Mk6 Projectile Replacement

[scotsnatorg]

Hi All,

I am new to the Forum and being from the UK where we have a somewhat stodgy gun culture I thought I would ask some advice from the folk from the land of the free where you have the right to bare arms.

In my line of work I am required to euthanise stranded whales & dolphins that are deemed unfit to be refloated due to condition, disease etc. Normally we would use Lethal drugs administered by a veterinary surgeon, however the drugs required to effectively kill a whale are no longer produced so that has meant we have had to turn to shooting, which was always held as a 2nd option in the UK.

To effectively kill a toothed whale up to 8m in length I require .308 180gr FMJ round. However it is recommended by our partners in New Zealand that to kill a baleen whale (filter feeder) they recommend a .303 Mk6 projectile, however this round is now obselete and .303 ammunition although available in the UK is not common or readily available.

Mk.6 projectiles are a 215 grain full nickel jacket round nose .303 projectile, loaded with 40 grains of Du Pont 4895 powder. Firing trials in New Zealand many years ago demonstrated penetration of these rounds through more than 3.35 m of blubber and soft tissue.

.30-06 is not a common calibre in the UK either and I would prefer not to have to go and purchase a .30-06 as it is a lot of hassle to get my Fire arms license changed to hold another firearm.

Does anyone think that it would be possible to custom load a Mk6 Projectile style round for .308 that might have simillar ballistic characteristics? From what I have been reading elsewhere, I fear not as the .308 brass is too small for the required powder charge to develop the rerquired muzzle velocity, however distance is obviously not required as shooting is carried out almost point blank at around 3 foot away from the animal, so penetration is what I am after, so thought I should ask the experts for their thoughts and suggestions.

Any thoughts or suggestions Folks?

[Marco Califo]

Projectile: http://www.midwayusa.com/product/752...cket-box-of-50
The product description says these are steel jacketed FMJ Big Game Bullets

Load Data #1:
308/7.62 220 grain JSP (Spitzer or Spire Point) or JRN
H4350* 46.0 gr. 2,369
* use magnum primers
http://www.reloadammo.com/308load.htm


Load Data #2 NOTE THAT THIS IS FOR A 200 GR BULLET, BUT USES 4895 in your stated range
Cartridge: 308 Winchester
Load Type: Rifle
Starting Loads
Maximum Loads

Bullet Weight (Gr.) Manufacturer Powder Bullet Diam. C.O.L. Grs. Vel. (ft/s) Pressure Grs. Vel. (ft/s) Pressure
200 GR. SFT SP IMR IMR 4895 .308" 2.700" 40.0 2302 47,500 PSI 43.2C 2476 59,000 PSI
http://data.hodgdon.com/cartridge_load.asp

[saddler]

The actual dia of the 303 is .311"

It may also be possible to swage down a 220gr 303 bullet to fit a 308 barrel

Not sure why you think that the 30-06 is not common here, I have a couple of them (pre-war Winchester Model 70 & a WW2 Springfield sniper)

Not sure where you are as it is missing in the profile, but from the user name you are possibly quite close (I'm in East Lothian)

PM me if you need any more local help as I am connected to a lot of the classic shooters and the companies that supply them with reloading items.

For penetration I'd also look at the 6.5x55 Swedish Mauser - but as you already stated you didn't want to have to do any FAC changes then this may be a moot point....

[scotsnatorg]

Thanks Saddler,

I am North of you up in Caithness. When I was looking for an alternative to the .303 mk6 I did think about a custom load for a .30-06 but my local (and only Gunshop for 140 miles) advised against the .30-06 due to it not being very popular in the UK.

Saying that if I only need a custom load then it's not like I have to go looking for ammunition when I am somewhere remote like the Western isles as I would be taking the ammo with me, but it does seem like a waste of money to buy a .30-06 rifle for only firing a single round once or twice a year, hence the reason if I could have gotten a suitable alternative to .303 Mk6 specs for a .308........

Maybe I will just have to get my FAC changed for .30-06 and bite the bullet (excuse the pun)

Do you know of anyone in Scotland that could help with such a custom load as I am not a reloader? It would also have to be with new brass as HSE will not let us discharge on a public beach using reloaded rounds!

[Jimro]

Cartridge, Mk VI
Accepted 1904
Smokeless powder load. Berdan primed. 215 gr RN bullet.
Muzzle Velocity - 2050fps

Easily replicated with your 308 Win,

Use a Woodleigh 220gr FMJ round nose http://www.midwayusa.com/product/752...vc=subv1767743

Once you reach 2050fps with the woodleigh with whatever powder you choose, you are good to go.

You will probably use more bullets in load development than anything else.

Marco Califo's suggestion of the 240 woodleigh makes sense, but if a Mk6 does the job sufficiently, then a 240gr bullet is not necessary, and I'm afraid the long bearing surface would cause some problems.

Jimro

EDIT: It is interesting, the old data for the 30-40 Krag:
220 GR. HDY RN Hodgdon H4350 .308" 3.080" 40.0 1874 42.0 1947

I think that 30-40 U.S. 58gr H2O capacity is close enough to the 308 Win, 56gr H2O capacity that I feel comfortable using it as a starting point for load development.

[wogpotter]

You should be able to load an equivalent to the old 215 GR RN .303 in 7.62 mm fairly easily, after all .308 has a little (100 or so) more FPS available than the old Mk 6 .303 British load. Modern double based powders should deal with any case capacity issues.

I'm actually curious as to why they suggested the Mk6 round instead of the newer Mk7 one, as it hasn't been made since 1910?

In fact many Lee Enfield’s aren’t throated for the 215Gr bullet, but for the pointed Mk VII spitzer shaped load! Maybe it’s something to do with deeper penetration? The Mk 6 was a thin-jacketed Mk5 supposed to expand even though technically a FMJ. It didn't work however, but maybe in a thick layer of blubber it would?

Your components may differ slightly because of what is, or isn't, available in the U.K. as compared to what we get here, but substitutions can be fairly simple with a decent cross reference.

Question. Are you allowed to use FMJ types for your work? I ask because I know they aren't legal for game stalking, in England, but I don't know if you have different regulations for euthanasia purposes in Scotland.

Heres a couple of loads I found in a manual.

For .308 Win:
Accurate Arms 2520 powder: 190 Gr SIE bullet (HPBT) 38.3 Gr for 2235FPS min to 42.5 Gr for 2500FPS MAX LOAD.

208 Grain Hornady A-Max bullet #30702, driven by Win 748 will go MAX LOAD, to 2450FPS.

Hornady makes a 220 Gr RN InterLock bullet number 3090, but again its not a FMJ, but a softpoint, or there is a #30903 225GR HPBT. Both could be reloaded with a slightly reduced starting charge from the list above for the 190GR.

Sierra makes a .311" 180 Gr that you could reload into .303 British cases as well. or there’s a FMJBT 174 Grainer # 3131 for the .303 as well. Load data for that gives me top loads of 46.4 Gr of H414 powder for 2500FPS (MAX LOAD) which is more than the old Mk6's 2200FPS.

These would all be hand loads.

Hopefully this is a good starting point to work up a load that will do the job humanely for you. Based on these numbers it seems fairy easy to do, as long as there aren’t any legal restrictions on bullet types I found for your needs.

[MikeG]

I'm actually curious as to why they suggested the Mk6 round instead of the newer Mk7 one, as it hasn't been made since 1910?

I think because the old style heavy round nose military bullets were found to have lots of penetration.They were found to make through and through wounds on people.

Karamojo Bell used the 173 grain round nose in 7x57 Mauser to kill many elephants, after all.
There's a lot of elephant to get through, like there's a lot of whale.

The Germans then designed spitzer bullets, which tumble and break up on impact with flesh. The light nose filler making the .303 Mk7 more base heavy accentuates this.

So the Mk6 would penetrate enough on a cetacean to be effective where a Mk7 wouldn't.

[Marco Califo]

Jimro, my link is to the same bullet you linked to: 220 grain Wood. FMJ.
They are even in stock!
Yes, I agree that there appears to be room in 308 loadings to duplicate, and even exceed, the old loading OP asked about with IMR 4895 or H4350.

[Jimro]

Marco Califo,

I don't know how I ended up on the 240gr Woodleigh slugs when I clicked your link, my apologies.

Jimro

[Marco Califo]

J. No problem.

Do you know of any 308 loading data for 240 gr bullets in 308??
I know the bullets exist but have not seen any loads for 240 in 308

[Jimro]

Marco Califo,

Yes, but only for subsonic loads out of 1:8 twist barrels using the 240gr SMK. Kind of a specialty load for "subsonic sniper" applications.

So in reality my answer should be "no", but I am tempted to give it a shot someday with some powder in the IMR4831 to WC872 burn range. I'm guessing that one would be hard pressed to get past 2k fps but penetration with a Woodleigh should be "spectacular."

Jimro

[scotsnatorg]

Guys,

Thanks for all the info and advice. I guess the thing to do now is to trial some customs loads on dead cetaceans and see how things go. I will let you know how I get on.

[Marco Califo]

Jimro,
What you describe in paragraph two, is actually what I had in mind. WC872, most likely with a WC844 starter. I am wondering what a good starting point would be for the 872 while starting with one gr. 844. Any suggestions for 240 OR 220?? I only have 1:10" twist in 308.

[Jimro]

Marco Califo,

I have a lot of thoughts on that, but I don't have a lot of data.

I load WC872 in my 6.5x55 Swede pushing a 140gr BTHP bullet to around 2200 fps (calculated by drop from 300 to 500 yards). That load is very accurate, shooting 97-4x at 300 and 92-1x at 500. The case fill is right at 100% (or slightly more). I'd love to get a set of swaging dies to swage 7mm 162gr BTHP bullets to 6.5 bore for use with 872 (duplicating the muzzle velocity of the original military load with a much slicker bullet).

Because 872 is so slow, I don't think you could get enough of it in a 308 case to cause a pressure event, even with a 240gr bullet (if the data about 46 grains of 4350 you posted is accurate). 46 grains of 4350 under a 220gr bullet is filling that case.

That being said, the data I have for AA8700 pushing 220gr round nose bullets indicates that a full case of 30-06 will only get to 2k to 2.2k fps. The lower capacity of the 308 indicates that 2k would probably be the upper limit for a straight charge of 872 no matter the bullet mass.

I think that having a lot of 872 is a really great excuse to buy a 243 Win so you could push heavy slick bullets like a 115 Dtac.

Jimro

[wogpotter]

The Germans then designed spitzer bullets, which tumble and break up on impact with flesh. The light nose filler making the .303 Mk7 more base heavy accentuates this.

That was kind of my thinking as well.
I don't know how much help this is, but a lot of the non British made (Indian & Pakistani) "MKVII" doesn't have the filler in the tip they're just lead inside a jacket! The last known real MkVII is the South African R1M3Z, as it still has the filler. Maybe you could reload pulled Indian Or Pakistani heads in new brass for the best of both worlds, availiability & penetration?

[Unclenick]

Originally Posted by Scotsnatorg

Mk.6 projectiles are a 215 grain full nickel jacket round nose .303 projectile, loaded with 40 grains of Du Pont 4895 powder.

Scotsnatorg,

Something is amiss with your information, there. The Mk.VI was introduced in 1904 and supplanted by Mk.VII in 1910. IMR4895 was introduced in 1941 by DuPont. I think you'll find all the Mk.VI was loaded with Cordite. That explains the low (by modern standards) velocity. It burned too quickly for them to be able to safely put enough in the case to achieve higher velocities.

Duplicating the .303 in the .308 should be easy, as both cases have about 56 grains of case water overflow capacity in their military formats. The .30-06 has more like 68 grains of water capacity, which is unnecessary for this task. The .308 may have a shorter throat and barrel than the Enfield, but it also has a higher standard peak pressure and modern powders offer more velocity potential if it’s needed, so it should all balance out.

The trick is to determine what the New Zealanders were actually shooting (this could be critical for reasons I'll outline below). Was it Mk.VI? Or did they reload Mk.VI projectiles into .303 Cases using IMR4895? Also, it's important to know the barrel length they were using: the MLE (797 mm barrel) or the SMLE (640 mm barrel). Also, I don't know what barrel length the Mk.VI specification of 2050 fps was developed in? I'd assume the longer barrel from the date of development, but military pressure/velocity test barrels and military rifle barrels don't always match in length.

The reason all these details matter, and what makes up the can of worms you’ve opened, is you want to duplicate the tested New Zealand load and shooting conditions as closely as you are able. That is, you want the same bullet configuration, same rifling twist, same muzzle velocity, and same firing distance from the target.

A bullet of matching sectional density to the .303 would be about a 210 grain round nose in .308, but I don’t know of one available off-hand, so the 220 Woodleigh is probably as close as we’ll get, despite the greater length making the bullet a little easier to yaw. A pointed bullet, though, will have much more propensity to yaw in a close range impact, turning sideways then tumbling, but failing to penetrate as far. Too much muzzle velocity will also tend to promote yawing in the target medium in a close range impact, so that even if the round nose bullets don't tumble as easily as pointed ones, faster traveling round nose bullets, ironically, may not penetrate as far as they do at lower velocities because they still yaw partly sideways into the medium, greatly increasing their drag.

Randy Garrett gave an example from Linebaugh Institute experiments of a .45 caliber bullet in wet newspaper. They found a 500 grain Hornady round nose solid at 1500 fps penetrated 6 feet of wet newspaper, while the .458 Win Mag at 2100 fps penetrated 4½ feet, and a .458 Lott at 2500 fps penetrated about 3½ ft.
Hatcher's Notebook has photos (pp. 406 & 407, 1961 ed.) of the same effect for a 150 grain pointed .30-06 round fired into oak. This is a harder medium than blubber, obviously, but the results are remarkably analogous to the wet paper tests. At 2700 fps, at 50 feet range, the bullet turned sideways in the oak and penetrated 11.5 inches. At 200 yards and about 2300 fps, it penetrated straight in for about 32½ inches.

All bullets yaw some just after clearing the muzzle due to the bullet shifting over from spinning around the bore axis to spinning around its center of mass angled over at the yaw of repose, plus some yaw due to muzzle blast playing off the base of the bullet as it initially shifts position. Unless they fly far enough to settle out all but the yaw of repose (far enough to "go to sleep") they will be yawing more than the yaw of repose when they impact a medium. We're talking fractions of a degree here, but at bullet velocities it doesn't take much to give the medium a toehold with which to try to turn the bullet.

At your close firing range, you'll have the most muzzle yaw at impact. Indeed, even getting back a dozen feet could allow significant epicyclic correction of the initial yaw. If that’s not possible, using a rifle with a muzzle brake (loud, unfortunately) could help by mitigating muzzle blast effect on the bullet base; so may using a long barrel, as on an MLE, as the muzzle pressure is then lower. Choosing the fastest powder (lowest charge weight) that gets you to the desired velocity will likewise cut down on muzzle blast.

At any rate, these are the reasons I wouldn't mess with the tested firing specifications. Too little or too much velocity can reduce penetration in a short range firing. Too little distance from the target can do this, too. If the NZ boys were actually using ancient Mk.VI ammo, you’ll have a fairly low muzzle velocity to duplicate. You'll probably need a chronograph to verify your load’s performance matches what the New Zealanders did, but the .308 should handle it easily, but it would be something on the order of just 32 grains of IMR 4895.

[wogpotter]

The way I interpreted the original post was that MkVI projectiles were reloaded with 40 grains of Du Pont 4895, not that the MkVI ball round which was loaded that way was used. I'm guessing they reloaded pulled milsurps maybe?

All .303 British including the newer MkVII ball was loaded with either black powder pellets for the early versions but cordite for all later rounds up till the Mk VIIz was produced. The "z" designated IMR3031 as a propellant.

[Unclenick]

It was ambiguous to me, which is why I included both possibilities in my post. In that case velocities will be around 400 fps higher than the original round had. And if that's what worked in NZ, that becomes the match he wants to load to.