.280 remington Numbers...

[Dups]

Thought this was more appropriate here... so here's the question.

My Nosler Reloading Manual 6th edition shows my rifles favorite load of 3152 FPS out of a 26" barrel... with that being said, my rifle is a Winchester 70 featherweight with a 22" barrel. assuming the proverbial 20 fps per inch... is 80 FPS difference seem logical in this situation? Here's my load data

WARNING!!!!
MAX LOAD, USE CAUTION!!!
.280 remington
140 grain Nosler Ballistic TIPS and 140 grain Nosler ACCUBONDS
Reloader 19 @ 57 grains !!!MAX LOAD!!!
Rem 9 1/2 LR primer
Remington bulk brass

 

[Dups]

oh, the reason i'm asking is i'm calculating my bullet drop, and a few fps difference makes a pretty large difference at 300+ yds...
Thanks

 

[NM Mountainman]

I'm sure you are aware that velocity typically varies from one barrel to another, even when the barrels are the same length. So the the best we can do is to make an educated guesstimation. If I cut a 26" barrel down to 22", I would expect my velocity loss to be in the range between 90 to 120 fps with a cartridge like the .280.

Over the last 40 years I have heard many rules of thumb about velocity loss per inch of barrel, and I have read at least 8 or 10 test reports where a barrel was progressively shortened to measure the velocity loss. 20 fps per inch overall seems a bit optimistic. Reducing barrel length from 26" to 24" might result in a loss of 40 to 50 fps. Reducing the length from 24" to 22" could typically result in a 50 to 60 fps loss. So I think a predicted loss of 100 fps for the shorter barrel is reasonable.

Thus it seems reasonable to guess that the velocity of the test barrel used in the loading manual might be around 3050 fps if that particular barrel were shortened to 22".

But your barrel could easily vary by plus or minus 50 to 60 fps from another barrel of the same length, brand, and rifling twist. So my guess is that it is reasonable to expect the velocity to be somewhere between 3000 fps and 3100 fps from a 22 inch barrel.

The trajectory of the bullet at 3000 fps will be quite close to the trajectory at 3100 fps. So entering a velocity value of 3050 into your ballistic calculator would seem to be a reasonable starting place.

But this is all hand waving, smoke and mirrors guesswork. Even if you knew the actual velocity in your rifle, the calculated trajectory could easily vary by an inch or more from the true trajectory at 200 yds. Using our guesses about the velocity in your rifle could easily result in a 1 to 2 inch difference at 200 yds between the calculated trajectory and the true trajectory.

The calculated trajectory will give you a fairly close prediction of your true trajectory in your rifle. In order to get a true picture of what is happening with your rifle, you will need to chronograph the velocity in your rifle and confirm the calculated trajectory by test firing at different ranges (100, 200, 300 yd, for example)

 

[Dups]

THAT was an awesome answer. Thanks!!! Glad you spoke in on this. I just dug my chrony out of the dust, and loaded 40 rounds tonight for my .280. time to shoot stuff

 

[NM Mountainman]

When I was hand loading for the .280 Remington about 20 years ago, the manuals I used showed maximum loads for 140 gr bullets at velocities from 2950 to 3000 fps from 24 inch barrels. Most factory loads produced velocities of around 2950 fps with 140 gr bullets from 22 inch barrels, but it wasn't uncommon for some shooters to obtain velocities around 2900 fps with 140 gr bullets from 22 inch barrels. Many shooters who shot 140 gr factory loads in their 7 mm Rem Mag. rifles with 24 inch barrels obtained velocities in the neighborhood of 3050 fps to 3100 fps.

If your .280 loads yield chronographed velocities near 3050 fps from a 22 inch barrel, then that load is probably pretty well maxed out for the .280.

 

[Ridgerunner665]

My $$$ says the 280 will lose more like around 50-80 fps per inch when you get below 24 inches...I have a 280 with a 24 inch barrel, but nothing shorter to compare it to.

That said, you've got a decently large case stuffed with pretty slow powder...that usually equals a lot of lost velocity per inch, which gets worse as you get shorter.

 

[Dups]

well thanks for all the input. I"m going to try to chrony the load this weekend. I also loaded up a few batches of 150 grain winchester power points that i had left over from my 7mm mag days... according to load book they should push around 2700 fps... low recoil i'm hoping.

 

[GooseGestapo]

And, with three different lot#'s of RL19, I've never gotten anywhere close to advertised velocities.

With my Rem M7 in 7mm08, I'm getting 2,850fps from a 20" bbl with 48.0gr of RL17. (140gr bullets). I've stuffed it with 51.0gr of RL19 (highly compressed) and only got 2,690fps, with two different lot#s tried.

I know this is something of an apples vs. oranges comparison, but same situation was presented with the RL19 in two different .30/06's with 180gr loads.

Even my .260 has failed to give decent performance with the RL19, but is a stellar performer with RL17 and RL22.
Go figure!

The only way you'll know what YOUR rifle and YOUR ammo is doing is to chronograph it.
Chronograph = "lie detector"..... only they typically work (chronograph).

 

[NOLAEMT]

My imput would be to get a chronograph. they're not too expensive, and they are awfully neat. Plus than you can be sure, it also allows you to find standard deviation etc of your loads, and that can help with long range accuracy.