Home Forums Reloading Reloading Software Difference in velocity of 22" vs 24" barrel?

Have a Hornady 7th edition reload manual (older) and it lists loads for the 243 Winchester in 24" barrels. What is the velocity difference between a 22' and the 24" approx? Seems have read a while back the difference, but cannot remember. Don't have a chronograph so need some help. Bullet in question is the Hornady 100 gr. BTSP # 2453 using H4350. Thanks.

20-30 fps per inch
A good read for you, but I would suggest popping a hundred bucks or so for a chronograph, otherwise you’re just guessing.

https://rifleshooter.com/2016/04/243-winchester-effect-of-barrel-length-on-velocity/

If you are reloading and don't have a Chronograph (the cost of 3 boxs of bullets) why are you worried about the speed of your rifle?

Well, if you look in the book and see the loads for a round and the min. and max recommended and the listed speed for the loads, they are taken with a 24" barrel. When I load up rounds according to what is listed I never know my true velocity, or close to it, until i go to comparing trajectory out to like 300 yds as compared to my sight in at 100 yds, then I can get an estimate as to velocity. Using JBM Ballistic table I know most of the data except velocity, which I will now have a better idea as to what a 22" barrel will be as compared to a 24". Post above by Swifty said 20-30 fbs per inch, which probably is about right. Anyway, gives me a figure to work off of when looking at book figures. Thanks for the reply.

If you're starting with a known velocity and cutting THAT barrel, 20-30 fps for each inch you cut. If you're working with 2 different barrels there is no way to know until you shoot them. The rifle with the 22" barrel could be 50 fps faster than the one with the 24" barrel. Or the 24" barrel could be 150 fps faster than the 22" barrel. Or they could be the same.

My 20" Tikka CTR is the fastest 308 I own, shooting loads 25-30 fps faster than the two with 22" barrels. It isn't unusual to see differences of over 100 fps between barrels the same length. My 22" Winchester 30-06 is always 60-90 fps faster than my 22" Remington 30-06. It varies depending on the exact load.

There are fast barrels and slow barrels.I once did a test on four 7mags shooting the same 160gr load.One must also keep in mind,just because it's the same load,the amount of freebore has an affect on velocity too.At the time I wasn't looking for a load that was specifically tailored for each rifle,I was looking for a load that shot really well in all four.First rifle was a Ruger 1V with a 24" barrel,velocity ran 2960fps.Next was a 26" barrel Remington 700 Sendero,velocity ran 3000fps.Next was a Remington 700 with a 24" Douglas barrel,velocity ran 3050fps.The last rifle was a Ruger 1B with a 26" barrel,velocity ran 3100fps.So that was quite a spread even with same length barrels.Without a chronograph there is no way of knowing what your velocity is.You can't go by how it kicks either.A faster burning powder can sometimes give you a lot less felt recoil,but a much higher velocity.I've even had some of the slower burning powders,using the same charge weight,giving a big difference in felt recoil and velocity.The one that had the highest felt recoil ended up with the lowest velocity.

So how did handloaders get their velocities before the advent of cheap home chronographs?
Well back in the 70’s and 80’s you would zero the rifle @ 100, then take it out to 200 using the same bullseye aim point without adjusting and see how much it dropped, then out to 300 and repeat. By looking at ballistic charts for say Hornady and Nosler which they had in the back of the manual and see what your drops are at those distances compared to calculated. Crude yes, but it can get you close. It’s a fact that as tech advanced, we got more exacting and spoiled to where we forget a lot of the basics that were used before the advent of cheap chronys and ballistic software running on that portable phone.

Swifty, that exactly the way I have been doing it for years...and it seems to work for me. Mostly why never bought a chrony and probably never will. With a little studying of ballistics in manuals you can figure out a load for your gun pretty quick and know what will work and what wont. Save lot of money buying different powders, latest bullets, even the latest and greatest 6.5 Creedmoor. Thanks again for your knowledge on this.

Does it really save you a lot of money? If you have to shoot several rounds at three different distances to estimate your velocity, then I'd think you'd be shooting significantly more rounds and therefore using up significantly more powder, bullets, and primers. Don't kid yourself—that adds up quickly.

No it doesn’t, but if I have a load for say 25.06, 117 gr. bullet that I chronograph @3000. Therefore 2” high at 100 will give me dead on at 200 and 7” drop at 300 theoretically. The proof is in the pudding at those distances by shooting to confirm the drops.
Now if I don’t have a chronograph and the book says 3000 fps for that charge, caliber and bullet, I zero at 100 and the bullet drops 3” at the 200 and 9” at the 300 then I am not getting 3000 more like 2900- 2950. So you are just basically working backwards by using known drops at distance to determine velocity rather than confirming drops at distance with a known velocity. As I said it’s crude but works

Other assumptions in that method are the accuracy of the BC value and the line of sight above bore height.

Heck even worse than those is the assumption that the 100 yd zero is really zeroed. Seems to me most of the guys doing stuff like this are shooting 3 shots at best (and sometimes just one) to "zero", not wanting to consider how randomly distributed those impacts may be, or how much that affects the results down range.

Mathman did bring up some valid points but it also brings up the fact that if you used the ballistic charts in the Hornady and Nosler books from the 80’s and 90’s that these manufacturers didn’t know sh*t about what their BC was nor the line of sight above the bore for deriving said charts was all a bunch of horsesh*t. To which I may tend to agree at times which is why I always confirm drops even with a known velocity and when using Sierra infinity drop calculation.

Now the real assumption that is a bunch of Sh*t is that I don’t know how or when my rifle is zeroed and that I make that determination on just 3 shot groups or just a plain 3 shots and call it good. Unless you have been to the range and witnessed my zeroing you haven’t got a clue which you don’t since I know for a fact you have never been there.