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Case Bulge, is this it? And, should I worry?

7552 Views 24 Replies 10 Participants Last post by  John Kort
I am working uo loads for my new production Winchester(miruko) 1892 in .45 colt. I am using new brass (Win) and 300gr Nosler Partition HG bullets. Powder is Lil' Gun. I noticed that about .35" above the rim is a nice little raised area that extends about 3/4th of the way around the shell case. I am wondering if this is a "pressure bulge" indicating I am to hot in the loading department. I am loading with 19.5 gr of powder up to 23 gr of powder. I checked the velocity of the 21.0 and 21.5 gr loads at 1438 and 1488fps.
Here is why I DON'T think it is a pressure problem but I want to get many more opinions,1)It is on all cases the exact same no matter the charge. 2) it is not a random "round" bulge, but an a very precise inverse Bottle Neck. It looks like the neck on a bottle neck cartridge(.30-06) only it is the other direction. A definite slight angle outwrds and then the rest of the case is that "new"size.
My theory is my chamber is cut poorly, allowing these reletively higher pressure loads to deform to the shape of my sloppy chamber. Comments please.
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Hi, Cub:
This sounds like the Lee-Enfield .303 bulge. The chamber is oversized and the cartridge is lying on the bottom, unless the extractor is pushing it elsewhere. The firing pin nails it in place long enough for the brass on top of the case to bulge up to the top of the chamber. The bottom side stays straight.

The .303 solution is mapping tape. It's 1/16th wide and a wrap just ahead of the rim adds .008". This centres the case in the chamber and you only have to do it once if you neck size. Once you get the length right, so the ends almost butt, you can do a box in a couple of minutes and it's a lot nearer than masking tape. It's an old British trick. I use Geotape, made in the USA, and a good stationary store should have it. The roll I bought cost $5 a while back and should do 450 .303 cases.

Somewhere I read that the original .45 Colt cases had a slight taper, and carbide dies overdo the base of the case. The author (Dave Scoville???) used a steel die with the proper taper for reloading for an old Colt, IIRC.

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Very interesting. I did resize the new cases with a Redding carbide die. Would recutting the chamber make it uniform? Is it anything to worry about? Do I have to throw the cases away after they have been fired in this rifle chamber? If not I suppose that it will really shorten their reloading life.
Sounds like the chamber is too large. What does the case measure across it's widest point (the bulge) after being fired?

Many semi-autos, notably the Glocks, leave the brass looking a little 'pregnant' as they suffer from the same malady.
Hi, Cub:
If the chamber is concentric with the bore, but oversized, recutting it will just make things worse. If it's not concentric, it's unfixable. I'd try the mapping tape, then I'd neck size the cases down to about .01" below the base of the bullet. Case life likely will be shorter, but that's a shoot it and see situtation. Try fireforming a few new cases with a 1/8" wide strip of masking tape around the base. It might take 2 wraps to fill the chamber. Likely the bulge will be uniform all the way around.

If you throw those once fired crooked cases away, Mike will be there to catch them. :D

You got that right Jack!!!!!!!!!1
FA18, you are describing my 45 auto brass perfectly! The web of the case is thicker and does not expand the way the rest of the case does. I believe the thinner part of the brass just expands to fill the chamber. This is more pronounced (depending on the loading) in standard 45 brass as opposed to 45 Super brass which is much stronger.
You're probably around max (don't know Lil gun) with the 300grs. Ken Waters was doing those vels with 225gr Speers. (Pet Loads 1/91) He was pretty conservative with the Trapper he was using, though. I think he was more concerned about case construction rather than carbine construction. He wasn't big on magnumizing the .45 colt for that reason.

That is the "pressure bulge" that you measure for excessive pressure. Waters' process is to fire a factory load and measure the max width at the pressure bulge and compare that to your handloaded. He advises staying within .0010-.0015" expansion, with .0020" being too far. You need a mic for this.

The problem is factory .45s are going to be wimpy, so you might need to build a moderate load baseline.

What cases are you using?

Waters found W-W cases bulged and compressed the extractor groove at the rim (in 1991). Federals, he said were beefier and didn't move as much. Both are far stronger than the older cases. But the FCs were the strongest found.

On another note: What sights are you using on your '92? I have the same in .44mag and I have trouble with the bead front and notch rear (they seem mismatched). I'm planning on adding an AO front blade and maybe later one of their peeps (reluctant to drill the receiver).


- Charlie
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I am using Winchester brass. The Lil' gun powder produces less pressure then other powders. The web site for the powder company lists loads up to 20.2 gr.

My 94 AE Trapper does the same thing to the cases that yours does. It's not because of pressure, it's because of oversized chambers.
I have fired everything from target loads, to Corbon factory loads and the ofset bulge is always there. It just varies with the pressure of the load.

.45 colt brass isn't always easy to get so I never throw them away. I carefully resize them in a carbide die and keep using them. Never had one fail. Not yet anyway.

The only cure for this problem is to rebarrel the rifle, and have a minimum chamber cut in it..

While making a bunch of chamber casts with cerosafe I have found that most tubular magazine lever actions have a slightly oblong chamber to aid feeding. The Marlin .32-20 and .25-20 are notable for this. With them it shortens brass life.
When starting our newest project, a .30-30 Ackley Improved we noted this while reaming the chamber. The Model 94 had what we thought was a smooth chamber but the reamer proved otherwise by taking off metal on one side and not the other for quite awhile. Finaly we got down to where the reamer was bigger than the original case and it began to ream all the way around. This was only toward the base. It never did cut 360 degrees right at the base.
If you full length size your cases and measure the pressure ring, how much expansion do you get with your maximum loads?
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I think I am going to buy some Cor-Bon and or Buffalo Bore loaded stuff and compare it to my handloads. if they look the same I will be more comforted. I will try some of the masking tape loads also, to see if that centers them up better. Having tape on them seems like it would interfer with cycling and chambering. I will measure some of my fired cases and see what the numbers are.
What I do to get around this exact same problem in my Bisley Blackhawk is to only partially resize the cases, it makes them last quite a bit longer. I only resize the portion of the case that actrually holds the bullet. This poses no problem for chambering in my pistol, but you could try a few this way in your rifle and you will likely have the same results. I also use this same technique for 38-40 brass that I use in a Buckeye Blackhawk that I like to shoot. The 38-40 brass lasts much longer this way. All you need to do adjust your decapping stem way down, which I'm not sure is possible with the Redding dies, and size only the portion of the case down to the cannelure that your WW cases likely have. Worst case, you could size as stated and use a universal decap die.
I may have a workable solution to this. Given that both Cor-Bon and Buffalo Bore think 1300 fps from a pistol is max, I will load my loads in my Ruger Bisley 5.5" to duplicate these factory loads. Then I will test them out of my Win. '92 and see how they chrono. that will be my hottest load.
Hi, Gents:
An out of round chamber is curious. That isn't easy with a conventional reamer. Incidently, I get basically zero runout on my fired .35 Remington cases out of the old Marlin, but both my Remington 700s have about .002" runout.

Feeding taped cartridges isn't a problem in a Lee-Enfeld, but you might have to hand chamber them in your Winchester. Mr. Gates noted that seating the bullet long so it's snug in the throat centres the front end of the cartridge and aids in getting an even expansion.

Sizing the neck to just the base of the bullet is OK for revolver bullets, since recoil trys to pull the bullet. The slamming the bullet takes in a tubular magazine tends to seat a bullet deeper, so I'd like a little more resizing to put a ledge in the case to hold the base of the bullet.

If you work up a load with new brass, you can see the bulge move closer to the rim as you go from min. to max. It's real easy to see with a Lee-Enfield.

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You will have some pretty warm loads if you want to get 1300 out of a 5.5" barrel. I know it can do more. The technique I mentioned will almost certainly work in your carbine and it will work in your Bisley. Keep in mind, as Jack mentioned, that good bullet pull and a good crimp will be mandatory with this round, whatever you decide to fire it in. If you have problems related to this, it will likely be with your expanding stem, not the resized case diameter. The good news is that you are using Redding dies, and if you have a problem, they will make it right. I have experienced this several times over the years, usually related to something out of the ordinary that I'm trying. I can't say enough about the quality and customer service of this company and it's products. Please let me know what velocities you're getting from both guns. I mainly shoot 300gr XTP-Mags out of my 7.5" Bisley with a healthy dose of 296 behind them. I haven't seen the need for the Partition, as I only use them for deer. I shot a big (175lb dressed)doe in Minnesota last week with that gun, and it just knocked it over. The expansion didn't seem to be extreme, but I'll never know because penetration was complete. I'm interested to see what velocities you get with the powder you're using, as well as if the SD is better than the 296.
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Another interesting thing I found on chamber cut, my fired cases from the Win. '92 will NOT chamber in my Ruger Bisley, but the fired cases from the Bisley will chamber in the '92.
I don't know how hot my loads will be as far as pressure goes. I do know that Cor-Bon don't you a long barrel to get their velocities. I shoot their 265 gr .41 mag load in my 6.5" Blackhawk. It Chronos at 1400fps. I asked them why I was getting so much more then they published and they said because they used a 4" barrell for development. So I am figuring they used a reletively short barrel to develop their .45 loads. I could be wrong.
1400 with a 265 is stompin load. I used to use some 300gr SSK design bullets in the 41 when I had access to a mould, I could get a little over 1300 in the 7.5" Bisley. Funny, they felt the same as the 1300 fps 300gr lead loads do in the 45 Bisley. Recoil is stiff, but manageble if you ride with it. I have a 4 5/8 and 6 1/2 in Blackhawks in .41 Mag, but I haven't put more than a 5-600 rounds through them. I got them when I thought ruger was going to stop making them, and the price was right. How was the recoil of the CorBon load with the Blackhawk grip frame?
Great topic. Good advice all around. I have a few observations:

1. Winchester pistol brass deforms more than rem or Federal.

2. I work with Lil'gun a LOT, and it is a very unusual powder. It gets its power from a
pressure curve that is flatter than traditional powders - a lot of area under it, but not such a high peak. It can show a lot of deformation in soft brass for the peak pressure listed.

3. Your loads sre 1-2 grs over Hodgdon's Max. They list 20.2 grs at 29,800 CUP. This is the limit for the Colt BRASS, but probably not your rifle.

I would trim some 454 Casull brass to Colt length, and try a few to see what happens. These cases are designed for 65000 psi, and very strong in the web. Work up your loads again, as the trimmed Casull cases will have a smaller capacity than the Colts. Remember, the Casull uses small rifle primers. Try for 1500 fps and stop there.

This sounds like a lot of work, compared to just buying the Colt brass, but the Casull cases will last forever at these pressures. If this approach does not work, try Jack's tape method.

Hope this helps.
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