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The 24 Mamba Project

13K views 64 replies 8 participants last post by  briannmilewis 
#1 · (Edited)
So no disrespect to Tennyson intended, "In fall an older man's fancy lightly turns to thoughts of more shooting projects.":tango_face_grin:

Why a 24 Mamba? Cheap brass, cheap bullets and unbridled hubris that we can concoct the "universal round" that no-one else has been able to create to date! (I warned you it was unbridled.) Being the cheap ******* I am, I can preserve my investment in my 223 Short project rifle and just change barrels if I don't want to get a new rifle. Also the 223 Short is winding down for me when the final load testing is completed, hopefully by Spring 2018.

Short team AZ member George A's research has led us to understand that thru a case redesign using a larger case capacity, using new powders and bullets, a 30º shoulder to enhance accuracy and ignition, and using a Wylde throat specification that supports accuracy and higher pressures, we can build a single rifle that can excel at any varmint shooting, ethical large deer harvesting at extended ranges, and long range target shooting, while using 40% less powder than the 243 and 5% less than the 6mm BR.

What is the 24 Mamba?

A modified 6x45 that does not require a big investment in reloading gear or supplies to adopt it.

A 6x45 is a 223 Rem case necked up to 6mm/243 with no other changes.

The new design can use the cheapest and most common once fired brass; will need a custom PT&G finish reamer costing less than $200 for the team to purchase; will need a new barrel to be chambered; will need a neck expander before cases are fire formed; will NOT need custom dies; will be easy to develop loads for because of pre-existing data from the 6x45; will be economical to shoot for any required task.

The basic 6x45 design was revised until we reached a 6x45 + 8% case capacity, which brings it close to the classic benchrest 6PPC case capacity. George ran the numbers to discover the performance potential of the design.

A regular 6x45 has a standard 223 Rem .376 case body base and a standard .354 minimum taper, a standard 23º shoulder and a longer than standard neck length of .225", a standard 1.438 base to shoulder, and a standard 1.76 case length.

The 24 Mamba has a standard .376 case body base (0%) and a .369 minimum taper (-1.5%), a 30º shoulder (+30%) and a .203 neck length (-10%), 1.478 base to shoulder (+3%), and 1.76 case length (0%). We get the extra base to shoulder length from the 30º shoulder which is much shorter than the 23º shoulder, and the .020 neck length reduction adds to the case capacity.

We have not determined the maximum cartridge overall length yet.

Welcome aboard and stay tuned.

P.S. In pursuit of a more recognizable name for this new cartridge design, and in keeping with the team's first project recent official name change from the 223 Short v2 to the 22 Mamba, we decided to rename the 6x45AL, the 24 Mamba, in a direct reference to the small and deadly snake that bears the name, which is also known as "The Kiss of Death".

There are a few of common features the first two Mamba cartridges share, but we do not know if we will adhere to these with future designs. A 30º shoulder, a 0.007" case taper, a slightly shorter neck than is typical for the caliber, a 223 Remington parent case.
 

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#3 · (Edited)
I have high hopes for this cartridge as I feel it will appeal to alot of people.

This cartridge in a bolt gun will give exceptional performance in the varmint fields and deer fields alike. This cartridge will open to the doors to our youth and our elder's that shy away from the heavy recoilers of yesteryears giving them a cartridge good enough to hunt with at respectable ranges, yet with less recoil and muzzle blast than most other cartridges in its class.

Being 6mm (.243) makes it hunting legal in most states and due to modern advancements in bullets and propellents this cartridge should yield performance beyond it's diminutive size.

One design goal we a shooting for which will make this cartridge a true triple threat is offering a affordable low recoiling long range ability. with modern high bc bullets like the nosler rdf, berger vld's, sierra match kings, and so on we can meet and exceed the tried and true 175 smk .308 load(m118lr) in external ballistics the military uses in their sniper rifles out to 1000 yards and beyond.
 
#5 · (Edited)
Requested a PT&G Chamber Reamer Quote Etc.

I have requested a quote for a custom finish chamber reamer for the 6x45AL.

If you want to adopt the cartridge in a bolt rifle or single shot, you will need a new round barrel blank in .243/6mm, like the $110 1:9 from Green Mountain, or 1:8 if you can find one, if you don't already have a 6x45 barrel.

The potential performance improvement with an 8% case capacity increase and 30 degree shoulder invites the idea of upgrading current 6x45 rifles.

Ideally, you would be able to upgrade to the 6x45AL from a regular 6x45 by simply running the finish chamber reamer into the existing chamber.

Theoretically, because the body is longer, the taper is less and the neck is shorter, that should all add up to an easy upgrade.

However, if that does not work out technically for some reason, the alternative is setting back the barrel by cutting a small amount off the end, that should be enough to support an upgrade. <--- I have to run this upgrade idea past team member George first before we can confirm that. Stay tuned.

I will try and arrange either a reamer rental thru a commercial source, or some kind of reamer loaner program that will protect the investment in the reamer for everyone who adopts the cartridge.
 
#7 ·
Brian current 6x45 users should be able to do a straight re-chamber as the 6x45AL should clean everything up.(there are always slight variations from reamer to reamer) a single thread setback would be a wise idea to ensure a fresh chamber/throat.


While the $110 1:9 twist blank from green mountain is a great buy, if you want to run the long high BC vld's and have the full potential of the cartridge a 1:8 twist is a must have item. Cheapest I'm finding currently is x-caliber blanks at $175 unturned or $230 profiled (this is the route I plan to go) I still plan on hunting for a better bargain.
 
#8 ·
Thanks slownsteady22 I hope we can keep your interest.

This should be a pretty quick and very low budget project for us to get some decent results.

It looks like 4D Reamer Rentals are willing to take donated PT&G Reamers and gauges into their inventory when offered. I have just started the conversation with them about doing such with the 223 Short v1.
 
#10 ·
Fine by me Brian. you should still be able to stabilize the shorter hunting bullets fine with the 1:9 like the 95gr nosler partition possibly even 100gr spire points.

I think the 85-95gr hunting bullets will be optimal for deer. some say with good shot placement the 87 vmax is a good do-all bullet. I would feel better using a nosler partion or accubond or the sierra game king.

I could go on and on for awhile. lots of great bullets out there for the 6mm.

make sure you build a trailer to take that puppy into the field with. ;)
 
#12 ·
this case should give slightly more case capacity as it will have a shorter neck, but the main reason was to try the 30' shoulder as many believe it promotes better accuracy and ignition/burning characteristics.

Another thing we are after is higher pressure capablility (much like a 5.56 vs .223) so there will be some throat and lead angle differences. and lastly we'd need either a custom reamer or throating anyways since the cartridge is being built around the 105 nosler rdf. which is in my opinion one of the best bang's for the buck in terms of cost per performance.

I feel some of the 95gr berger and smk may offer better potential ballistics as they would be better suited to a case of this size, however they come at a premium of cost so we are willing to sacrifice some velocity in favor of the more affordable solution. and with the BC differences it could potentially be a wash.

This cartridge is more designed for bolt actions and is also taking aics mags into consideration as we wanted to maximize the potential of the cartridge and limiting bullet weight or having heavy bullets eat up case capacity wasn't worth it being AR friendly.

At the end of the day we want to have a cartridge that uses readily available brass (read cheap) that's capable of being used as a varmint.predator cartridge, medium game cartridge at moderate distances, and a good entry level long range cartridge that will open options for young shooter and our elders that are just not into the big boomers or may not be able to sustain the abuse to their bodys anymore.

From my limited experience having a smaller case capacity will reduce muzzle blast, lessen recoil from the gas aftereffect, and is less sensitive to reduction in barrel length.

It's all theory as of now but in due time we will hopefully have a couple working prototypes to experiment with.
 
#13 ·
this case should give slightly more case capacity as it will have a shorter neck, but the main reason was to try the 30' shoulder as many believe it promotes better accuracy and ignition/burning characteristics.
No, actually it will have a lower capacity. The TCU has a case cap of 32.2, you did not state your cap, but since you did state it was close to the PPC which has a 33.0 I suspect your case is around 31-32.

Another thing we are after is higher pressure capability (much like a 5.56 vs .223)
The TCU is based on the .223/5.56 case and as such has the same pressure spec.


we'd need either a custom reamer or throating anyways since the cartridge is
The TCU is set up for a very long throat since heavy bullets are exactly what it is designed for.

I would recommend you study it and its loads, I think you will find that it will provide a lot of help for any load development you are planning as well as design parameters.
 
#15 · (Edited)
Online Calculator for Wildcat Case Capacity

If you have ever wanted to play around with case dimensions for your own wildcat, here is the best calculator I have found that will quickly allow you to enter case body dimensions and get a volume, making comparisons of your wildcat to the standard cartridge it is based on if that is relevant.

Tip: Remember to subtract the distance from the case base to the start of the body from the height (start of body to start of neck), which on a 223 Rem is .124". It will be different on every family of cases.

http://keisan.casio.com/exec/system/1223372110
 
#16 · (Edited)
New rifle will be home to all my calibers

Came into some unexpected $ so I just purchased a Savage 223 Remington 16 FLCSS WEATHER WARRIOR which I will use as the final platform for all my chamberings.

I will convert the stock barrel to 22 Mamba as soon as the reamer arrives. I will buy a 243 barrel for the 24 Mamba project and a 308 barrel for future project also. I will use my modified Axis as my test rig.

If you buy a Savage rifle before Nov 19th you can apply or a $50 rebate postmarked no later than Dec 18th. Without asking, my local gun store gave me a price that matched Bud's Online, $700, their policy is $40 over cost on any new rifle. So I traded in a rifle for $120 and ended up paying $618 including local tax. So after rebate it will have cost me $568, a little over 60% of what the factory considers MSRP.

Rifle Link
http://www.savagearms.com/firearms/model/FLCSSWeatherWarrior

Savage promotions
http://www.savagearms.com/promotions/
 
#18 ·
My barrel muzzle diameter is too big!

The good folks at MagnetoSpeed Sport chronographs told me that the barrel mounted unit will not work with 17, 20 and 22 cal. bullets with my heavy Axis barrel, which measures 1.033" at the muzzle.

So I will have to wait till my 16 FLCSS arrives and use that barrel, or have someone on the team turn down the heavy barrel to say 0.75" at the muzzle to make sure the MagnetoSpeed works.

http://magnetospeed.com/products/chronographs/#sporter
 
#20 · (Edited)
Invested in a short bipod for use on the bench today

I added a short Champion bipod to the test rig tonight at $44 from Wally World. It is for use on the bench, not prone.

This is a step prior to investing in a Lead Sled. The next round of load tests I will take the bipod and the Tack Driver bag to the range and see how it goes. I am heeding the advice of using a blanket under the bipod legs on the concrete bench.

All I have to do now is read up on correct bipod technique from a bench...a few hours later...It would appear that putting forward pressure, or pre-loading the bipod, is the trick to accuracy on or off the bench. So from a bench, a C clamp with a board infront of the bipod legs will do the trick.

Was looking online to find a rear bag to use with the bipod...well, the humungous Tack Drive would seem to work fine, I tried it on at the dining room table and it seemed to fit...we'll see.
 

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#21 · (Edited)
Savage 16 FLCSS Has Arrived - Worth the money?

I received my Savage 16 FLCSS Weather Warrior yesterday. This is the rifle which will be fitted with the 24 Mamba SS 17" Sporter profile barrel.

So it now begs the question, "Is the $400 price difference ($700) compared to the basic Axis ($300) worth the difference?"

While no one ever wants to admit they spend money unnecessarily, in this instance, it is obvious where the money goes, and I think it is well spent.

Here is why I think so, not in any particular order.

(1) The 16 action is much "tighter" than the basic Non-Accutrigger Axis. There is very little bolt free-play in any direction on the 16 when chambering and extracting, whereas the free play is noticable on the Axis.

(2) The 16 synthetic Accustock is solid polymer and factory bedded in 3-dimensions to an aluminum frame, unlike the basic hollow synthetic Axis non-reinforced stock.

(3) The magazine fits more tightly, the latch is in the stock on the 16, unlike the Axis magazine latch integrated into the magazine body.

(4) The 16 safety is three position - Fire, Cycle Mag, Bolt Lock, the Axis has Fire and Cycle Mag.

(5) The 16 stainless steel improves bad weather resistance compared to the basic Axis black steel barrel and receiver.

(6) The 16 feels "substantial" out of the box, the Axis feels "light" out of the box.

(7) The 16 bolt handle has a nice grip pattern, the Axis handle is smooth.

(8) The 16 bolt removal is assisted by a slide infront of the trigger guard, unlike the Axis two handed contortions required to remove the bolt.

Negatives

The 16 scope mount holes do not match the Savage 110 standard pattern, they are 7/8" apart. A scope mount in matching stainless costs x2 compared to the same black steel mount.

The 16 will not add to the educational experience of having to re-engineer the Axis to turn it into a decent test platform. I cut my gunsmithing teeth on converting the original 25-06 Axis to 223 Rem, complete with bolt head changes, modifyng and adding an Accutrigger, reinforcing and filling the stock forend, loading the stock butt with lead shot, adding a heavy barrel and head spacing it.
 

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#25 ·
#24 ·
Team member Randy has finished turning the barrel and threading and crowning it, and is ready to send it on team member George for chambering, when we eventually get a chamber reamer from PT&G. I am going to finish the barrel with Scotch Brite pads to give it a brushed look to begin with.
 
#27 ·
Weaver Manual Torque Screwdriver for Savage Accustock

Just got my Weaver Manual Torque Screwdriver, $64, free Amazon Prime shipping, ordered at 2am this morning, arrived 6pm. <--- Must have a warehouse somewhere nearby I reckon.

I got this because my Savage 16 has an Accustock built-in aluminum bedding frame. It needs to be screwed down to specific torque specs, 45 in/lbs, in 10 in/lbs increments. Also comes with a Calibration Certification Sheet so you can actually tell the "slop" in the indicated torque.

Wheeler, Weaver, Stark, Craftsman and others all sell basically the same unit, but some have different ranges of torque, I had to get at least 50 in/lbs for my Accustock.

It will also be useful for torquing down scope mounts and rings to specific recommendations.

You will need one if you buy one of the new Savage 110 Storm rifles, which come with 5 cheek risers, and 4-LOP spacers, Accustock and Accutrigger.

Looks like Savage has discontinued the Savage 16 FLCSS in 223 Rem. The Storm has a Suggested Retail $150 less than a Savage 16 SS, but that only translates to about $50 savings if you look at Bud's intro price, which may be higher than it will settle at in the longterm.
 

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#28 ·
Final Changes to 24 Mamba Reamer Print

Just requested the last change to the 24 Mamba finish chamber reamer from PT&G.

It will take 12 weeks max to get the reamer after I order it, exact date yet to be determined.

Then I will order the 24 Mamba die reamer so we can make our own basic FL Sizer.

When this is done we will have access to all dies necessary to support the 24 Mamba. :)
 
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