243 or 270 for short barrels?

[Maverick223]

Maverick223, since that's the purpose of the OP, are you really sure you'd want a .308 or an '06 as a varmint gun?

Nope, but I wouldn't want a carbine length rifle for that task either (due to blast, noise, and loss of efficiency). He asked which one afforded the best performance, and that is either the .308 or '06 depending upon our definition of performance. I figured he was talking about efficiency, so I answered....308Win. If it were energy the answer would be .30-06 instead. FWIW, I think the .260Rem. or .223Rem. fits his needs best (but not ideally by any stretch), but neither are offered in his chosen carbine so that is a beside the point.

 

[Lloyd Smale]

Ive killed quite a few deer with the 243/6mm in barrel lenghts from 18 to 24 and ive yet to see a bullet bounce off a deer because it came from a 18 inch barrel. As a matter of fact i doubt your ever going to notice a differnce in killing power out to 300 yards. A 243 with a 100 grain bullet can easily run 2800 fps and thats as fast as most 06 factory loads will run out of a 22 inch barrel so its darned near as flat shooting. A long barrel isnt a bad choise for open country hunting but in a thick area where shots are seldom out past a 100 yards the extra velocity can actually be detrimental to bullet performace. Hard to get an exit wound with a 243 running 3000fps when the animal is only 50 yards out. As to the 308 3006 debate. Dont let anyone tell you that because your using a 2o inch barrel there equal. Id bet you a dime to a dollar i can push a 150 out of an o6 faster in a 20 inch barrel then your going to get a 308 up to out of a 22. Make that bullet a 165 or 180 and the o6 will open up the spread even more. You need to keep in mind that when comparing the two that factory 308 is loaded to higher pressures the the 06 and thats what keeps them close. Load both to the same pressure and the o6 will pretty much stomp on the 308. Dont get me wrong i love the 308 too. It just goes back to the fact it again is about a 2800 fps round and theres nothing wrong with that and it allows for a short action which makes for an even lighter shorter handier gun. A 308 is no more equal to an 06 then the 06 is to a 300 mag. As to a little more muzzle blast thats not much of an argument. I wear ear plugs at the range and bottom line is in the field shooting one or two shots without them i doubt its going to mean the differnce in you going deaf or not. I know a few guys that just have to have 26 inch barrels and load there guns well above book pressures thinking there really accomplishing something. Me im just the oposite. Rarely do i run a gun at the absolute max. If my 308 isnt enough for the job at hand i grab a 06 if thats not good enough then i grab a 300 mag. One of my favorite deer rifles and a gun thats accounted for a truck load of deer is a ruger international 250-3000 and its pet load is a 120 nos solid base or a 117 sierra loaded to just over 2500 fps. Ive shot deer out to 250 yards with that combo and have yet needed to track a wounded animal. It has been used by everyone at camp and has aquired the nickname thor because most deer shot with it drop like hit with the hammer of thor. Its nothing majical and certainly less gun then alot of guys would recomend but it works and its almost as handy as a 94 in the thick stuff.

 

[Dallas Jack]

A simple answer, if you want to shoot lighter bullets (55 to 105 grains) then .243. If you prefer a little heavier bullets (100 to 150 grains then .270.

My preference is the .243.
Dallas Jack

 

[Ridgerunner665]

Somebody up there said the 243 didn't lose 100 fps per inch below 22 inches...

That may be your experience, but it wasn't mine...trying to shoot 100 grain bullets from a 20" barrel (Remington youth model) mine is pathetic...literally pathetic.

It did lose 200 fps compared to a 22" barrel (another Remington...an older one with many rounds down the tube) with the same loads...tried different powders, settled on a compressed charge of Reloder 19.

I know no 2 barrels are alike...but this has came out the same way on a couple other 243's I know of.

 

[jmr40]

Ridgerunner, I've done a LOT of reading on the subject and have never seen an example where 1" of barrel length made 100 fps difference. I have read of 2 different guns with the same barrel length haveing 100 fps difference. There are numerous articles written where people have started with long barrels and gradually cut them off 1" at a time and measure velocity.

The trend I've noticed, regardless of the round, is that the difference in the first few inches is very minimal. Going from 28" down to 22" may only result in 10-15 fps velocity loss for each inch of barrel.

At some point you reach a length where you do suddenly see a large drop off. For example the difference between 22" and 21" may well see 50fps loss. This trend may continue for 2-3 inches then you go back to only 10-15 fps for each inch.

To say that a given cartridge looses a certain velocity loss per inch can be very misleading. Many people will observe the 50 fps of velocity loss between 22" and 21" and assume that trend continues for each and every inch. Others may only observe only 15fps loss between 18" and 19" and assume the same.

The only thing I can assume is that it is not an exact science. And is far less important in the real world of hunting. 200 fps either way is not that big of a deal in a hunting rifle at typical hunting ranges. For the guys target shooting at 1,000 yards, or the guys who want to shoot deer at 600 yards it may matter. But those guys are not asking for advice here.

 

[Ridgerunner665]

I haven't done much reading on it...just my own load development.

And from that, I've seen that much of what I have read is wrong. Mainly due to blanket statements of 35-50 fps.

Short barrel performance is very dependent on case capacity to bore ratio (or over bore if you wanna call it that)...and some rounds have shown to be very fussy with it.


200 fps may or may not be a big deal...depends on the application.

I don't expect to change anybody's mind...I'm just stating what I've seen.

 

[Grey Morel]

Here the main varmints are Coyotes and Muskrats. Neither one are very tasty, or worth anything as pelts. We have ways of dealing with them:

Coyotes: A war of attrition. Application of dynamite to suspected dens in not considered uncalled for.

Muskrats: These cause so much damage to local irrigation, that it not only damages crops, but causes machinery to be lost when portions of undermined fields collapse. The standard method of disposal is to shoot them in the water with a large caliber weapon: this often results is spectacular displays of aerial acrobatics on the part of the muskrat.

So... no I don't personally consider 30-06 to be too much for varmints. It sure is fun to see those muskrats fly.

 

[R.W.Dale]

I haven't done much reading on it...just my own load development.

And from that, I've seen that much of what I have read is wrong. Mainly due to blanket statements of 35-50 fps.

Short barrel performance is very dependent on case capacity to bore ratio (or over bore if you wanna call it that)...and some rounds have shown to be very fussy with it.


200 fps may or may not be a big deal...depends on the application.

I don't expect to change anybody's mind...I'm just stating what I've seen.

JUST TO BACK UP THIS STATEMENT

100g Remington 243 loads I chronographed from a 788 carbine (18.5"IIRC) averaged a mere @ 2674 FPS

 

[Grey Morel]

From what I'm hearing, I think I will probably go with the 30-06. I appreciate everyone's input, and the lively debate.

 

[Ridgerunner665]

Krochus,

I didn't quite get that much speed from my youth model with a 20" barrel...compressed Reloder 19 till it crunched, and I got 2,608 fps.

Those ole 788's have better barrels though...

Edited to add: Same load in a 24 inch barrel chrono'd 3,060 fps.

 

[R.W.Dale]

Krochus,

I didn't quite get that much speed from my youth model with a 20" barrel...compressed Reloder 19 till it crunched, and I got 2,608 fps.

Those ole 788's have better barrels though...

Edited to add: Same load in a 24 inch barrel chrono'd 3,060 fps.

I only had the factory ammo spec to compare to so IMO your tests are a bit more conclusive.

Either way i think what the op should take away from our posts is that a 243 carbine is little more than a really loud 30-30 in terms of power and to a certain extent external ballistics.


while not what it's intended for the below chart reads like a list of best to worst performers in a carbine barrel

 

[Ridgerunner665]

Yep...good post.

That chart says it all for short barrels.

 

[R.W.Dale]

I should also point out that even though I don't have the hard numbers on a 270 carbine by the math it should perform almost as poorly from a short tube as 243

 

[Ridgerunner665]

I haven't worked with a short 270...but I believe you are correct.

I noticed he said he was gonna get a 30-06...he may as well get a 308 because thats all a 20" 30-06 is (a 308 that wastes a lot of powder, with a HUGE muzzle flash)

 

[R.W.Dale]

A quick view of hodgdon's handgun data for 308 vs 30-06 really tells the story of how 308's higher pressure rating and lower expansion ratio really help it edge out the 06 in a carbine barrel. Again see the chart


An easy way to relate to the handicap with a carbine vs rifle 243 (using our figures in any ballistics calculator) is that when using a short barrel you're effectively making every shot you take a 100yds farther away than it really is

 

[Ridgerunner665]

I'm gonna say this just to qualify what I've said here...


I HATE long barrels...I have spent a pretty fair sum of money and time finding what works in shorter barrels. If one were to search back through all my posts they would see that most of my shooting has been with 2 calibers. Believe me, I have no shortage of guns to choose from, yet I do my hunting with either a 308 or a 45-70. There is a reason I ended up with those 2 calibers...

I won't carry a gun with a 24" barrel...and I don't like rounds that give up all their benefits when fired in a short barrel.

I am FAR from an expert on much of anything...but I have put a lot of effort into this, I didn't read it in a magazine or on the internet.

 

[Ridgerunner665]

A quick view of hodgdon's handgun data for 308 vs 30-06 really tells the story of how 308's higher pressure rating and lower expansion ratio really help it edge out the 06 in a carbine barrel

Yep...and Sierra's reloading manual will back that up (compare rifle to handgun...they list those calibers as well)

 

[Ridgerunner665]

I just looked over Hodgdens pistol data...actually the 30-06 and 308 are identical in velocity pretty much across the board (bullet weights).

I don't have the Sierra manual in front of me, but IIRC in Sierra's manual the 308 was slightly ahead of the 30-06.

That doesn't really surprise me though...Sierra is VERY conservative in their load data, Hodgden is not...they will load it right up there.

 

[R.W.Dale]

Right!

From a rifle 30/06 has appx 100 fps on 308 with like weight bullets. Untill you shorten the bbl at which point this advantage disappears. In other words a short barreled 06 is simply a 308 that burns more powder

 

[Maverick223]

From a rifle 30/06 has appx 100 fps on 308 with like weight bullets. Untill you shorten the bbl at which point this advantage disappears. In other words a short barreled 06 is simply a 308 that burns more powder

Yes sir, you guys are on the right track. And this is coming from someone that greatly prefers the .30-06 to the .308Win. in most cases, and like other cartridges (like the .260Rem. and .280Rem.) better than both for the most part. You also have to factor in the fact that the .30-06 generally uses slower powder than the .308, which at least theoretically (or in the Sierra manual) could lead to the .308 being faster.

 

[jmr40]

I've got to disagree that a short barreled 30-06 is only a 308. For one thing that statement is almost true even if both barrels are the same length.

Take a 300 mag, 30-06 and 308 all shooting the same bullet. With equal barrel lengths the 300 will always be the fastest and the 308 will always be the slowest with the '06 in the middle. It does not matter if the barrels are 30" long or 16".

 

[R.W.Dale]

It does not matter if the barrels are 30" long or 16".

but that's just it. It does matter, a great deal in fact.

A 300wm will indeed pick up a greater boost in velocity from a 30" bbl vs 24" than 308 and 30-06 will and on the flip side 308 will lose less velocity from a 16" barrel than 30-06 or 300wm does. According to the numbers at some point around 16" or less the higher pressure more efficient round (308) actually begins to leave the muzzle traveling faster than the 30-06

Look at it this way the higher the bore case capacity is the longer the barrel needs to be to allow time for all that high pressure gas in the chamber to get out that little hole in the end and actually push on the base of the bullet

 

[Maverick223]

but that's just it. It does matter, a great deal in fact.

A 300wm will indeed pick up a greater boost in velocity from a 30" bbl vs 24" than 308 and 30-06 will and on the flip side 308 will lose less velocity from a 16" barrel than 30-06 or 300wm does. According to the numbers at some point around 16" or less the higher pressure more efficient round (308) actually begins to leave the muzzle traveling faster than the 30-06

Look at it this way the higher the bore case capacity is the longer the barrel needs to be to allow time for all that high pressure gas in the chamber to get out that little hole in the end and actually push on the base of the bullet

+1; this is an exaggerated situation, but a .308Win. would almost certainly outclass a .300WM in a sub-12in. bbl (and likely a longer one) due mostly to the powder designed to burn slowly and keep up pressure throughout a relatively lengthy barrel.

 

[Ridgerunner665]

I've got to disagree that a short barreled 30-06 is only a 308. For one thing that statement is almost true even if both barrels are the same length.

Take a 300 mag, 30-06 and 308 all shooting the same bullet. With equal barrel lengths the 300 will always be the fastest and the 308 will always be the slowest with the '06 in the middle. It does not matter if the barrels are 30" long or 16".

With all due respect...you are leaving out one VERY important aspect.

And that aspect is the "time" it takes to burn the powder...the more powder, the more time it takes. And that time is referred to as "barrel time" (the length of time the bullet is in the barrel after firing).

Short barrel, magnum powder charge = powder blown out the muzzle, some still burning...some unburned. (unburned = loss of velocity)

Oh...and a 20 inch 300 Win Mag, can be exceeded by a hot 30-06 load from a 24" barrel.

 

[Grey Morel]

Nice Chart. Could come in handy later.