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RIGGS68

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Reply with quote  #1 
I have been researching in the attempt to talk myself out of another build-specifically a Mongoose. I happened upon this article and was wondering if I am missing something. According to this, a 20" Mongoose will run with a .243 (16-18") using 80-90 grain fodder.(I realize that most .243s have longer barrels). Am I missing something or should I plan on ordering parts now?

http://rifleshooter.com/2016/04/243-winchester-effect-of-barrel-length-on-velocity/
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wikster1983

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Reply with quote  #2 
I too once researched a mongoose........ Just finished cerekoting my 20" build! My advice...... just build one you will like it. It runs 80-90gr pills easy- check out the mongoose section for better details on loads though, I'm pretty new to it yet.
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RIGGS68

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Reply with quote  #3 
Quote:
Originally Posted by wikster1983
My advice...... just build one you will like it. check out the mongoose section for better details on loads though


 [thumb]....not helping the cause...or my finances! I am trying to decide between a Grendel or a 'Goose actually. I know they are different animals but which one will suit my "needs" better.. BTW, There is probably enough load data on the Mongoose that a load spreadsheet may be warranted....hint hint.
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Talenel

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Reply with quote  #4 
https://docs.google.com/spreadsheets/d/1dEmHCV3VyJP1s-RTpxW8G68UQ-cd1cfMfP25hDdiY9A/edit#gid=167449889

[tongue]
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RIGGS68

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Reply with quote  #5 
Quote:
Originally Posted by Talenel
https://docs.google.com/spreadsheets/d/1dEmHCV3VyJP1s-RTpxW8G68UQ-cd1cfMfP25hDdiY9A/edit#gid=167449889
 

Thank you. And I thought I had read every post on here at least once! You are not helping either!!![biggrin]
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wikster1983

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Reply with quote  #6 
Since when has anyone here been talked out of building something? Let me throw the Biggdawg spin on it......... build both! lol
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RIGGS68

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Reply with quote  #7 
Quote:
Originally Posted by wikster1983
Since when has anyone here been talked out of building something?


I know...wrong group to ask! Mark piqued my interest several months ago with his 80 TTSX loading and I have been mulling it around since. The only caveat is I really like a melonite treated barrel so if I want one from MDWS it sounds like it will be a while. I realize I will probably never shoot-out a SS barrel- but I am willing to try. I could "afford" to shoot-out a Mongoose....quality brass and projos for a Grendel might break the bank.  

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Bajabusdoc

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Reply with quote  #8 
Ok " high I am addicted to AR platforms " i was just cruising the internet and some one said come in just to talk............. OK build two go for the goose! There is no support group like this one.


I just finished one for my son. And now BD has me thinking, rationalizing a 257 bobcat please some one help me stop. Or at least buy another bigger safe
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hunttomuch

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Reply with quote  #9 
I'm getting 2500fps with 95gr SST out of a 20 inch 6x45 so mongoose speeds should be faster than that
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surveyor

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Reply with quote  #10 
Sorry, I'm no help to talk you out of it.

http://mdws.forumchitchat.com/post/first-time-out-im-pleased-8203274


http://mdws.forumchitchat.com/post/cz-527-barrel-in-mongoose-8138307?pid=1294364731

I had to have a pair so they wouldn't get lonely you know.
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RangerJoe

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Reply with quote  #11 
RIGGS - Stop... just STOP!  There is NO point trying to talk yourself OUT of building the coolest 6mm rocket launcher on an AR15 platform!  Stop the internal strife and go with the flow... you won't regret it.  LOL  [biggrin]  My 18" Mongoose prototype is the only AR in any caliber that I've ever shot a 3-round group of 0.20" with!  And that was just in my first test ladder.  http://mdws.forumchitchat.com/post/show_single_post?pid=1289729090&postcount=4&forum=467583
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RIGGS68

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Reply with quote  #12 
Quote:
Originally Posted by RangerJoe
There is NO point trying to talk yourself OUT of building the coolest 6mm rocket launcher on an AR15 platform!

Alright...I will comply! But.....since your the one that might be able to answer my original question-will a 'Goose really run with a .243 when 80 or 90 projos are used?

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bedlamite

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Reply with quote  #13 
Quote:
Originally Posted by RIGGS68
Alright...I will comply! But.....since your the one that might be able to answer my original question-will a 'Goose really run with a .243 when 80 or 90 projos are used?

Not quite. I can get 3040 fps with the 80gr Nosler BT using AA2230 in my 22" barrel. The 243 Win can get 3300-3400 fps with the same bullet and barrel length. It's about as good as you can get with the 5.56 case, but the case volume of the 243 is going to beat it.
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RIGGS68

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Reply with quote  #14 
Quote:
Originally Posted by bedlamite
Not quite.

I know the .243 will beat it with hand loads but with standard ammo and 2-4" shorter barrel, it sure appears that it will run with it. The main reason I am asking-my B.I.L., even after repeated hunting success with my Wolverine, refuses to believe I am "ethically" taking deer at the ranges I do. BTW...he is using a lever action .243 with an 18" barrel and standard factory ammo. (It is actually kinda a pissing match)
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wikster1983

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Reply with quote  #15 
Quote:
Originally Posted by RIGGS68
I know the .243 will beat it with hand loads but with standard ammo and 2-4" shorter barrel, it sure appears that it will run with it. The main reason I am asking-my B.I.L., even after repeated hunting success with my Wolverine, refuses to believe I am "ethically" taking deer at the ranges I do. BTW...he is using a lever action .243 with an 18" barrel and standard factory ammo. (It is actually kinda a pissing match)
Which venison tastes better should end that match! lol

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RangerJoe

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Reply with quote  #16 
Riggs - I don't own or shoot any .243 Win rifles (I have dies and have loaded for friends though), thus I have no "real world" experience to compare the Mongoose and .243 Win.  From a purely theoretical perspective, even using factory ammo, the .243 Win should be able to out-perform the Mongoose.  Just like a .308 Win will always outperform a X40 and a 6.8SPC a .277 WLV.  The real question is how close do the smaller case MSR Wildcats come to their big-cased relatives?  80%, 85%, 92% ???  In most instances, we are getting very close to the "classics" with lots less powder (which means less recoil and better economy) and doing it in the AR15 MSR platform with minimal component changes.
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RIGGS68

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Reply with quote  #17 
Quote:
Originally Posted by RangerJoe
Riggs - From a purely theoretical perspective, even using factory ammo, the .243 Win should be able to out-perform the Mongoose.

This is from Mark's 80TTSX/Tac loading for comparison...

Attached Images
jpeg 80ttsx.jpg (183.52 KB, 33 views)
png overview-243-bbl-length-and-velocity.png (61.31 KB, 29 views)

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Dogtired

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Reply with quote  #18 
I have a Grendel and am building a Mongoose...if the barrels ever come back to the store...

The Grendel is a great, field proven round with a lot going for it. Considerable downrange power, factory ammo, easily purchased brass, and if you build a Beowulf, think of the epic battles you will have in the gun safe! You can also fire form your own brass from brass AK rounds.

That said, you need a special bolt and special magazines to run it, as well as 6.5mm bullets, which, unless you are already shooting them, adds to your start up costs.

The Mongoose only needs a barrel change to get in business. However, it's lacking barrels at the moment. You also need to make your own brass (from 223) and ammo, which if you are looking at it, suggests that's of negligible concern to you. The start-up costs will be slightly higher, since you've only got the one supplier of dies and case trimmers at the moment, but at least the bolt is the same [wink]

I've got two 243s kicking around for the kids. I also stumbled on Uber cheap 86gr Nosler eTips that should keep me shooting for the rest of my life (unless I ONKY shoot the Mongoose, but where's the fun in that?).

Want to be economical? Buy your Grendel upper from Radical Firearms or Hardened Arms. Radical sells through Primary Arms and Joebob Outfitters as well as their site, and periodically has 20-22" stainless match grade barreled uppers with a hybrid keymod/quad rail designed and built by Seekins WITH BCG for about $500 (I bought an entire rifle complete with Ergo grip and LUTH-AR adjustable stock for $800 on sale--thing is a TACK driver!). Hardened Arms just started with the Grendel in January or late last year--also about $500 on sale for a 20" if I recall correctly.

Both RF & HA are inexpensive AND solid performers! I bought my stainless 300 Blackout upper with BCG FROM them for $325 on sale--shoots sub-moa all day long--and an 18" 1:9 556 upper to be my coyote gun for $225 on sale. Stocked up on uppers for the kids (16" melonited 1:7) for $180 on sale. Got a 1:7 match grade hand-lapped stainless upper from Radical Firearms (with the Seekins handguard) that I bought with BCG FOR $300 on close out, and, as the description suggests, it shoots better than me. I swapped out the 12" quad rails on the HA uppers with US-made slim keymod handguards I got for under $100 each and was STILL money ahead, PLUS I had a quad rail to put the Blackout my oldest and I built together after Christmas. Both RF & Ha are 100% US made--RF in TX and HA in WA.

My point on the above isn't to show how many guns I have or how awesome I am for accumulating loads of what some might consider dubious steel, but to show you CAN go cheap AND get solid quality for your Grendel. Honestly, I couldn't have built the Grendel or the HA Blackout (or any of them) for less than it cost premade AND they are ALL great shooters--not a bad one in the bunch (OK, haven't tested the 18" upper yet...) (Even with the quad rail and getting all the parts on sale, it cost $200 to build a melonited 300 with my son.)

Grendel problem solved.

NOW, you can go and spend the REST of the budget you had set aside for this project on the Mongoose build. Go to Schuyler Arms and pick up an Aero Precision upper for $60-70, an Aero FDE handguard for $115 (buy the barrel nut for another $15-20), an Aero lower with parts kit for $90 (when on sale--or go buy a PSA complete lower with ACS OR STC stock for $170-200), swap out the trigger for a LaRue LMT, and... you get the idea...

Find the best deals and sales with a little patience, and you'll have TWO rifles for the price of one (or maybe a bit more, but hey! Two rifles!).

I could find all the parts for the rifle minus the barrel and optic for under $600 easily--all US-made, all solid quality.

Personally, I am being picky and particular with my Mongoose build because it's the first I am totally building from the ground up. It's an FDE build (all external parts minus the barrel, trigger, and buffer tube are FDE), with an Aero upper and lower set, Seekins ambi safety, Odin Works adjustable gas block, Ergo grip, Ergo stock (the one they and Magpul made jointly), extended takedown pins, Geissele SD-C trigger, etc. Just need a barrel and a handguard (still trying to figure out what I want...). It's a special rifle and deserves to be treated as such [smile]

I even found a Weaver Grand Slam 3-10x40mm scope for $150 new on eBay (same deal on Amazon--close out model that listed for over $500 initially!). Go get yerself some! It is without a doubt the best deal I've seen yet on scopes (says the guy that got his 4200s for the same price). It's in the same class as the Leupold VX-3 or a high-end Monarch. I've got a Super Slam and it is far and away the best glass I have--over the Zeiss Conquest, Bushnell 4200s, or Leupold VX-2s.
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MDWS

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Reply with quote  #19 
Mongoose barrels are the next in line after the WLV.  Will not be a very long wait at all.
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RIGGS68

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Reply with quote  #20 
With the recent release of the Mongoose barrels, I have decided to "crawl into the den".

What is the recommended set-up for a Mongoose? ie: Is an adjustable gas block suggested? Buffer weight?


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BIGGDAWG

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Reply with quote  #21 
all stock ar parts nothing special needed

just get the barrel and you are good to go no adjustable blocks needed or special buffers.

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RIGGS68

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Reply with quote  #22 
OK, I made the leap but I have a couple questions.

  1.  I sized my cases using BIGGDAWG's method and it worked great! Fired cases measured + .007 - I don't think I want to "fine tune" this any closer due to potential spring back variances.
  2. I am ejecting at 5:30 and did have some feeding issues as a result. Some of the feeding problems, I surmise, relate to the "donut" and my mags not playing nice. I am using a standard carbine buffer and spring (I don't have the actual weight due to my scale range resolution) and I am SURE the gas block is aligned properly. Could this short-stroking be due to the reduced charge?
  3. I used Mark's suggested H335/55 Shots forming load but have sadly run out of H335. Does anyone have a quick and dirty forming load for 55 Shots and TAC? (I have an "ample" supply of it) 20170524_120050.jpg 

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BIGGDAWG

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Reply with quote  #23 
Quote:
Originally Posted by RIGGS68
OK, I made the leap but I have a couple questions.

  1.  I sized my cases using BIGGDAWG's method and it worked great! Fired cases measured + .007 - I don't think I want to "fine tune" this any closer due to potential spring back variances.
  2. I am ejecting at 5:30 and did have some feeding issues as a result. Some of the feeding problems, I surmise, relate to the "donut" and my mags not playing nice. I am using a standard carbine buffer and spring (I don't have the actual weight due to my scale range resolution) and I am SURE the gas block is aligned properly. Could this short-stroking be due to the reduced charge?
  3. I used Mark's suggested H335/55 Shots forming load but have sadly run out of H335. Does anyone have a quick and dirty forming load for 55 Shots and TAC? (I have an "ample" supply of it)



tac and the shots -- tac is a little slow but 30 grains shows about 50k and a slight compressed load in quickload. so 29 or 30 grains would be a fire form load for me and should cycle the gun.

my h335 shots load cycles 100% but i am running a 22" it is on the low side of charge. 28 grains of h335 shows 45k psi, 27.5 shows 44k psi. i run 28 grains

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RIGGS68

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Reply with quote  #24 
Quote:
Originally Posted by BIGGDAWG



tac and the shots -- tac is a little slow but 30 grains shows about 50k and a slight compressed load in quickload. so 29 or 30 grains would be a fire form load for me and should cycle the gun.

my h335 shots load cycles 100% but i am running a 22" it is on the low side of charge. 28 grains of h335 shows 45k psi, 27.5 shows 44k psi. i run 28 grains


I know I am not doing myself any favors by trying to make it function with a slower powder but I would like to save my Benchmark, 8208, and others for future load development. Thank you for the information. I searched 6x45 data but the only 55 grain load I found using TAC was 27.5 grains from a bolt gun- I knew that was too low. I will probably run a ladder between those charges and see what transpires. (Or make a powder run)


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