Muzzle velocity difference between manufacturers

[BarnOwl 6.5]

Muzzle velocity is mainly a function of the ammunition and barrel length (time under pressure). It seems reasonable to expect minor speed differences between manufacturers (all else being equal), but I wouldn't expect substantial differences. That being said, I have seen posts that suggest otherwise. Here it is.

I'm trying to build a light weight, short, suppressed back country hunting rifle chambered in 6.5 PRC. I was looking at the Tikka T3x with 24" barrel, but found myself attracted to a shorter 20" barrel made by Seekins precision in their new Element Hunter. When I considered how much speed it would cost me for the shorter barrel by Seekins I looked up speeds on other outside forums that guys had posted. The results are below.

Rifle Model	Barrel Length	Muzzle Velocity (fps)	Bullet / Ammunition
Seekins Element Hunter	20"	~2,865	143gr Hornady Precision Hunter ELD-X
Tikka T3x (discontinued I think)	22"	~2,690	140gr Hornady ELD-M
Tikka T3x Roughtech	24"	~2,860	143gr Hornady Precision Hunter ELD-X

I was surprised to see that the shortest barreled 6.5PRC (by Seekins) had the highest muzzle velocity. If we assume those posted numbers to be true, the only explanation I can think of is that maybe Seekins has tighter manufacturing tolerances.

Is it even reasonable to think that might have such a great effect as to completely offset a decrease of barrel length by 4"?

 

[oldrifleman]

Each manufacturer and even within the same manufacturer targets a specific application for their load targets. A 308 for hunting will likely have a different recipe and outcome than one for say target work. A 168 OTM for target will get a different powder mix (manufacturers do not use commercial powder mix's) than say a 168 for law enforcement or a budget blaster load. You have to check each load/lot for velocity. Generally a Hornady backpacker load (same Bullet) will be different than a similar load by Winchester or Federal.

 

[DemonicLemming]

Is that averaged data across multiple rifles of the each barrel length/ammo, or individual reports for each? It's not uncommon for people to bump their "recorded" speed up a bit when posting online (sort of how a gun that shot a 0.5" group once is now a "half-MOA rifle").

One thing to note is that Tikka is generally known for having slow factory barrels. I don't know if Seekins falls on the slow, average, or fast part of that chart. I also wouldn't expect different ammo (even if all Hornady and similar weight) to have the same velocity, which is why the ELD-X is likely faster than the ELD-M.

Either way, I wouldn't worry about 4" on a hunting rifle. Ease of carrying and use beats maybe 75 - 100fps.

 

[Emerson0311]

Tikka barrels have longer throated chambers, so shoot factory ammo slower than other barrels with shorter throats that mean higher pressure. Yes, I’ve got several, and have compared factory vs custom barrel velocities with a Garmin, and seating depth requirements for reloads in each barrel.

 

[Oldloser]

You should go with the rifle you like. All in all, shorter is better. You can then get the ammo to where it needs to be.

Too many variables in the published numbers to make sense of things. Your powder charge, powder relative humidity, case firings, and then chamber dimension variability are the big ones vs barrel length. A new case alone and a looser chamber will take away 100 fps.

 

[diggler1833]

Barrels are individuals, so your results WILL vary some even within a specific manufacturer. I agree with the above that Tikka/Sako barrels are generally a tad slower, and that their throats are long. I'm out way over 2.9XX" in OAL in my TRG in .260 Rem.

I'd certainly be buying based upon what specifications I wanted in a rifle, rather than which one shot factory ammo faster. Tikkas and Seekins will both serve you very well...but perhaps the Seekins will meet what you want in a rifle more.