.243 velocity

[Steve123]

Hi all, just put some Hornady 58g vmax Superformance rounds through my 20 inch barrel Sako, the packet says 3900 plus fps and my crono read 3542fps and 3545fps for two consecutive shots. Just wondered what peoples thoughts are . on the face of it nearly 400 fps loss. In the Nosler reload guide it shows a 24 inch barrel with 55g bullets doing 3800 approx. I was expecting around 20fps per inch loss not 100fps. Unless Hornady over inflate their figures.
Is that velocity drop normal or would I be better off reloading with a faster burning powder. I have RL15 and Viht N140 in stock.
Thanks in advance for any advice.

 

[PEA]

They test in a 24” barrel so that will be where some of the FPS has gone

 

[Steve123]

Yes I guessed that, but its the amount that surprised me.

 

[PEA]

Maybe inflated figures just like VW

 

[ejg]

I always understood Sako barrels are a bit slow. Some say Blaser are even slower. (makes barrels last longer)
The 20" 243 T3 I had was very slow with a few factory ammo types I tried. Then again my 20" CTR in 308 was very close to factory box claims of Hornady Match 168bthp.

edi

 

[Freeforester]

Anyone ever found their velocity exceeded the somewhat optimistic 'packet speeds'?

Thank goodness deer don't use chronographs for incoming!

 

[Dan Newcombe]

My .260 with federal 120gn is only about 40fps slower than at says on the packet.

22 inches from the end of the barrel to the front of the action so it seems a pretty quick barrel.

 

[User00044]

Anyone ever found their velocity exceeded the somewhat optimistic 'packet speeds'?

Thank goodness deer don't use chronographs for incoming!

Yes , a recent batch of 17hmr ammo was doing 2650 fps over the chronograph , box claimed 2550 fps. This was the exception to the rule ,though , I've never seen this in any centre fire ammo and that includes 58 grain Vmax.

 

[Sonicdmb73]

Don’t forget to allow for the accuracy of your chronograph. You could “lose” some of your speed there.

 

[Steve123]

good point, I didn't think of that.

 

[JH83]

The only factory ammo I found to be on the nose for velocity was sako factory in 6.5x55, albeit through my 26” barrel. I chronographed some hornardy super performance and it was 150fps slower than advertised which made sense as I got a lot of runners, again that’s through a long barrel!

I’m now on hand loads

 

[Doric]

Hi all, just put some Hornady 58g vmax Superformance rounds through my 20 inch barrel Sako, the packet says 3900 plus fps and my crono read 3542fps and 3545fps for two consecutive shots. Just wondered what peoples thoughts are . on the face of it nearly 400 fps loss. In the Nosler reload guide it shows a 24 inch barrel with 55g bullets doing 3800 approx. I was expecting around 20fps per inch loss not 100fps. Unless Hornady over inflate their figures.
Is that velocity drop normal or would I be better off reloading with a faster burning powder. I have RL15 and Viht N140 in stock.
Thanks in advance for any advice.

I am led to believe that 243 win velocities are effected quite a bit on shorter barrels compared to some other common calibres.

 

[Sonicdmb73]

Hi all, just put some Hornady 58g vmax Superformance rounds through my 20 inch barrel Sako, the packet says 3900 plus fps and my crono read 3542fps and 3545fps for two consecutive shots. Just wondered what peoples thoughts are . on the face of it nearly 400 fps loss. In the Nosler reload guide it shows a 24 inch barrel with 55g bullets doing 3800 approx. I was expecting around 20fps per inch loss not 100fps. Unless Hornady over inflate their figures.
Is that velocity drop normal or would I be better off reloading with a faster burning powder. I have RL15 and Viht N140 in stock.
Thanks in advance for any advice.

I am led to believe that 243 win velocities are effected quite a bit on shorter barrels compared to some other common calibres.

First most box figures are optimistic for a standard rifle. They are shot in test barrels usually longer than the most common maker’s ones. So the test barrel is possibly 26” and many modern 243’s are 20” or 22”.
If you home load you can get a bit more speed by choosing a powder to suit your rifle rather than the average.

 

[Sinistral]

I am led to believe that 243 win velocities are affected quite a bit with shorter barrels compared to some other common calibres.

Fixed that for free…. a didact is worse than a pedant, but my conscience is clear.

I thought I'd look into this theory in a non-confrontational frame of mind. Obviously if it's true then it follows that there must be .243 rifles with 20" barrels which don't make the legal 1700 fpe threshold. My sums say that's an 80gr @ 3100 fps, or a 100gr @ 2775 fps.

With its low expansion ratio this calibre works best with slow-burn powders which aren't designed for short barrels.
If you switch to a faster powder then pressure becomes a worry.

Manuals do vary, but it's instructive to look at those put out by the bullet-makers rather than the powder manufacturers. Until recently Speer used off-the-shelf sporting rifles, and tested all powder makes & types with their own bullets. In their #13 Manual they used a Ruger M77 in the 22" barrel length common to the .243 in the U.S.

Only the very slow powders - H4350, AA 3100, IMR 7828 - made 2775 fps with the Speer 100gr.

The slow powders - Vit N160, Reloder 22, and Reloder 19 - were just under at 2720 - 2740 fps.

The medium-slow powders - IMR 4831, AA 2700, IMR 4350, IMR 4320 - were all 100 fps shy.

The latest #14 Speer Manual uses pressure barrels, and all the loads above have been reduced.

Can somebody explain how using a faster powder which doesn't make the minimum in a 22" barrel will make it in a 20" ?

 

[Alantoo]

Hi all, just put some Hornady 58g vmax Superformance rounds through my 20 inch barrel Sako, the packet says 3900 plus fps and my crono read 3542fps and 3545fps for two consecutive shots. Just wondered what peoples thoughts are . on the face of it nearly 400 fps loss. In the Nosler reload guide it shows a 24 inch barrel with 55g bullets doing 3800 approx. I was expecting around 20fps per inch loss not 100fps. Unless Hornady over inflate their figures.
Is that velocity drop normal or would I be better off reloading with a faster burning powder. I have RL15 and Viht N140 in stock.
Thanks in advance for any advice.

Most important I would think is whether they shoot well in your barrel? Is the trajectory and energy at 3540fps actually a problem for you? Or you are just feeling a bit shortchanged?

Have a look at some ballistic tables and see if the 400fps makes a significant difference to the drop at the ranges you will be shooting? If you are range finding and dialling in, does it make much odds if after going through the process you just have to add an extra click or two...if it does then yes do some reloading experiments.



Alan

 

[Lateral]

The only factory ammo I found to be on the nose for velocity was sako factory in 6.5x55, albeit through my 26” barrel. I chronographed some hornardy super performance and it was 150fps slower than advertised which made sense as I got a lot of runners, again that’s through a long barrel!

I’m now on hand loads

Are you suggesting that a 150fps velocity reduction, was responsible for lots of runners ?

 

[NP435]

Yes I guessed that, but its the amount that surprised me.

The rule of thumb is 50fps per inch less barrel and unless you have a chronograph its guessing. The published manuals have tighter than saami spec barrels too. I tried to achieve 4400 fps with a 36 grn Barnes Varmint grenade in my CZ22-250 and I hit 3850 and that was it. My barrel was fairly well used at that point and had loaded the max charge shown in there manual number 4. I gave up and enjoyed shooting with the results I had. It is common for factory loads to not do what the box lists, be happy when they come close. Before handloading for all my needs the deer and pronghorn died just fine when I placed the shot with whatever factory ammo i had at the time.

 

[JH83]

Are you suggesting that a 150fps velocity reduction, was responsible for lots of runners ?

Yes. 150fps down on an an already fairly crap advertised velocity=poor performance. We also chronographed some 120gn Norma stuff and it was also terrible, 120gn doing 2550fps, barely 243 power. Read the terminal ballistics piece on 6.5x55 and you get the gist. It seems to be a hand loaders calibre only imo.

 

[User00035]

I chronoed 58 grn Superformance in my 24" Sako 75 and I was averaging a whisker under 3800 fps. few years ago though. I assume the ammo hasn't changed in the meantime.

 

[sako85708]

I always understood Sako barrels are a bit slow. Some say Blaser are even slower. (makes barrels last longer)
The 20" 243 T3 I had was very slow with a few factory ammo types I tried. Then again my 20" CTR in 308 was very close to factory box claims of Hornady Match 168bthp.

edi

How are barrels made faster or slower ?? I load my sako 22 250 to 3600fps and no fox has told me its too slow, but I load for accuracy not speed and I hope longer barrel life.