how to build a special magazine for a special cartridge?

[MBTcustom]

I have just completed making a new rifle on an enfield no4 mk1 platform. I started with a 303 British case. I opened the neck up to .358 straitened the walls and gave it a 45degree shoulder. The rifle works grate but the cartridges do not feed very well if at all. My question is, does anybody know of a source of information "book, web sight, etc." that tells how custom magazines are built and explains the critical elements of magazine making?

[waksupi]

For feed problems, the first thing to try is different followers. The way a cartridge lays in a magazine can have a big effect on how it feeds.

[jhrosier]

I would start by studying how an unaltered Lee Enfield works with the standard cartridge.
That will show you the path that your new cartridge should follow.
I've seen Enfields in .375 Flanged that work well so yours should be possible.

Jack

[jerry_from_ct]

I have to agree with Waksupi, I've done lots of work with auto-loader type conversions and the problem is usually the feed angle and/or the feed-ramp geometry.

If the current load fits in you mag O.A.L. and will load w/o resistance, check the angle of bullet to feed ramp. check there's no interference in the bullet nose to mag end, a larger bullet may drag on the mag front recess and the mag may need some relieving.

Making a mag is a major deal with trail and error without a guarantee of good results, avoid it if possible.
It's much easier to work with an existing Mag and modify.

[jerry_from_ct]

*** Just for safety sake ***

BTW, Make up some "Dummy" rounds (3) for testing purposes, and mark them as such.

This way you can check load, ejection and next round strip-off.

[MBTcustom]

I have made 6 dummy rounds. This doggon rifle has one of the most complex breaches I have ever encountered.
The problem started with the follower, I used quiksteel putty to build the back of the follower up so that it will provide even pressure to the cartridges and keep the bases locked in the rear mag lips. Now I am trying to get the cartridges to strip cleanly. Either I bend the front feed lips out and get the left position cartridge to strip but not stay captured, or I bend them in and I have solidly captured cartridges that strip too low to properly engage the feed ramp. So far I see no evidence that they are hitting the forward wall of the mag. I also started achieving better results when I bent the front of the magazine out making the side wall a little more parallel as the angle of the new cartridge is a degree or two shallower than the original.
I was not planning on building my own magazine from scratch, but if I could find some info on that subject I would feel much better prepared for this project than I do now. My experience with magazines up to this point is to buy a new one if the one I have starts to be problematic. since this is a totally new cartridge, that is not even close to being an option. I'm just tired of stabbing around in the dark. and eventually this magazine is going to get work hardened and break.[smilie=b: I need a direction and a process like: work on the follower first, then the rear lips, then the front lips, then the feed ramp.... etc.
I would like too say that all advice is welcome! Don't hold back because you assume that I am unable to do this or that. I consider myself a master machinist and I have tools at my disposal that the average fella might not, such as a sheet metal break, brazing and welding equipment milling machine etc.
What I do not have is a working knowledge of rifle magazines and their operation. This is a whole different ball of wax than pistol magazines.
What I need to know is, in a perfect world what needs to be in place for a magazine to work properly.
Here are some pictures of the magazine and cartridge conversion.
http://castboolits.gunloads.com/imagehosting/thum_177714dc6d5f27edb4.jpg (http://castboolits.gunloads.com/vbimghost.php?do=displayimg&imgid=795)http://castboolits.gunloads.com/imagehosting/thum_177714dc6d5f28b4e9.jpg (http://castboolits.gunloads.com/vbimghost.php?do=displayimg&imgid=796)http://castboolits.gunloads.com/imagehosting/thum_177714dc6d6042e422.jpg (http://castboolits.gunloads.com/vbimghost.php?do=displayimg&imgid=798)http://castboolits.gunloads.com/imagehosting/thum_177714dc6d6043ab58.jpg (http://castboolits.gunloads.com/vbimghost.php?do=displayimg&imgid=799)http://castboolits.gunloads.com/imagehosting/thum_177714dc6d5f297c1d.jpg (http://castboolits.gunloads.com/vbimghost.php?do=displayimg&imgid=797)

[Cap'n Morgan]

Don't stagger the cartridges too far apart sideways or they'll tend to bind instead of pushing upwards. A pointed "V" shape may be better than a parallel sided magazine as this will keep the rims from interfering and at the same time keep the cartridge nose from "diving".

This should be obvious, but remember to load the cartridges from the front of the magazine and then push them back against the rear to avoid the rim locking behind the underlaying round.

[btroj]

Me thinks this is part of the art of a good custom rifle. You have chosen a task which I would not want to do. I wish you luck. Getting a modified round to feed can be a real bugger from what I have heard.
I have a feeling that you will find that what seems like a minor change can at times have a huge impact upon feeding. Make small changes and don't be amazed if the problem turns out to be something you never though of.

I wish you luck and those are some nice looking rounds.

[jerry_from_ct]

There's a member by the name 0f "Zeb Deming" on the garagegunsmithing.com forum who converted a Mosin-Nag to .450 Marlin, he had issues w/ loading and feeding from the original design and resolved the problem, you could reg. there (V.Good forum) and drop him a line.

I Talked to him a few times and I,m sure he would glad to tell you how he resolved the Mosin feed issues.
May have some info you might be able to use, links below.

Just a thought,
Jerry

http://garagegunsmithing.com/index.php?p=7830&jfile=viewtopic.php&option=com_jfusion&Itemid=54#p7830

http://garagegunsmithing.com

[JIMinPHX]

I have a similar dilema. I have an old pistol in 9-largo cal. That ammo is getting hard to find & star line stopped making brass in that caliber. I was thinking that if I press fit a ring in the chamber, I could convert it to take 9-Luger ammo, but I don't know how I would get the short little Luger cartridge to feed out of the long Largo magazine. I'll be watching your progress with great interest.