M94 Extruded Primers

  • 1K Views
  • Last Post 31 March 2024
  • Topic Is Solved
Aaron posted this 23 March 2024

I have two IDENTICAL Cimarron Arms (Uberti) Model 94 rifles chambered in .38-55 Winchester. After filing a radius at the 6 o’clock position on the breech face, both rifles now feed ammunition without a hitch. While shooting the second rifle last week, I noticed that it simply would not open the action after the shot. It was jammed up tight.

The load is a very moderate load with Starline 2.085” (short) brass. The propellant is 28gr of IMR-3031, a Hunter Supply 260gr FP bullet, and lit off with a Winchester Large Rifle primer. This was the third such load tested in the rifle with the same result. Propellants varied on previous loads with Buffalo Rifle, RL7, A2520, and another with a propellant I can’t recall at this writing.

ALL of the loads resulted in a jammed-up action which could not be opened with normal force on the lever. To get the fired cartridge out of the chamber I had to cock the hammer and drop the hammer on the fired case. The lever could then be operated in the usual manner and the fired case extracted. Once ejected, the backed-out primers became visible. The primers are extruding at least .015” and may have been seated a tad deeper with the firing pin strike on the fired case.

A focused internet search on M94 backed out primers seemed to yield a consensus of a Headspace issue which was(is) endemic to the M94 family of rifles. Of course, there were dissenting opinions which ran the full gambit from Alien interference to dirty chambers. Rest assured, my chamber is “normal” and operating pressures are within industry standards.

I am believing the headspace argument is valid based on a few things:

  • Winchester made thicker locking bolts to accommodate headspace issues in decades past. A .005” thicker locking bolt was normal and can still be purchased on various sites.
  • When my bolt goes into battery, I can use my thumbnail to push it forward just enough to be visible. The locking bolt also appears to rise just a little bit too. That could be my imagination, but it does seem to rise a bit and hold the bolt forward.
  • The Starline .38-55 brass I have is measuring .056” rims and not the .063” as called for by SAAMI. Not as thick as they could be, but not by much.
  • My measurement for headspace is .071” or 1 thou greater than the SAAMI spec.

One thing is certain, the SAME cartridges fired in the first rifle DO NOT have extruded primers. The bolt on the first rifle can not be manipulated forward on that rifle either. Two identical rifles. One extrudes primers, one does not.

I have to say the headspace argument is correct although I have to admit, I do NOT see how excessive headspace will allow a primer to extrude. That case is going rearward when fired and should seat that primer flush, if anything, with the case head. I simply can’t envision it in my feeble little brain.

I may order a “Field” gauge to see if the action will close on it, but still have a few comparative tests to make before I spend even more money. I’ll try the 2.125” brass to see if it also extrudes primers. It could be the brass primer pocket with this lot of Winchester primers is incompatible. Like I say, a few more tests are in order.

Do any of you who shoot a M94 and have experienced extruded primers have any input here?

Rifle-1, Extruded Primers

Rifle-2, Normal Primers, Same Load

 

With rifle in hand, I confidently go forth into the darkness.

Attached Files

Order By: Standard | Newest | Votes
Wilderness posted this 24 March 2024

 

MP1886

These big blocks of italicised text are difficult to untangle.

With the best possible intentions, and with a background including editing, I can offer some suggestions. Having opened the gate, I will of course expect some of the same in return.

The first suggestion is to reduce the quote to just that part of it to which you are replying. The unwanted parts can be edited out before you start on your own reply.

The next suggestion is to separate the italicised quote from the text of the reply by removing the italics on the reply. Now we can see who said what.

The last suggestion concerns sentence length. Even if you start with long sentences, go back over your work and cut them up into shorter ones. Anything over about 20 or 30 words needs a second look. That said, I can see that my post ended with a long sentence. This just goes to show that sentence length requires discipline.

 

 

Attached Files

admiral posted this 29 March 2024

Right now over on the Accurate Shooter forum some people are having issues with Winchester LR primers. Mainly gas leakage around the primer edge etching the bolt face. They had this issue about 10 years ago with some lots and were taking them back and issuing refund checks. After having it happen to me Winchester paid to have my bolt face bushed. I returned a case (5000) of LR primers to them for a refund. It was like $135, those were the days, lol. Winchester did decrease their primer dimensions, we're talking a few 10,000's, for easier function in progressive reloading presses. This was reported in Handloader magazine a decade ago by, I think, John Barsness. I haven't shot millions of Winchester primers as MP1886 has but have shot hundreds of thousands of Winchester LR primers since the early '80's and never had any issues with the older style silver colored primers. I don't like the brass colored Win LR primers and will not use them anymore.

Attached Files

Wilderness posted this 23 March 2024

Aaron - if the lockup is a headspace induced issue, you may be able to prove the point by rigging some cartridges with headspace circlips as per my recent post:

https://forum.castbulletassoc.org/thread/headspacing-30-30-and-other-rimmed-bottleneck-cases/

From the rim and chamber dimensions you describe, you are looking at about .015" of slop. This is exactly the issue I was addressing when describing a way of reducing this to zero with shoulder headspacing. Of course with .38-55 you do not have  the shoulder to fall back on, so all the circlips will do is prove the point. Unless of course you find it expedient to circlip all your ammo.

Material for the circlip will be electrical copper wire, or hobby shop brass wire. Think old electric motor windings or multi-strand cable. In the first instance you can try .015" wire, but you may lose some of that .015" on chamber bevel, if the bevel is all the way around the chamber. If necessary use heavier wire. Leave a gap in the circlip for the extractor, though with the smaller wire you might get away without it.

I have a nagging suspicion that you may need to look further to solve the lockup issue, e.g. by swapping or polishing parts, but you can at least eliminate the headspace possibility first.

The image shows circlips that have been flattened because the wire was too thick, but you may not have to do that.

Incidentally, you can also run a headspace measurement without gauges by partially seating a primer in an empty case, preferably new, closing the action on the case, then afterwards measuring primer protrusion.

Attached Files

  • Liked by
  • Aaron
  • sluggo
Ken Campbell Iowa posted this 24 March 2024

looks like too much bolt-to-head clearance ....   " headspace " for our purpose ... ...

i would establish this first so that you can move directly to the next decisions.

a decent kitchen table crutch to check this is to cut little squares from a business card and use fast dry fingernail polish to glue them on the back of a case or cartridge ...  these will usually mike from 3 to 5 thousandths each.   

if you reload cases you really need not over 0.004 clearance  ...  the brass is going to be stretching when you fire it ... as described above the brass is shoved forward then it sticks at the front  when fired and at some pressure the back of the case is stretched back into the bolt.  at some less pressure the brass is not stretched but the primer is blown out the back a little to hit the bolt.

at low cast loads some grease the case and avoid stretching ...  at high pressures this crutch might peen the rifle parts eventually ... 

***************************

if you dont reload you can grit your teeth and get by with 0.008 or 0.010 head clearance ...  probably wont seperate new factory brass but just not a good feeling thing to do.

above 0.010 static head clearance you really need to tighten that clearance.,  for one thing a lever action rear locker metal is going to stretch a little more to add to the case stretch.

**************

i am not a lever action fixer guy, but the cheapest simple fix might be to braze a little metal to the locking bar and then file and lap back to a snug lockup ...  

enjoying this thread and hope this helps.

ken

 

 

Attached Files

  • Liked by
  • Fitzpatrick
  • mashburn
pat i. posted this 29 March 2024

With my low pressure pb 06 loads I get some primer protrusion using Winchester primers. Not so much with Federal or Remington primers. The WW are a lot easier to seat too. Don't know if it's diameter or just harder cups but that's my experience and maybe why with the Lee hand primer tool they tell you not to use Federal primers. I just measured a Fed, WW, and Rem lr primer. The Fed and Rem are .210 and the WW .2095. I don't know if half a thousandth would make a big difference but the WW are a lot easier to seat and I get more of the primers backing out.

Attached Files

  • Liked by
  • Aaron
  • Ken Campbell Iowa
Bill*B posted this 23 March 2024

I've been told that light loads can push the primer out like a piston and push the case forward.  Pressure then develops enough for the forward part of the case to grab onto the chamber wall, but too little to push the case head back again.  If load was hotter, developing pressure would rise high enough to push the case head back, and reseat the primer. Should this be your situation, cure would be to load hotter. Just a thought.  Bill

Attached Files

  • Liked by
  • John Carlson
Clod Hopper posted this 24 March 2024

You do have excess headspace aggravated by the thin rims on your cases.  You should not be able to move the bolt like that. That sounds excessive to me.   A heavier load would cause the extruded primers to be fully seated after firing.  This does not solve the problem though.  At full power the brass moves forward, the pressure pushes the primer back since there is nothing to stop.  The brass case clings to the chamber walls for a miilsecond and only after pressure gets higher does it slam back in the breech block.  This reseats the primer, but you may get a flattened primer that looks like excess pressure.  You could only partially size the cases so that the case headspaces on the shoulder like a .30-.06.  That may work for your currrent load.  The .38-55 headspaces on the rim.  You could also find some thicker brass, maybe some .30-30, or .375 Winchester.  If it were my rifle, I might send it back.  At least have a gunsmith look at it.

Dale M. Lock

Attached Files

  • Liked by
  • Aaron
pat i. posted this 24 March 2024

No sweat but the offer's there.

Attached Files

  • Liked by
  • Aaron
MarkinEllensburg posted this 25 March 2024

MP1886

These big blocks of italicised text are difficult to untangle.

With the best possible intentions, and with a background including editing, I can offer some suggestions. Having opened the gate, I will of course expect some of the same in return.

The first suggestion is to reduce the quote to just that part of it to which you are replying. The unwanted parts can be edited out before you start on your own reply.

The next suggestion is to separate the italicised quote from the text of the reply by removing the italics on the reply. Now we can see who said what.

Edit: You may need to do this by posting THEN editing.

The last suggestion concerns sentence length. Even if you start with long sentences, go back over your work and cut them up into shorter ones. Anything over about 20 or 30 words needs a second look. That said, I can see that my post ended with a long sentence. This just goes to show that sentence length requires discipline.

 It is really just as simple as un-clicking the " button. If only folks would just learn this little "feature" of the forum and how it works. Poorly designed, but it works.

Attached Files

  • Liked by
  • Sevenfan
Premod70 posted this 25 March 2024

Add the two clearances for the rim and the chamber and you will come up with excessive headspace, SAAMI specs or not. The protruding primers are an obvious problem that should be corrected before any firing of the rifle. As I said before send the rifle back, shooting low pressure loads can just as dangerous as the high pressure and in this case both are equally so.

Forrest Gump is my smarter brother.

Attached Files

  • Liked by
  • Bud Hyett
Ken Campbell Iowa posted this 26 March 2024

 ... i think someone in the band is playing a plastic flute ...

Attached Files

  • Liked by
  • mashburn
Wilderness posted this 29 March 2024

I just remembered another way I checked HS on a M94 - with the bolt closed on an empty, but the locking lug not yet home, put a (narrow) feeler gauge between the back of the bolt and the locking lug. Continue to close. Repeat until you find the right thickness.

Attached Files

  • Liked by
  • Ken Campbell Iowa
Aaron posted this 29 March 2024

The WW are a lot easier to seat too. Don't know if it's diameter or just harder cups but that's my experience and maybe why with the Lee hand primer tool they tell you not to use Federal primers.

Absolutely agree. WW primers seat easily. CCI are the worst and my thumb gets squashed when using the Lee Auto Prime hand tool. I ended up getting a RCBS Automatic Priming Tool. Glad I did. My thumbs are now normal size and this rascal seats any primer easily with its mechanical advantage. The Lee hand prime tool is the easiest to use but man, it does a number on your thumbs.

 

With rifle in hand, I confidently go forth into the darkness.

Attached Files

  • Liked by
  • admiral
Aaron posted this 29 March 2024

Right now over on the Accurate Shooter forum some people are having issues with Winchester LR primers. Mainly gas leakage around the primer edge etching the bolt face.

And sure as heck, a few months ago I was getting gas blow-by on my WW primers. It was the 7.62x54R. I KNOW the pressure wasn't the culprit and was scratching my tiny little head about it. Good to know. Thanks for the post Admiral

 

 

With rifle in hand, I confidently go forth into the darkness.

Attached Files

  • Liked by
  • Bud Hyett
pat i. posted this 30 March 2024

The rim thickeness of the case min = .063 and max = .073

Actually the case rim thickness spec is .063 - .010, in other words.053 to .063 so the cases are well within spec.

Attached Files

  • Liked by
  • Aaron
Wilderness posted this 31 March 2024

Original post, third paragraph, .015".

Attached Files

  • Liked by
  • Fitzpatrick
Aaron posted this 23 March 2024

Thanks Bill. This isn't a light load issue. Boiler pressure is normal albeit on the low side. I will however work up a stiffer load to see what happens in Rifle-1.

 

With rifle in hand, I confidently go forth into the darkness.

Attached Files

pat i. posted this 23 March 2024

I don't know how well this will work with a lever gun and a rimmed case but have you tried seating the bullet out a little longer so there's a little resistance when closing the bolt and slight land marks on the bullet. It might keep the case head tight enough on the bolt face to stop the primers backing out. How does the gun shoot?

Attached Files

MP1886 posted this 23 March 2024

Aaron you said "I have to say the headspace argument is correct although I have to admit, I do NOT see how excessive headspace will allow a primer to extrude. That case is going rearward when fired and should seat that primer flush, if anything, with the case head. I simply can’t envision it in my feeble little brain."

First let me tell you an expriment that Ackley did.  He removed the locking lug from a Model 94 Winchester in 30-30.  The he loades some normal pressure cartridges. He cleaned all oil, lube, wax off the cartridges. He did the same to the chamber.  He fired the rifle in a fixture and it didn't blow the action open.  The reason is the case at the moment of firing obturates to the chamber until the pressure is gone.  Ackley wanted to prove that and he did.   I feel your rifle has a little excess headspace and the case is obturating to the chamber and letting the primer blow out some.  Try this, take your same load, but lube your case up, the entire case. Don't need to touch the bullet. Then fire it and tell us if the primer is protruding. 

Attached Files

Aaron posted this 23 March 2024

I don't know how well this will work with a lever gun and a rimmed case but have you tried seating the bullet out a little longer so there's a little resistance when closing the bolt and slight land marks on the bullet. It might keep the case head tight enough on the bolt face to stop the primers backing out. How does the gun shoot?

I'll add that to the list of "try this" stuff to see if I can stop the primers backing out on this rifle. OAL is a very serious issue with the M94 in 38-55 Win. Picture stuffing a cigar back into a cigar tube held horizontally. Feed angle is critical when stuffing a fat long bullet into a narrow chamber. The angle of attack is critical. Even the Starline 2.125" cases can be difficult. The 2.085" cases are better but extending the bullets out aggravate the matter substantially. The M94 in 30-30 is a no-brainer. It shoves a thin bullet into a large hole. Easy peasy there.

There is something else going on here and I am determined to find the issue. I think step one is to bring the boiler pressure up near max and see what happens.

 

With rifle in hand, I confidently go forth into the darkness.

Attached Files

Show More Posts
Close