Author Topic: 280 AI Reaming (Read 4126 times)

Mitch in MI · « **on:** April 23, 2004, 06:35:14 AM »

Is there any interest in passing around a 280 Ackley reamer, like was done earlier with a 357MAX, or more recently with a 45/70 throater?

I was thinking I could buy a reamer and maybe a go or no-go gauge, then sell it all to the next user for $10 off, and so on down the list until everybody's had it or some lucky guy keeps it for $30.

If that works out, maybe we can do it again with a K-hornet?

Mitch in MI
PS It took me a while to find this forum. It was interesting to find I'd already gotten my name in the FAQ. I'm also glad that SilverV repeated his trigger post on this forum, it was one of the first things I'd saved to my hard drive when Marlin closed the old forum to new posts.

Leftoverdj · « **Reply #1 on:** April 23, 2004, 08:12:46 AM »

Mitch, the K Hornet is very doable because it is rimmed. The rimless .280 is way too tricky for home jobs. The problem is a gauging one. Without getting into detail, you are entirely too likely to wind up with chambers in which it would be unsafe to shoot factory ammo.

Mitch in MI · « **Reply #2 on:** April 23, 2004, 09:23:22 AM »

Quote from: Leftoverdj

The rimless .280 is way too tricky for home jobs. The problem is a gauging one.

Deej, if we don't go into details, nobody really learns anything.
Seems like anybody who's much into reloading ought to be able to handle this job. And if he messes it up, the worst that happens is that he ends up with a wildcat like the 7mm JRS instead of an improved chamber.

How I'd do it:
1.Get the reamer and the AI go gage.
2. Figure out how much reamer should be sticking out of the breech when finished, and
plan on stopping about 50 thous short. Everybody who reloads at least has an accurate
caliber with a depth gage on the back of it, right?
3. You're going to have to stop reaming when one of the following happens:
a: The 280AI go gage sits flush with the breech.
b: A short factory round (Remington) starts going in farther than it did originally.
My factory chamber will take a Remington 0.003 to 0.004" past the breech, so I
would not want the improved chamber to let one drop more than .006" past flush.
4. When you're within 50 thousandths, stop and check every five thous until you've
got the AI go gage within 0.020 of flush. Then proceed 0.002 at a time until one of the
endpoints in step 3 is reached. Ideally you will end up with a chamber that will accept
the go gage without increasing the headspace on the factory round, but I would expect
the factory round to start moving deeper before the go gage is entirely flush. If you look
at a fired case under a loupe, you will likely see a little ring at the base of the neck where
the 40 degree shoulder transitions into a 17 degree shoulder because the factory
shoulder wasn't entirely removed, but that will not hurt anything.

If you don't take it slowly and end up with a too long chamber, you can still seat bullets into the rifling to safely form cases with a light load, but you should restamp the barrel markings and never fire anything but your own custom formed cases in the gun.

Mitch.

Leftoverdj · « **Reply #3 on:** April 23, 2004, 10:26:06 AM »

There's a slight problem, Mitch. To my knowlege, there's no such thing as a .280 AI go gauge. The usual method is to set the barrel back a thread and rechamber to AI, setting headspace at -.004" using a regular .280 go gauge. You need the negative headspace because the factory cartridges headspace on the very narrow juncture of the shoulder and the case neck and is forced foreward by the firing pin.

You can't set the barrel back on a Handi and you are stuck with the existing barrel shoulder juncture which is almost certainly a few thous over minimum headspace, anyway. You can use a fired AI case from another rifle as a headspace gauge and rechamber as you suggest, but even if done perfectly, you have increased the effective headspace several thous by reducing shoulder support. There's likely to be a couple of thous error from the improvised gauge, a couple more thous from the limitations of hand work, and a few more thous from the tolerances of factory cartridges. I dunno about you, but I do know that I can't count on taking a .002" cut by hand. Might be .000" and might be .004" or anywhere in between.

I've done a couple of rechambers like this and gotten lucky, but it's not something to count on. I treated mine as though they were true wildcats and formed my brass from larger calibers to get my jamfit for fireforming.

If you are willing to do this and willing to restamp, it's doable, but you're only gonna get a true AI capable of safe use with factory ammo if you are lucky enough to have a minimum headspace chamber to start with and do a near perfect job. Even at that, the fireformed cases from factory ammo are going to have stretched considerably, because the effective headspace was near max to start with.

Fred M · « **Reply #4 on:** April 23, 2004, 01:36:22 PM »

When fire forming with factory ammo you need the .004" crush fit. The head space datum is minus 4 Thou. If for some reason you have a max. SAAMI chamber the set back of the barrel would have to be considered.
Wich is max head space.

In a rigit barrel such as the H#R you could end up with too much head space resulting in a ruptured case. If you did chamber long you could fire form with a false shoulder and use hand loaded ammo only and rename the chamber like 280xyz, or go for a 7mm Gibbs which would clean up the chamber totally. But I don't advise any of it stay with the 280Rem it is a fine cartridge as is.

Fred M.

safetysheriff · « **Reply #5 on:** April 23, 2004, 03:51:24 PM »

Mitch

Is that rifle a Goooood Shooter? If it is, why not leave the chamber alone and shoot some of the Alliant Reloders in it to maximize velocity? Alliant puts out some very energetic propellants; and coupled with the right Hornady bullet (if that's what your rifle likes) you should have a 350 yd' deer rifle -- easily, if one dares to say so.

Otherwise, I like the man's idea of going with the false shoulders to help with headspacing the cartridge.

Take care.

Leftoverdj · « **Reply #6 on:** April 23, 2004, 05:14:16 PM »

Mitch PMed me a link to a source for .280 AI headspace gauges. They are new since I was messing with this sort of stuff and make the project a bit more possible.

Imho, Fred M is pretty much right on about this.

Mitch in MI · « **Reply #7 on:** April 23, 2004, 05:40:26 PM »

Whatever happened to the Alaskan who helped talk me into this idea?
Seems like it was HRAKONE, and if I recall correctly he had a couple of 280AI, one in 26" from a 280 barrel, and one in 24" that I believe started out as a 7x64.
Mitch.

Edit:
I found an old email from HRAKONE. He had a 280 and a 280AI, the AI started out as a 7x64, which, as he said, "cleans up easier" when rechambering. He could drive a 140gr about 200fps faster in the 24" 280AI than in the 26" 280, for some reason his 280 wasn't very accurate with max loads but the 280AI liked them just fine.
So I guess I don't know of anybody who has actually converted an '06 based handi to the AI version of the same cartridge.

Fred M · « **Reply #8 on:** April 23, 2004, 06:19:42 PM »

One other consideration to think about, if the rifle does not shoot worth
a hoot in the standard H&R 280 Rem version, it certainly will not improve with the AI version. What is usual done on bolt guns is to cut 1/2" off the back end to get rid of the old neck and throat, which most of the time will improve accuray providing the barrel was a good shooter to start with.

A good 280 AI reamer should also allow for the shortning of the brass during fire forming. Depending on the brass this is 12-15 thou.

Consider this. A 280 case is about 2.538" and the chamber 2.550 to 2.555.
This allows the the case to grow 12 to 17 thou now you shrink the case by fire form 12 to 15 thou and you end up with a big gap for nasty carbon to build up. If not cleaned out religiously you can kiss accuracy good by.

The 280 H&R is not a good candate for an AI. Now if you had a 7mm-08 the 280AI version would make some sense. We have mulled about this before. You need a longer case to get rid of the old chamber.
Fred M.

Mitch in MI · « **Reply #9 on:** April 24, 2004, 01:28:06 AM »

Fred: I see what you are saying about case length shortening as the sides are blown out to fill the improved chamber (more on this topic available on Fred's web site: http://www.angelfire.com/ma/ZERMEL/280AI.html )

However, in making the chamber shorter than SAMMI specs, it seems that you no longer have an improved chamber, but a short chamber that can't safely fire factory ammo because the neck will get pinched between the bullet and the throat. The PTG 280AI reamer has a nominal chamber length of 2.560 according to PTG's chamber print.

BTW, I see from your web page that you also find Remington cases to be on the short side. Perhaps I should get a 280 Rem go-gage, and find out if I have a minimum chamber now. Winchester Silvertip factory ammo stands a bit proud of the breech, and gets forced into the chamber when I close the gun. Unfired Remington ejects fine, unfired Winchester does not.
Mitch.

Fred M · « **Reply #10 on:** April 24, 2004, 05:39:11 AM »

Hi Mitch.
Please don't confuse the standard chamber with the AI. The AI is a Wildcat and standard specs do not exist everybody has their own idea of what the dimensions should be. The idea was to shoot factory ammo to fire form. A chamber of 2.540 will certainly do that.
Once the case is formed the length will be about 2.525 or less some brass will go 2.518.

The neck diameter on a 280 Rem is .318. But a good AI reamer will be .314. This will still allow usage of factory ammo and gives a chance of minimal outside neck reaming.( requires 1/2 cut off at the rear end).

After to go through all the trouble of case forming you don't want to end up with split necks be cause of over working the necks

.A 2.560" chamber in an 280 AI would not turn me on for reasons stated above. I have a custom reamer that is 2.530 with a tight neck, no way can you fire a factory cartridge in that chamber. Forming is done with inert filler.

My 280 AI reamer design is used on three continents for long range target use.It works well.

I would not waste my money turning an H&R 280 Rem into an AI.

Fred M

Mitch in MI · « **Reply #11 on:** April 24, 2004, 04:26:05 PM »

Quote from: Fred M

Hi Mitch.
Please don't confuse the standard chamber with the AI.
A 2.560" chamber in an 280 AI would not turn me on for reasons stated above.

Fred:
I wasn't confusing the 280 with the 280AI, when I mentioned SAMMI I was referring to 280 Rem, as I assume you were doing when you mentioned SAMMI in an earlier post. I was just pointing out that you seem perfectly happy with a chamber that cannot safely fire factory 280 Rem ammo. I don't plan on buying any factory ammo, the cheap Remingon stuff is three times the price of brass, and a lot of the premium ammo is twice the price of Remington.
I do think that my factory chamber (I really should cerrosafe it) would have to be cut beyond the normal no-go in order for the effective headspace of my improved chamber to go beyond field reject. (for those who are wondering, SAMMI headspace for 280Rem is 2.100 minimum, 2.110 maximum, and Forster gages are 2.100 go, 2.104 no-go, 2.108 field)

If I use the PTG reamer with the 2.56" neck, it won't cut into my barrel's lead, as my chamber is roughly 2.575" from the factory.

With this conversion, I expect to pick up a bit of velocity, increase case life, and reduce 'bolt thrust' on the action. The biggest drawback I see is that factory ammo would shoot less accurately and with more stress on the case than it does in the factory chamber.

Mitch.

Fred M · « **Reply #12 on:** April 24, 2004, 05:22:58 PM »

Hi Mitch.
As long as the chamber can handle factory ammo you should be ok. But I would not use factory ammo to any extent. Make your brass from new cases and form a false neck and fire form with Cream of wheat.

I amsurprised that your chamber is that long 2.575"? I is very easy to measure long and include some neck transitition. Some where on my web site is a calculation with a drawing how to measure exact chamber lenght. IOf you can't find it I will dig it up and post it.

Who makes the PTG reamer? Do you mean Pacific Tool in White City?
Fred M

Mitch in MI · « **Reply #13 on:** April 25, 2004, 01:44:58 AM »

>> Make your brass from new cases and form a false neck and fire form with Cream of wheat.

My first thought is to load lightly and headspace on the ogive instead of working the neck, is that workable?
Do I need to crimp to keep the case from crawling up the bullet when the firing pin strikes?

>>It is very easy to measure long and include some neck transitition.

That's why I said "about", it's hard to be precise when probing around blindly with a depth mic. I don't think I'm off by more than five thous though. I've got to get some cerrosafe.

>>Who makes the PTG reamer? Do you mean Pacific Tool in White City?

Yep. If you need anything from their chamber print book let me know.
Mitch.

Leftoverdj · « **Reply #14 on:** April 25, 2004, 03:23:04 AM »

I got a very high percentage of misfires on the couple of occasions I have tried headspacing on the ogive. Suspect it was from the bullet being forced deeper into the rifling because I have debulleted a couple of misfired cartridges in extracting them. Since then I have used false necks and annealed as needed.

Fred M · « **Reply #15 on:** April 25, 2004, 05:09:58 AM »

Mitch and Leftoverdj.
I never had much faith head spacing on the ogive, and I don't like crimping bullets since it distorts the case mouth.

In your application the false shoulder is the only way to go. Neck annealing is no big deal. I do all the brass work first and then anneal.
Annealing is an intrinsic part of wildcatting. You can't have one without the other as the song goes :grin: .

When I convert cases like 22-250 to 25 Hunter or 30-06 t0 7mmSSAI, I leave the necks 15 thou longer than the chamber and force the necks into the chamber transition for solid contact and fire form with cream of wheat. Basicly simular to a false neck only more positive.

There has to be enough resistance to prevent the primer explosion and the firing pin impact from pushing the case forward.

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safetysheriff · « **Reply #16 on:** April 25, 2004, 12:17:58 PM »

Mitch,

On a Handi, if I was hell-bent on making an AI' out of it (if the original chambering dimensions necessitated all this...) I'd find a good smith that would remove .030 off the back of the barrel/chamber of the Handi, install a .060 over-sized pivot pin in the frame, with the bearing surface of the underlug/ejector housing being redone Properly to allow barrel setback with that oversized pin. That .030 set back will be enough to allow a good 'smith to Carefully rechamber to an AI' that will fire factory ammunition as well. He's just going to have to be intelligent while working with that AI' reamer.

Maybe nobody wants to hear it, but I think I'd still get very good velocity out of a standard .280 Handi' (unless it was machined with a 'slow' barrel) by using compressed loads of an Alliant Reloder powder.

Fred M · « **Reply #17 on:** April 25, 2004, 05:29:48 PM »

Wow.
This thread is getting a lot of attention, and most are unfavorable for the
conversion to 280 AI and for many sound reasons.

Now here is a wildcat that would solve most of the problems instead of using a 280 Rem case why not go for the 30 Blaser case simply necked down to 7mm.

The 30 Blaser is a very strong case and it has a rim, designed for the Blaser break open single shot 95 rifle. with the power of a 30-06 AI plus .

Case length 2.673, Base .476, Rim .525, Shoulder .444, Neck length appr.270 . Shoulder angle looks like about 30 degs. RWS makes the cases.

The case is .135 longer than the 280 REm. That will make one heck of a 7mm wildcat and a very simple concept. The reamer would be the same price as the AI.

I would push down the shoulder a bit for a longer neck and a bit less case capcity. I would call it the 7x68 R or the 284 RR for rimmed remedy.

Fred M.

Fred M · « **Reply #18 on:** April 26, 2004, 05:32:24 AM »

Mac.
I 100% agree with what you say. As I mentioned above I am against converting an H&R to a more powerful cartridge. But since people want to do it. I just make suggestions. The 30 Blaser is a very modern case and has enough taper to allow extraction in weak extraction systems and is a little bigger in all directions, not much but enough to clean up a 280 Rem chamber.

Yes the European cases are not likely to found in your favorite gun shop.

I think that with the 06 type family of cases the H&R rifles are already stressed, since all these cases can be loaded to 60 kpsi without any problem and the Handies are not designed for this kind of pressure.

Setting the barrel back 30 Thou and installing a new hinge pin reworking the extractor, rechamber to 280AI could easy exceed the price of a new rifle. But that is only money, if you got it, so what? Fred M.

Mac11700 · « **Reply #19 on:** April 26, 2004, 08:10:02 AM »

Fred M:

This is true...most wildcatters really don't figure in the actual cost envolved..they just want to have something different. :wink:

Have a Great 1

Mac

handi35 · « **Reply #20 on:** April 26, 2004, 09:30:58 AM »

There are 3 ways to have a handi rifle in 280AI. The easiest is the 7mm08 rechambered 22 in. stainless great idea and something very few will ever own. 2nd a 7x64 Brenneke rechambered 24 in blue, but rifle not to easy to find. 3rd 280 rem rechambered by a good gunsmith try for 1 to 2 thousands short for a crush fit to fire form new brass. the more straight wall case of the AI. cartridge has never failed to eject in either of my 280 AI Handis even with fairly hot loads worked up for 160 gr failsafe bullets for moose and bear.

Mitch in MI · « **Reply #21 on:** April 26, 2004, 11:25:46 AM »

Quote from: Fred M

I think that with the 06 type family of cases the H&R rifles are already stressed, since all these cases can be loaded to 60 kpsi without any problem and the Handies are not designed for this kind of pressure.

I've been wondering about that. SAMMI pressures for the 30-06 and 280 are 50kcup, 243,270, 7-08 and 308 are 52kcup, while the 22-250 and 25-06 are 53kcup. I'm assuming that current production brass for any of these can handle 53k, and if the gun can handle 53k factory loads in 22-250 or 25-06, it should handle 53k in any of the above chamberings, right? It's my understanding that the only reason for the 280 Rem pressure to be lower than 270 Win is that the Remington semi autos of 50 years ago operated better at the lower pressure.
Mitch
PS: Handi35: Is that you, Gary? Do you have two 280AI Handis now? Did one of them start out as a 280?

Fred M · « **Reply #22 on:** April 26, 2004, 04:22:21 PM »

Mitch.
The brass is not the problem. Any modern brass for the 06 class cases
will handle a lot more pressure than 53 kcups.

Just because a factory load will generate 53K does not mean it will do that in a Handy with the long free bore and a loose chamber. That free bore was put in the rifle to lower the pressure. 49kcup was what I believe is the factory recommended pressure limit ? Don't know for sure but sounds ok.

I have some new 25-06 Win brass that measures .464 at the base pressure ring .200 above the bottom. The case expands to .4715 when fired with a standard hand load. The case has now a larger volume.

If that was a factory load it would not develop 53 K cup with that much expansion. When you add an extra long throat you be down to where a Handy could handle it.

This is in a Ruger #1 chamber. a pretty big chamber. My custom 280 AI reamer cuts a chamber of .468".

Since lower part of the case is unsupported it wont take long and the primers will be loose. On the first firing the extractor groove expanded by 0.0015 to .407. I have no Idea why Ruger would produce such a big chamber.

My 25 Hunter uses 22-250 cases which also measure .464, the chamber is cut to .466. These cases do note expand even with hot HBR loads. Loads develop 56k psi according to Quick Load. Its all in the chamber. Fred M.

handi35 · « **Reply #23 on:** April 27, 2004, 05:13:08 AM »

Mitch
Yeah its me. Have now worked up 2 Handis in 280AI 1 from a 7X64 Brenneke and the other from a 280 rem. the rem was a very slow hand job using a neck sized case from the 7x64 rechamber as the go gage. then went with a neck reamer to give the chamber 10/ ths. freebore, it never hit bottom. both guns shoot best with the bullets seated long. one full turn of the RCBS seater die off of the lands.
If someone could find 7mm reamer off of the 30 Blaser mentioned in this thread it would make a great start for a handi rifle project.
Ill have to try the folks at RCBS to see what I can find out.

Mitch in MI · « **Reply #24 on:** April 27, 2004, 06:33:30 AM »

Handi35:
Care to give a before/after comparison on the 26" gun?
Was the AI conversion worthwhile?

Mitch.

handi35 · « **Reply #25 on:** April 27, 2004, 09:42:39 AM »

Mitch
So far have only shot old 280 loads to make 280AI cases, accuracy seems to be ok. have learned the hard way not to work up handloads during the winter.
If I get done bear hunting will most likely start on loads for the 26 in. gun in late May.
The fact that the AI case seems to be inherently accurate extends case life and always ejects should be well worth the $50 in gas spent going to my partners shop to do the work. if the gun likes 160 gr. failsafe bullets it will be going moose hunting this fall.
Will let you know how it shoots as we get into working loads up for the gun.

safetysheriff · « **Reply #26 on:** April 28, 2004, 05:46:44 AM »

Fred M'

The 'maximum product average chamber pressure for .270 factory ammunition should not exceed 57,200 c.u.p." per NRA "Handloading: book 1991 edition. I would have to think that the NEF engineers know about things like that.

These Handi's will take it!

Take care.

SS'

Leftoverdj · « **Reply #27 on:** April 28, 2004, 12:10:46 PM »

Quote from: safetysheriff

Mitch,

On a Handi, if I was hell-bent on making an AI' out of it (if the original chambering dimensions necessitated all this...) I'd find a good smith that would remove .030 off the back of the barrel/chamber of the Handi, install a .060 over-sized pivot pin in the frame, with the bearing surface of the underlug/ejector housing being redone Properly to allow barrel setback with that oversized pin. That .030 set back will be enough to allow a good 'smith to Carefully rechamber to an AI' that will fire factory ammunition as well. He's just going to have to be intelligent while working with that AI' reamer.

Can we have a price estimate here?

Face off barrel
Redo ejector
Check and possibly rework locking bolt fit
Remove hinge pin and ream hole
Fabricate hinge pin and harden
Install new hinge pin
Recut radius on barrel lug
Chamber and test fire

Seems kinda silly when NEF will fit a 7-08 barrel that can be easily rechambered to .280 AI. Several hundred dollars worth of silly.

safetysheriff · « **Reply #28 on:** April 28, 2004, 01:24:52 PM »

Quote from: Leftoverdj

Quote from: safetysheriff
Mitch,

Seems kinda silly when NEF will fit a 7-08 barrel that can be easily rechambered to .280 AI. Several hundred dollars worth of silly.

DJ'

Am I wrong; or do I smell a put down with that repetition of "silly"?

Would you honestly expect an owner of a 26" barreled .280 Rem' to step down to a 22" barreled 7mm-08, then after paying for that barrel pay to have it Improved, knowing that he'd just goofed up his gains in re-chambering by going to a 4" shorter barrel???

Sounds kind of silly to me! Sounds terribly silly to me!

I'd only Improve a .280 Rem' or a .308 Win' as I've said before; but since I Really would prefer to shoot compressed loads of Alliant's double-based powder (if looking for more velocity) that's what I've really suggested. That doesn't seem to be enough for Mitch, so I've suggested an alternative.

Truth be told, I'd rather shoot a 24" barreled Weatherby Vanguard in .270 Winchester than do any of this kind of work on a Handi' -- even if I do love the ones I own.

BeigOLDOC · « **Reply #29 on:** April 28, 2004, 01:41:10 PM »

Howdy fellars, Just thought I'd stop in and say Hi. Been traveling about and haven't made time to keep up on things.Look forward to chewin' the fat again on a regular basis again :wink: Will update on my 7-08 to 284 Win AI rechamber after I knock down some off the "Honey-Will Do" :evil: List. Regards Oldoc p/s I see things haven't changed much 'round' here,cept' maybe just watered down a-bit :wink: