Barrel Length VS Velocity

[KLS]

2 243 rifles were used in this testing. One with a 20” barrel and one with a 24” barrel. Various ammunition was used the newer stuff has manufacturer claimed velocity. Garmin Xero used to measure velocity. July 6, 2025 in the afternoon ~20 C.

Ammo. 20” 24”. Claimed
Federal 75 grain Vmax. 3317. 3427. 3425
Hornady SF 75 g Vmax. 3322. 3391. 3580
Hornady SF 58 g Vmax. 3638. 3740. 3925
Federal Hi-Shok. 80 gr 3272. 3374
Federal Sierra Pro 80 gr. 3094. 3200
Federal Red box 80 gr. 3134

My conclusions ~25 Feet per second is lost per inch of barrel in a 243. Hornady Superformance isn’t so super. It is approximately 200 FPS below advertised.

I tested my 17 HMR box value is 2550 FPS and it was 2678 Hornady ammunition 17 gr vmax.

I’m looking forward to reloading my ammunition and building a load specifically for my 20” 243. Any suggestions for powder and loads would be appreciated. Let me know your thoughts and experience.

 

[guntech]

The problem with using two different barrels is that there can be a difference within the barrels.

You need to shoot and record the velocities in the 24 inch barrel and then cut and crown the barrel shorter and shoot and record the velocities again. Repeat for a shorter barrel again.

Ackley once tested two factory Husqvarna 30/06 rifles with factory same length barrels with consectutive serial numbers (so they were pretty well identical) and there was 100 feet per second differences in velocities. Barrels can be individuals, not always, but often.

 

[156821]

I had two 30-06 rifles. One with a 24” barrel and one with a 20”. With the same ammo I witnessed a 100fps difference. 100fps doesn’t matter at the distances I shoot, but 4” of barrel does when I’m climbing through heavy alder on a mountain hunt.

 

[KLS]

The problem with using two different barrels is that there can be a difference within the barrels.

You need to shoot and record the velocities in the 24 inch barrel and then cut and crown the barrel shorter and shoot and record the velocities again. Repeat for a shorter barrel again.

Ackley once tested two factory Husqvarna 30/06 rifles with 24 inch barrels with consectutive serial numbers (so they were pretty well identical) and there was 100 feet per second differences in velocities. Barrels can be individuals, not always, but often.

Gotcha, lots of variables can come into play. I read a fair bit on the topic, my results seem typical. Just like Superformance not performing anywhere’s close to what’s advertised on the box.

Short barrel 243 definitely 4 decades newer than older 243.

 

[Weatherby Fan]

My brother and I have the same stainless steel 26 inch barreled 300 Weatherby rifles, out of the same box of ammo his shoots it at 3200 fps and my rifle shoots it at 3100 fps, so different barrels are hard to compare velocities, as guntech says you must do a test on the same barrel reducing one inch at a time to see actual difference in that barrel,

With that being said on average I see 25 fps difference out of the same cartridge/ammo per inch of barrel

 

[guntech]

I think factories sometimes test velocities from longer test barrels... rather than factory rifles. Their velocities almost always are high.

 

[Beeron]

There are lots of youtube vids taking barrels and cutting them down inch by inch.

Mdt even made a double lwngth barrel and noted an increase in velocity after shortening it before it slowed down again when it got too short.

Based on what I have seen, 18-25fps/inch seems pretty consistent between 18”and 24”.

I shoot 85gr barnes tsx over 36.5gr Varget and get about 2815fps out of a 18” barrel. Cut and crowned by Guntech himself at one time

It is a very accurate load in my particular gun.

Good luck.

 

[Potashminer]

OP's post is implying that only "muzzle speed" counts as important. Hornady Superformance will put two holes cutting each other at 100 yards from my Ruger Compact 243 Win - it has done that 3 times for 3 attempts - maybe that rifle does that with any ammo - I do not know - I never tried anything else - no need to. I have no clue what I am getting for speed from that 16.5" barrel - Hornady Superformance - 95 grain SST bullets - lot #3235583. For what it is worth, the Muzzle Velocity, as listed on the box, is given as 3185 fps. As mentioned - I do not know or actually care what it is emerging at. The performance is going to be "good enough" for anything that I would use a 243 Win for.

 

[KLS]

OP's post is implying that only "muzzle speed" counts as important. Hornady Superformance will put two holes cutting each other at 100 yards from my Ruger Compact 243 Win - it has done that 3 times for 3 attempts - maybe that rifle does that with any ammo - I do not know - I never tried anything else - no need to. I have no clue what I am getting for speed from that 16.5" barrel - Hornady Superformance - 95 grain SST bullets - lot #3235583. For what it is worth, the Muzzle Velocity, as listed on the box, is given as 3185 fps. As mentioned - I do not know or actually care what it is emerging at. The performance is going to be "good enough" for anything that I would use a 243 Win for.
View attachment 977401

2 identical bullets, from 2 different manufactures, advertising 2 very different velocities. One is close the other not so much. I didn’t have time to test the accuracy between the 2 loads, it stormed. I’m planning to load my own. Accuracy matters. This 20” 243 jumps, I’d better make the first shot count…

 

[track]

I shoot 90 grain accubonds out of my 240 Weatherby at 3,684 fps. The barrel is a 27" Bob Jury, 1-10 twist. I have 4 rifles that have 27" barrels, all Bob Jury stainless steel. My Ruger #1 chambered in the 6mm Remington is content with 90 grain Accubonds at 3,366 fps. Barrel length matters.

 

[dgradinaru]

I think factories sometimes test velocities from longer test barrels... rather than factory rifles. Their velocities almost always are high.

I've found hornady ammo to be some of the most inconsistent when it comes to advertised velocity. I've found an average of 150-200 fps slower than what the box shows on several cartridges, not all but several. Yet I've found federal, Remington, S&B, PPU, Rws, Norma to be near spot on or within 50 fps on average.

Hornaday must be using 26-28 inch test barrels

 

[MTM]

Just for the record, when I cut my first .416 Rem to 22” from 24” I lost 50 fps with my 300 gr. X load. 2950-2900.

 

[jparent]

I haven't done a lot of velocity testing, but I've always preferred shorter barrels, for balance and handiness. For me accuracy is more importance than chasing another 100 fps.

I did notice that when i shortened a 243 barrel from 22 to 20", that the previously used factory ammo, shot differently. At 22" it consistently grouped the best with 90 grain loads. Once shortened, the rifle preferred the heavier 100 grain load. Consistently. Same ammo, same lot numbers.

I have had the same unimpressive results with Hornady Super Performance.

 

[R005t3r]

6.5 Creedmoor 136grn Lapua Scenar on 41.5grn of 6.5 StaBall

30" barrel; 2800 fps

20" barrel; 2650 fps

 

[MRP]

I've done some, one 300wsm from 22 to 19". 4 different powders and 2 different factory total loss was not over 50 fps, one powder, Winchester 760 only lost 10fps. I've been looking at barrel length for a long time, in general the larger the bore the less loss per inch. But powder, bullet and the tightness of the bore all make a difference and you'll never know till after you cut. My 300wsm non max load for 165 gr is going 3000fps, tested some reloader 17 at 3200. I don't need anything longer or faster.