max effective barrel length for .243?

[CBS]

Ok guys I'm rebarreling my .243 to a faster twist barrel. It's a sako action w/ McMillan hunter stock. The barrel is at the smiths chambered and ready. It's currently 28" but I'd planned on 26" and the Smith asked if he could do some testing to see the affect of 1" of barrel on velocity in a .243. Before he starts cutting away inches I'd like to decide where to stop before it's too late. I'm leaning toward 26" .

Barrel is a Krieger 1/8 and I'm planning to shoot 95-105 vld bullets. powder is tbd, I'm open to suggestions. I've got lots of rl 22 and varget but I think there are some others that are better for this caliber.

I'd like to hear some opinions on barrel length and I'd like to hear the basis for your opinion.

This is a deer/coyote rifle that isn't going backpacking so weight will not be a factor.

 

[johnnyk]

I would leave it at 28". More velocity means flatter trajectory, and that's always a good thing, especially with those heavy pills. JohnnyK.

 

[jhibbard24]

what contour? now days i have been leaning towards the shorter, stiffer barrels. less harmonics and vibration. i know that with a shorter barrel one is sacrificing velocity but some cartridges don't gain much, if anything with excessive barrel lengths.

Velocity vs. accuracy ..... there is definitely a fine line there to figure out. personal preference is what is comes down to.

IMHO with the .243 I think you could probably make do with a 23" to 25". with some of the newer powders you should be able to make some good speed outta the 24".

i got a .300 WSM with a 23" barrel and got the berger 190 vlds running at 3050 fps. RL-17 powder and shooting .248 3 shot groups.

 

[gebhardt02]

I have two .243 Win rifles with Bartlein barrels, both 8 twist. Rifle 1 with Lapua brass, BR-2 primer, H4350, and Berger 105 VLDs is getting 3030 fps from a 22" barrel measured from the front of the lug. The other is 21" from the front of the lug and is running the 105 AMAX with similar powder charge. Haven't chrono'd this load yet but I expect it to be around 3K also. Rifle 1 has slight pressure sign in high temps, no problems with temps less than 70. I'm going to back down the powder charge by .2 grain and see how accuracy and velocity are affected, but again don't expect much change. The 243 is fine with a 22" barrel. Longer than that will get you higher velocity though if you need it.

Geb

 

[jhibbard24]

Good input Geb.

If the need is there for higher velocities is the issue, a guy could always bump out to .243 Ackley

 

[MarcS]

I've been running .243's in my tac rifle match guns for years and burned out more barrels than I can count. Mostly Bartleins with some Kriegers too. I've always built mine with a 7.5 twist and shot only 115 DTAC's. They've all been 26" MTU contours and velocities run around 3K. I could get more out of them but I don't step on them too hard so my brass will last longer. My load was usually Lapua brass, either CCI BR2's or Fed 210 M's, and H4350 powder. Some of my customers ran 4831 short cut and had good results with it too.

Those were heavy rifles for tactical/practical style competition so probably not a good way to go for a hunting rifle. I would recommend you have your smith call you and tell you what he gets for velocity loss after every inch. I bet you don't see a whole lot of difference down to 25" and I would stop him at 24". I would think you could get a 105 Berger close to 3100 fps from a 24 and it would be a little nicer in the field than a 27.

As a side note, barrel length is measured by the actual barrel itself as it lays on a table. Not from lugs or anything else, just the actual barrel. Depending on the receiver manufacturer and the lug thickness there's usually about one inch of barrel from the front of the lug going back into the receiver.

 

[CBS]

thanks for the responses guys. i'm feeling more comfortable about having this coversation on this forum considering the quality of the responses thus far. this barrel is MTU contour. not really what i'd prefer for this rifle but the barrel channel in the stock was already widened by the previous owner for a similar sized barrel (1-14 twist).

i'd like to get a little more specific about your experiences with the .243. while longer barrels produce more velocity and everyone likes to use the 50fps/inch rule of thumb that i think is very vague and rarely true. i've seen experiments where guys cut an inch at a time off of a .223 to test velocity loss per inch and i was surprised at the relatively small amount of velocity loss per inch. (if i remember right the largest velocity loss per inch was 33fps.) i'd like some estimate from some of you as to how much velocity is actually given up by cutting a .243 barrel down based on the barrels that you've had experience with. i.e., the velocity loss from 30" to 25" is going to be less significant than from 25" to 20". but it would take some significant testing or experience to say just how much the velocity loss would be. granted this may be affected by the powder that you're using.

at first i was leaning toward a 27-28" barrel but i'm not shooting an RUM case that benefits significantly from the extra length. i'm willing to consider a significanty shorter barrel if i can generate anywhere close to the same velocity. i have no problem "hot rodding" this barrel and don't care about barrel life. this barrel will be threaded for the future addition of a can if that itch persists and i really don't hate the idea of a shorter barrel if i'm going to have a can because 28" + can will look like i'm heading for a jousting match.

 

[jhibbard24]

go for it ..... the shorter barrel that is. work with you smith and log all data and records of velocities and loads and let us know.

like you said, there is no set rule of thumb for exact velocity loss per inch of barrel lost. it is all determined by that cartridge and how efficient of a design it is. I bet you would be happy with a 23"

hell, look at the .308s out there with 20" barrels that shoot bugholes and are at the average speeds for that round

 

[MarcS]

What he said ^^^^^

If it's an MTU and you think there's ever a slight chance of a suppressor being used, I'd keep it at 22" to 23".

I just built a .243 with a Bartlein MTU for a customer that insisted on it being cut to 20" with a Badger FTE brake. It's his coyote hunting rifle in Nevada. It went into a KRG Whiskey 3 chassis and that little rifle is surprisingly quick and handy for such a truck axle tube. It's shooting in the .1's and .2's very consistently with 115 DTAC's but I don't know what his velocity is. I'll ask him and get back to you on it.

 

[Cruizin]

I've been running .243's in my tac rifle match guns for years and burned out more barrels than I can count. Mostly Bartleins with some Kriegers too. I've always built mine with a 7.5 twist and shot only 115 DTAC's. They've all been 26" MTU contours and velocities run around 3K. I could get more out of them but I don't step on them too hard so my brass will last longer. My load was usually Lapua brass, either CCI BR2's or Fed 210 M's, and H4350 powder. Some of my customers ran 4831 short cut and had good results with it too.

Those were heavy rifles for tactical/practical style competition so probably not a good way to go for a hunting rifle. I would recommend you have your smith call you and tell you what he gets for velocity loss after every inch. I bet you don't see a whole lot of difference down to 25" and I would stop him at 24". I would think you could get a 105 Berger close to 3100 fps from a 24 and it would be a little nicer in the field than a 27.

As a side note, barrel length is measured by the actual barrel itself as it lays on a table. Not from lugs or anything else, just the actual barrel. Depending on the receiver manufacturer and the lug thickness there's usually about one inch of barrel from the front of the lug going back into the receiver.

Hey Marc... can I ask how many grains of H4350 you are running on that first 243?

 

[MarcS]

Yes I shot it in several different barrels almost always the same. With a 115 grain BN coated DTAC I used between 42 and 42.6 grains of H4350. As I remember it would have been about a grain and a half less using the same bullet without the BN coating.

Marc