I'm wondering if I can mount my new short-chambered 22-250 barrel to the action and then finish ream it to 22-250AI? Anyone done this? Also, does anyone know where I can get a drawing of the 22-250AI chamber?

Toomanytools-- (me too)

You should ream to the AI chamber BEFORE the barrel is mounted. Otherwise you have no way of headspacing it the required +.004 on a GO gauge.

The reamer makers make two 22-250 "Ackley Imp." reamers. The original has a 35 degree shoulder and the newer one has 40 degree, which makes it more consistant with some other Ackley designs.

For dimensions check "Designing and Forming Custom Cartridges" by Ken Howell. All the reamer makers have the information on the more popular 40 degree case.

Toomanytools,

To clear up any confusion about the .004 tolerance that is usually quoted by myself and other gunsmiths on this site regarding the Ackley Improved chamber, and so there is no confusion, the ideal "Ackley Improved chamber" provides for a crush fit of approximately .004. on beltless/rimless calibers. This means a factory round would need to be forced into the chamber, an additional .004 as you cam the bolt closed.

In a conventional beltless/rimless chamber, the reamer would be advanced until the bolt would just close on the go gauge. This would provide the necessary tolerances for using standard cartridges in standard chambers. In the improved chamber you need to tighten things up. You need to provide proper support to the cartridge while fireforming. This is accomplished by having a chamber that is .004 shorter than standard, or, go gauge -.004.

This will cause the cartridge to protrude the extra .004 which will provide the necessary contact at the neck/shoulder junction of a factory case, that is needed for proper fireforming.

"Do not" run the reamer in to the standard go guage depth and then "add" another .004 to it. The term "-.004" means .004 less than "go".

Regards,

Malm

Perhaps one could consider this an "anti-flame"...

I just wanted to thank Malm and JBelk for the posts above, and the many other posts that they have on AccurateReloading.

Seeing the two post back to back above reminded me how fortunate we are to have two such serious gunsmiths take the time to share their knowledge.

When I visit the "today's active topics" and see that the last post is by either of these two guys (or Atkinson and a few others), I tend to take the time to read what they said. I often learn something.

So JBelk, Malm and Atkinson, when some a$$ pisses you off with some stupid post, remember that there are a bunch of us who appreciate your continued contributions.

jpb

jpb---

You're most welcome and I appreciate your post.

Malm--- I appreciate the clarification. My post wasn't clear to one not familiar with the math associated with headspacing.

JBelk & Malm

Ditto the comments by jpb. I appreciate your responses; however, I have a follow-up question: Do your comments only apply if I use a 22-250 Go-gauge to headspace on? What about a 22-250AI Go-gauge or doesn't anyone make one?

Thanks again.

Gentlemen,

Men like JBelk, Malm, Atkinson, and many, many others, make all the expenses we put into this site very worthwhile.

The whole idea of us starting it was to offer the opportunity for people involved in the hunting and shooting sport a sort of a platform to share thier own experiences, and may be also help others who might require some of thier questions answered.

I think I am not exagerating when I say that this idea has ceratinly succeeded.

And on behalf of everyone here at your favorite website, I would like to extend my sincere thanks and appreciations.

Have met some of my old friends whom I have known from my time in the US, and have also made some new friends, whom I have not had the pleasure of meeting yet, but will certainly look forward to it.

Gentlemen, thank you all for your time and contribution to the success of these Forums.

Toomany Tools---

There's no need for an Ackley Improved headspace gauge because there's no factory brass available for the caliber. The barrel has to be headspaced for what's going to be shot in it. Once the brass is fireformed for your rifle there's no need for the gauge. The important part is to have the correct HS for that all important first shot with standard brass.

Saeed---

Any chance of you making it over for the SCI show in Reno?? If so, I'd be pleased to have you as my guest at the ACGG/FEGA show that's at the Silver Legacy in Reno at the same time.

Jack,

Thank you very much for the invitation my friend, but I am afraid that might not be possible.

I normally get a chance to go away for a few days a year, and when that chance comes, I just cannot resist another African safari.

But, hopefully we will meet one day, and I would love to share a drink or two with you.

Jpb,

Thank you for the post Jpb and you're welcome.

No problem Jack. We speak the same language, we just explain it a bit differently is all. I could see where someone might see a discrepancy between your thoughts and mine and I didn't want them getting the wrong idea. Your +.004 and my -.004 reference could be a bit confusing to those who are not familiar with the subject. Thanks for your posts Jack...

Malm

I appreciate Jack and Malm although I differ with them regularly. I have learned a lot and expect to learn more. When we disagree, the difference is between the exact precise way to do things and the way a poor boy gets the job done.

I believe there is room for both approaches. And I hope that they agree.

Leftoverdj,

There is probably room for both approaches. My approach and that of Mr. Belk, is one that is directed at the public, who demand and expect the very best that we can produce. We, on occasion, volunteer our assistance in forums like this, to assist those who will listen, and put into practice those things we speak of, that directly affect accuracy and safety. The poor boy approach on the other hand, which you must assume that neither of us would ever consider to offer, is geared to those who don't care as much about the precision aspect of accuracy, as long as it's close. Though however defined or administered, the poor boy approach must never compromise safety.

Let me leave you with this thought that is as true today as it was over 30 years ago when I was a young Marine Corps armorer. "Practice does not make perfect, Perfect practice makes perfect" therefore, "Any deviation from perfection, results in misses".


Regards,

Malm

Toomanytools,
All the reamer maker's gauges for the Ackley Improved cartridges are simply go gauges for the parent cartridge shortened by .004". Regards, Bill.

I guess I just feel like being argumentative here; but JBelk, are you sure about the shoulder angles on the two version of the 22-250 AI?

I own a rifle chambered for 22-250 AI that has the "original" shoulder angle of 28 degrees. Sure, the 40 degree shoulder angle is the most popular, but some of the older gunsmiths around still have reamers for the 28 degree version.

Just curious, R F

R Flowers--

The original 22-250,...... AKA 22-Varminter and the .220 Wotkyns Original Swift (which has to be one of the all time great cartridge names)....and made standard by Remington, has a 28 degree shoulder. P.O. Ackley blew the case out straighter and put a 35 degree, and later, 40 degree shoulder on them.

28 degree = 22-250
40 degree = Ackley Imp
35 degree = old Ackley Imp.

JBelk, I agree with everything you have posted here.

HOWEVER, I still have in my safe a 22-250 AI that has a 28 degree shoulder. This is another version that has floated around for a long time.
I seem to remember that RCBS came up with this one, but I am not sure.

Frankly, I have several friends who own the 40 degree version and I can tell darned little difference. I can get the same velocities with my version and have been shooting it for over 10 years now.

I have PO Ackley's books on my Christmas list, maybe I will get some better reference material.

R F

Amen to jpb and Saeed. Thanks to the knowledgeable guys for all the good advice.

R Flowers,

Ackley's book Vol 1 talks of 2 improved versions of the 22-250. The first being one that retained the original 28 degree shoulder and the second being the more radical (as described) 40 degree shoulder. Little is said of performance differences between the two but I would imagine with the 40 degree version, you have a little better case capacity over that of the 28 degree, with the biggest benefit of the 40 degree version, being the ability to contain the majority of the burn within the case and thus supposedly sparing the throat. I believe the 40 degree version maybe a little easier on brass as well... but, I may be wrong.

Regards,

Malm

Malm, thanks for your post, I thought maybe I was dreaming here.

I have had a 28 degree version for over 10 years now and it has been a great rifle. My dad and a buddy of his do get more performance out of their 40 degree versions, but they cheat--they use 30 inch barrels!

When chronographed next to a couple of other 40 degree version rifles with more reasonable 26 inch barrels, my 28 degree version gives up very little in performance.

My rifle has a 26 inch Hart barrel and while it is getting tired, it has had more than 4000 rounds through it. It still shoots under an inch.

In regard to case life, it seems quite comparable in my experience once the cases are fireformed. However, the 40 degree shoulder versions seem to have more case failures during fire forming.

R F

RF,

What kind of case failures are you experiencing? Case failures during fireforming can usually be traced to a couple of problems. 1. Incorrect chamber/headspace dimensions, 2. Incorrectly assembled handloads, 3. Bad or previously fired brass, or too light a load for fireforming.

30 inch barrel 22-250 AI, really? Not much difference in performance over a 26" barrel? Try this, take your dads buddies gun and cut off an inch at a time while chronographing it. Continue doing this until you reach the point where velocity stops increasing. Add 1" to the final barrel length and cut your dad's gun back to that length.

Regards,

Malm

How do you make a 28 degree Ack. Imp from a 28 degree factory round?? What's the difference?

Now ya'll got me confused.

I'm with Jack on this one. The case could be blown out so there is less taper but the real gain comes from moving the shoulder forward by increasing the angle.

Good question Jack. These 28 degree improved cases were originally made by necking down .250/3000 brass to .22 and fireforming in the 28 degree improved chamber. The .250/3000 brass has a 26 degree 30 minute shoulder angle...

Malm

That is exactly right... Those were the first improved versions of the round and were not P.O.'s. I didn't find any reference though to the 35 degree configuration in Ackley's writings. I have heard of the 35 degree version, but not seen it. There was another cartridge spawned from the 22-250 40 degree. It is the .22 Cheetah...

Regards,

Malm

Firing a necked down 250-3000 in the 28 degree improved chamber would not give you the W.O.S. because the W.O.S. retained the original body taper which the improved did not.
Dave Kiff has drawings, purported to be from Ackley, showing both the 28 and 40 degree versions. Like many of Ackley's drawings the dimensions on the 28 degree version are incorrect and cutting a chamber with a reamer made to those specs to the standard -.004 HS measurement would result in a chamber that was too short overall. The dimensions given on the drawing for the 40 degree version are correct.
These dimensional anomalies are present in a number of the Ackley drawings and it would behoove the gunsmith to investigate this prior to ordering a reamer so he can be sure of his dimensions. Specifying the correct dimensions for a given cartridge should not result in a "special dimensions" charge.
A similar error exists in the drawings for the 250-3000 improved. SAAMI specs call for a dimension from the base to the juncture of neck and shoulder of 1.6369.If this is the case then the same measurement for the AI version should be 1.633 or so. On Ackley's drawing though it is given as 1.6742 yet overall case length is given as being the same.
So, if the reamer is made to these dimensions and a chamber is cut to the usual -.004 then the chamber will be around .040" too short. This is not good. It might work out ok since the max case length is -.010" and new brass may be shorter than that. In addition, if the brass is a few thou longer than the chamber the shoulder will likely just collapse a little and it is not uncommon for the case to shorten up a bit on fire forming.
So the change in the 28 degree Improved is in the body taper with no change to the shoulder angle while the 40 degree version forms to the same taper as the 28 and adds a 40 degree shoulder. Regards, Bill.

My print shows the 22/250AI 28* to be 1.4733 to the shoulder with a diameter of .455- OAL 1.9240 with 1.6605 to the neck/shoulder junction
The 40* version is 1.5375 to the shoulder, diam. of .455- OAL 1.9240- 1.6555 to the neck/shoulder junction.
std 22/250 from same reamer maker is 1.5104-.4156 dia-OAL 1.9240-1.6595to n/s junction.
So fellows that is why they are called a wildcat every reamer maker has a different idea of what is right. Like the guys have said the go gauge becomes a no-go gauge and the brass needs a slight "crush" fit to decrease the chance of case failure while fireforming and even then with the occasional batch of brass there will be some cases that just can't handle the strain.

JBelk and Malm,
I can't thank you guys enough for clarifying the +/- .004. Would you believe I have a barrel in my headstock that I am going to chamber in the morning to 22/250 AI and if I had not read your posts this evening I would have made a boo-boo. Y'all are a fountain of knowledge for someone trying to pick this stuff up as a hobby. Thank You Thank You Thank You. Jim

Jim,

You are welcome. Let us know how it went...

Malm

The damned "SEND" button is like a trigger, once you hit it, there is no calling it back.


P.S. Remember, you will lose approximately .002 in the overall length of your finished chamber as you torque the barrel into position. Do not forget to allow for this barrel/shoulder crush as you calculate your final chamber depth. To be safe, run the finish reamer in an additional .002 beyond what you have calculated as your final depth. You will get this back when you torque the barrel into place...

Good luck,

Malm

The 28 degree shoulder, or RCBS Improved, was usually on the 257 Roberts. The 40 degree shoulder was Ackley's version, and the 35 degree shoulder was Gibbs (and later Jon sundra's) versions (of improved cartridge shoulder angles). However, all these people experimented with various shoulder angles, so I believe that these angles and their names are just what "came to be" over the years and not a hard and fast rule. My thanks to Jack and Malm as well, I've learned a lot here. - Dan

I too, have to thank you guys for all the information provided here. This has been a very informative thread.

I have been real pleased with my 28 degree improved 22-250, whatever name it should go by.
The gunsmith made it so that a standard 22-250 Remington case was a slight crush fit upon chambering. I have had NO case failures while fire forming cases in MY gun. I did the first big batch by shooting a hell of a lot of prairie dogs with that gun. I just loaded up standard 22-250 ammo and had fun.

You are right, old cases will split often. I have a cheap friend who continues to try to fire form old cases and they split the necks about half the time.

My dad and his buddy have had some trouble in fire forming cases and I can only guess that the 40 degree shoulder is just a little harder on cases during the forming (that and the fact that it is just slightly forward).

In regards to the performance question what I meant to say was that in comparable 26 inch barrels, I have not seen much difference in the 28 degree or 40 degree versions. However, I DID NOT mean to say that my dad's 30 inch barrel did not go faster. He has built two of them so far and they really scream. He shoots 50 grain Nosler BT's about 4250 fps in one and 40 grain Nosler BT's in the other at 4550 fps!!! (These are moly coated bullets, but yeah, he does go through barrels.)

He shot 6 coyotes last week with the 40's at that speed and all were one shot devastating kills.

Thanks again for all the information.

R F

I too have to publicly thank JBelk and Malm for the information they freely share with all of us, it's timely, informative and very helpful.

Now to my question; Is it necessary to use a lathe to do an Ackley chambering of a factory chamber? I have a .338-06 that I want to "Improve", but don't have access to a lathe.

Thanks for all your advise and help gentlemen,
-Mr Mike

[ 11-25-2002, 03:39: Message edited by: Mr Mike ]

Keep in mind that it is mandatory that the barrel be set back slightly to rechamber to the improved and this is difficult to accomplish without a lathe. Regards, Bill.

Mr Mike,

You are not only going to need to set the barrel back a bit like Bill was saying, but you want the accuracy and control that only a lathe can provide.

Malm

Thanks for your replies,

Would the barrel set-back also apply to a Savage 110 action? With the way it headspaces using the barrel nut going to affect anything?

Thanks,
-Mike

Mr Mike,

If you are going to cut the improved version of the existing parent cartridge, then barrel set back has to occur regardless of the action type. How to best accomplish this then becomes the question.

With the 110 and it's barrel nut, If you can turn the barrel in far enough to get the proper crush on the cartridge after the chamber has been cut, and, provided there is still sufficient clearance between the breech end of the barrel and the bolt nose, and there are no sights to align, then you are probably going to be fine. You know what has to be done. How you accomplish it, and to what degree of precision and accuracy you are seeking, will dictate the course of action you take in achieving the end result.

Malm

Thanks for the insight and wisdom Malm, I really appreciate it.

-Mike

Mr Mike,

You're welcome...

Malm