5 years

Just wandering what kind of velocity the round pushes 80-100 gr bullets.I've read that it has been used at 1000 yd matches. ramrod340, 10-15fps doesn't seem like much of a gain, is that vel normal for the Ack Imp?

I agree with Ramrod - you won't see a whole lot of improvement over a standard 243W. The 243W case has little body taper to begin with so all that you are really changing is the shoulder angle. But, wildcatters are willing to do the work for even a tiny improvement in ballistics.

Like most wildcats and Improved cartridges, most of the claims for greatly improved ballistics are the result of loading to higher pressures.

There is probably more to be gained in the way of longer case life than in velocity.

Both the straight 243W and the 243 AI have been used for 1000 yard Benchrest. A good shooter can win with either one. A lousy shooter can lose with either one.

Ray

quote:

ramrod340, 10-15fps doesn't seem like much of a gain, is that vel normal for the Ack Imp?

I will never say that someone doesn't have a rifle that will give a huge gain. My first question is compared to what? Since I've had twin rifles give 150-200FPS different velocities if the gain isn't between a std and AI in the same barrel the data is already suspect.
I don't have time to go into a lot of detail today. Do a search on AI with me as the author. I've done a lot of testing over the years and time and time again the results say a 1% velocity for 4% capacity in an 06 based case, less in a 308 and a little more in a 7x57 when loaded to the same pressure. My measurement in a 243 shows 1.6% capacity increase. Like Cheechako said the taper is already pretty much an AI. So figure 1for4 that is .4% on 3000fps that is 12fps.

The 243 is loaded to 60,000 fractory load it ot 65,000 like a 6mm and go shooting.

Don't get me wrong I have plenty of AIs and full wildcats. Most AI gain is pressure related or like in the case of the 7x57 and 257Rob compared to factory loaded in the low 50,000.

As to longer case life. I have never seen it compared to PFLS.

If your looking for velocity gain, open it up to 6MM Rem. Improved. The only thing you'll have to change from the 243 is the brass. Pick up some 6MM Rem brass and go to town.

Had this piece of data from testing. Same 24" barrel, 243. 243AI 6mmAI with a 100gr bullets. These velocities are just below head expansion.

243 3170fps
243AI 3185fps
6mmAI 3225fps.

For my cases the volume of the 6mmAI is 9% larger than my 243. A 1 for 4 would equate to 49FPS expected gain.

Yes I know some of you probably get 240Wby or 6-284 velocites from a 243AI. I don't argue with peoples claims I wasn't there. I just share my findings from testing in the same barrel. In my findings PRESSURE is where most of the AI claims come from.

I always use a new barrel when I have an Ackley chamber rifle same way when I rebarrel my 243. My new 243 is faster than the factory rifle. In the 243AI Hart 1/10 twist barrel I used a max load for the 243 using 45gr/IMR-4007ssc with 80gr bullet @3425fps working up to 47grs @3654fps. I used 46gr/IMR-4350 with 87gr @ 3456fps thats a gr under max for the 243.

In my 6RemAI with 95gr Nosler I'm getting 3393fps.

I don't think anyone can say the 243AI is equal to the 243 in term that you cann't chamber the 243AI in the 243. You can chamber the 300 H&H in the 300Wby so are you going to load the Wby to H&H levels.

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I don't think anyone can say the 243AI is equal to the 243 in term that you cann't chamber the 243AI in the 243. You can chamber the 300 H&H in the 300Wby so are you going to load the Wby to H&H levels.

Well let's see a 300Wby is 14+% larger than a 300H&H a 243AI is only 1.6% larger than a 243. Don't see that as an apples to apples. I will say it anytime. Loaded to the same pressure an AI will only give you around 1% velocity for 4% cpacity. So to me a difference of 12-15fps the 243 and 243AI are basically equal. People don't agree that is fine with me.

Like I said I don't argue with anyones velocity claims. I wasn't there. I only point out my findings tested in the same barrel to the same point just shy of head expansion.

Anyone that really wants an 243AI should build one.

quote:

Originally posted by ramrod340:
[QUOTE]I don't think anyone can say the 243AI is equal to the 243 in term that you cann't chamber the 243AI in the 243. You can chamber the 300 H&H in the 300Wby so are you going to load the Wby to H&H levels.

Well let's see a 300Wby is 14+% larger than a 300H&H a 243AI is only 1.6% larger than a 243. Don't see that as an apples to apples. I will say it anytime. Loaded to the same pressure an AI will only give you around 1% velocity for 4% cpacity. So to me a difference of 12-15fps the 243 and 243AI are basically equal. People don't agree that is fine with me.

Like I said I don't argue with anyones velocity claims. I wasn't there. I only point out my findings tested in the same barrel to the same point just shy of head expansion.

QUOTE]

How do you come up with the 243AI is only 1.6% larger than the 243. Handloader has the case capacity of the 243 @ 52.81gr water and the 243AI @56.31gr of water. In my cases for the 243/243AI there is appr 4gr difference.


Paul, I would like to see the 1% velocity for 4% capacity in loading data in the 243/243AI you given the velocity only. If you look at the reloading manual for the 243 the start to max loads is around 3/4grs velocity spread is around 200fps so do I assume your loading for pressure first then powder last for the 243AI.

I don't mean to argue but you do all these test and never give any loading data. I've printed my load for the 243AI and you can open Hodgdon reloading manual and see what max is.

Here we go again.

The only issue I've had with the 243IMP is using too light of a load for fire forming. If I seat the bullets into the lands and use a normal 243 load, the case head stays against the bolt face and cases come out perfect. With too light of a load, I get incipient case head separations.

Some people talk about the donut effect at the bottom of the neck, but I've not had a problem with this.

I get 3700fps with 70gr bullets in a long barrel.

quote:

Originally posted by jpl:
The only issue I've had with the 243IMP is using too light of a load for fire forming. If I seat the bullets into the lands and use a normal 243 load, the case head stays against the bolt face and cases come out perfect. With too light of a load, I get incipient case head separations.


Some people talk about the donut effect at the bottom of the neck, but I've not had a problem with this.

I get 3700fps with 70gr bullets in a long barrel.

The best way that I found, and I really like it, is to expand the neck up to 260 or 6.5 Cal. Then size it down to create a false shoulder in the neck. Size it so that the case head spaces on the false shoulder. This will keep the head firmly against the bolt face and form perfectly. Works great on my 6 mm Rem. AI and my 25-06 AI.

quote:

How do you come up with the 243AI is only 1.6% larger than the 243. Handloader has the case capacity of the 243 @ 52.81gr water and the 243AI @56.31gr of water. In my cases for the 243/243AI there is appr 4gr difference

Well first off I made an error in my first post. I should have pulled my data first nor trusted my memory. I had a 1.6gr increase in capacity with my 243 Winchester brand brass reading 54.7 and in AI 56.3 for an icrease of 2.9%. A 4 gr increase would be more what I normally see in a 257 roberts with a higher body taper. Again I haven't measure your case.

Nothing against Handloader but comparing capacities they list for 243 & 243AI means nothing. When a change in brand can give you a a 3-4 gr difference in capacity. What brands are they quoting. Same? Different? I make my wildcat cases from Norma 280Rem it happens to be 3-4grs larger than a Rem 280 case if I were to use a posted capacity I would overstate my gain. Only true messure in AI gain is the same brand case (better yet same case) messured before and after.

As to the 3-4grs of powder in a 243 loading manual giving you a 200fps gain. Yes Not sure where you are going. Going to a larger case you sure can't assume that burning 4 grs more powder will get you 200fps. You have a bigger case.

In my testing I simply took a MKX factory 243. Worked up a load till I got head expansion in my rifle backed off a gr and called it max. No serious science. Then I took the same barrel (didn't set it back) and then chamber it for 243AI then 6mmAI. Each increasing the load to expansion over the same Chrony. I don't like to list powder charges (because last time I did someone decided to ream my A$$ because my load happened to be surplus 4831 and I wasn't in his mind clear about it) but here you go please do not use them.

Base 243 H414 45.5grs 3170Fps
243 AI H414 46.1 3185fps

My case had a capacity increase of 2.9% the powder charge increase 1.3% and velocity increased .5%.

I also had Imr 4831 49.5grs 3190
MRP 51.4grs 3187FPS Trying to use more of the larger case.
In 6mmAI My load was H414 47.5grs at 3225 That case measured 60.5grs over the 243 that is a 10% capacity increase 4.4% powder increase and 1.7% velocity. I can only assume that the head expanded at the same pressure. It could just as easily be higher or lower.

As I have said time and again. I don't dispute any velocities people claim from their AIs. My only position is what assume as the base and the resulting AI gain.

I have had twin rifles give me 150-200fps difference. So if the higher speed barrel should be an AI is the gain from the AI or the barrel or both. Comparing your measured AI velocities to a factory listing, load or a number on the web to means very little. When you do you are adding in difference in barrels, chamber quality, pressures, cases capacity etc. In my opinion true AI gain is only measured in the same barrel at equal pressures.

Simply taking 243 normally loaded to 60,000 psi taking it up to 65,000 will give you around 75fps gain. So comparing my 243AI load to a normal 243 load I would see around 90 to 100fps. But most of that is pressure.

As I have said time and again. I own more AIs or wildcats than factory. I have done a lot of testing over the years. At equal pressure I still use a 1 for 4 as my rule of thumb. If you want to use something else please do I will not loose any sleep.

I will also say if you want an AI go for it. Sure not trying to . AS I stated in my opinion (that and a $$ will buy your a cup of coffee) the majority of the gains quoted for the AI are the result of something other than the small capacity gain. If you happen to have a program like Quickload play with the case capacity and see what it gives you as a gain.

You used 49.5 grains IMR 4831 behind a 100 grain bullet in the 243 Ackley? And only 3190 fps?

My max in 6mm Ackley with a 95 grain bullet and IMR 4831 is 47.5 grains for 3400 fps.

That is some weird stuff going on for either you or me.

quote:

You used 49.5 grains IMR 4831 behind a 100 grain bullet in the 243 Ackley? And only 3190 fps

Like I said. Different barrel, length, bullet shape, seating depth, powder lott, primer, brass brand, chamber size chronograph. Comparing one rifle to another doesn't tell you much.

quote:

Originally posted by ramrod340:

quote:

You used 49.5 grains IMR 4831 behind a 100 grain bullet in the 243 Ackley? And only 3190 fps

Like I said. Different barrel, length, bullet shape, seating bept, powder lott, primer, brass brand, chamber size chronograph. Comparing one rifle to another doesn't tell you much.

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