Rossi 92 blowback issues


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FSJeeper
November 7, 2009, 10:27 AM
I bought a used, less than a year old Rossi 92 lever action in .45 long Colt yesterday. The rifle appears to be in perfect condition and the PO said he put around 200 rounds through it and had zero issues with it.

I put around 30 rounds through it yesterday. Love the rifle except for one issue. The fired cases have powder chars along one side of them and I got blowback in my face from 3 rounds. I did not have shooting glasses on at first and the hot gas was not pleasent in my eye. Not a lot, just enough to annoy you.

I was shooting new factory Winchester light Cowboy rounds through and I put one handload in it to see if that would change anything. All had the powder chars along one side of the case.

I have never seen brass have black powder residue like this before.

My first thought is the chamber is out of spec somehow.

I would love to sort this problem out easily and enjoy the rifle but I will ask for my money back if the rifle has a defect.

Anyone have any ideas on what is going on with this little 92?



Thanks in advance.

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Ed Ames
November 7, 2009, 11:09 AM
Yep.

To get a good seal, the chamber pressure must be high enough to hold the case mouth/walls tight against the chamber walls. The .45 colt, with its large piston area (fat bullet), doesn't have much pressure for a given bullet velocity. Cowboy loads are on the low end of low. Therefore, they leak.

The problem is made worse with a long barrel. As the bullet travels down the long barrel the pressure will actually go down... the pressure can start at 12000 PSI and drop down to something quite low (perhaps only a few hundred PSI, I haven't seen anything authoritative on the subject). The case relaxes, the seal is broken, and a little bit of gas travels between case and chamber. That can happen in a short revolver too but by the time the pressure starts really dropping there is usually an unobstructed .45caliber opening in the front and the gasses will take the path of least resistance.

The basic solution is to use standard loads. There may be other solutions too.

As an observation: The chambers I've seen that were designed specifically for cowboy loads (e.g. C&B conversion cylinders) tend to be TIGHT. If the chamber is tight, the brass doesn't have to expand as much to seal, which means they'll seal with less pressure. Maybe it's coincidence but I strongly suspect the designers used tight chambers because they knew standard size chambers would leak. I saw one example where the chamber would friction fit factory ammo and wouldn't accept some snap caps. Cowboy loads sealed just fine in that cylinder.

Float Pilot
November 7, 2009, 04:45 PM
Back when Winchester and Marlin were making pistol cartridge carbines in the late 1800s, the 45 colt was NOT one of the cartridges that they offered. Even though they would have sold a bunch had they been able to make it work.

That was for two reasons.
A. The rim size on the original 45 colt cases were not big enough for positive extraction.

B. The straight side walls of the 45 Colt case did not seal black-powder loads very well when used in the more sensitive Winchester & Marlin lever actions. (Compared to the Colt SAA revolver)

So..
1. Hand load your own loads. Try a good roll crimp and a touch warmer load.

2. Buy some different types of factory ammo until you find one that trips your trigger.

Ed Ames
November 7, 2009, 06:13 PM
I have read (could be wrong) that nobody made .45 Colt leverguns in the 1800s because:

A. Colt had a patent on the .45 Colt case design, including rim size, and
B. Colt refused to license their patent to other manufacturers.

By the time the patents ran out the market had moved on, and didn't cycle back until after WW2.

FSJeeper
November 8, 2009, 09:54 AM
Thanks for the replies. I am glad it is just the low powered rounds causeing the issue cause I really like this rifle.

Yes I handload for my revolvers and I am certain this will solve the issue.

gglass
November 8, 2009, 02:56 PM
I love both of my Rossi M92's!

I have never experienced the blow-back issue, but then again mine are chambered in .357 Magnum and .44 Magnum. I will look for the issue by shooting some .38 Special rounds next weekend.

Float Pilot
November 8, 2009, 06:16 PM
A. Colt had a patent on the .45 Colt case design, including rim size, and
B. Colt refused to license their patent to other manufacturers.

Brother Ed is correct.

However the same problem arose when Marlin wanted to chamber rifles in cartridges like the 38WCF and 44 WCF. They just changed the name on the barrel to 38-40 and 44-40 and so did various ammunition manufactures.

Since the US military and other companies made 45 Colt ammunition I doubt that Winchester and Marlin would have not tried chambering & marketing it had it worked correctly.

Please note that when double action revolvers were later added to the military inventory, it used a somewhat modified 45 cartridge with a larger rim to facilitate extraction.

Modern 45 Colt cases are made with a groove above the rim to aide extraction. The old balloon head case design on the 1800s did not include this.

Ed Ames
November 8, 2009, 06:55 PM
Not so much correct as perhaps quoting a correct source.

I'm not a patent expert, but... my understanding is that a patent covers the thing, not the name. OTOH, trademarks cover the name and not the thing. Maybe Winchester had a trademark on WCF while Colt had a patent on the case design for the .45 govt.. A rename from .44 WCF to .44-40 changes the name and would get around trademarks. Renaming .45 govt. to .45-40 doesn't change the design of the case and so wouldn't get around a patent.

Interesting question. :)

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