8x57 Plus

[Good Cheer]

Do any of yall make your 8x57's from 30-06's to take advantage of a little longer neck?

[mikeym1a]

Huh??

[bruce drake]

Do you mean rechambering the rifle to 8mm-06? If so, than yes. I own two.

Bruce

[dragonrider]

Yes I do,

[338RemUltraMag]

Yes, I make my 8x57 from 30-06 then trim the necks on the "long" side to better fit the military chamber of my M48

[Hardcast416taylor]

I understand the answers...I just don`t understand the question.Robert

[45 2.1]

Helps on longer chamber necks and usually provides a little thicker case neck wall.

Edit: Robert, he is forming 8x57 cases from 30-06 fired brass.

[Multigunner]

You don't want a neck wall that's too thick, you need to maintain some clearance to allow smooth release of the bullet.
If the neck is too long you can end up with the case driven deeper into the chamber by the primer ignition and pin fall causing the case moth to crimp down on the bullet with no room to release as the bullet leaves the case mouth.

I can see the advantages of a longer neck, expecially if its long enough that the gas check of a long heavy bullet remains above the shoulder. More of the lube grooves would be protected by the neck as well reducing the chances of grit contaminating the lube.

If you wanted to deepen the chamber neck to make a sort of cast boolit wildcat using the 63mm case length with the 57mm case body the barrel should be clearly marked so regular 7.92X57 ammo is never fired in the altered chamber. That might result in stripping of bullet jackets.

[Baron von Trollwhack]

You don't want a neck wall that's too thick, you need to maintain some clearance to allow smooth release of the bullet.
If the neck is too long you can end up with the case driven deeper into the chamber by the primer ignition and pin fall causing the case moth to crimp down on the bullet with no room to release as the bullet leaves the case mouth.

I can see the advantages of a longer neck, expecially if its long enough that the gas check of a long heavy bullet remains above the shoulder. More of the lube grooves would be protected by the neck as well reducing the chances of grit contaminating the lube.

If you wanted to deepen the chamber neck to make a sort of cast boolit wildcat using the 63mm case length with the 57mm case body the barrel should be clearly marked so regular 7.92X57 ammo is never fired in the altered chamber. That might result in stripping of bullet jackets.

Baloney !

BvT

[Larry Gibson]

Do any of yall make your 8x57's from 30-06's to take advantage of a little longer neck?

Yes. Additionally I also trim my formed (from '06 cases) 6.5x55, 7x57. 7.65 Argentine and 7.7 Jap case necks to just under the chambers neck length. I also set the shoulder back to fit the chambers headspace. Much better fit and advantageous with cast bullets instead of following some arbitrary headspace and OAL figures.

Larry Gibson

[Multigunner]

Baloney !

BvT
Explain.
Considering that most here prefer over sized cast boolits neck clearance is an issue.

Heres a less radical wildcat that takes advantage of a longer neck. Though the shoulder is set back and the case shortened to give a reduced capacity more efficient with lighter loads.
http://www.google.com/url?sa=t&rct=j&q=&esrc=s&frm=1&source=web&cd=1&cad=rja&ved=0CCsQFjAA&url=http%3A%2F%2Fcastboolits.gunloads.com%2Fshowth read.php%3F14415-303-Pygmy&ei=CThrUt2xNtCFkQf0_oCQAQ&usg=AFQjCNG4tunTKgjKa6TgtpfH18tkWywfqw&bvm=bv.55123115,d.eW0

PS
I do see what Larry and others are getting at. If theres far more slack in the chamber neck than necessary a slightly longer neck might improve efficiency.
But remember that the reason we trim cases is to prevent fouling of the crimped case mouth by the end of the chamber neck, and non crimped primers do drive the case deeper into the chamber. For that matter rapid bolt manipulation has been shown to set back a case shoulder by as much as .006 reducing clearance to pretty much zero. Hatcher wrote of tests run on this many years ago.

When I was loading for my 7.92 Persian Mauser carbine light loads of 4198 or 4227 resulted in the shoulder being set back a little further with each firing. Combination of heavy pin fall and primer push without sufficient chamber pressure to fully expand the case was the cause. After several reloadings and neck sizing only those case shoulders were set back enough that head gap was too great to safely use the cases for full power loads.

[JHeath]

I thought about the same thing converting 5.56 to 7.62x25. The Tok bores are oversize and the chamber necks tight, so I was going to use an off-the-shelf .340 reamer to enlarge the chamber neck slightly, and at the same time make it longer. Then cut the converted cases long to make a long-neck cast-boolit optimized case. Since I am going to the effort of converting cases I might as well cut the necks a little longer.

You could do the same with a lot of calibers and not need special reamers or dies. Say I wanted to cast for .308 Win. but wished the neck was longer. I could form the cases from '06 with long necks, and make a .308 "wildcat" on the cheap, with necks as long as .30-40 cases. A straight reamer would extend the chamber neck. If I wanted to save reaming/turning the necks, I could use a slightly oversize straight reamer. The only hitch would be the leade. At some point I would have to extend that, too. Not sure the easiest way to do that w/o a custom reamer.

I would happily shoot it for 20 years, then pass it on to some poor factory-ammo shooter who did not know to cerrosafe the chamber. Unless I marked it, something like .308 AI for "Amateur Improvised".

Anyway I think you are on to something.

[45 2.1]

Explain...Considering that most here prefer over sized cast boolits neck clearance is an issue.
Lets see if you understand this. Military 8x57 chambers are cut to ensure function. If one makes 8x57 cases out of military 30-06 cases, you can trim the case to fit your chamber (so it does not bind in the lead) or be too short to allow a lead/lube ring to form at the case end. Without turning the reformed case neck, it has plenty of room to accommodate a 0.326" boolit without any problems in the chamber and the fired case will accept a 0.326" boolit after firing. Considering most people use that size or less, then it seems more than adequate not withstanding the folks with oversize barrels that shoot the Lee 8x56R boolit.

[EDG]

Push a over size spire point bullet or a tapered steel punch into a case mount until you get a .010 to .015 over size funnel (trumpet shape) on the end of the case mouth. Force this case into your chamber and extract. After the chamber neck has squeezed the case down you can measure it and find out your chamber is way larger than your loaded brass will ever be.

[Multigunner]

Explain...Considering that most here prefer over sized cast boolits neck clearance is an issue.
Lets see if you understand this. Military 8x57 chambers are cut to ensure function. If one makes 8x57 cases out of military 30-06 cases, you can trim the case to fit your chamber (so it does not bind in the lead) or be too short to allow a lead/lube ring to form at the case end. Without turning the reformed case neck, it has plenty of room to accommodate a 0.326" boolit without any problems in the chamber and the fired case will accept a 0.326" boolit after firing. Considering most people use that size or less, then it seems more than adequate not withstanding the folks with oversize barrels that shoot the Lee 8x56R boolit.

So long as the '06 case you use isn't too thick at the new neck that's sounds fine. Many milspec chambers have generous clearance at the neck, the older J bore Mauser chambers are sometimes a bit tight at the neck compared to the later S bore chambers, one reason many of the early J bore GEW88 rifles failed reproof in the 60's and 70's when the 7.92 Proof cartridges were used.
Cast boolits are a bit more forgiving in this respect than jacketed bullets would be.

I get good centering of the case neck by only sizing the front 2/3rds of the neck, this centers the bullet to the origin of rifling.
Having once had an excessive pressure problem due to hardened carbon fouling of the neck of a .303 chamber I'm a bit more leery of a tight fit chamber neck to case neck .

[Multigunner]

I thought about the same thing converting 5.56 to 7.62x25. The Tok bores are oversize and the chamber necks tight, so I was going to use an off-the-shelf .340 reamer to enlarge the chamber neck slightly, and at the same time make it longer. Then cut the converted cases long to make a long-neck cast-boolit optimized case. Since I am going to the effort of converting cases I might as well cut the necks a little longer.

You could do the same with a lot of calibers and not need special reamers or dies. Say I wanted to cast for .308 Win. but wished the neck was longer. I could form the cases from '06 with long necks, and make a .308 "wildcat" on the cheap, with necks as long as .30-40 cases. A straight reamer would extend the chamber neck. If I wanted to save reaming/turning the necks, I could use a slightly oversize straight reamer. The only hitch would be the leade. At some point I would have to extend that, too. Not sure the easiest way to do that w/o a custom reamer.

I would happily shoot it for 20 years, then pass it on to some poor factory-ammo shooter who did not know to cerrosafe the chamber. Unless I marked it, something like .308 AI for "Amateur Improvised".

Anyway I think you are on to something.

Well I can't take credit for the principle. One thing that got me thinking of this is the deepening of a .303 chamber neck to allow fire forming a .30-40 Krag cartridge to have the longer body of the .303 with a bit longer neck.
I'd heard of some No.4 rifles in Alaska being re-chambered to take the .30-40 case because it was more easily available at the time and boxer primed making reloading easier. I never heard any details on these so I put my imagination to work on possible advantages.
I do remember one person posting of using home made smokeless powder in his handloads for one of these rifles. The powder was one used by Austria in WW1, very cheap and easy to make, also a bit dangerous to handle unfortunately.

[303Guy]

I've been wanting to fit a chamber insert to set the shoulder back for a longer neck. This specifically for a pair of rifles that should not fire standard ammunition, one due to the inner recoil face having set back leaving the now mismatched bolt bearing only on the outer lug. The other is old and has suffered both recesses setting back so these are for low pressure loads only.

[gew98]

So long as the '06 case you use isn't too thick at the new neck that's sounds fine. Many milspec chambers have generous clearance at the neck, the older J bore Mauser chambers are sometimes a bit tight at the neck compared to the later S bore chambers, one reason many of the early J bore GEW88 rifles failed reproof in the 60's and 70's when the 7.92 Proof cartridges were used.
Cast boolits are a bit more forgiving in this respect than jacketed bullets would be.

I get good centering of the case neck by only sizing the front 2/3rds of the neck, this centers the bullet to the origin of rifling.
Having once had an excessive pressure problem due to hardened carbon fouling of the neck of a .303 chamber I'm a bit more leery of a tight fit chamber neck to case neck .

There you go again. The only .318 bore gew88's existant were those rebarreled by the czechs for south american use. The germans went to a nominal .321 bore previous to 1900. I have seen many gew88's - especially turk surplus 88's when they were around in gobs being shot all day long with surplus chinese S patrone..and it was hot ammo mond you. As well alot of hevay ball being shot in them. Never saw nor heard of one failing back in the 70's and 80's. The european commercial market predominately used .318 bores in '8mm' sporters up until the 1950's.
As anal as the germans are I don't see them reproofing 88's with sS patronen loads as they do KNOW what the are dealing with. There are a handfull of germans in collector circles I know that shoot gew88's in mil bolt rifle comps in germany and they do spectacular shooting with them - all using .323 bullets. The 200 gn BTHP Sierra is a favorite among them.
So where did you read about this reproofing failure epidemic... obviously not practical experiance.

[Multigunner]

The only .318 bore gew88's existant were those rebarreled by the czechs for south american use.
The milspec barrels were originally .321. The 1905 conversion did nothing to change that.
The J bore bullet was a .318 bullet intended to bump up to fill the .321 bore.
The problem was not in the bore size, though a bullet .002 oversive does raise chamber pressure a bit.
The problem was when a 7.92X57S cartridge neck did not have enough clearance in the chamber neck because the bullet was .005" larger than the original .318 bullet.
Not all the early rifles were re barreled or given the long throat of the 1905 coversions and many older J bore Gew 88 rifles were sold off to civilian gunmakers.
Look up the old ads for these some time.
Many of those re proofed in the 60's and 70's failed. The proximate cause was the original chamber having a too tight neck.
Also many of the sporting Rifles built on the GEW88 action had barrels that were never proofed for the FMJ military bullet to begin with, look it up some time.
The original proof was to 58,000 CUP.

You won't see the rifles that failed re-proof........wait for it...........because they failed re proof.

None of those rifles re-proofed during a six year period when using a proof cartridge with a 318 bullet failed proof, only those re-proofed using a proof cartridge with .323 bullet.

There have been more complete articles on these failures , the PDF below tells part of the story.

http://www.riflemagazine.com/magazine/PDF/ri142partial.pdf

PS
Ever wonder why the Turks took all those nice shiny 1905 conversion the Germans gave them and re-barreled them with .323 bore barrels properly chambered for the 7.92X57 S cartridge.

For those interested the following explain pressure increases due to bores that are too tight. Insufficient neck clearance is another issue.
http://www.border-barrels.com/articles/Pressure_Trials_Consortium.htm

[frnkeore]

This is the drawing of the "S" bullet, as you can see it tapers from .3208 (8.15mm) to .324 (8.23mm) over a .315 (8mm) length. The necks of the 8x57 have always been generous at .357 (9.065mm), the maximum neck diameter of the cartriges is .355 (9.02mm) and the 88's were checked to be sure that a "go" gage would enter the chamber and marked S as proof.

If there were any failures of 88 barrels, I would guess that the Ss (196 gr) cartridge did that with it's 3600 bar pressure as opposed to the 2800 - 3000 bar of the S (154 gr) cartridge. 9000+lb less pressure.

Frank

PS
Thank you for that excellent Rifle article.
85626

[Multigunner]

If there were any failures of 88 barrels, I would guess that the Ss (196 gr) cartridge did that with it's 3600 bar pressure as opposed to the 2800 - 3000 bar of the S (154 gr) cartridge. 9000+lb less pressure.

Frank

PS
Thank you for that excellent Rifle article.

I had not realized that the WW 1 era German cartridge gave that low a pressure, but I was speaking of the proof test cartridges used in the 60's and 70's, which would have been of much higher pressure than the Ball cartridges of either war.

Theres a very good run down of pre WW1 era proof testing of German military rifles in W W Greeners "the Gun and its Development", 1910 edition IIRC.
To proof test the Gew 88 they found that using a proof cartridge with an increased charge of the standard powder would cause far higher pressures than they needed and many rifles were un necessarily destroyed in the process. They then formulated a special powder that duplicated the expected characteristics of the standard powder after years of deterioration in the tropics. The charge weight and volume was the same, the powder itself had very different burning characteristics.

Excessive feebore can also cause pressure spikes when a free running bullet is suddenly subjected to engraving pressures at the end of the freebore.
The barrel blow outs of the Gew88 rifles could have been due to a combination of factors working together.
Increased pull strength at the neck can alter the burning characteristics of the charge, a sudden increase in friction at the end of free bore would then increase pressure even more.
Early production barrels were known to blow out so they had already increased barrel diameter to compensate.

Some rifles may have developed fire cracking in the freebore that became deeper with long use. pressure spikes at origin of rifling would be concentrated at that spot. By the 1970's many of those old rifles should have been re barreled long before.

PS
From what I've read the deeper grooves of later J bore barrels were not due to an increase in major diameter but rather a decrease in minor diameter. This would have given a slight increase in engraving pressures.

[offshore44]

Do any of yall make your 8x57's from 30-06's to take advantage of a little longer neck?

Only in my accuracy rounds... A little longer to fit the chamber and a little bigger in diameter to fit better as well. This is for two Yugo's, an M48 and the sterling shooter of the bunch - a three digit serial number 24/47.