Modern Sporter - Build Discussions

[jiffx2781]

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[apex survival]

I'm sure this has been covered before, but going through all 180 pages is daunting.
Has anyone put together a MS in .308 or even 7.62x39?
I understand with the discontinuation of the slick side uppers which had huge ejection ports this might be trickier with the FA uppers.

anyone care to point me in the right direction? I have a friend thats working on a .223 wylde build but thought it would be cool to have one for coyotes and one for bigger things.

It is impossible to build a MS in 308, but you can certainly build one in a number of other chamberings. I am building a 6.5 Grendel, you could also go 300 Hammer (Wilson Combat), .277 Wolverine, 7.62x39, 6.8 SPC, 458 SOCOM, 50 BEOWULF and probably at least a couple others I forgot about.

 

[DK23]

I'm new to this whole building process so excuse my ignorance. Why is 308 impossible but 458 socom and 50 Beowulf are?? I guess 6.5 Grendel would be similar in performance to 308. My buddy is just waiting to get his MS assembled by ATRS but is now thinking he'll want to do another one with 4th production run reciever set.

 

[JayCarver]

I'm new to this whole building process so excuse my ignorance. Why is 308 impossible but 458 socom and 50 Beowulf are?? I guess 6.5 Grendel would be similar in performance to 308. My buddy is just waiting to get his MS assembled by ATRS but is now thinking he'll want to do another one with 4th production run reciever set.

Length

308 is just simply too long to fit platform with its bolt travel and magazines.

458 and 50Beo are shorter cartridges based off the 223.

 

[Ryang5177]

I'm new to this whole building process so excuse my ignorance. Why is 308 impossible but 458 socom and 50 Beowulf are?? I guess 6.5 Grendel would be similar in performance to 308. My buddy is just waiting to get his MS assembled by ATRS but is now thinking he'll want to do another one with 4th production run reciever set.

You get into different cartridge lengths. .308 is a short action while your .223,6.5gren, 458 SOCOM etc. Are all what I call “mini action”. not sure that’s the legitimate term but I recall Howa using it and it stuck with me. If you wants 308,6.5 creedmoor, 7mm-08, etc. You’d be looking at one of the other offerings by ATRS i.e modern hunter/varmint or stag 10, bcl102, Troy102, etc.

 

[kolumbo69]

Has anyone done a 9mm upper with a manitcore or other magwell adapter?

 

[Brian46]

I'm new to this whole building process so excuse my ignorance. Why is 308 impossible but 458 socom and 50 Beowulf are?? I guess 6.5 Grendel would be similar in performance to 308. My buddy is just waiting to get his MS assembled by ATRS but is now thinking he'll want to do another one with 4th production run reciever set.

6.5 Grendel is not even close to 308 performance wise. The highest performing 30 cal round available to fit in a platform that uses ar15 parts is going to be the Remington 30 AR. ATRS will not build you one though (I asked directly). I can tell you who has built rifles in this Caliber though.

 

[DK23]

6.5 Grendel is not even close to 308 performance wise. The highest performing 30 cal round available to fit in a platform that uses ar15 parts is going to be the Remington 30 AR. ATRS will not build you one though (I asked directly). I can tell you who has built rifles in this Caliber though.

Thanks! I appreciate you sharing that insight. Sounds like I have some research to do to find a caliber that could be a viable bear gun in the MS platform.
I suppose I could look into the Modern hunter as well.

 

[DK23]

You get into different cartridge lengths. .308 is a short action while your .223,6.5gren, 458 SOCOM etc. Are all what I call “mini action”. not sure that’s the legitimate term but I recall Howa using it and it stuck with me. If you wants 308,6.5 creedmoor, 7mm-08, etc. You’d be looking at one of the other offerings by ATRS i.e modern hunter/varmint or stag 10, bcl102, Troy102, etc.

Thanks for the insight! I appreciate it, i've got some research to do clearly.

 

[no-one special]

Thanks! I appreciate you sharing that insight. Sounds like I have some research to do to find a caliber that could be a viable bear gun in the MS platform.
I suppose I could look into the Modern hunter as well.

If you are looking for bear medicine a Modern Hunter in 308 fits the bill nicely. A 168 gr GMX made my 6.5 medium brown colored blackie into a ready to rug form 1 shot at 325 yards

 

[mileageman]

Thanks! I appreciate you sharing that insight. Sounds like I have some research to do to find a caliber that could be a viable bear gun in the MS platform.
I suppose I could look into the Modern hunter as well.

any of the big bore AR15 calibers would be suitable for bear at less than 150m. 50 Beowulf (also called 12.7x47), 450 bushmaster & 458 Socom. 450 bushmaster is the eaiest to get loaded Ammo for and longer than 18.6" barrels.

 

[Brian46]

Remington has 5 different loading for the 30 AR, never had a problem buying it in Canada. I wouldn't hesitate to use it on medium/large sized game up to 400yds and have taken animals with mine already.

Remington only has one loading for the 450 bushmaster to put things in perspective.

 

[ATRS Shaun]

Remington has 5 different loading for the 30 AR, never had a problem buying it in Canada. I wouldn't hesitate to use it on medium/large sized game up to 400yds and have taken animals with mine already.

Remington only has one loading for the 450 bushmaster to put things in perspective.

The other side of that coin, is Hornady has 4 loadings of 450 bushmaster, and 0 loadings for 30 AR.

 

[Drummondhunter]

Any updates shaun on run #2 still waiting for mine I know I was one of the last numbers in batch#2

 

[ATRS Shaun]

I'm getting similar results searching Federal for the two calibers.

 

[Brian46]

The other side of that coin, is Hornady has 4 loadings of 450 bushmaster, and 0 loadings for 30 AR.

Only ever been able to find the 250gr ftx in Canada. Having used both it and the 260gr accutip from Remington on game, I can tell you I prefer the Remington.

Where are you buying the 3 other loadings from hornady and what has your experience been on animals?

 

[Brian46]

30 AR and 450 bushmaster are so far apart wen it comes to effective range on medium-large size game, I am not sure why we are even discussing which has more loadings available in the first place like they interchange.

 

[jacotsmith]

Anybody have fitment issues with CMMG .22lr conversion kit? The mag has a couple tabs about 1.75" from the top that impede it from being inserted all the way.

 

[ATRS Shaun]

Anybody have fitment issues with CMMG .22lr conversion kit? The mag has a couple tabs about 1.75" from the top that impede it from being inserted all the way.

Nope, can't say I've seen or heard of anything in relation to that. Could you post a picture for clarification?

 

[jacotsmith]

Nope, can't say I've seen or heard of anything in relation to that. Could you post a picture for clarification?

I just bought the kit used (from a reputable CGNer), but just realized it doesn't fit in my AR mag well either.