243 or 270 for short barrels?

[Grey Morel]

I'm researching the performance of various calibers in short barrels for use in a dual application.

Since this gun will pull double duty as short to medium range varmint gun, as well as a brush gun, I'm focusing on high muzzle velocity and flat trajectories rather than muzzle energy.

My research indicates that the 243 and 270 are the two best contenders for highest velocity in a short barrel among the common hunting cartridges.

The dilemma reveals itself when you take into account different bullet weights: the 270 is the clear winner when using bullets from its lighter end (100-100gr), but the 243 is the best overall contender, maintaining high velocities across its entire range of projectile weights.

The 30 calibers are out; even though they may have more energy, they also have as much as 50% more drop at longer ranges when fired from a short barrel.

So what do you think? Should I go 270 and get the best possible performance, or should I go with 243 and take advantage of more bullet options?

 

[dakotasin]

why do you need velocity and flat trajectory in a brush/med range gun?

between a 243 and 270 for hunting purposes i would take a 270 every time.

 

[floridabou3]

hunting i would take the 243 myself own 2 of them a 7400 and a rem 700 and i love both of them and if im hunting in brush area's take a 30-30. also they say 270 will not shoot hole for hole after the 2 or 3rd shot it gets 2 hot. im sure someone on here that knows more about it can explain it to you better.

 

[Abel]

Varmints/deer under 200 yards ='s 30-30!

 

[Arkansas Paul]

also they say 270 will not shoot hole for hole after the 2 or 3rd shot it gets 2 hot.

I don't see that happening. I don't see how a .270 could be any hotter than any other round with the same powder charge and bullet weight.
I think the OP is trying to have a combination that's hard to get. When you're talking about a varmint round and a brush gun, there's just a lot of room in the middle there. Both calibers you mentioned are great, but the .243 certainly doesn't qualify as a brush gun. Of the two mentioned, I'd go with the .270. You can get round nose soft points for it that are what you want in the brush.

Just one fellers opinion

 

[R.W.Dale]

My research indicates that the 243 and 270 are the two best contenders for highest velocity in a short barrel among the common hunting cartridges.

What gives you this impression?

243 in particular from a carbine is one of the worst possible rifle/caliber combination's. Taking a MASSIVE hit in performance from bbls under 24"

http://www.thehighroad.org/showthread.php?t=510646

If you can wade through the parts where the 243 fanatics call me everything but a THR member for daring to question their cartridges precieved superiority you'll find some very valuable information about just how 243 is put in a straight jacket when fired from a short bbl.

The 30 calibers are out; even though they may have more energy, they also have as much as 50% more drop at longer ranges when fired from a short barrel.

I don't know where you get your info for comparison but it doesn't seem to be grounded in reality. The more overbore 243 and 270 you mention will both take huge hits in the FPS dpt from a carbine compared to the larger bore, higher expansion ratio 30 caliber cartridges

Please elaborate

How short a bbl

and what do you consider long range

 

[jmr40]

Read this

http://www.tacticaloperations.com/SWATbarrel/

If you want a shorter barrel there are plenty of options. I haven't seen any data on the 243, but would think it would benefit from a longer barrel more than most.

I don't have a link to the data results, but recently read of a gunwriter who took a 27" barreled 270 and cut 1" off the barrel at a time and measured velocity loss at each increment until he got to 21". There was a total of 114fps velocity loss. TOTAL.

If you want a shorter barreled gun for hunting the 270 should do just fine, but so would a 308, 30-06 or most anything else.

The guys who want to push cartridges to the limits and shoot at extreme long range need every little bit of advantage they can get. In their case 6-8" more barrel may make a difference. But in a hunting rifle 2"-4" is not worth worrying about.

 

[Grey Morel]

Take it easy Krochus! I am not an expert, and claim no such knowledge.

I based my research on generic formulas for velocity reduction per inch, of hot factory loads with a common test barrel length (24").

IE: 2500-3000fps = 20fps per inch, or 3000-3500fps = 30fps per inch.

I realize that these formulas are simply estimates for a wide range of cartridges. That's all I was aiming at was a rough estimate of velocity loss from an 18" barrel.

Additionally, this is not a deer rifle, so don't think of "brush rifle" in that sort of application. I consider "long range" to be 400 yards.

 

[bpl]

I think that both .243 and .270 are poor choices for a short barreled rifle. Both depend on high velocity for effectiveness, which in turn depends on adequate barrel length. You'd be better off with 7mm-08 or .308, they do better in a short barrel.

http://www.chuckhawks.com/rifle_barrel.htm

 

[bpl]

Additionally, this is not a deer rifle, so don't think of "brush rifle" in that sort of application.

Sorry, didn't catch this part. What will you be hunting with your "brush rifle", varmints and predators only?

 

[Maverick223]

I think that both .243 and .270 are poor choices for a short barreled rifle. Both depend on high velocity for effectiveness, which in turn depends on adequate barrel length. You'd be better off with 7mm-08 or .308, they do better in a short barrel.

Agreed, particularly WRT the 7mm-08. Plenty of energy to kill shrubs and those pesky brush monsters as well as maintaining a fairly flat trajectory for varmints.

 

[don]

Pardon my ignorance, but wouldn't the velocity loss also be a function of the powder used? I mean that wouldn't a .270 or a .243 loaded with a faster burning powder loose less velocity when shot from a short barrel than a slow burning powder?

 

[Maverick223]

Pardon my ignorance, but wouldn't the velocity loss also be a function of the powder used?

Sure, but the biggest factor is the case to bore relationship. The larger the case capacity and smaller the bore diameter, the longer the barrel required for efficiency. The inverse being true, a relatively large caliber with a moderately sized case would afford the best performance in short barrel lengths.

 

[don]

Thanks Maverick. What you say makes sense. Just as an academic experiment, It would be interesting to compare the loss rates between say, H4831 and IMR4895 all other factors being held equal.

 

[husker]

I know im A BROKEN RECORD
but a few years back Rem made this rifle called the MOHAWK 600 & they made it in many cals. EVEN 243 & as matter of fact.i think the 243 version sold the most. i dnt call them a brush gun. But my dad did.
i call it a WALKING RIFLE
he had 2 for many years but sold the 243 when he quit hunting deer. the other 1 i still have & EVERY 1 on the THR knows it. & i came DAM close to buying a 600 in 243 when i first joined this great site.
but it just wasn't DADS!!!

 

[Maverick223]

Thanks Maverick. What you say makes sense. Just as an academic experiment, It would be interesting to compare the loss rates between say, H4831 and IMR4895 all other factors being held equal.

Glad to be of some assistance. There is a good bit of difference in the burn rate for those two powders. I would hazard to guess that there would be a good bit better burn for the 4895, but the velocity would still be reduced a bit. Heavier projectiles would also result in a small increase in efficiency.

 

[pikid89]

i dont like short barrels but to answer your question straight up...i think the 243 would be better suited to a short barrel for its faster burn rather than the 270....

i came across the same debate in regards to the ruger international (18.5" bbl) in 308 or 30/06 and the 308 seemed to be the better choice because the 3006 had a slower powder=less velocity+more fireball

 

[Slamfire]

I don't remember the barrel length, whether it was 20" or 22" in my 243 M70 featherweight, but I do recall I was not impressed with 2830 fps with a 100 grain bullet.



243 M70 Featherweight Classic



100 grain BT Spire Point Hornady Factory Ammo
26 Jun 01 T=84° F

Ave Vel = 2830
Std Dev = 17
ES = 79
Low = 2803
High = 2882
N = 18

 

[kludge]

6.5x55, .7mm-08, .260 Rem.

No lack of good bullets, velocity, flat trajectory or energy, out to 300 yards and perhaps more for varmint up to deer. All would work fine with a shorter barrel.

 

[Ridgerunner665]

The 308 Winchester is best suited to the OP's task...

 

[R.W.Dale]

The 308 Winchester is best suited to the OP's task...

A agree and the cartridges the OP mentions are some of the least suitable to the task he outlines.

With regard to 270 and 243 they both suffer from the same problem small/medium bore belted magnums do in that they take a long bbl to reach their full potential.

 

[Grey Morel]

I think that both .243 and .270 are poor choices for a short barreled rifle. Both depend on high velocity for effectiveness, which in turn depends on adequate barrel length. You'd be better off with 7mm-08 or .308, they do better in a short barrel.

http://www.chuckhawks.com/rifle_barrel.htm

Funny you bring that up. HIS formulas were the ones that I used to calculate velocity loss.

I suppose I could warm up to a 30-06 for ammo commonality reasons. Would that be a better performer?

 

[Ridgerunner665]

No it wouldn't...a short barreled 30-06 is nothing more than a 308 that wastes a lot of powder.

There a chosen few rounds that do well in shorter barrels...and the 308 is at the top of the heap (the rest being the 30-30, 35 Rem and such)

In order to get the good out of a short barrel...you need a round with a small case capacity No long action caliber meets that requirement.

The problem with the 243 is a tad different...it would seem to have a small case capacity, but it only seems that way. For those small 6mm bullets...it has a rather large case capacity...so you're right back to square 1.

Short barrel requirements (medium bore, medium capacity rounds)

The 243 will lose 100 fps per inch below 22 inches (with 100 grain bullets)...I know, i have a 20" 243.

The next best thing to the 308 I believe would be a 257 Roberts...it would lose a lot, but not as much as a 243.

 

[PedalBiker]

The Hodgdon annual reloading manual has a lot of reloading data for rifle cartridges in 14" barrel handguns. The exact same load data is shown in the rifle section for 24" barrels. That can give you a good feel for short barrel performance.

The 243 and 270 are in both sections. Check it out, slow powders don't take the hit I expected they would.

 

[Abel]

Believe it or not, you're right back to the 30-30! In an 18.5"-20" barrel, its efficient. Consider the Ruger Compact in 6.8mmSPC.