....Hi today I was chronographing some 458 stuff and came on something that suprised me .. My 19 1/2 " barreled 458 win mag got 2076 fps avg for 3 shots with the 450 gr Swift A-Frame Remington factory load and my 25 " barreled CZ 550 in 458 Lott got 2087 fps avg vel with the same ammo..In the win mag that is 75 fps slower than it says on the box ,, but I would think 5 1/2 " of barrel would make more of a difference in velocity .................. The Lott gave 2260 fps avg for the Hornady factory ammo 500 gr fmj ................................The Lott was 45 fps faster than the win mag with my handload of a 300 gr X moly tumbled pushed by 73 gr IMR 4198 with a fed 215 primer ........Last year I noticed that I got simular speeds between the shilen stainless 19 1/2" barrel and the 24" barrel on the Interarms mkX.,.,..................................Has anyone got simular results with short barreled 458 win mags or Lotts and how short has anyone chronoed their Lott/Watts,Ackley,Mashburn ect ........Or better said ,how short a barrel can you have and still get full long magnum speeds ??? Elevation 500 feet approx , Temp 32 deg F . 100% humidity .

gumboot -- I chrono'd some Hornady Lott ammo (both soft and solid, as well as their Heavy Mag .458 win mag ammo. I don't have the exact numbers in front of me, but the Lott ammo was all at or very near 2300 fps (within 10 fps if I can recall), and I saw a best of 2150 fps out of the win mag ammo. I shot all of this ammo from my CZ with a 25-inch barrel.

Same results here. When I chronographed some Hornady 458 Lott ammo from my 24 inch barrel, all were over 2300.

450 Watts, 21 Inch Barrel, Hornady Factory Lott Ammo, 2260 fps over chrono

jnc91

What temps were the ammo when you chronographed it ... it ,,,, Roughly if you can remember ...I,m totally happy with the 2250 fps velocity for a 500 gr bullet but if I can get it with a 20 " barrel ,,,Ye Haw ....long sight radius is nice but I need the rifle to be short enough to not get wacked off the handle bars of my 4 wheeler ...

When I chrono'ed some Hornady Lott ammo a few years ago, IIRC it all shot to 2,250-2,280 fps (plus or minus) from my rifle's 24 inch barrel.

I believe it was in the mid-60 to low-70 degrees when I chrono'd the Hornady ammo.

.....O K that is right close enuf to be the same .,.,.Has any one chronoed much 458 Win mag in the full lengths chambers ???....I,ve been wanting to find an excuse to put a band sling stud on the barrel , and shortening it would be a good excuse all around ...

A little late in reply:
My Roger Ferrel/CZ 458 Lott with 21" Barrel. Hornady 458 Lott 500grn 2215fps avg. My loads with AA2520 500grn 2210fps.

[Thanks Mopane .,., Well with yours and jcn 91,s I,m definately going to give my Lott a 5" chop job ....Be a good time to put on a barrel band and mayby a brake for blastin .......The load I,m probably going to settle on in the rifle is a 450 gr or 400 gr bullet @ 2350 -2450 ...fps ....Don,t really need 500 grains here .......

Btw.. Shoot the same factory ammo in my old 24" AHR 458 Lott.. Vel was 2300fps right on the dime..

Gumboot, I'm hoping you'll remove your brake when going into the woods. You'll only make the mistake of shooting it once without ear protection & the brake

........Yes I will ., But in very thick brush and timber your ears are going to get clapped either way if you don,t have hearing protection ......I use the electronic ones ...