The 223 Short Project. - Page 66 - Graybeard Outdoors
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post #651 of 658 (permalink) Old 06-21-2019, 12:06 AM Thread Starter
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Default Fine tuning the Proxxon KGS 80 Mini-Mitre Saw

I use the Proxxon Mini-Mitre Saw KGS 80 to cut the extra long necks off my 22 Mamba/223 Short and 308x45 cases.

I have posted previously how the saw could not be trimmed (to use an aviation term) to give repeatable cuts with a +/- 0.001" to 0.002".

Briefly, regardless of setup, could not obtain that tolerance, even with an extra nut on the horizontal adjustment shaft.

I found a solution which looks like it will allow the cut variation to be pretty repeatable in that range.

It consists of two 2-part collars with 8mm inside diameter that you tighten around the shaft either side of the left frame. It pretty much eliminates the "thread creep" that causes the length of the trimmed case to be reduced by 0.005" or .0010".

Here is the product a link and my setup. Whatever works for you.

1) I wound the lateral adjustment as far to the left as possible.
2) I put a collar on the left and right side of the left frame member.
3) You must have two collars, one on each side of the frame, (2 in the package) because, if it is not secured, the shaft moves with each stroke of the saw.



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post #652 of 658 (permalink) Old 06-24-2019, 02:49 AM Thread Starter
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Default More work on the AR 22 Mamba Magazine

Working on the AR 22 Mamba 10 Round PMag

Feeding more than 3 rounds has been problematic, the cartridges cant with 4 or more in the magazine and end up more or less vertical at the throat. Jam-o-matic.

George and I discussed possible solutions, and short of modifying the magazine follower, or extending the lips, reducing spring tension may help. (Mockup in Photoshop of an extended lips magazine.)

I got radical, and after fixing the follower I had previously butchered in search of part of the solution, I cut 3 or 4 coils out of the magazine spring. (See pic.)

You will need bolt cutters, heavy duty wired cutters, or some kind of cut-off wheel. I used a Dremel abrasive cut-off wheel and then bent the spring at the the place I had been trying to cut with pliers and side cutters, and snapped the spring.

I think that cases loaded to about 1.6" or longer are the best candidates for a standrd magazine, with the bullet tips as close as possible to the front of the mag.

Before the cut, 5 rounds would not feed without a jam, after the cut, 5 rounds fed and ejected correctly in my reloading room. The range is the real test.
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Last edited by briannmilewis; 06-24-2019 at 02:58 AM. Reason: Update pic.
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post #653 of 658 (permalink) Old 07-04-2019, 10:29 PM Thread Starter
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Have designed a solution using 2 10 round PMags, a Primary mag that will be notched to accept feed lip extensions donated from a Secondary mag.

This just proves how impatient I am, did the following in 2 days of coming up with the idea. I notched the primary magazine feed lips using a standard hacksaw (vertical cuts), and a Stanley knife (Horizontal cuts).

I cut along the molding line between the vertical notch cuts about 10 times, then gently grabbed the part to be removed with pointy nosed pliers and rocked the flap back and forth till it separated.

Then I finished it off with a flat file. The rear vertical cuts are undercut a little and so I cleaned up with the file.

* You may want to wear safety glasses and a dust mask. I wore neither, so I am not leading by example. The plastic dust from cutting is like powder, very fine.

Started work on the secondary AR (feed lips donor) mag.

The vertical cuts were made with a standard hacksaw after taping it off with Scotch tape.

Then I started scoring the horizontal cuts with a Stanley knife the same as the primary magazine. That got old, and 100 strokes of the Stanley knife surely would not get thru the wall of the PMag. Mechanical solution required.

My Dremel tool needed a new battery and I ordered one. However, I got impatient and put the Dremel basic cut-off wheel on my cordless driver to finish the horizontal cuts. Worked very well, because the cut-off wheel is smaller diameter than the length of the cut.

When the feed lips have been removed from the secondary, I finished them off with a flat file, used what I had. You could use sandpaper.

The rest is a hand-fit job. I only removed material from the back side of the lips until they were snug in the notch.

All I am waiting for the UV resin welding tool tomorrow.
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post #654 of 658 (permalink) Old 07-07-2019, 06:35 AM Thread Starter
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Update 7/7/19 7:20am. Success, success, success...

I have a properly formed magazine with extended feed lips as envisioned. A bit rough, but better than my failures.

Gorilla Super Glue Gel is the glue that was successful for me. Careful not to glue your fingers together. Build up a good 1/32 bead around the magazine cut only, then carefully place and line up the lip...once you actually push it/hold it in place it is too late to adjust.

It looks like cartridge lengths at or above 1.700" are the solution to jamming. I was dry testing with 1.600" rounds and I watched them very carefully and they would cant/tilt if loaded from anywhere 2-10 rounds. They often plow straight ahead into the nose of the mag as the lead tip got caught rather than ride up on a synthetic tip.

I just successfully dry test fed 7 x 1.700", and with the Wylde throat on the 22 Mamba, even longer bullets will be allowed.

I also cut a few more coils off the magazine spring, this helps to prevent cant/tilt.
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Last edited by briannmilewis; 07-07-2019 at 11:30 AM.
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post #655 of 658 (permalink) Old 07-20-2019, 03:08 AM Thread Starter
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Default 22 Mamba AR Magazine - What we know so far

22 Mamba AR Magazine - What we know so far in the reloading room. We still need field tests.

1 - No matter what, 2 or more 1.4" - 1.5" COAL rounds do not load without jamming in any magazine version. (Lab Tested) I need a custom short cartridge magazine and mag well adapter.

2 - Unmodified 10 Round PMag: Load maximum 3 x 1.6"+ COAL feeds no jams. More than 3 rounds turns the rifle into a Jamomatic. (Field Tested)

3 - Add a front ramp, shorten spring, trim follower and spring base of 10 Round PMag: Load maximum 10 x 1.6"+ COAL feeds no jams. Loaded tip close to front or cases base at the back of the magazine. (Not Field Tested)

4 - Add extended feed lips, a front ramp, shorten spring, trim follower and spring base of 10 Round PMag: Load maximum 10 x 1.55"+ COAL feeds no jams ###. Loaded tip close to front of the magazine only. (Not Field Tested)

### - Stay away from soft point, round nose, exposed lead hollow point bullets. Synthetic tips work best. Fully jacketed tiny hollow points may also work.

Update 7/21/19:

Extending AR Mag Feed Lips - Warning, of sorts!

After messing around with a couple of mags with extended lips, I decided to test George's speculation that the "glued" on lips may not stand up to rigors of the spring pressure.

I deliberately pushed on a glued extended lip to break it off...took a lot of pressure to break off the glued lip extension.

George was sure that plastic welding would do the trick and make them unbreakable. I have not tried that.

So bottom line: Extended feed lips on a 10 round PMag with the ramp modification only buys you 1.5"+ rounds to the already 1.6+ rounds.

If you decided to add a ramp to the mag, trim the spring and the follower and spring base and run 1.6+ rounds...and forget the extended lips, will save you a lot of work.

Good luck.
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Last edited by briannmilewis; 07-22-2019 at 01:41 AM.
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post #656 of 658 (permalink) Old 07-24-2019, 06:09 AM Thread Starter
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Default Have Ended 223 Short Testing - However

I decided to end 223 Short testing and just change straight over to 50yd 22 Mamba testing, so I sent George the "truck axle" to rechamber for me.

As we also discovered we cannot fire form the 223 Short brass into 22 Mamba brass, I decided to have George chamber my Savage 16 barrel in the Short, as I have 1000 cases ready to load.

The Savage has an AccuTrigger and AccuStock so it is about the best production rifle to chamber the Short and Mamba in. I will burn up all this brass over time until it is all scrapped, then determine what I will rechamber the barrel in without legacy brass influencing the decision.

I will provide some additional 100 yard range results from time to time.
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post #657 of 658 (permalink) Old 07-28-2019, 02:51 PM Thread Starter
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Default Conversation with a potential 22 Mamba adopter

Brian Chase writes: Have you tried any 55-70 grain in the Mamba yet? Curious about velocity levels

George A: In Brian's 21.5" AR I tested a 53gr with CFE BLK and we got low to mid 2900's with it and there was a little more left in it. I also tested some 55's in my shorty and they are within 20-30ft/sec of the 53's.

I have considered trying some 80's supersonic just to get an idea but I'm more interested in my short barrel testing at the moment. I want to say Brian is limiting his testing 55gr and below.

Brian C: Beats the pants off a hornet. I used to have one and loved it. You designed a very efficient cartridge would like to see it commercially adopted!! (I stole ideas from Bench Rest cartridges to come up with the 223 Short design. Then George and I brainstormed and came up with v2, the 22 Mamba.)

George A: That would be nice no doubt. It is a very efficient little booger. So running #'s in QL with a 75gr Amax and 21.5" barrel it is predicting 2500 ft/sec with a COAL of 1.84" now i'm not sure if our throat will allow said length so throating my be necessary.

1.84" puts the shank of the bullet to a depth of .175" equal to the length of the neck.

Brian C: Whats the guess on powder weight say lil gun for a 75 grain?

George A: Per Quickload Hodgdon Lil'Gun 12gr 89.7% fill 2440 ft/sec 100% burn and 62,500 psi aka max load

AA1680 would be a more appropriate powder or CFE BLK if you could get enough in. My Version of QL does not have CFE BLK to test unfortunately.

Brian C: In the 24-2600 f.p.s range.. perfect. I kept the hornet around that speed when i used to handload

George A: Here is the results for the 53gr varmageddon 21.5" ar and CFE BLK
just fired 2 each as it was just a workup looking for pressure signs. zero pressure signs just running out of capacity. maybe could squeeze in another .3-.5gr before being too compressed.

15.0 gr 2807, 2772
15.2 gr 2766, 2789
15.4 gr 2789, 2855
15.6 gr 2861, 2867
15.8 gr 2855, 2904
16.0 gr 2904, 2936

Brass life would likely be very good at that range for the lighter bullets. Speaking of on the 7th loading (8th if you consider it being 1x as .223 rem) with my LC cases. Still look great FC not so much lol they started dying off around the 4th loading and most may not go the 7th if any. (splitting necks)

Brian C: Impressive velocity nearing .223 level with way less powder

George A: Yup and more importantly is the milder report and muzzle blast. My 13.5gr Lil Gun load in the standard .223 short sounds about like a 22 mag yet its launching a 40gr v-max at 3264 ft/sec from an 18" barrel. 3.5gr of Titegroup was doing 2200 and sounds like a 22lr.

Brian C: Amazing on both ends. Some 40 gr w 3.5 would be fun too. Wouldn't think it would be a hard sell to the commercial side hornet is out-dated and the magnum just isn't enough

George A: I haven't worked up a Lil Gun load in the 22 Mamba yet. I'm curious as to how much more we will get from the extra capacity.

I did use the 13.5gr Lil Gun 40gr as fire forming loads which did 3316 in the 21.5" QL is predicting 14.8gr as max and 150 ft/sec faster than the .223 short

The .22 hornet's brass is just too thin and low pressure to keep up with todays advancing cartridges.

I think our biggest hangup is finding a repeating host weapon that can handle the pressures we run.
Howa's new Mini action just may be the host but I have yet to buy one for testing.

Brian Lewis: The CZ 223/221 using a 221 magazine and 221 trigger guard should work fine. The only other mini-action using Mauser ejector.
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post #658 of 658 (permalink) Old 08-02-2019, 11:13 PM
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I've decided to offer up my savage barrel for sale if anyone is interested. It is a factory small shank .223 rem blued sporter barrel 1:9 twist that I set back .675" and chambered in .223 short then shortened to 19" and re-crowned. I can chamber it into a 22 Mamba for no extra charge if wanted. I can even thread it 1/2x28 for an extra $30. This barrel achieved 3260 ft/sec with 13.5gr of lil gun and a 40gr vmax and in my limited workup a few just under MOA sized groups, but I never did a true workup. It was more of a pressure workup than accuracy.

with the .223 short I was resizing brass by FL sizing and decapping with a .223 rem die (this sizes the base) then I adjusted a lee .22 TCM die to bump the shoulder/size the neck.

If you wanted to go the 22 mamba route I plan on trying to make a FL die in the near future from a 4140 blank. Price/availability TBD ~$35-40

I can make you a headspace gauge and case gauge if interested for $20 ea.

I have a 100-200 PMC formed brass (1x fired as .223 rem) $12 per 100.

Lee 22 TCM pacesetter 2 die set $30

Asking $100 + shipping and any extras above.


Last edited by squirrel_slayer; 08-03-2019 at 11:11 AM.
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