.357 max or .360

[just bill]

I have scrolled through the archives and searched the sites. Has any one successfully converted/reamed a handi barrel for .357 or .360. I see where there are plans to try but no successful attempts. It would be nice to have a.357 max rifle if sorts.
Bill

[Mica_Hiebert]

Lots of people have reamed out 357 mag handis out to 357 max. Same with contender barrels.

[shoot-n-lead]

Some Contenders and most Handi's will shoot the DW360 without anything done to them as their chambers exceed SAAMI specs.

[jmort]

Handi Rifles have SAAMI spec chambers.

[Artful]

http://www.bellmtcs.com/store/index.php?cid=121




357 Remington Maximum was given a death sentence by SAAMI the day it was born.....
due to the forcing cone type chamber design they gave it for closed breech guns and the rather quick demise of revolvers chambered for it. Click on the page link below:





.357 Remington Maximum chamber drawing (http://www.bellmtcs.com/store/index.php?cid=241&)
This page shows the design of the SAAMI .357 Rem. Max. chamber compared to what a chamber with a true throat is. The best solution we have come up with for accuracy with the forcing cone chambers is to use long shanked, wide flat nose cast lead, gas checked bullets +/- 200 gr that seal off the bore sooner than shorter bullets do. The LBT designs such as put out by Cast Bullet Performance and others are recommended.

Factory .357 Maximum chambers have about a .4" long forcing cone instead of a true throat. Accuracy from such a chamber by design can never give the true accuracy potential this round is capable of. This same forcing cone design is now used by TC in all of their .357 Magnum chambers as well. Rechambering to the longer .357 Maximum chamber cuts out all but about .1" of the cone. SOME cone IS required for shooting cast lead bullets, so the .1" of cone remaining after rechambering to Max IS perfectly acceptable. In fact, on the older .357 Magnum chambers with a very short cone, no cone is left after rechambering and I DO cut a short, BUT abrupt cone at the mouth of the chamber so firing cast lead bullets does not leave a ring of lead between case neck and the end of the chamber neck.

In the diagram of a TC factory, SAAMI .357 Rem. Maximum chamber below note the gap between the base of the bullet and the red outline of the forcing cone:
http://www.bellmtcs.com/store/images/category120/357%20Max%20final%20drawing.JPG







The SAAMI spec. forcing cone factory chambers do not support the shank of the bullet as it engraves into the rifling. The forcing cone design nearly gave the .357 Rem. Maximum a death sentence, but we are changing that.

You will see below what chamber throats look like in .357 Mag., .357 Rem. Maximum, virtually all of the straight wall handgun chambers, and many rifle chambers.

Then in the last diagram you will see what a true throat looks like, one that delivers superb accuracy!


For best accuracy, the full diameter shank of the bullet must be guided and supported by a throat, that part of the barrel just in front of the chamber neck where the riflings are cut away that is supposed to be cylindrical and only a few tenths of a thousandth inch larger than the groove diameter of the barrel, just enough to allow the bullet to enter it.

The forcing cone arrangement in factory barrels gives no support to the shank of the bullet at all.























I finally stumbled across how the forcing cone chamber below came to be!
The March 1982 issue of The American Rifleman Magazine had an article by C.E. Harris, page 30, detailing the source of this well intended, but in reality, abomination you are stuck with yet years later.

The title of the article is "Proper Throating Is The Key To Accuracy."
Older versions of .357 MagNUM chambers had only a very short, abrupt cone between the end of the chamber neck and the start of the riflings. Accuracy was usually rather dismal in the Contender.

What the principals working with the Contender did back then was to theorize that the Army Marksmanship Unit (AMU) version of the .38 Special chamber used in their 1911 type target pistols was the answer, and the long forcing cone ".38 AMU" designated chamber DID in fact improve accuracy when that design was incorporated into the Contender barrels being tested.

HOWEVER, without going back and researching the bullets used in .38 AMU ammo, common practice in those days especially was to use hollow base 148 gr. wadcutter bullets in the NRA Bullseye competitions the AMU guns were designed for.

I can see how the very thin, very frail soft lead skirts of those bullets would NOT work in the old style chamber but WOULD expand pretty uniformly and flow more smoothly through the long forcing cone diagrammed in the .357 Maximum drawing below.

Thus, I can somewhat understand now the logic behind the long forcing cone, especially with plain lead bullets, either soft swaged hollow base or cast lead flat based.

While the .357 Remington Maximum IS an excellent cartridge for shooting cast lead bullets, it is perhaps arguably (cast lead shooters may disagree) at its very best with jacketed bullets, and jacketed bullets just don't expand, "obturate", sufficiently in the oversize forcing cone and thus enter the rifling at random angles with the shank of the bullet not supported and held in alignment with the bore.

Unfortunately, the long forcing cone chamber design has been applied to all of the straight walled, revolver type rimmed chambers found in Thompson Center's barrels today with the result that accuracy still remains far below the potentials of these rounds such as the .357 Magnum, .357 Maximum, .44 Magnum, .454 Casull, and .460 S&W frequently encountered in TC barrels.

(Then they put essentially NO throat in .375 Win. and .45/70 barrels and a very short almost non existent throat in .444 Marlin barrels. Go figure.)

Interestingly, the article goes on to state that a cylindrical section of throat was recommended to the researchers as an alternative to the forcing cone. Harris even acknowledges it would reduce flame cutting of the bullet shank.

But this brings to mind the Winston Churchill quote:
"Most men occasionally stumble over the truth, but pick themselves up and continue as if nothing ever happened."

My advice is to rechamber the forcing cone chambers for a longer cartridge, thereby cutting out most or all of the forcing cone and permitting cutting a cylindrical throat that DOES guide and support the shank of the bullet as it enters the rifling.

That, or the best solution shooters have come up with for accuracy with the forcing cone chambers is to use long shanked, wide flat nose cast lead, gas checked bullets +/- 200 gr in .35 cal. for example, that seal off the bore sooner than shorter bullets do. The LBT designs such as put out by Cast Bullet Performance and others are recommended.





What you have in a forcing cone SAAMI factory chamber is basically the same thing as a barrel that is literally SHOT OUT!
If you do a chamber cast of a barrel that has thousands of rounds run through it and no longer gets decent accuracy, you will find the same approximate shape in front of the chamber neck...... a cone worn into the opening of the bore.

If there is any logic applied to throats in the close breech guns, it sure does not show.

It is a real travesty that dim wits in high places dumped this bad chamber design on the American shooting public! You just can't fix stupid.








As you see in the targets above, accuracy in properly chambered and assembled guns is absolutely superb, BUT not from the ill-conceived forcing cone chambers the industry is forced to adopt in order to march lock step with SAAMI, insurance companies, and our sue happy American legal system.

Working outside of "the industry," we in the custom trades have the option of cutting chambers for .357 Maximum that are not ruined by a poor chamber design. We can cut chambers that have true throats in them, throats kept to minimum diameter, and aligned with the bore properly for superb accuracy.

.357 Remington Maximum is one of the most inherently accurate .35s available when chambered right. It is also one of the very easiest and cheapest hunting rounds to load for overall. And for those that do not reload, it is our hope that we can garner enough momentum for the round that a major manufacturer will once again supply not just loaded ammunition at SAAMI revolver specs, but loaded to the full potential of this little Mighty Mite!

In the meantime, there are smaller commercial loaders that do supply .357 Maximum loaded ammo and will also custom load ammo for you.

The three major ammunition manufacturers, Remington, Winchester, and Federal, all made ammunition for it when introduced, but today not even Remington, the company that gave birth to it, loads ammunition for it, and only Remington still sells empty .357 Remington Maximum brass which is only produced periodically.

LET'S CHANGE THIS!

I ENCOURAGE YOU TO MAKE YOUR INTEREST IN THE .357 REMINGTON MAXIMUM KNOWN TO WRITERS AND AMMUNITION MANUFACTURERS.

WE NEED A LONGER OVERALL CARTRIDGE LENGTH AND BONA FIDE HUNTING LOADS FOR CLOSED BREECH GUNS THAT EXCEED THE SPECIFICATIONS FOR THE REVOLVERS IT WAS ORIGINALLY DESIGNED FOR.

THE .357 REMINGTON MAXIMUM HAS A TOTALLY NEW HOME IN THE BREAK OPEN GUNS WHERE IT REACHES ITS FULL POTENTIAL.
















There are a number of ways to get a .357 Maximum barrel. Below you will see the various avenues explained.







DO THE MATH......THAT IS A .358" DIAMETER BULLET STARTING OUT IN A .381" DIAMETER HOLE. THE DIFFERENCE IS .023" OR .0115" OFF THE AXIS OF THE BORE THAT THE BASE OF THE BULLET CAN DEVIATE IN ANY RANDOM DIRECTION!

It is amazing this design shoots as well as it does!

But when the shank of the bullet is contained and guided by a cylindrical throat centered with the bore, distortion of the bullet from entering the rifling at an angle is virtually eliminated and accuracy is much improved.







Here is a graphic example of the exact same forcing cone arrangement from a factory .357 MAGNUM chamber. Note the gap between the base of the bullet and the case neck. While the bullet is moving this distance, powder is being blown around the bullet since the bore is not sealed off at the nose of the bullet.



http://www.bellmtcs.com/store/images/category120/longsht.JPG





With the chamber cast, .357 MAGNUM case, and bullet laid side by side, you get a better picture of what is going on inside the chamber. Bullet is placed at approximately where it will first contact the rifling. (photo courtesy D.W. Murphy)





The only difference between a current vintage factory .357 Magnum and a factory .357 Rem. Maximum chamber is the 1.610" length of that portion roughly .380" in diameter for the longer .357 Rem. Max. case.

You can see the shape of the cone compared to the shape of the bullet shank and see that while the nose of the bullet may get centered at with the bore at its nose, the base of the bullet is sitting in a much, much bigger hole that cannot align it with the bore.









http://www.bellmtcs.com/store/images/category120/357%20Mag%20chamber%20cast%20closeup.jpg (http://www.bellmtcs.com/store/index.php?cid=120&)





Close up of the .357 Mag. chamber cast. (photo courtesy of D.W. Murphy)
Again, note the gap behind the bullet before it makes contact at the nose.








The spot where the bullet is sitting is the point where it hits the rifling.

If you were to do a chamber cast of an old totally worn out barrel that had thousands of rounds shot through it, a cast of it would look almost exactly the same as the above factory SAAMI chamber!

Is that what you want? Do you want to pay hard money for something worn out and useless? Not likely.

But that is what you are buying with a brand spanking new, out of the box .357 Magnum or .357 Remingtom Maximum barrel with a SAAMI factory chamber, a throat cut too large in diameter and cone shaped.
As you can see, with this long forcing cone in the stock .357 Magnum factory chamber, the bullet is completely free of the case by the distance shown between bullet and case above before it hits the rifling. Between the long jump and no alignment of the base of the bullet, a chamber like this can hardly be expected to give good accuracy. Again, you have the same long forcing cone arrangement in factory .357 MAXIMUM chambers as well.

Rechambering to the longer .357 Max. case cuts out all but about .1" of the long Mag. forcing cone. Note that a SHORT cone IS necessary when shooting lead bullet to prevent lead from shearing off the bullet as it enters the throat. Thus the .1" of factory cone remaining after rechambering to .357 Maximum is a benefit. In fact, if there is no short cone, I use a separate reamer to create one since quite a few shooters do find the .357 Rem. Max. is excellent with cast lead bullets. The cylindrical section of throat then extends forward of the short, abrupt cone.

Quoting Mr. Murphy, "I dropped the bullet into the barrel and used the depth rod on my calipers to get a reading of 1.4" from the back end of the barrel to the bullet. I did my best to align the case, bullet, and chamber cast as accurately as possible to show how much room there is for improvement. I should still have at least 0.20" left before the rifling starts. the cannelure of the bullet is about 0.10" to the right of where the (.357 Maximum) case will stop."






Once again, cast lead bullet shooters seem to have the key to accuracy with the forcing cone chambers.
The consensus is to use a long shanked, heavy cast lead gas checked bullet with a wide flat nose. Cast lead shooters claim the heavier weights of wide flat nose bullets kill as well or better than lighter weight jacketed bullets.

And since there is a distance the bullet travels TOTALLY unsupported before even sealing off the bore at the muzzle, the longer shanked lead bullets eliminate powder blow-by around the nose of the bullet by sealing the bore off sooner. Ie, seat these bullets out as close to or just contacting the riflings at then forward end of the cone.





What you are looking at in the above drawing and photos is what you DON'T want.

This forcing cone arrangement above is what you get in factory .357 Mag, .357 Rem. Maximum, .44 Magnum, .454 Casull, .460 S&W, and other similar straight wall chambers. However, this same cone is also cut in .22 Hornet and .22 rimfire Mag. chambers as well. On the other hand, some factory chambers such as .30/30, .375 Win., and .45/70 have NO throat in them.





Older Vintage .357 Magnum chamber for comparison to the current long forcing cone design.



http://www.bellmtcs.com/store/images/category120/357%20Mag%20old%20chamber.jpg





Top, cast of a current .357 Magnum TC factory chamber long forcing cone design. Below it, an '80s vintage .357 Magnum TC factory chamber cast with a much shorter forcing cone design. Bottom, .357 Magnum case. (Courtesy, D.W. Murphy)




Second from the top is a chamber cast of an older vintage of .357 Magnum chamber with a short cone, as opposed to the current long style that is about .4" long. Note how much farther forward the rifling start in the top cast.

This one is still a cone, but it is quite short in comparison and a much better choice either to shoot as is as a .357 Magnum or to rechamber to .357 Maximum, which will cut out all but about .1" of the forward end of the factory cone, then I cut a new, proper throat as shown in the diagram below.

Once again this is a .357 Magnum case which demonstrates where the case mouth ends and where the riflings start.

Bear in mind that a number of companies have supplied reamers to TC over the years, and that there are a number of variations that are all construed by the reamer manufacturers to be "SAAMI Standard." There are apparently choices that are acceptable, but some of the designs TC has adopted over the years exhibit a gross disregard for the accuracy you are presumably expecting and paying for.

[shoot-n-lead]

Handi Rifles have SAAMI spec chambers.

Some of them WILL shoot the DW360 brass.

[GhostHawk]

If you want the max go over to the graybeards outdoors site, join up, get on the list for the .357 max reamer.

EVERYONE that I heard from who had reamed a Handi .357 mag to max said it shot BETTER after doing so, even .38 special loads.

If you have a .357 mag, measure your chamber. Myself and many others are able to use untrimmed .360dw brass which is longer than .357 mag. I think it is something like .357 mag = 1.2 inches, .360 = 1.4 and Max = 1.6.

But the only way to know for sure is to do a pound cast of your chamber/throat.

I know mine likes them in .360dw. Not for more powder room as I am loading the same in both.
But I have my dies carefully set to leave the boolit just a half a hair from touching the rifling.

First 3 I shot in .360dw brass did this.156469
Only 50 yards, but 3 boolits went through that one hole.
That black stickon bull is 2"

[Mica_Hiebert]

http://www.midwayusa.com/product/734226/ptg-solid-pilot-chamber-finish-reamer-357-maximum

[chutesnreloads]

My old Handi will also chamber 360DW.In fact can seat bullets so long it will safely shoot .357MAX. loads.Try yours and see.Ditto going to Greybeards for Handi Info.Those guys know more about handis than the makers.

[Nobade]

One nice thing about this conversion is if you have a lathe you can use a .381" (or whatever your chamber actually measures) chucking reamer to lengthen the chamber to 357 Max dimensions. No need to buy a chamber reamer, and no chance of going too far and deepening the headspace. I did that to my own Handi barrel and it does indeed shoot more accurately with both naked bullets and paper patched ones.

-Nobade

[just bill]

At this moment the only shortfall is a handi rifle or a .357 barrel to convert and add to another handi, oh say 45/70 or one of those. Don't know which other cal be reamed to .357 max.

Bill