Thread: 308 barrel length velocity loss

One more point I found with the short barrels, even with a can on in a couple of cases - they had a LOT more flash out the end of the tube on firing which while impressive was a really annoying pain in the arse in heavy bush where there is less light to start with. The bright flash makes your eyes/pupils react leaving you with a few seconds of reduced vision. That can be the seeing or not of which direction an animal gaps it in, which could be the difference of a recovered animal or a lost one. I went back to the 18" and then 20" in .308W, just for that reason. Yes, not quite as handy in thick bush but then not quite the same level of anti-social as well.

Originally Posted by No.3

One more point I found with the short barrels, even with a can on in a couple of cases - they had a LOT more flash out the end of the tube on firing which while impressive was a really annoying pain in the arse in heavy bush where there is less light to start with. The bright flash makes your eyes/pupils react leaving you with a few seconds of reduced vision. That can be the seeing or not of which direction an animal gaps it in, which could be the difference of a recovered animal or a lost one. I went back to the 18" and then 20" in .308W, just for that reason. Yes, not quite as handy in thick bush but then not quite the same level of anti-social as well.

Never had that issue, even when spotlighting.....interesting...maybe your load?

I can just imagine those extra 2 inches would be a massive pain in the arse....imagine if the old guys with 303 could see us now

Hamish

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I’ve just had a 20” 308 tikka taken down to 16” running Sako Gamehead pro 150gn at 2767fps/20” to 2664fps/16”. Sako ballistics app is pretty accurate for their barrel lengths and factory rounds and didn’t look like I’d lose much and I didn’t.

Yeah, run the load thru QL or GRT. What %age of the charge is being burnt in the barrel (or being burnt outside the barrel).?
Muzzle flashes are worse in some cartridges. My 22/250s have always been impressive at night, even with un-shortened barrels.

Originally Posted by No.3

One more point I found with the short barrels, even with a can on in a couple of cases - they had a LOT more flash out the end of the tube on firing which while impressive was a really annoying pain in the arse in heavy bush where there is less light to start with. The bright flash makes your eyes/pupils react leaving you with a few seconds of reduced vision. That can be the seeing or not of which direction an animal gaps it in, which could be the difference of a recovered animal or a lost one. I went back to the 18" and then 20" in .308W, just for that reason. Yes, not quite as handy in thick bush but then not quite the same level of anti-social as well.

Well, that must be the reason both of my hunting .308 rifles have 20 inch barrels although they have arrived at that more by accident than design. The Bergara single shot is pretty short as well.
GPM.

My 308 tikas have gone from 22,18,16,18 and now back to 22 1/4inchs.Quieter n less dial up.

There is alot of variables when it comes to barrel length vs speed so theres no real once size fits all, you can estimate and theres some general rule of thumb "x fps for y inches of barrel" you can follow but alot of things can change the outcome like powder type used, and how hot the load is as that effects not just the peak pressure but the pressure curve as a whole.

Also worth noting that its not a linear thing, the shorter you go velocity exponentially drops. For instance a .308 shooting a 168ELDM in front of a stout load of 2206h, Will lose right around 50fps going from 24" to 22". However if you were at 18" and went to 16", you would lose around 80fps.

In respect of the OPs question, As some others have confirmed with real world results, Powder dependent if your doing 2680fps currently, you should land somewhere right around 2540fps.

I’m shootings the 168 eldm factory round in my 16 inch work gun and getting 2526fps bloody good ammo

Well the extra 4 inches may not seem like much but for moving through the tight stuff we have down here and then getting onto clearings quietly.

As I've found with my 16" model 7 it does make a world of difference.

So cheers for the replies.

Off to custom guns to get the work done then

Originally Posted by HNTMAD

I get that, but some are saying they are chopping for easy of handling based on being shorter....when they are not lol

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DPT add f-all weight and length, but very effective sound moderation.

168 ELD-M 2650FPS with 17" DPT

Originally Posted by Jacobframe

168 ELD-M 2650FPS with 17" DPT

Out of interest what powder are you running?

Originally Posted by mattstr

Out of interest what powder are you running?

i run a load similar velocity @ 2620fps definately no where near max but super accurate using 2208
granted I am using a 22" barrel

Originally Posted by dannyb

i run a load similar velocity @ 2620fps definately no where near max but super accurate using 2208
granted I am using a 22" barrel

I’m only getting 2541 with 2208 no pressure signs but loads at compressed in Lapua brass at 44grains.

I'm running Sako brass seated at Saami length will have to check when I'm home this evening for charge weight