4 Land

7mmfan · Rookie Member Joined: Jan 12, 2008 Posts: 8

I'm having a Rem. 700 rebarreled in 7mm STW and going to a 4 land Lilja barrel. How much velocity increase should I expect in going from 6 lands to 4 lands?

1895ss · Posted: Wed Feb 13, 2008 8:33 pm Post subject: Re: 4 Land

Welcome aboard 7mmfan, I would check with the people at Lilja, they should know something folks here don't.

Pumpkinslinger · Posted: Wed Feb 13, 2008 11:27 pm Post subject: Re: 4 Land

I wouldn't expect any velocity increase. Am I missing something?

1895ss · Posted: Thu Feb 14, 2008 12:11 am Post subject: Re: 4 Land

Pumpkinslinger wrote:

I wouldn't expect any velocity increase. Am I missing something?

We all know barrel length makes diff but I didn't know amount of groves made a diff. Maybe Lilja is up to something we haven't heard about. Smile

7mmfan · Rookie Member Joined: Jan 12, 2008 Posts: 8

Maybe I am thinking about this all wrong but, it would seem to me that if you are digging 1/3 less grooves into the bullet then for a given barrel length, powder charge and bullet weight the resulting reduction in friction/restriction would have to result in increased velocity .

Pumpkinslinger · Posted: Thu Feb 14, 2008 6:42 am Post subject: Re: 4 Land

Fewer lands but I bet they are wider. Either way I wouldn't expect any appreciable increase. If you find out different let us know!

mikeleduc · Posted: Fri Feb 15, 2008 7:11 pm Post subject: Re: 4 Land

I don't think the original 2 land 30-06 barrels had any advantage in velocity over the later barrels.

Dimitri · Super Member Joined: Nov 25, 2005 Posts: 5946

The barrel lands are propotional in general, and after the initial shock of forming at the throat of the chamber it really doesn't effect anything all that much I dont think. And as Mike mentioned the "cheaper" 2 land barrels produced by various militaries for different firearms in times of war shot the same as the non-wartime production 4 grove barrels, but required less cutting passes to cut hence the money and time savings. Smile

Dimitri

7mmfan · Rookie Member Joined: Jan 12, 2008 Posts: 8

I took 1895SS's advice and emailed Dan Lilja. Pumpkinslinger was correct in that when they reduced the number of lands they kept the nominal about of bearing surface the same so there will be essentially no net gain in velocity. However, there is a slightly longer service life due to the lands being wider and that is important with an overbore like the 7mm STW that I am going to.