Need opinions on rim cut repair

[revbc]

My 357 maxi that shoots lights out has been an on going problem created by me, I think.  I think I cut the rim deeper when I reamed the barrel to maxi.  I have had FTF's and have used the extractor, (ground off the face and shimmed the back) to hold the brass at the proper headspace to prevent the FTF's.  Has worked ok for about 30-50 rds.  Today the rim edge of the extractor broke off, I guess from the fact it was holding the brass out somewhat away from the bottom of the rim cut.

Here are the questions.  Should I redo the extractor the way I had it, or should I go ahead and bite the bullet and grind down the barrel face to reduce the depth of the rim cut and reshim the barrel?  Or is there another repair better than these, short of sending it in for a new barrel?

Any advice welcomed.

Bobby

[moorepower]

I would think a machine shop or gunsmith could make a sleeve for the back .250 or so of the chamber and then you could recut for headspace. A sleeve would be as strong as the chamber and would support the brass. If it fits tight, that would be my first choice.

[trotterlg]

That is the down side of holding the cartridge back with the ejector, I have also had that problem using that solution on a 17 Velociraptor conversion, fire enough rounds through it and that will happen.  You may take a good small center punch and punch the face of the rim cut in about 6 places around the chamber.  It will move the rim back by .005 ot .008 or so depending on how hard you whack the punch.  First you really need to measure what you have got as far as head space.  Someone needs to round off the edges of that maxi reamers rim cutter so someone else doesn't do the same thing.  Larry

[revbc]

Larry,

I did it awhile back, it was a reamer from another member here, not the deal Tim is doing.  I am not positive I did cut it, but it's a good possibility.  It has about .012-.013 space between the cartridge head and barrel face.  I reamed it before it had 10 mag rds through it, so it's possible it came with the problem.  However, it's a mute point now.

Bobby

[trotterlg]

12 or 13 is more than you want to have but it really isn't too extreme  especially with a straight walled case.  Check the fireing pin protrusion, I get about .055 on mine and I think that .065 would be just fine.  Larry

[revbc]

Larry,

If I remember correctly mine has about .045.  If there is a way to increase firing pin strike length, do you think it would solve the FTF's?  Do you know if there a supplier for the 357 extractor, other than H&R?

Thanks,
Bobby

[torpedoman]

exact results i got shimming the 45-70 extractor to compensate for the mis-cut factory chamber. so i must assume that shimming extractor is not a fix so much as a way to break the extractor.

[D Humbarger]

I would machine a sleeve & "press fit it" in place then machine the rim cut to the proper depth.

[Dinny]

Larry,

If I remember correctly mine has about .045.  If there is a way to increase firing pin strike length, do you think it would solve the FTF's?  Do you know if there a supplier for the 357 extractor, other than H&R?

Thanks,
Bobby

PM sent.

Thanks, Dinny

[trotterlg]

.045 is not enough for sure, especially if you take away .013 for the headspace.  If the thing that is stopping the fireing pin is the stop on the hammer hitting the frame, then just take some metal off the hammer until you have about .055 to .060.  I would be very surprised if that didn't fix it.  Larry

[revbc]

Larry,

I'll try it and see if I can get a little more protrusion.

Thanks

[quickdtoo]

I wouldn't be so quick to condemn this work around for deep rim cuts so quick, unmodified ejector and extractor posts have been broken before, it could just be a bad extractor, The only source for the extractor is H&R that I'm aware of, Brownell's and maybe Numrich carry ejectors which will work with an extractor cam with modification and the addition of a short spring, see the hybrid extractor in the FAQs.

Tim

[mechanic]

I agree with Larry on modifying the hammer.  I took a needle file to mine and slowly removed metal then tried primed cases until the firing pin strike looked decent, then I tried loaded brass.  Problem solved for over 200 rounds so far. 

Best of luck,

Ben

[quickdtoo]

I've done a bunch of the hammer mods to improve pin projection, I've only ran into trouble once doing that, all hammers aren't the same and on that one the hammer was resting against the firing pin pushing it thru the breech face, so make sure the hammer has clearance at the firing pin before using it, you might have to remove a little material from the hammer at that point to make clearance.

Tim

[Spanky]

How could you cut the rim too deep? I thought it was pretty simple to do... turn the reamer until it touches the rim and stop.
Is there more to it or am I missing something?



Spanky

[quickdtoo]

Excessively deep rim cuts have always been common on H&R rimmed chamberings, but ejectors held the round back enough that FTFs weren't an issue, it's only been since extractors came about that FTFs became an issue due to the increased head space, I suspect it plays a part in the rimless FTFs also.

Tim

[bilmac]

Have you measured the rims of your brass? There just may be some brands that have rims just a few thousands thicker that may be enough to solve your problem.

[Goatwhiskers]

Re: excess headspace cut.  Back in the day when we found excess headspace on a shotgun we would machine a good steel washer and solder it into the rim groove, then use the chambering reamer to carefully recut the groove to get the correct headspace.  Permanent fix and easy.  Here endeth the lesson.  Goatwhiskers the Elder

[moorepower]

Not that uncommon of a fix.

[OR-E-Gun Bill]

How could you cut the rim too deep? I thought it was pretty simple to do... turn the reamer until it touches the rim and stop.
Is there more to it or am I missing something?



Spanky

It is a very simple proceedure Spanky, perhaps too simple.
The reamer cuts the chamber faster than what some folks think it will and when it hits the rim edge one might have the tendency to "do just one more revolution to clean things up". The cutter is scary sharp and with this one being a 6 fluted design, just 1/6 of a turn it can cut the rim a few thousandths deeper. I like Larry's idea of dulling the rim cutting blades a bit to help prevent over cutting of the rim depth.




Bill

[quickdtoo]

That's not a bad idea, but there have been a few members that cut new chambers with my reamer which makes it more valuable to GBO, so I won't be doing it to mine. 

Tim

[OR-E-Gun Bill]

 Ah yes, excellent point there Tim.

Bill

[jeepmann1948]

Tim,
  Here a a while back wasn't there a post on shimming extractors a bit to compensate for deep rim cuts? When I reamed out to maxi with the reamer i used some very fine solder around the rim cutter so it would not cut when it got down to it i removed it and very slowly and carefully finished up. Stopping when the cutter made contact with the Magic marker ink I had in the rim cut

[trotterlg]

When I chamber a new barrel for a rimmed cartridge, I do the rim cut first using the lathe, get that to the right depth, then run the reamer in until the rim cutter touches the already cut rim.  It is very easy to cut the chamber too deep if you are using the cutter built into the reamer.  Just look at all those factory H&R barrels that have deep rim cuts.  Larry

[trotterlg]

Also, the extractors and ejectors are made from very brittle metal.  I have broken one while using it to hold the cartridge back just as others have, drop the hammer on them enough times and they will crack right off.  Second try with mine I annealed the end of the ejector, as far as I know it is still functioning.  Larry

[quickdtoo]

Also, the extractors and ejectors are made from very brittle metal.  I have broken one while using it to hold the cartridge back just as others have, drop the hammer on them enough times and they will crack right off.  Second try with mine I annealed the end of the ejector, as far as I know it is still functioning.  Larry

I think you hit on the key there Larry, I've only done the repair on one of mine, the 45-70 Ultra which I've shot less than 50 rounds so far which is still intact, but I've done at least two others on barrels for other members, Pete's 445 Supermag is one of em, but on his I had to make an extractor for it and annealed the post to cut it, so annealing the post may be the key to better longevity.

Tim

[quickdtoo]

Tim,
  Here a a while back wasn't there a post on shimming extractors a bit to compensate for deep rim cuts? When I reamed out to maxi with the reamer i used some very fine solder around the rim cutter so it would not cut when it got down to it i removed it and very slowly and carefully finished up. Stopping when the cutter made contact with the Magic marker ink I had in the rim cut

The extractor shim is what Bobby did which may or may not be a good idea without annealing the extractor post first.

That's not a bad idea at all, I was trying to think of something you could use to protect the existing rim cut, a wrap or two of fine copper wire should work as a stop too.  

Tim

[gcrank1]

This surely makes the point that those 'new' to machining metal (and this is that) means understanding the process before you begin, and if in doubt, stop and reconsider. Think about what can go wrong before you get there. Whenever you get close to the finished depth, stop, take a break, have a pop or coffee, etc. and think about what you are doing.
In the case of these rim cuts, it would be a good idea to have actually checked it on the factory job before you began.
Sorta complicated and sorta simple; know where you started, know where you want to go, and do only what is neccessary to get there.
It aint rocket science, but it is working to a few thou' in a very methodical process.

[trotterlg]

Although I have never done one, you can likely stop cutting the maxi chamber several thousanths before you touch the rim and be just fine.  I would start checking the fit about .010 inch out.  Larry

[watkibe]

I am probably somewhat below average in mechanical skills, but I followed the directions that came with Tim's reamer. I stopped reaming when the first tiny scratch appeared on the rim cut. The reamer is much sharper and cuts much faster than I expected, so I rotated the reamer with partial revolutions at a time, and pulled it out to clean off chips and add oil about once a full revolution. Tim's reamer came with a 357 Max case, so I dropped it into the chamber each time after I cleaned out the chips to check progress. When the scratch appeared, the rim of the case was  seated flush with the barrel face. I looked inside, and there were some burrs at the muzzle end of the chamber. I was tempted to give it another turn "just to clean things up a bit". Instead I inserted a .40 cal bronze cleaning brush, and gave it a few turns. The burrs were gone, headspace was still good, and it looked nice and "cleaned up".
So far it has had no headspace or FTF problems at all.