Barrel length question

[Mambochicken]

Hello all you wise gun nuts. Lend me some expertise.

I purchased a suppressor for my hunting rifle, and am now in the process of spec’ing out a new barrel to accept it. My question is how much of an impact barrel length will have in my case. Here’s the info:

I’m shooting a Savage 11/111 in 30-06, and will be hand loading with Barnes 150 or 168 TTSX bullets. I’ve settled on a Shilen match grade stainless barrel, and am leaning towards the 1-10 ratchet rifling. The faster twist rate is based on Barnes’ recommendation of 1-11 or faster.

Currently my barrel is 22”. My suppressor will add 7.75” length, so if I keep that length, I’ll be darn near 30”. That seems long for hiking in the woods.

I have a self imposed max range of 400 yards for hunting. I’m just not comfortable shooting much beyond that, nor does the landscape lend itself to it here.

Given all that, here’s my question: how much accuracy do I give up if I go down to a 20” barrel? Or can I go shorter and still be okay?

And also, I’d love it if you could educate me on the why as well. This is my first custom barrel, and I have been learning a ton.

Thanks!


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[JeffreyDeGraff]

10” twist is pretty standard on 30-06’s, as are 22” - 24” barrels.

Shorter barrels are typically more accurate than longer barrels of the same contour. Shorter barrels generally yield less velocity though. Shorter barrels have less barrel whip due to harmonics.

I don’t use suppressors, but have friends that do. They tell me that you still gain velocity with a suppressor. I have no personal experience with it, but if that information is true, you may get the same velocity with a 20” suppressed barrel as a 22” unsupressed?

So long story short, figure out how much velocity you are going to need to get the trajectory you want out to 400 yds, and choose your barrel length accordingly.


JTD

[Mambochicken]

That’s a great way to look at it. Start with terminal ballistics and back into it… smart.

I’ve heard suppressors do give higher velocity for the same charge, but probably smart to just ignore that for now.

Is there a way to calculate the velocity given by a barrel of a specific length?


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[JeffreyDeGraff]

There isn’t a way to do that because each barrel is different. Some are faster than others, some are slower.

I can say that my two 22” 30-06’s, both get very similar velocities with the same loads and those velocities are very close to the velocities given in the Hornady and Lyman manuals.

What length barrel does Barnes use to get their data?


JTD

[Mambochicken]

They show a 24” 1:10 twist barrel in their book.


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[JeffreyDeGraff]

I was just looking also, max velocity with 168gr in 24” barrel is about 2850fps. Not much faster than a 22” barrel, about 50fps more than I get with max charges in my 22” barrels.


JTD

[JeffreyDeGraff]

A 22” barrel with 7.75” suppressor is 29.75”. 20” would be 27.75”, which in my opinion is still too long on a hunting rifle. 18” would be 25.75”., which is max in my opinion.

This is just me thinking out loud here.

24” = 2850fps
22” = 2800fps
20” = 2750fps
18” = 2700 fps

These are all guestimations based on max charges and assuming 25fps velocity loss per inch of rifle barrel.

There is no way to know how much velocity you’ll gain back with the suppressor until you put it on and try it yourself.


JTD

[JeffreyDeGraff]

So after plugging in some numbers.

A 168gr ttsx at 2750fps and a 100yd zero, will drop approximately 31” at 400 yds.


JTD

[Mambochicken]

That’s fair I suppose. And I can always drop down to 150’s and pick up extra velocity. Either one should work on mule deer.

18” just seems really short somehow. Luckily where I hunt isn’t thick timber. It’s a lot of open sage brush, but definitely some trees around. Maybe the 20” compromise would be a good fit.


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[Mambochicken]

Yeah, I’m not terribly likely to take a 400 yard shot. But I might. More likely I’ll zero at 200 and shoot to 300. A 165 at 2750 would only drop 8” below 0 at 300 that way. And 24” at 400.

Sounds manageable.


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