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41 JMP LOADING HELP NEEDED
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buckstix View Drop Down
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Joined: 09 Sep 2012
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    Posted: 23 Sep 2012 at 5:54pm
I just purchased an original unfired 6-1/2" Lee Jurras 41 JMP barrel and have a few reloading questions. 
 
Does anyone have any dimensions for the case?  It seems that the chamber of this barrel is a little deeper than I expected.  Any idea of variations throughout production?
 
I've formed a few cases and headspaced them off the shoulder and fired a nice 1-1/2" 25 yd group with 25.5g H110 w/ 170 JHP but they seemed a bit light and although they ejected, feeding was poor.
 
Any help would be appreciated.
"..You never pay too much for someting, you only buy it too early.."
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Joined: 08 Mar 2008
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Points: 2091 		Post Options Post Options   Thanks (0) Thanks(0)   Quote Auto Mag Quote  Post ReplyReply Direct Link To This Post Posted: 23 Sep 2012 at 6:35pm
Hummm,,,
 
Not 100% sure by any means, but I thought the 41 JMP headspaced against the case mouth not the shoulder???
 
LEJ what say you?
 
gh
Who was that masked man,,,
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curmudgeon View Drop Down
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Points: 747 		Post Options Post Options   Thanks (0) Thanks(0)   Quote curmudgeon Quote  Post ReplyReply Direct Link To This Post Posted: 23 Sep 2012 at 7:58pm
Shoulder, check magazine for rough follower or burrs on lip edges, then check feed ramp to chamber, have you cleaned inside magazine?
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buckstix View Drop Down
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Points: 20 		Post Options Post Options   Thanks (0) Thanks(0)   Quote buckstix Quote  Post ReplyReply Direct Link To This Post Posted: 23 Sep 2012 at 8:22pm
Oh yes, everything was checked.   The only reason I mention that there is a feeding issue is that I think the load is a bit light.  It seems to short-strokes the bolt, not grabing the next round and not locking open when shooting last shot.  I'm going to "up" the load 1/2 grain to 26.0 and try again. 
 
I haven't been able to locate ANY information on loads or case dimensions.  Can you point me in the right direction on these?
"..You never pay too much for someting, you only buy it too early.."
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BEEMER1 View Drop Down
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Points: 1366 		Post Options Post Options   Thanks (0) Thanks(0)   Quote BEEMER1 Quote  Post ReplyReply Direct Link To This Post Posted: 24 Sep 2012 at 3:26pm
I have no idea on where to find load data or chamber drawings other than Lee or Bruce Stark.
 
If you have your fired brass you can measure these as that is your "true" chamber dimensions.  If no dies are available, they can make dies from these.
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buckstix View Drop Down
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Points: 20 		Post Options Post Options   Thanks (0) Thanks(0)   Quote buckstix Quote  Post ReplyReply Direct Link To This Post Posted: 24 Sep 2012 at 5:43pm
Well I've got a set of CH dies coming, so that's taken care of. 
 
I actually formed 5 cases with my RCBS 44AMT form dies, and swaged a 41 neck on these using 41 Rem Mag dies. 
 
Even with this Laborious seat-of-the-pants method, I was able to obtain a 1-1/2" 5-shot group at 25yds.   I used 25.5g of H110.
 
I sure would love to have someone Else's "load" data to build on.
 
thanks
"..You never pay too much for someting, you only buy it too early.."
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Originally posted by buckstix buckstix wrote:

Well I've got a set of CH dies coming, so that's taken care of. 
 
I actually formed 5 cases with my RCBS 44AMT form dies, and swaged a 41 neck on these using 41 Rem Mag dies. 
 
Even with this Laborious seat-of-the-pants method, I was able to obtain a 1-1/2" 5-shot group at 25yds.   I used 25.5g of H110.
 
I sure would love to have someone Else's "load" data to build on.
 
thanks
WOW, never heard of that one.
 
Unless you are 100% sure your method is producing brass to the proper specs I would suggest you wait until you get a set of 41 JMP dies or you risk destroying your Bbl and bolt and possibly damaging your frame,,,
 
Sorry for the doom and gloom but these guns can be broken easily.  Used properly they are solid, but improper ammo is a sure fire way to ruin an Auto Mag.
 
LEJ, any words of wisdom???
 
Good Luck either way.
Who was that masked man,,,
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buckstix View Drop Down
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Joined: 09 Sep 2012
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Points: 20 		Post Options Post Options   Thanks (0) Thanks(0)   Quote buckstix Quote  Post ReplyReply Direct Link To This Post Posted: 25 Sep 2012 at 1:05am
"... WOW, never heard of that one.
 
Unless you are 100% sure your method is producing brass to the proper specs I would suggest you wait until you get a set of 41 JMP dies or you risk destroying your Bbl and bolt and possibly damaging your frame,,,
 
Sorry for the doom and gloom but these guns can be broken easily.  Used properly they are solid, but improper ammo is a sure fire way to ruin an Auto Mag. ..."
 
 
Yes, this is not a practice for a novice.  One must get the headspace correct.
 
Having said that, I've used this method many times in the past to get brass ready for dies that have been ordered.  I've got about 220 sets of reloading dies and if you mix & Match, you can just about load anything. 
 
I just wouldn't want to use this lengthy time consuming method more than required for run-of-the-mill reloading.  That's where the factory dies will come in.
 
I even modified a 40-65 bullet swage die to swage some mean looking  .41 cal 170g jacketed bullets.  They look real nasty with their little points.  They feed very good and they seem to shoot well too.
 
 
 
 
Still looking for some reliable loading info of the .41 if anyone out there can help with that.
 
"..You never pay too much for someting, you only buy it too early.."
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Still looking in the archives, have you checked the AM newsletters???
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buckstix View Drop Down
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Points: 20 		Post Options Post Options   Thanks (0) Thanks(0)   Quote buckstix Quote  Post ReplyReply Direct Link To This Post Posted: 25 Sep 2012 at 8:33pm
I've got 14 of the AutoMag newsletters, but they end with the announcing the availablility of the new Lee Jurras 41.  But no loading data in that one.
"..You never pay too much for someting, you only buy it too early.."
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