Barrel length and powder

[Revilo]

Caliber is 243 Win. With powder and bullet shortages, let’s assume all I have is Ramshot Hunter powder and Nosler Accubond 90 grain tipped boat tail bullets. All load data seems to be for 1:10 twist in a 24-inch barrel.
my Model 70 is also 1:10 but only has a 22-inch barrel. Question: Given this moderate to slow powder, am I likely to find the “sweet spot” closer to the “starting load” or towards the “max load?”

 

[Jim Watson]

Sorry, that is unpredictable, you are going to have to shoot the gun.

 

[greyling22]

As a rule of thumb, I typically find my most accurate load more toward the starting, rather than max loads.

Heck, I found an accuracy node 15% below the starting load on a 308.

 

[Seedy Character]

The answer is MAYBE

 

[Revilo]

I suppose the real question is whether a barrel length 2” shorter (22”) than the load data test barrel (24”) measurably affect the loads? I did read an opinion that one should use faster powders on shorter barrels but nothing on powder volume.

 

[Jim Watson]

To quote a usually reliable source (me) 2" difference in barrel length is unpredictable and probably unmeasurable. You might have a "fast" 22 inch and a "slow" 24 inch.
That opinion is wrong.
Powder volume is good, high case fill to keep the charge from slopping around is usually beneficial, we are a long way from a light load of Hi Vel No.2 being a top performer.

 

[CoalCrackerAl]

2 inches won't matter. Work up your loads in steps until you find the sweet spot.

 

[243winxb]

The Hunter powder is double based. Best with a magnum primer & near maximum loads, should be more accurate? This is going by the "book"

Real world can be different. My 18.5 bbl doesnt like long 88, 90, 100 gr bullets. The 27.5" does better up to 90 gr Berger match hpbt. Both 10 twist. Velocity & RPMs make a difference.

 

[GeoDudeFlorida]

I suppose the real question is whether a barrel length 2” shorter (22”) than the load data test barrel (24”) measurably affect the loads? I did read an opinion that one should use faster powders on shorter barrels but nothing on powder volume.

Rate of twist makes a far bigger difference than a few grains of powder or an inch or two of barrel. If you're really, really worried about running out of something, use different components for which you have plenty. That's why loading manuals and testing data is for a multitude of choices. Otherwise, start at the beginning and work for a happy ending.

 

[Charlie98]

2" prolly doesn't make any difference... Hunter is as slow as IMR/H4350... I'd just load it until you found an acceptable accuracy node. Now, if you were going from 24" to 16"... then we might talk about powder efficiency. I have that exact issue in .308... a 24" bolt gun, and a 16" autoloader. I use 2 different powders not only because of the barrel length, but the bullet weight as well.

 

[JimKirk]

I have found accuracy nodes near beginning loads .....in the middle .....and most often near or at maximum.

You can take this to the bank ....what ever powder that gives you the most velocity in a 24" barrel ....with a bullet will also give the most velocity in a 20" barrel with the same bullet.... Your chronograph will prove that ....

Hunter is a great powder and will work well at full loads .....

Just for information ....my current .25/06 22" is faster than my previous .25/06 with a 24"...

 

[Charlie98]

You can take this to the bank ....what ever powder that gives you the most velocity in a 24" barrel ....with a bullet will also give the most velocity in a 20" barrel with the same bullet.... Your chronograph will prove that ....

I've read that statement a few times over the years, and to be honest, I don't believe it. I also don't like absolute statements, because there is almost always a caveat somewhere. I think that statement is generally true... but not always. I think I might have to investigate further...

 

[GeoDudeFlorida]

I've read that statement a few times over the years, and to be honest, I don't believe it. I also don't like absolute statements, because there is almost always a caveat somewhere. I think that statement is generally true... but not always. I think I might have to investigate further...

Well, like all hard and fast rules, it's all conditional. The one true fact of life is every rule has an exception.

Kind of an interesting case study if you have the parts: compare a Super 14 .35Remington to a Marlin 336 .35Remington with the same powder and bullet. There are some combinations of powder/bullet for which the Super 14 gives better velocity and accuracy and vice-versa. The .35Rem is a odd creature in some ways and that there's one of them.

 

[JimKirk]

Well I don't really care if you believe me or not ....why don't you believe your chronograph?

 

[Charlie98]

Well... my experience was with my .348WCF. Typical book load of H4831 in my 20" Browning... sounded like a cannon going off, with muzzle blast to match, with very poor ballistics. A switch to IMR3031... and it was like a completely different cartridge. I don't know... as I said, I'll have to dig around in QuickLoad... and maybe load up some test cartridges. It is an interesting question.

 

[Charlie98]

Well I don't really care if you believe me or not ....why don't you believe your chronograph?

Jim, that wasn't aimed at you personally... this is not the first time I've read that statement. Maybe I'm reading it the wrong way... because I've also heard a slower powder will always give higher velocity vs a faster powder, all else being equal.

 

[JimKirk]

Jim, that wasn't aimed at you personally... this is not the first time I've read that statement. Maybe I'm reading it the wrong way... because I've also heard a slower powder will always give higher velocity vs a faster powder, all else being equal.

Sorry ....

I wish RC Model was still around ...he had much supporting evidence on that statement....

Generally a slower powder will give the most velocity (didn't say accuracy) ... and if it does say in a 24" barrel ....it will also give the highest velocity in a 24" barrel .....

Powder burn normally happens in the first few inches of the barrel regardless of barrel length (talking rifles center fire)...however the high pressure gas has longer to work say on a 24" than say a 20" ....

So the powder that gives the highest velocity in a 24" will also give the highest in a 20" .....the velocity will not be the same because the gasses have less time to work in a 20"

 

[Charlie98]

So the powder that gives the highest velocity in a 24" will also give the highest in a 20"

Re-re-rereading your initial statement, I can see where I got all bent out of shape... and I would tend to agree with that statement... ^^^ I guess I could monkey-wrench with that formula and start changing barrel lengths... but that's not in the spirit of what you are saying.

 

[JimKirk]

Thanks ...

Had a friend that had a .270 Win Savage 22" ....never got it to shoot better than 2" @ 100 yards .... he planned to rebarrel to a .30/06 anyway ....

We cut the by one inch cuts ...did nothing to the crown(except cut as straight as possible and file it flat) as it was going in scrap metal ...

Back then we had a real good supply of powders, bullets and primers ...
We made four different loads with H4831, IMR 4350 and two other faster powders( I forgot those two) ...same brand brass, same bullet(130 grain), same primer(CCI 200)...

We started at 22"

As suspected H4831 gave the fastest velocity ... of the four loads ...
We sawed the barrel to 21" ....again H 4831 gave the highest velocity..
Another cut to 20" ....H4831 was again the highest...

Next we cut to 18" ....and yes H4831 was the fastest again ..

Another cut to 16.5" and yes H4831 was fastest....

We did a final cut splitting the chamber in half length wise ...he wanted to make sure nobody got hands on a trash barrel ...in the scrap it went ...

All this was shot over my Pact Model 1 that tested correct with match .22 LR ammo...

So from that experience the slowest powder gave the highest velocity at each length ....

 

[AJC1]

I think good burn, using the correct primer, barrel tightness and case fill are bigger factors than 2" above 20" barrels. If your worried about accuracy the bullet is your biggest factor bar none.

 

[stillquietvoice]

my Model 70 is also 1:10 but only has a 22-inch barrel. Question: Given this moderate to slow powder, am I likely to find the “sweet spot” closer to the “starting load” or towards the “max load?”

My m11 savage 243 win has a 1:9 twist and a 22" barrel. I primarily shoot 100 gr bullets from it. My best load is 42.1 gr with ramshot hunter, that's a grain below max charge.

The fact is you won't know what is going to work best for, or in your rifle until you work up the loads and shoot them. I get similar accuracy results from h 4350 and prefer it to hunter but it's harder to aquire than hens teeth where I'm at

 

[Revilo]

All great stuff. I’ll load a few soon

 

[jmr40]

You're way overthinking this. IME Ramshot hunter does about the same thing as H4350 and H4350 would be a good choice in 243.

And yes, whatever powder gives you the best velocity from a 26" barrel will yield the best velocity from a 16" barrel. And barrel length simply isn't a factor in making the choice.

Two inches of barrel with most cartridges means 20-50 fps difference in velocity, but only if you start with the same barrel and cut it shorter. Two different barrels of the same length can be 30-130 fps different with ammo from the same box. A 22" barrel COULD be 200 fps slower than another 24" barrel. Or it might be 100 fps faster. Or anywhere in between.

I own 2 rifles in 30-06, both with 22" barrels. The Winchester is always faster by 60-90 fps depending on the exact load. I have a friend with another 22" barreled 30-06 and his rifle is always 130 fps slower than mine.

I have multiple 308's with barrels ranging between 18" to 22". The fastest is the one with a 20" barrel. It outshoots one the 22" guns by about 30-40 fps. And the other 22" gun by 50-60 fps.

 

[length_of_pull_1]

I would start at 42.0 gr and work up. Nosler lists their mid range load at 83% case fill for that bullet and powder combo. Only 87% case fill at max charge according to their data. I would be quite surprised to find your accuracy node in the lighter loads. Just my thoughts.