Custom Winchester in 30-378

[bullethead]

Hello all,

I'm new to this post.  Made my way hear researching single shots.  But I have a question for y'all.  I am not a gunsmith.

I had a Winchester Classis SS in .375 re-barrelled and consequently chambered for WBY 30-378.

I have two problems one bad, one annoying.

Bad:  I have signs of high pressure, namely I at about 1 of 5 shots my bolt is a b!(@* to open.  I had a first production run of WBY ammo that I found out was loaded really hot, I only got through 5 rounds, everytime I had to almost hammer the bolt up.  Also, I can see striation marks on the spent cases, so I know the brass is being "swaged" under pressure.  I know that the free bore was under cut compared to spec.  I have lapped the lugs and headspace checked 3 times.  Would the lack of full free bore be the culprit in the high pressure problem?

Annoying:  The smith stretched the magazine wider and open up the magazine feeding ramp, but my shells didn't feed into the bolt properly.  I used a dremmel and took out some of the rail.  Now, well it feeds really good, in fact on occassion I can get both shells jump up, which doesn't work to well.  Do I need to live with it 'cause I probably cut the rails back too far?  Can I get more work on the mag to cure this?

[gunnut69]

First as to the pressure signs..  Short throats in Weatherby calibers can indeed lead to higher pressures but not just 1 in 5 rounds fired..  Check the fired cases for concentricity.  Is the case head square with the axis of the fired case.  If it isn't you may have discovered the problem, an out of square chamber/boltface.  Difficult extraction may or may not indicate high pressures.  Are the striations in the fired cases circumferential of longitudinal?  Perhaps just a rough chamber is causing the difficult extraction.  One must not grind on feed rails without absolute knowledge of what one is doing.  I truly don't know if terminal damage has been done but double feeding is not a good sign.  If the smith had already worked on the feed rails and they were not satisfactory you mostly likely should have taken them back and allowed him the chance to correct the problem.  If you've removed too much rail and the action already a 30-378 there is a real problem.  Opening the mag side of the feed rails a bit more may cure the problem but if its already maxed out you may really have created a dilemma..  There are solutions but none are really good and all require no small amount of skill of the smith.  Of course feeding problems are always thorny..  A lot depends on where you applied the dremel.  Just a little warning-these little tramel tools are wonderful gadgets, I have 4, but their danger lies in the speed at which you can use them to get yourself in trouble..Caution!!

After I submitted I realized I should try to describe how a bolt action magazine functions..The rounds are retained in the magazine by angular pressure applied by the follower and its vertical spring pressure.  The rails need be no wider than the round being fed, the key is the diameter of the round and it's relationship to the width of the magazine.  On long cased rounds it is sometimes necessary to shorten(from the front) the rails to allow the cartridges to feed without binding as they exit the magazine.  Cartridges popping from the magazine usually indicate 1 of 2 possibilities.  The magazine is too narrow OR the rails don't project enough into the magazine opening.  The former is remedied by widening the magazine, the latter is more difficult.  If the magazine width can be widened it may solve the problem.  More likely the mag is already as wide as it can be and still feed.  We then need to add metal to the feed rails.  This is possible but is a lot more difficult than removing it..  and more expensive.  TIG welding is probably the best way to add this back but I have seen it done other ways.  Strips of steel or brass can be added to the inside of the action to provide the retention needed.  Find a reliable smith and keep us up to speed.  This is indeed an interesting problem..  Also please note-it is quite difficult to diagnose feeding problems long distance.  I may as usual be quite wrong .

[bullethead]

Gunnut69,

Thanks for the response.

The striations run longitudinally.  There seem to be more of them right in front of the belt.  They have equal density as you go around the circumference.  I did my best to examine the spent cases for squareness.  From what I can tell, with a caliper and rotating them on a flat surface with a vertical reference, they are still square.  Is there anything I can do to ensure the chamber is correctly polished?

Regarding the feeding, I watched it cycle slowly for the nth time.  I don't know why, but the light bulb went off as I was looking at the mag from the bottom.  The smith did slightly stretch/widen the case, but it still has the tapered H&H shape.  Yup as I cycle it slowly the shoulder jumps up (at least first).  I believe I need to have the length of the magazine to widened to roughly the width of the rear of it (near the belt).  That seems to be where the smith did most of the work.  

The smith took out some of the rail where the belt is.  I took out the same amount for the length of the rail.  The reason why I did this was originally the shell would not "jump up" into the bolt/extractor.  During feeding it would bind.  I am not near the original gunsmith anymore, so I need to find one here in Tampa.

Regarding the pressure.  If I can't do anything to the rifle, I am going to handload some lighter rounds and test for seizing and accuracy.  Thanks again for your help, advice is always welcome.

[Judson]

First off I would never build a .30/378 on a Mod 70 action for the reason that the barrel shank is too small in diameter.    As for the marks on the brass, check to see if the chamber edges and the belt area are radiused, if left sharp then this would cause scuffing.    As for the feeding problem and the high pressure, didn't this "gunsmith" test the rifle before taking your money?    I see this stuff way to much!!!!    You paid for a job and what you got was not what you should have.    Stuff like this makes all gunsmiths look bad and bends me the wrong way!    As for the high pressure, even a short throat should not make factory ammo give that type of pressure where the bolt is that hard to lift.    I hate to say this but I think you have real problems and probably an unsafe rifle.    I think I might call that Gunsmith and mention such things as money back or lawyer in the same sentence.      By the way as far as the barrel shank diameter, I am sure someone will feel I am nocking the Mod. 70 but have you noticed that Winchester does not chamber for a bigger case then the .458 and resently the .404 size case, there is a reason for this!

[bullethead]

Judson:

Wow!  I just got a bad feeling in my gut.  I have about 80 rounds through this thing.  

I did take it back to the gunsmith, twice.  He did test it and made some improvements regarding the tight action.  I really don't know what he did.  The feeding action problems he gave up on to be honest.  The gunsmith, is well, kind of a friend of my uncle (who by the way had the same gun made, with same problems).  He gave us a deal, so we were trying not to work him over.

So for the really serious topic.  I am not greatly familiar with the barrel shank OD implications relative to the receiver.  Are you implying they will separate under stress causing catastrophic reaction to my gun and head!?

To be honest, I have been under the impression that the Winchester Classic action was one of the stronger ones, that is why we went with it.  Any further information you could provide would be greatly appreciated.

[gunnut69]

I did a bit of checking on shank sizes and noted that Winchester chambers the M70 in the 416 Rigby.  This of course is the case from which Weatherby designed the 30-378(actually the 378 Wby was designed from the 416Rigby).  It simply has a belt added and the changes made (necked down and shoulder squared) to create the Weatherby round.  There would be weakening of the barrel shank further where the recess was cut for the belt but that is at the rear of the case in the web portion of the case and should not affect shank strength.  I believe the action will most likely be strong enough for this conversion but admit I've never done one..and likely never will.  FEEDING- this is a huge case and pretty square.  The magazine should indeed be widened for it's entire length.  The round must move forward before it moves up into the boltface.  Getting a controlled round action to feed is a bit more difficult but can be done..  I will also stress that the throating can create catastrophic pressure spikes and the Weatherby rounds are bad in this respect.  The freebore built into the chamber was one of the secrets to the extra velocity and if the chamber was not long throated the bullets may be jammed into the rifling while still in the case.  This will cause problems but, BUT, it would cause them consistantly.  Not just 1 of every 5 rounds, all would be hard to open..
Are all the fired caases marked the same?  Check for extractor marks in the recess between the case head and the belt, the extractor groove.  I have seen extractors the were a bit too long that were gouging the extractor groove so hard that it made opening the bolt difficult, depending on the tolerances built into the brass..  Are there any other signs of over pressure situations on the fired cases..  I believe this rifle can be fixed but it may require a bit of detective work...  It's likely the marks on the cases were caused by burrs or chatter marks in the chamber or perhaps sharp edges.  Any of those is bad but if bad enough to make extraction difficult in one case it should have effected all cases.  Extractor groove tolerances though may well cause problems in only one case out of 5..  If there are no other overpressure signs(cratering,flat primers, excessive case expansion in front of web etc) we need to concentrate our search other places.

[bullethead]

Gunnut,

Thanks for taking the time to research.  I am feeling a little better/safer.  Still concerned though...

There are no marks in the extractor grooves.  It did have some gouging from the extractor on some of the first shells fired, but those are the ones I had to use a rubber mallet to coax the bolt up.  Those rounds were the "hot" ones, Weatherby's first lot of ammo.

I do not see any other signs of high pressure.  The primers are slightly flattened.  I compared them to some spent 30-06, 7-08, and 300 Win Mag cases and to be honest the seem about the same.  There is powder burn residue about down the exterior of the throat about 1/4 inch.  Consistent on all shells.  To an earlier point, there is a small amount of free-bore.  When we were first fooling with these and my uncle was reloading, we figured we were 0.2 of an inch from the lands with factory 180 X's.

The only other things that I can think of are that the tight action only occurs after the gun has heated up.  Say after the first 5 shots.  I try and rotate the guns I am shooting, just to keep this monster cool, but maybe not enough.  Also, I was cleaning last night, I did notice a some very small filings in the lug area behind the chamber.  Probably from my dremmeling exercise  :cry:

The last thing on my mind is to do an aggressive copper cleaning job on the bore.  I am not sure what to look for regarding fouling, but nothing seems apparent.  I am going to research and purchase some supplies...

So far I have only shot factory 180 Barnes X bullets.  I am headed to PA for the weekend and will reload a couple batches with minimum powder to a few steps up.

I have a pic of a case, but don't have a URL to host it...

[Judson]

One thing to keep in mind, yes Winchester did a few .416 Rigbys but they have lots of money and lawyers.    However the .416 Rigby is a very low pressure cartridge, around 45,000 PSI max, unlike the Weatherby family that operate in the 60,000 pluss PSI range, big difference!!!
    Acording to S.A.M.I., I think I have that right,    The Mod. 70 action is not big enough for the .375 Weatherby class of cartridges.    I do not have the specs right here but am rather sure you will find this correct.    As to safety though acording to SAMI a mauser should have 1.1" chamber diameter but how many original mausers have you seen with blown barrels and they measure around .9"    Even so using a Model 70 for that conversion is something I would not do or recommend.    Now a P-17 or P -14 action that would be another thing.

P.S.   Want to get rid of copper fouling on that canon?    Use Barnes CR10 beats any bore cleaner I have ever tried and I have tried alot, but read the directions!

[gunnut69]

Actually I can't say I've ever seen a mauser burst a barrel.  I've seen a few that set back the lugs but the barrels have held.  don't have the specs her on shank diameters but I still contend the winchester will most likely be just fine.  I have heard the stainless barrels were giving the manufacturers fits in their ultra lite guns.  Seems they were cracking when fired at very cold temps.  Something about the alloy being more temp sensetive than chromoly, but let me say again this was just heresay..  I believe this rifle may have less safety margin than a MK-V.  We should note that weatherby started out converting mausers and winchesters to his calibers, only later having the MK-V manufactured.  Probably to gain the size.. still he used M70s and of an older manufacture..  In any case I can think of few things that could be causing the problem you describe.  The marks on the fired cases indicate the smith did not polish the chamber and didn't properly debur the chamber.  You also seemed to indicate the  rear of the magazine was widened but not the front.  This case is close to square or parallel sided.  The magazine should only have a minimum amount of taper.  This should be worked on by a smith with some knowledge not a hack..  You could not find any marks on the cases that were hanging up that would indicate an extractor binding or a case head out of square.  Clean the action carefully to remove all grit and check the the cocking cam on the rear of the bolt body and the primary extraction cam on the rear of the back of the receiver ring.  Were excess pressure causing the extraction problems there would be some signs on the cases of too much pressure.  My guess is the difficult extraction is mainly caused by a rough chamber and perhaps a galled primary extraction cam.  Do NOT polish the camming surface on the rear of the receiver ring, lubricate and work the bolt to burnish the surfaces.  This primary cam should be lightly lubed with a high pressure sybthetic lubricant(grease) as should the cocking cam.   Chceck the bolt to be sure the extractor is moving freely and the bolt is not too tight..  You spoke of the smith working on the 'tight ' action.  I truly wonder what was tight.  Was the bolt difficult to cycle?  The filings in the lug bay may well have come from the sharp edges of the chamber shearing off brass from the cases as they were fed into it from the magazine.  Check the end of the extractor that enters the front receiver ring for scratches or marring.  Clean the piece and lube the cam surfaces and the rear of the locking lugs.  Fire 5-6 rounds, loading them single shot(do not use the magazine).  But before anything else take the rifle to a smith and have the chamber polished and deburred..  
PS_one other thing, before going further check the bolt face for brass shavings or residue.  Probably OK but I forgot to ask..  My bet is a rough chamber and a stainless action without proper lubrication..

[Judson]

69 made some good points, some of which I have also made such as a sharp edged chamber but that would not cause extraction problems.    However like 69 said a rough chamber could.    I would be a little concerned that by the time you polish out the chamber you might end up rather oversized since .001 to .0015 is what is considered maximum for head expansion.    I have to back up alittle after some checking as to the shank diameter.    It SUCKS to be humble, I have built a .30/378 on a Mauser single shot action and the shank diameter is within specks, the Mod 70 not far behind.    The Mauser does have a lot more meat in the receiver ring area so I was willing to do this but shank diameter wise there is not much difference.    I CAN NOT BE HUMBLE ANY MORE!!!    The Mauser is greater! It is Better! and The Mod. 70 is just a cheapened copy!!!!    Now I feel better, sorry about that.    One more thing that might shed some light on your problem, how does a re sized case that was fired in your rifle chamber in your rifle?

[gunnut69]

I hadn't thought of that yet..  and I too adore the mauser.  To think that today after more than a hundred years and 2 world wars it has not been improved on mechically.  I love the M70(especially the pre-64 flavor) but for hunting a slick 98 is a wonder for the senses.. Actually polishing the chamber is a kind of last resort.  I'd try burnishing it first.  Use a bob made of steel wool and spin it in a drill motor at as high a speed as is possibler.  My DeWalt does 2500 rpm/s.  Use a worn out bush of the proper size on the end of a section of old cleaning rod(a piece of an aluminum arrow shaft with the broadhead adptor in it will work also)((Don't ask how I came by that)).  Wrap the steel wool around the brush(the bristles will help hold it) so that when the brush is turned by the drill the wool won't unravel.  Make the bob the length of the brush and a tight fit in the chamber.  Debur the chamber mouth first and then burnish.  I am still troubled by the intermittant nature of the problem..  and Judson, I've seen your work, you need not be humble.

[bullethead]

Gentlemen,

Once again thank you for your responses.  I have just returned from PA and getting back to this project.  I am searching for a local gunsmith to check everything once again and to machine out the receiver to expand the mag.

Gunnut, you outlined the procedures to burnish the chamber and I do have all of the supplies (aluminum arrow pieces included).  Do you think I can tackle this myself?

I have never lubricated the bolt points as mentioned with high pressure grease.  Makes sense.  

I inspected the bolt again, no strange markings on the extractor.  I don't think I am getting brass shavings from the feeding.  When a case does make contact the marks are very light.

Here's something new.  When looking at the bolt, I noticed on the face I have grooves that match the OD of the case.  The grooves only exist where the bolt face is open.  They are about 1 mm wide and are deep enough to have a finger nail almost hang up on them.  Do I have an out of square face or is this normal?

Judson, I cycled several spent cases through it.  I tried 3 different ones, rotating the case to four different positions.  All of them feed and extract with no binding.

I am going to procede with the above actions and then bore cleaning (thanks for the tip Judson) and head to the range with some factory ammo.  My uncle is going to reload some lighter loads and I will test them in a couple weeks.  Thanks again everyone.

[gunnut69]

Burnishing is fairly simple. The metal is not removed so much as rubbed flat or smoothed. The burnishing bob should be tight enough to be hard to get into the chamber. Running the drill slowly as the bob is fed will allow it to enter where it can then be run at a higher speed. Be cautious as it will get quite warm. Polishing is the use of abrasives to remove bits of metal to smooth the chamber. It may be necessary but should probably be done but someone familiar with the process. The chamber mouth should also be deburred and always when doing anything of this type to any weapon clean thoproughly before reassembly and use. If as I think it's just a rough chamber, burnishing may do the trick but if it's really bad it may require a light polishing. In burnishing no measureable amount of metal will be removed and even in polishing only the tiniest amount of metal will be removed. The primary extraction cam and the cocking cam should also be lubed lightly with a bit of high pressure grease.

I'm assuming the circular grooves are in the bolt face, the recess that the casehead fits into in the end of the bolt. They are probably not the reason for the hard extraction problem. They are however an indication of poor worksmanship. Unfortunately their removal would most likely induce excessive headspace. When the rifle was built it would have been no problem.  

Be cautious when reducing loads in that cavernous case. Light loads of slow burning powders can lead to a phenomina called 'detonation'. The exact causes are open to some speculation but that it happens is a certainty. It causes a massive pressure spike and usually destroys the weapon. Powders at the 4350 and slower level at reductions of more than recommended by the book in large capacity cases are the culprits. Follow book loads and go not go lower than they say with the slower powders.  Keep us informed.  Thanks!!!