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41 JMP LOADING HELP NEEDED

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jurras View Drop Down
Callahan's Auto Mag
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Post Options Post Options   Thanks (0) Thanks(0)   Quote jurras Quote  Post ReplyReply Direct Link To This Post Posted: 25 Sep 2012 at 11:01pm
Still searching the archives. LEJ
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buckstix View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote buckstix Quote  Post ReplyReply Direct Link To This Post Posted: 28 Sep 2012 at 12:18pm
Is the 41 caliber Automag so rare that no one shoots it? 
 
Is that why no one has loading data to share?
"..You never pay too much for someting, you only buy it too early.."
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Auto Mag Quote  Post ReplyReply Direct Link To This Post Posted: 28 Sep 2012 at 9:40pm
Well yes and no,,,
 
They are around and a few here like it and a few dont.
 
I happen to be one of the folks who has shot it and just did not see the advantage. 
 
Unless you make your own bullets you are stuck with a limited selection, and I see no performance or accuracy advantage over either the 357 AMP or the 44 AMP but I do see some disadvantages.  Its extra work to form the brass and having been necked down it will not last as long as 44 AMP brass.  And the current going rates for 41 JMP Bbls are quite a bit more than the 357 or 44 and with nothing to gain (ballistically) thats just good money out the door just to say your shooting a 41 JMP. 
 
I would love to hear some sound reason that the 41 JMP is better then either the 357 or 44, but to date no one has come up with one, and having shot it years ago I already got my check mark to say I did it.  So shoot it if you must, but dont expect anything special. 
 
LEJ himself has said many times that its was a bastard round and he prefers the 357 AMP over it.
 
I have no hands on experience with the smaller than 357 AMP calibers, but I have shot the 357 AMP - 41 AMP - 44 AMP - 45 Win Mag - 475 Wildey rounds through Auto Mags and after thousands of rounds I personally feel like they got it right at day one, the 357 AMP and 44 AMP are solid performers and I have not found anything better for the Auto Mag.
 
Well thats more of an answer than you were probably looking for,,,  Sorry I rarely short on opinion,,,
 
Hopefully Tony, Gerry and LEJ will offer up their words of wisdom.
 
ATB - GH
Who was that masked man,,,
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buckstix View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote buckstix Quote  Post ReplyReply Direct Link To This Post Posted: 29 Sep 2012 at 1:58am
Cool,
 
But I'd still like to shoot mine with different loads ...
 
I found that at least so far, I like the 41 better than the 44 ... lower felt recoil, with good accuracy.
"..You never pay too much for someting, you only buy it too early.."
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paul v. View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote paul v. Quote  Post ReplyReply Direct Link To This Post Posted: 01 Oct 2012 at 7:04am
Here's some data I worked up to carefully in my 6.5" LEJ custom 100 barrel extention on an El Monte frame. I used CH4D 41AMP dies adjusted to headspace on the shoulder according to archive instructions similar to 357 AMP I believe.
O.A.L. 1.6"
170g Sierra
28.5g H110 (worked up to cycle & lock slide open consistantly)
Starline 44AMP brass sized to 41JMP
CCI350 primers
@1700fps
Good luck- it's a fine cartridge - expensive to obtain? - yes- difficult to load for?-  no more difficult than most bottle-necked cartriges... it exhibits qualities of both the 44 & the 357 Automags. (I shoot all 3 calibers)
Paul v.
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buckstix View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote buckstix Quote  Post ReplyReply Direct Link To This Post Posted: 01 Oct 2012 at 11:34am

Hello Paul V,

Thank you so very much for the info.  When you say O.A.L. I assume that is with the bullet in place?
 
My CH4D dies finally arrived and I find loading very straight forward and simple.  As you, I adjusted to headspace on the shoulder like any ordinary bottle-neck cartridge.
 
Although my recently obtained 41 cal. barrel was an unfired original 6-1/2" LEJ model 100 barrel, It has a chamber of slightly different configuration being about 0.050" longer (deeper) than typical.
 
  
 
I've been using this barrel on my early Pasadena Pat. Pend frame.
 
I have been loading H110 also and have worked up to 26.5g with my swaged 170g "pointed" jacketed bullet.  I too am using CCI350 primers.  My brass is FC 308 that was first formed and reamed in 44 AMP "form dies" and then run through 41 JMP dies, and fireformed.
 
With my load slide hold-open is at about 50% and cartridge pickup from the magazine at about 75%.  I'll be adding just a tad more powder on the next loading.
 
This barrel was indeed expensive to obtain, but it completes my 3 caliber set.  Undaunted, I enjoy shooting all 3 calibers.  In this case, the enjoyment I receive is worth the risk.
 
Do you (or anyone) have any original specification sheets that were published on the 41 JMP?  I'd especially like to see any published case specs.
 
 
 
"..You never pay too much for someting, you only buy it too early.."
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paul v. View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote paul v. Quote  Post ReplyReply Direct Link To This Post Posted: 02 Oct 2012 at 4:21am
buckstix,
You're welcome !
 Yes the O.A.L. included the bullet. I must have a standard size chamber because I haven't noticed any overworking of the brass (Starline 44AMP) from several sizing, firing and resizing events. I haven't found any original specs on this cartridge yet. Your load with 26.5g H110, FC 308 formed and reamed brass, CCI 350 primers seems to be right in the ball park.
 I noticed that formed, cut and reamed brass have, in general (varies slightly in diff. makes), less capacity than starline brass and take smaller charges of powder to equal the velocities and pressures in the Starline brass. ex: 27.5g of H110 in FC 308 formed, cut and reamed brass will reach 1700+fps, whereas in Starline brass it takes 28.5g H110 to achieve similar pressure and velocities. I believe that you will find better functiioning at slightly higher carefully increased charges of H110.
 Great minds think alike. I too enjoy shooting all 3 main calibers and have a similar set (if you can call it such). Oh well, to each his own. I thoroughly enjoy the diversity of people on this forum-and respect their opinions=from designers to gunsmiths to tinkerers, novices to grumpy opinionated old men and anyone inbetween. You guys are not only interesting, but a real hoot.
Paul V.
 
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buckstix View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote buckstix Quote  Post ReplyReply Direct Link To This Post Posted: 02 Oct 2012 at 4:53am
When I bought the barrel, I also bought a box of original "Quality Cartridge" 41 JMP empty brass.  When I tried one of these in the chamber, it went in so deep that the bolt's extractor wouldn't pick up the case to extract it.  I then did a chamber cast and found all dimensions correct except that the case shoulder was forward by 0.050" and the overall case length was also 0.050" longer.
 
Rather than re-form this factory brass by moving the shoulder forward (and having a shortened case neck) I decided to make cases from once fired .308 Federal brass.  I did notice that this formed brass had less capacity than the Precision cases.  I also discovered that re-formed rifle brass varied greatly from mfg to mfg.  Military brass had the least capacity, Remington next least, then Federal, and Winchester had the highest capacity.  But all 4 of these were still less capacity than the factory Precision brass.
 
I'm still hoping that someone will uncover some published data on the 41 JMP when it was introduced that shows case dimension and loads like was published on the 357 AMP. 
 
I read somewhere that only about 40 - 50 factory barrels (LEJ) were originally produced in 41 JMP caliber.  Anyone have any idea about the number produced?
"..You never pay too much for someting, you only buy it too early.."
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jurras View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote jurras Quote  Post ReplyReply Direct Link To This Post Posted: 10 Oct 2012 at 3:58pm
BUCKSTIX: I found my fire-forming, shooting and hunting load.
41 JMP,
Formed from new CDM brass, should work with Starline too. Do not load in cut down 308 Cases.
30 gr. 296....CCI 350 Mag Primer
1985 fps velocity
 
47,200 CUP
 
Used22.5 gr. 630
1634 fps
 
43,300 CUP
 
The 296 powder was the best by far, feeding, functioning, and terminal performance.
 
With 296 propellant in bot 44 and 41 calibers a .5 incremental changes makes little difference in P & V findings. The case is large enouch for this slow burning propellant. Now in 38 Spl, 9mm, 380 and faster powders a .5 grain increment does make or can make a substancial difference. Cheers
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jurras View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote jurras Quote  Post ReplyReply Direct Link To This Post Posted: 16 Oct 2012 at 10:49pm
BUCKSTIX, that second load was WC 680 not 630, There is still some around as surplus I believe. But 296 is the best.
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