Which and why? .270WSM .300WSM .338 Federal/Lapua

[budlight]

Before the housing melt down of 2006. There used to be a variety of bullet manufactures. Like Wildcat, They would make you about anything you wanted in .277 So I bought 1000's of 169.5 through 190 gr. Matrix also used to make all kinds of bullets. Both VLD match grade and hunting. The problem with over bore rifles is short life. I got so tired of rebarreling rifles every year or two. That I sold all my super guns 30-378, 7 STW wild cat. , and 270 ai all 30 inch target barrels

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270 WSM in an AR

I’m intrigued by the ballistics of the 270 WSM cartridge. Considering an AR build in this caliber. Would love to make this my all-around hunting rifle for coyote, hog, white tail. Anyone with AR experience in this caliber care to share their experience? Thanks in advance!

www.longrangehunting.com

 

[budlight]

Pictures of some heavy .277 pills. Back in the 2000's There was a rage of super magnum custom rifles called " Allen Magnums" Like taking a ultra mag case and necking it down to .277 using a 30 inch barrel and pouring 90 grains of powder like US 869 to it. These are Very high BC rounds.

Left to right .277 dia. 195 gr, 190 gr, 169.5, 150 gr BT, and a recovered 130 barnes

 

[Tactical45]

So you are just trying to tease me, right? Lol

 

[Ace Quackhunter]

I am researching a new upper for either of my AR builds. A few years ago I built a LR10 in .308. I have no issues with it, just looking for a harder hitting round at 500-700 yards. Five years prior to that build is my DPMS 5.56/.223, no issues here either.

While researching I have seen some issues with the .300WSM with ejecting, and such. I am well aware of the debated recoil with the .300 and .338 calibers. It is all subjective to the shooter, weight of the rifle, and all parts of the load used. I have a M44 Nagant that I call Thor because of the recoil of a wood stock, and a steel butt plate. So, needless to say, I am used to recoil when I have to be.

For those of you who have one, or more of these calibers in a AR platform, please chime in with what you max range is with a given load. Would you only hunt deer out to say 500 yards, or is Elk, and Bear still and option at that range? I would like to keep the upper at 16", but I do believe that may take away from the overall muzzle velocity... The more information the better...

I have a 338 Federal by DPMS and while I have not shot it past 300 yards, it does preforms well with 180 & 200 grain projectiles. I would give the edge to the 200 grain to use on Elk as you start to run out of energy past that distance .

 

[budlight]

So you are just trying to tease me, right? Lol

I was always the under dog at meets with a .277 I really don't think that people ever knew that super heavy .277 were even available

 

[jbs2014]

I am researching a new upper for either of my AR builds. A few years ago I built a LR10 in .308. I have no issues with it, just looking for a harder hitting round at 500-700 yards. Five years prior to that build is my DPMS 5.56/.223, no issues here either.

While researching I have seen some issues with the .300WSM with ejecting, and such. I am well aware of the debated recoil with the .300 and .338 calibers. It is all subjective to the shooter, weight of the rifle, and all parts of the load used. I have a M44 Nagant that I call Thor because of the recoil of a wood stock, and a steel butt plate. So, needless to say, I am used to recoil when I have to be.

For those of you who have one, or more of these calibers in a AR platform, please chime in with what you max range is with a given load. Would you only hunt deer out to say 500 yards, or is Elk, and Bear still and option at that range? I would like to keep the upper at 16", but I do believe that may take away from the overall muzzle velocity... The more information the better...

Having an AR10 platform with a 16" barrel will significantly lower your velocities. With my 22" barrel 6.5 Creedmoore AR10 I lose at least 150 FPS bellow what is posted for 24" barrels in every reloading book I have. I also have an older DPMS AR10 chambered in 300 SAUM with a 20" barrel, combine the effects of the gas system with the shorter barrel and I basically have a 3006 at 300 SAUM prices. Could you go out to 500-700 meters with a 16 barrel? Sure. But you will have a lot more effect on target with a 24-26" barrel.

If you do go with the 300 WSM make sure that you get a well made extractor. With the DPMS in 300 SAUM (less case capacity than 300 WSM) I wrecked 2 extractors.

Hope this helps and you are able to avoid the pain I went through with my AR10s.

 

[jfloyd]

I have found that the AR-10's are very hard on brass when loaded any where near max so you end up having to drop you charges or go to faster powders to drop the port pressures to the point your brass is still reloadable. The high port pressures really chew up the rims and leave some bad swipes on the case heads to the point you've got burrs to deal with. Not great for COL among other things. An adjustable gas port will help but will take some fiddling. The bottom line is slower velocities or short brass life. For your stated purposes, I think you are going to have to thread the needle and have very little margin of error unless you do some serious fiddling. Your results might vary but that has been my experience. Faster powder and dropping charges with slower velocities.
Good luck!!!

 

[budlight]

I have found that the AR-10's are very hard on brass when loaded any where near max so you end up having to drop you charges or go to faster powders to drop the port pressures to the point your brass is still reloadable. The high port pressures really chew up the rims and leave some bad swipes on the case heads to the point you've got burrs to deal with. Not great for COL among other things. An adjustable gas port will help but will take some fiddling. The bottom line is slower velocities or short brass life. For your stated purposes, I think you are going to have to thread the needle and have very little margin of error unless you do some serious fiddling. Your results might vary but that has been my experience. Faster powder and dropping charges with slower velocities.
Good luck!!!

I had this discussion with someone loading his 308 to service rifle type powder specs. The real cure for both AR-15 and Ar-10 is to use the longest length gas ports. rifle length in Ar-15 and Rifle length + 2 inches on AR-10's. also use the smallest gas port. My last barrels were .072 dia. I've seen advertised as big as .086.

I only have adjustables on my piston rifles. They kind of suck with the fiddling. It is better to balance the cycling with heavy full auto bolts , heavy buffer weight and a light buffer spring. I've also played with the drilling out the buffer tube end so you have less air compression during the rear thrust.

 

[jessej]

You are not being realistic Semi- autos are inherently inaccurate compared to their bolt action counter parts. 16 inch barrel and 500 yards is not what I would call ethical hunting

AR's bleed off pressure depending on the distance to the gas ejection port. I have 308 ar-10's with rifle length and rifle +2 inch ports and 24 inch barrels. They are made to eject properly with the slowest for 308 rem powders and achieving the highest velocities. Like Ram shot big game with 168 gr hpbt chronoed at 2800 fps with good groupings. or 175's with H414 and Hybird 100V with 180's

But if you must 270 wsm is an great round with 26 inch barrels

 

[jessej]

You are not being realistic Semi- autos are inherently inaccurate compared to their bolt action counter parts. 16 inch barrel and 500 yards is not what I would call ethical hunting

AR's bleed off pressure depending on the distance to the gas ejection port. I have 308 ar-10's with rifle length and rifle +2 inch ports and 24 inch barrels. They are made to eject properly with the slowest for 308 rem powders and achieving the highest velocities. Like Ram shot big game with 168 gr hpbt chronoed at 2800 fps with good groupings. or 175's with H414 and Hybird 100V with 180's

But if you must 270 wsm is an great round with 26 inch barrels

dang. My sig 716 308 Prints half moa groups at 500 with cheap ammo.
I'm all about precision bolt guns but 500 yrds is very doable in a high quality AR

 

[jfloyd]

I had this discussion with someone loading his 308 to service rifle type powder specs. The real cure for both AR-15 and Ar-10 is to use the longest length gas ports. rifle length in Ar-15 and Rifle length + 2 inches on AR-10's. also use the smallest gas port. My last barrels were .072 dia. I've seen advertised as big as .086.

I only have adjustables on my piston rifles. They kind of suck with the fiddling. It is better to balance the cycling with heavy full auto bolts , heavy buffer weight and a light buffer spring. I've also played with the drilling out the buffer tube end so you have less air compression during the rear thrust.

Good to know. My only 308 AR at the moment is a POD Revolution which is its own animal.

 

[iclick]

I am researching a new upper for either of my AR builds. A few years ago I built a LR10 in .308. I have no issues with it, just looking for a harder hitting round at 500-700 yards. Five years prior to that build is my DPMS 5.56/.223, no issues here either.

While researching I have seen some issues with the .300WSM with ejecting, and such. I am well aware of the debated recoil with the .300 and .338 calibers. It is all subjective to the shooter, weight of the rifle, and all parts of the load used. I have a M44 Nagant that I call Thor because of the recoil of a wood stock, and a steel butt plate. So, needless to say, I am used to recoil when I have to be.

For those of you who have one, or more of these calibers in a AR platform, please chime in with what you max range is with a given load. Would you only hunt deer out to say 500 yards, or is Elk, and Bear still and option at that range? I would like to keep the upper at 16", but I do believe that may take away from the overall muzzle velocity... The more information the better...

I have 308, 243, 338 Federal and a 300wsm uppers. All have their limitations due to having 20 inch barrels. However I used the 300 wsm to take the elk in my avatar. Shot was 180 yards with a 180 Grain Cutting edge bullet. The ejection issues with the 300 wsm depends on who did the bolt mods. I have at least a 1000 rounds down the pipe with mine and never has jammed or failed to eject correctly. I sent my upper during the build to Mountain Arms here in Northern California and he does them right. It is easily a 600+ yard rifle as I can ring steel at 1000 yards with it consistently. As far as the 338 Fed it is not a long range rifle but does very well on elk out to 300 yards. Used it to get my Cow last month at 227 yards. My 308 2nd build is a target gun with a 22 inch bull barrel. It is my bench AR and it will shoot 5 shot single ragged holes at 300 yards.

 

[budlight]

dang. My sig 716 308 Prints half moa groups at 500 with cheap ammo.
I'm all about precision bolt guns but 500 yrds is very doable in a high quality AR

Yes, high quality AR-10's can do pretty good. I have two 24 inch match rifles with target 11 degree SS fluted that have 11 degree target crowns on the ends of the barrels. 8X32 with 60 mm objectives. I use them for long range PD and Pig hunting.

One problem with 308's is low velocity down range. do some chrono time and then feed the numbers with the bullet BC, your altitude and temp..... If I launch a 168gr ELDX @ 2800 fps. it goes under the magic 2000 fps right over 400 yards. That is the bottom end of the expansion FPS.

The poster originally said 16 inch barrel which makes even magnums iffy at 500

 

[jfloyd]

Yes, high quality AR-10's can do pretty good. I have two 24 inch match rifles with target 11 degree SS fluted that have 11 degree target crowns on the ends of the barrels. 8X32 with 60 mm objectives. I use them for long range PD and Pig hunting.

One problem with 308's is low velocity down range. do some chrono time and then feed the numbers with the bullet BC, your altitude and temp..... If I launch a 168gr ELDX @ 2800 fps. it goes under the magic 2000 fps right over 400 yards. That is the bottom end of the expansion FPS.

The poster originally said 16 inch barrel which makes even magnums iffy at 500

That was the point I was trying to make but you said it much better and simpler.