SHERMAN MEGA LINE

[brittf]

MDT, just select the 3.56 option - perfect for Max/Mega:
https://mdttac.com/300wm-mdt-metal-aics-magazine/

Great on the Prometheus - I see it now, I glossed over it because it says "338" lol

So, really, you just need to decide what ballistics are worth to you... Barrel and brass life plus powder per charge vs how much better wind and/or energy at given distances. For rifle 5, you said ultimate flat shooting... 7 lapua Improved? Or is 338 Mega with Badlands 285's good enough...

My purposes are practical, i.e., to ethically put an animal down, repeatably and controllably, from a cold bore. So all of my decisions are based on that. I don't own a 6mm simply because the ballistics are inferior to 25 and up, and for my purposes, the reduced recoil or component wear doesn't outweigh the performance deficit.

So, for my purposes, and from my research and personal anecdotal data, it seems like the 6.5 Max is indeed a max for that caliber, at least with today's projectiles. I expect the 7 Mega to be very close as well. By max for caliber, I mean the point at which the benefits from more capacity diminish to negligible (for my purposes) while component wear goes exponential.

I really like the 338 Mega from the limited data thus far. I'm thinking about 338 Mega barrels for both of my 6.5 Max rifles - one a short light hunter, and the other a longer, heavier chassis rifle. The efficiency looks great from a powder/velocity standpoint, and the ability to use a shorter barrel is also a plus. But, it won't do what a PRC Imp would do, and certainly wouldn't hold a candle to an Edge or Norma Imp or Lapua Imp. Decisions!

Lots of details follow, so some may want to skip the post. However, IF you are interested in understanding M5 DBM magazines that properly feed the SAUM based Sherman cartridges (SST, SS, Max) and the WSM based Sherman cartridges (Mega), the post may be of interest.

I was afraid that might be the MDT magazine you were referring to in your earlier post. I could very well be wrong, but my 'internet and phone research' (not my own experience, because I don't have any) seems to be saying the following:

M5 bottom metal for long actions (as originally defined by Badger Ordinance and AICS) come in two lengths: (i) Standard 3.715" magazine outside dimension (typical for 30-06 and 300 Win Mag), and (ii) CIP 3.850" magazine outside dimension (typical for 300 PRC and 338 Lapua).

I don't understand the 3.560" length in the MDT magazine referenced. That is neither an AICS standard for magazines nor a Badger Ordinance standard for M5 DBM bottom metal (that I can tell). Those were the two firms who, together, designed and specified the feeding system. Various magazine and bottom metal manufacturers have 'copied' their standards, but they were the originals.

So, what specific DBM bottom metal does the 3.560" fit into?

To illustrate my concern, consider that I have in my hands two Badger DBM bottom metals (one for 3.715" magazine length and the other for 3.850" magazine length). Both fit into an M5 inlet in my Cerus GT-Hybrid stock since their OUTSIDE mounting dimensions are the same, per the M5 specifications. I also have four metal magazines in my hands: (i) AICS 3.715" length for 300 Win Mag, (ii) AICS 3.850" length for 338 Lapua, (iii) MDT 3.715" length for 30-06, and (iv) MDT 3.715" length for 300 Win Mag.

Note that ONLY the AICS 3.850" length for 338 Lapua magazine will seat in the Badger 3.850" CIP M5 DBM bottom metal. The others are too small and do not lock into the bottom metal. For the 28 or 30 or 33 Sherman Magnums (based off the 300 PRC case) you can order the MDT 300 PRC AICS (compatible) magazine, part #105123-BLK and it should feed fine.

The AICS 3.715" length for 300 Win Mag, the MDT 3.715" length for 30-06, and the MDT 3.715" length for 300 Win Mag will all fit into the Badger 3.715" standard M5 DBM bottom metal. For the 6.5, 280, 300, and 330 Sherman (based off the 30-06 case) you can order the MDT 30.06 AICS (compatible) magazine in 3.715" length, part #104269-BLK and it should feed fine.

The above I know to be true because I have them in my hands. That is why I bought them in the first place (even though they are expensive) - I want to understand compatibility.

So, now that brings us back to the MDT 3.560" length for 300 Win Mag that you reference, as well as the MDT 3.560" for 30.06 (also available) - what DBM bottom metal do they fit? Per my above experience, it would appear that I would have to find ANOTHER M5 DBM bottom metal (not one of the two 'standards' that Badger has) specific to this length.

On Hawkins' website, it says the have M5 bottom metals "Available in Short Action, Medium (Zermatt/Lone Peak/Stiller), Defiance XM, Long Action, and CIP/CIP+ Length 338 Lapua". I already know that the Long Action refers to 3.715" and the CIP/CIP+ refers to 3.850" (similar to what I have in Badger).

So, which one fits the MDT 3.560" magazines? I suspect the Medium (Zermatt/Lone Peak/Stiller) or perhaps the Defiance XM.

And, after all is said and done, it will have lips for a 300 Win Mag (which I already have in both AICS and MDT 3.715" magazines). The only advantage that I can see is the 0.155" or 0.290" shorter feed in the magazine. That may be enough, since the feeding problem for SAUM/WSM based cartridges is due to the cartridge coming free from the feed lips BEFORE the nose is sufficiently engaged in the chamber.

Do I basically have this right?

Sorry for the long post (again), but these kinds of details MAY be helpful for people interested in trying out the Sherman wildcats, if they are as detail-oriented as I am before buying into something...

 

[brittf]

MDT, just select the 3.56 option - perfect for Max/Mega:
https://mdttac.com/300wm-mdt-metal-aics-magazine/

Great on the Prometheus - I see it now, I glossed over it because it says "338" lol

So, really, you just need to decide what ballistics are worth to you... Barrel and brass life plus powder per charge vs how much better wind and/or energy at given distances. For rifle 5, you said ultimate flat shooting... 7 lapua Improved? Or is 338 Mega with Badlands 285's good enough...

My purposes are practical, i.e., to ethically put an animal down, repeatably and controllably, from a cold bore. So all of my decisions are based on that. I don't own a 6mm simply because the ballistics are inferior to 25 and up, and for my purposes, the reduced recoil or component wear doesn't outweigh the performance deficit.

So, for my purposes, and from my research and personal anecdotal data, it seems like the 6.5 Max is indeed a max for that caliber, at least with today's projectiles. I expect the 7 Mega to be very close as well. By max for caliber, I mean the point at which the benefits from more capacity diminish to negligible (for my purposes) while component wear goes exponential.

I really like the 338 Mega from the limited data thus far. I'm thinking about 338 Mega barrels for both of my 6.5 Max rifles - one a short light hunter, and the other a longer, heavier chassis rifle. The efficiency looks great from a powder/velocity standpoint, and the ability to use a shorter barrel is also a plus. But, it won't do what a PRC Imp would do, and certainly wouldn't hold a candle to an Edge or Norma Imp or Lapua Imp. Decisions!

*Edit - the projectile BC's available per caliber help to put velocity in perspective - my go to load for my 308 is a 208 eld-m @ 2640. Look at the velocities required of a 6.5 with a 156 to match that. Now look at the 156 with a Max case, @ 3160. What velocity is required of different 7mm or 30 cal projectiles to have equivalent wind at 500,1000,1500... And which cartridges/projectiles get you over 2K yards supersonic... You start building a nice matrix and decision tree. Then factor in energy, and it becomes pretty easy to see where you want to be for each rifle/purpose.

A different question here. I seem to be on the forum a lot today.

I don't typically run compensators/muzzle breaks for cartridges up to 30-06. However, there seems to be considerable use of them in the magnum (and magnum-like) cartridges on this forum.

I would tend to NOT run a compensator/muzzle break for the 7mm-Max or the 280 Sherman (whichever of the two I end up choosing). Is that the right decision, or would it potentially be helpful. This matters to me because I have to order barrels and length will change depending on break or no break.

I would tend to think a bigger hitter like the Mega or, especially, the Sherman magnum, I might want/need a compensator/muzzle break. However, again, I do not know and am seeing feedback before I order the barrel.

 

[Monkeygoat]

The 3.56" mag is for the Tikka long action and I believe some other medium actions, though unsure which. There are not many chassis that offer Tikka long action length. Mine is the Vision chassis. Moot here anyway, since you have a real LA. I would take advantage of it and the boltface options to run bigger cases... but this goes back to purpose and goals.

I have a brake on my 6.5 Max, and it makes trace/impacts easier to see than running it unbraked. I generally shoot by myself and will back off magnification and self-spot if the wind is kicking my ***. Unsure how well I could self-spot at distance without a brake, but I'm also sure I shoot "incorrectly".

Here's my control group with 153.5 Bergers, seating depth test of 135 Badlands, and the Tikka in Vision chassis w/ 3.56 mag. The Sherman short mags are perfect for the action and mags.

 

[GraemeH]

If I bought a 338 Mega reamer and sent it to PVA, would anyone be interested in renting it to have their barrel spun? It would take me 10yrs to shoot 3 barrels... so rather not buy a reamer to use only once.

I'd pull the trigger on a 338 Mega from PVA today - they have Rock Creek cut rifled 7.7 twist barrels in stock and on special for 329, begging for some Badlands solids...

I'd consider other smiths as well, but would be nice to pick one and have the reamer live thereI

I know it is a bit late but I would be interested in renting and getting a barrel from them. I don't have an action and I know lead times are a bit extreme now, I was just emailed 50 weeks from someone. Would they reimburse you or how would you work the rental?

 

[Monkeygoat]

I know it is a bit late but I would be interested in renting and getting a barrel from them. I don't have an action and I know lead times are a bit extreme now, I was just emailed 50 weeks from someone. Would they reimburse you or how would you work the rental?

I'm moving to TX in a couple of months and decided to wait until I am there to do a Mega barrel. But, yes, decided I'd buy a reamer and let others use it - they can send me some bucks on the honor system, and if someone stiffs me, I'd just stop offering it.

 

[bamban]

I'm moving to TX in a couple of months and decided to wait until I am there to do a Mega barrel. But, yes, decided I'd buy a reamer and let others use it - they can send me some bucks on the honor system, and if someone stiffs me, I'd just stop offering it.

Welcome to TX. May I ask on which area you are heading to? If you mentioned it before in any of the threads, I missed it.

 

[Monkeygoat]

Welcome to TX. May I ask on which area you are heading to? If you mentioned it before in any of the threads, I missed it.

We're going to rent first in order to get a feel for the area - we will be boarding horses between Dripping Springs and Bee Cave to begin, so will be finding a rental house as close as possible to the horses. Ultimately, I'd like a large property to have horses on, maybe a bit further out into the hill country, or near a big lake or with live water.

 

[Korhil78]

Doesn't get any better than Llano, TX. I grew up there on the river. Best memories ever!

 

[GraemeH]

I'm moving to TX in a couple of months and decided to wait until I am there to do a Mega barrel. But, yes, decided I'd buy a reamer and let others use it - they can send me some bucks on the honor system, and if someone stiffs me, I'd just stop offering it.

Good luck with the move, I'm sure it will go great. I'm in no rush and a longer wait is okay for me. When I get there I will message you about the reamer. And I'll be looking forward to your experience and to hear about your rifle here.

 

[Monkeygoat]

^Thanks, will keep updated here. Hopefully more data comes out as components become available.

 

[brittf]

We're going to rent first in order to get a feel for the area - we will be boarding horses between Dripping Springs and Bee Cave to begin, so will be finding a rental house as close as possible to the horses. Ultimately, I'd like a large property to have horses on, maybe a bit further out into the hill country, or near a big lake or with live water.

Welcome to the neighborhood. Be sure to ping me when you get to the Austin area. I can show you around. I will also have two Sherman 'sets' by then - if you have the Mega, then I will probably go with the 7mm Max and the 28 Sherman Magnum. I have a full shop and happy to have you use it to chamber and such.

 

[Monkeygoat]

Welcome to the neighborhood. Be sure to ping me when you get to the Austin area. I can show you around. I will also have two Sherman 'sets' by then - if you have the Mega, then I will probably go with the 7mm Max and the 28 Sherman Magnum. I have a full shop and happy to have you use it to chamber and such.

Definitely will, thanks. Very much looking forward to being part of a community of Americans again. Been living in a leftist hellhole for ~10yrs.

 

[brittf]

So, I have been doing some detailed drawings with Sherman chambers and various bullets to better understand jump and bullet selection.

I understand no one has the Mega brass yet, since it isn't available, but I would appreciate some information on jump for those of you who have the Sherman Max.

My CAD drawings and calculations show that the 7mm Sherman Max chamber is very well sized for the 180 and 190 gr Berger bullets, with the bearing surface just inside the neck/shoulder junction at 'touch'. That is essentially 'perfect' if you want full neck engagement with long bullets, but want to avoid the donut problem. You can increase jump to 0.020"-0.060" without the bullet taking up much (if any) powder 'real estate'.

When I play around with the 7mm Sherman Mega (based off a 'long-necked' 300 WSM), I find a similar situation where the chamber is essentially 'perfect' for the 180 to 197 gr bullets, in the STANDARD medium-action (0.205" Freebore) setup. The neck is longish, so even the shorter bullets have plenty of neck engagement (down to maybe 170 gr or so).

However, since I am building a LONG action, Rich suggested the LONG reamer (0.305" Freebore) setup for my Mega build. The extra 0.100" of Freebore length reduces the neck engagement by a similar amount on any bullet. For the very long bullets (190, 195, 197 gr) it seems to work out just fine - if I plan on 0.020-0.040" jump, I still have pretty good neck engagement (maybe 85% of bore diameter). That should work. However, once you drop below the 190 gr bullets, either the neck engagement gets pretty small (0.200") or the jump gets excessive (0.100").

Now, this isn't a problem if the bullets and chambers LIKE a good jump. However, I am learning my craft from a well-known Benchrest and F-Class gunsmith, and he is all about small (to no) jump and good, long neck engagement. So, I am at a crossroads...

What kind of jump are you guys running with, in particular, the Max cartridges? Are we talking 0-0.020" or much larger? Historically, overbore magnums had a LOT of jump to reduce chamber pressure and still get high speeds. Does the Max and, especially, the Mega fall in this category?

Thank you in advance for your time and consideration.

Regards,
brittf

 

[Monkeygoat]

6.5 Max with 153.5 Berger here in a 28" 7.5 twist Bartlein. She runs cloverleafs and smaller at anywhere from 7 jam to 7 off. 15 off is a big cloverleaf, or maybe 2 touching and 1 just beside it. This is at 100 and 200 yards. I'll be taking it out to distance this weekend to see if the jam gives me more vertical spread.

Weirdly, the Badlands 135 solids also seem to like being very close to the lands. 1's and 2's at 15 off... after being advised by many that it would run best around 40 off. So, it may simply be barrel dependent.