6mm Mongoose?

D

desertcj

New member
Anyone here heard of this yet? From what I understand, it is basically a 6mm tcu short (.070" shorter?). I know that the 6x45 is popular here, this is supposed to have a tad more case capacity as well as allow mag length seating of bullets up to 90 or 95 grains. I thought about doing something like this but going .100" shorter than the 6mm tcu for a 1.650" case length. The 6mm Mongoose is at 1.680"I think. The guys working with the Mongoose seem to still be struggling a bit to hit 2.260" length with the 90 grain and heavier bullets.
 
Last edited:
The creator claims 1.5 grains more capacity than the 6x45 with the same bullets loaded to 2.260". The real benefit is to be able to shoot 80 grain and up bullets at mag length. I don't have either yet, so I have no dog in the fight. Can you load 87 grain HPBT or V-max to mag length in a 6x45 or does the ogive seat below the case mouth? How about a 95 grain Ballistic Tip? I don't really care about the 105gr bullets because I have a .243 for that, but it might be nice to be able to use them.
 
It has slightly less capacity than a 6X45. It uses TCU dies for loading at this point. The neck is cut back form standrd 6X45 lenght. I shoot 87's HPBTM at magzine lenght, 2.260, in the 6X45 and if you step up to a $14.00 ASC you can load them to 2.316. And no it does not set below the case mouth. Well for the last 30 years it has not for me anyway.

From the write up:

I have been working on this for a little while now and its finally coming around. The reason for it is to have the correct case length in order to use longer bullets and still be able to fit them inside a mag. The old standards ( 6mm-223, 6x45, 6TCU etc. ) all have difficulty when trying to use non varmint bullets at mag length because of the nose length.
I chose to use a 40 degree shoulder in order to keep the neck length close to caliber size for all of the reasons longer length necks are good. The steep shoulder also allows the body of the case to be longer relative to 23 degree and 30 degree shoulder angles. This along with the decreased body taper allow the case to have nearly the same useful capacity as the 6-223 case despite it being .050" shorter.
Since the case has the same body taper and shoulder angle as the 6TCU, I use a modified 6TCU die for forming and resize.

Greg

 
OK,well the guy claims 1.5 grains more capacity when he measured with bullets seated in both. That is not reason enough to go through the trouble versus a 6x45. At what weight bullets do you run into seating depth issues with the 6x45? In the thread I read, he made it seem like you can't load an 87 grain V-max to mag length in a 6x45?
 
Well he is wrong in implying all 87's can't work. I don't shoot anything over an 87 at 2.260. Heavier stuff is not needed over a 90 or so and I use ASC STAINLESS 223 magazines. They MUST be STAINLESS. I don't shoot VMAX bullets normally as I am target shooting. There are some good critter bullets that aren't as long as the 87 VMAX. I would use the 75's if I wanted that style bulet plus I would get a higher velocity.

They are limiting themselves to 2.260 but lots of data is shot longer than that if you look at the data. It is a good little cartridge if you like to play with something different that IMHO offers nothing to the average shooter. The use of a 105 in a 6X45 variant is hardly a driving force because of the limited capacity. Fire forming and having to use special dies is not exactly a win win for me.. Better a 6MM TCU IMPROVED if you want to go that route for a higher performance 6MM 223 based case.

I'll just keep shooting my five 6X45's like an old curmudgeon and let the young pups play with the new ones.

Greg
 
Last edited:
I'm not bashing the 6x45, it's obviously the easiest option. I see that they were going longer than 2.260" with a lot of loads and I thought that was the whole point of the cartridge. Your saying that bullets over 90 grains aren't needed. I'd like to be able to shoot 95gr Ballistic Tips as well as 90 grain E-tips which I'm sure you know are longer than standard lead core 90 grain bullets. 80 TTSX would be a very good bullet as well I think.
 
Originally Posted By: desertcjI'm not bashing the 6x45, it's obviously the easiest option. I see that they were going longer than 2.260" with a lot of loads and I thought that was the whole point of the cartridge. Your saying that bullets over 90 grains aren't needed. I'd like to be able to shoot 95gr Ballistic Tips as well as 90 grain E-tips which I'm sure you know are longer than standard lead core 90 grain bullets. 80 TTSX would be a very good bullet as well I think.

No bashing noted on either side that I see. This isn't an Keith vs. O'Connor issue. More of a Neidner vs. Lindahl. Very similar cases with nuances in differences.

The big E-tips may well be problematic in either case. I will fire up my Sinclair tool tomorrow and look at the 95 BT's. I do think the Game King would be another good one. I do believe the TTSX may well slide in nicely in the 6X45.

The only thing I worry about is what velocities are usable down range in any of these bullets as the 6mm/223 variants aren't going to go ultra-fast unless you overload the pressure. There is a lot of documentation as to safe loading pressures directly on the powder sites and the 6X45 compilation here is a very educational thread with that huge data document.

I like everyone being able to compare opinions and that is what makes this board so great. Lots of knowledge and thought processes go through here every day. We don't always agree but we darn sure learn from each other.

Greg
 
The bullets I want to be able to shoot range from the 55gr Nosler BT as well as the lead free version (Which is close to the size of a 70 gr BT) up through the 95gr BT. The 90 grain E-tip might be longer, I can check.The 80gr TTSX would be an acceptable replacement for the E-tip and probably even preferable due to the higher potential velocity.
 
Last edited:
Originally Posted By: desertcjI'm not bashing the 6x45, it's obviously the easiest option. I see that they were going longer than 2.260" with a lot of loads and I thought that was the whole point of the cartridge. Your saying that bullets over 90 grains aren't needed. I'd like to be able to shoot 95gr Ballistic Tips as well as 90 grain E-tips which I'm sure you know are longer than standard lead core 90 grain bullets. 80 TTSX would be a very good bullet as well I think.

Sounds like you should be looking at a 6mm wildcat on the lbc/grendel case or 6.8spc case.
 
Originally Posted By: midwestpredatorOriginally Posted By: desertcjI'm not bashing the 6x45, it's obviously the easiest option. I see that they were going longer than 2.260" with a lot of loads and I thought that was the whole point of the cartridge. Your saying that bullets over 90 grains aren't needed. I'd like to be able to shoot 95gr Ballistic Tips as well as 90 grain E-tips which I'm sure you know are longer than standard lead core 90 grain bullets. 80 TTSX would be a very good bullet as well I think.

Sounds like you should be looking at a 6mm wildcat on the lbc/grendel case or 6.8spc case.

Negative, I don't care for the brass, bolt or magazine situation. I'm sold on the 5.56 parent case.
 
Im not sure there is a situation with bolts mags or brass but to each there own. Thats why there is an almost endless variety of chamberings to pick from.

IMHO, you are looking for the 223 case to do something that it will only barely do and do poorly compared to other options. I still hope it works out for you though.
 
Originally Posted By: midwestpredatorIm not sure there is a situation with bolts mags or brass but to each there own. Thats why there is an almost endless variety of chamberings to pick from.

IMHO, you are looking for the 223 case to do something that it will only barely do and do poorly compared to other options. I still hope it works out for you though.

To the contrary, I think the .223 case does it and does it very efficiently. "The situation" is a non standard bolt that is arguably marginal strength wise. Mags that I don't already have and brass that is less common and more expensive. Some guys don't care about any of that and that's fine too.
 
Id stick with the 6x45. Yes you can run 55-95g bullets at 2.260",(really depends on magazine). My antelope load was the 95g nosler HBT and yes it was seated deep almost to the point of no return on the ogive. They shot very accurately & no problem hitting steel at 700 yards.
The 80-85g barnes & 87g vmx seat fine and yes a tad deep they still are not over the ogive from all my testing and loads Ive yet to see any issues doing so.
Ive watched the 6 mongoose talk over there and nothing wrong with it except all the case work & forming keeps me building 6mm rigs that are easier to load for without all the prep work.
 
the 223 case is pretty small, I can't imagine ANY reason why someone would monkey with something that has less case compacity. I think more people should figure out how to produce plug and play parts with something that has the compacity of the BR case.
 
So I dug out every 6mm bullet I had on hand along with my ogive comparitor and calipers. I got some surprising results and I gotta say that I sure am interested in how you 6x45 guys are shooting some of the heavier bullets? I'll run through my math real quick to show what I found. First I'm going to list the bullets I measured along with the OAL as well as what I'm going to call Tip To Ogive (TTO) measurement which I got by subtracting the amount of bullet sticking out of the comparitor from the OAL of the bullet.

105 Amax-1.245" OAL, .592" TTO
105 HPBT-1.237" OAL, .541" TTO
95 BT-1.120" OAL, .527" TTO
90 E-tip-1.180" OAL, .517" TTO
87 HPBT-.957" OAL, .462" TTO
55 BTLF-.945" OAL, .530" TTO

The TTO measurement would be the front part of bullet past the Ogive/Bearing surface junction. You can't seat it deeper without the ogive falling into the case mouth. Still with me? 2.260(Mag length)-1.750(Case length)=.510" maximum TTO measurement.

So out of all those bullets, only the 87 grain HPBT makes the cut in a 6x45! Considering this, it seems that you would really want only a very small amount of free bore in a 6x45? It's just making it that much harder to get close to the lands. Some of the other bullets are close and you may be able to trim the neck back enough to seat the bullet deep enough? Maybe that's the trick?
 
Originally Posted By: desertcjSo I dug out every 6mm bullet I had on hand along with my ogive comparitor and calipers. I got some surprising results and I gotta say that I sure am interested in how you 6x45 guys are shooting some of the heavier bullets? I'll run through my math real quick to show what I found. First I'm going to list the bullets I measured along with the OAL as well as what I'm going to call Tip To Ogive (TTO) measurement which I got by subtracting the amount of bullet sticking out of the comparitor from the OAL of the bullet.

105 Amax-1.245" OAL, .592" TTO
105 HPBT-1.237" OAL, .541" TTO
95 BT-1.120" OAL, .527" TTO
90 E-tip-1.180" OAL, .517" TTO
87 HPBT-.957" OAL, .462" TTO
55 BTLF-.945" OAL, .530" TTO

The TTO measurement would be the front part of bullet past the Ogive/Bearing surface junction. You can't seat it deeper without the ogive falling into the case mouth. Still with me? 2.260(Mag length)-1.750(Case length)=.510" maximum TTO measurement.

So out of all those bullets, only the 87 grain HPBT makes the cut in a 6x45! Considering this, it seems that you would really want only a very small amount of free bore in a 6x45? It's just making it that much harder to get close to the lands. Some of the other bullets are close and you may be able to trim the neck back enough to seat the bullet deep enough? Maybe that's the trick?

I don't load to 2.260. I load to up to 2.314. Add that in and the envelope gets much bigger. That's the trick. If you want to save case capacity you have to load long. If you window the magazine you can load to 2.34 in a standard AR lower. I have a custom billet lower designed by Ritch that even lets me load longer.

Greg
 
Last edited:
Get the right mags and you can load to 2.3". Im with steve on this one. Cheaper brass isnt a justifiable reason to step on your own toes as far as performance goes in this situation.

 
Last edited:
Hmmm, ASC stainless mags for the win! Adding
.040" brings all of those bullets into play except for the 105 Amax. With a windowed mag, even the Amax looks possible in a 6x45.
 


Write your reply...
Back
Top