Any benefits of tight bore barrels for reloaders?

[mattj]

Pardon if this is covered ground -- didn't dig anything up with some searches.

Is there any net benefit with tight bore barrels for reloaders (as in, .298 bore in a .308 Win)?

Obviously, for factory ammo -- more pressure/more velocity for a given round.

...but if you reload, will it allow you to achieve anything performance wise that you couldn't with a standard bore?

-M

 

[EddieNFL]

Re: Any benefits of tight bore barrels for reloaders?

Be okay for building a bomb...if I understand you correctly.

 

[mattj]

Re: Any benefits of tight bore barrels for reloaders?

Well, obviously if you're not careful with your starting load, etc. But Lowlight for example uses a .298 bore in his 18" barreled Gladius (.308 Win) rifle to give it some extra umph (but he uses factory ammo, I believe).

As reloaders we can push the velocity more than factory loads up to pressure limits, what I'm wondering is if the tight bore does anything to the pressure/velocity relationship that gives us reloaders anything that we can't get from a standard bore barrel with a little more powder.

 

[MitchAlsup]

Re: Any benefits of tight bore barrels for reloaders?

Now, something like a 0.2995 bore HAS been shown to produce more velocity.

 

[Sig685]

Re: Any benefits of tight bore barrels for reloaders?

Palma barrels can have a bore diameter of .298 and a groove diameter of anything between .3065 to .3075. Regular .308 dimensions are .300 and .308. Palma rifles usually have much longer barrels than usual (Mine has a 32 inch barrel,) and one tries to get the maximum velocity out of these barrels for the long trip down range. A thight barrel should generate a bit more pressure and should get more MV than a regular bore. Definitely not something for fast powders.

 

[EddieNFL]

Re: Any benefits of tight bore barrels for reloaders?

For whatever reason, when I read this I was thinking .298 grooves. DOH! Carry on.

 

[Grump]

Re: Any benefits of tight bore barrels for reloaders?

Kinda the same effect as shooting those .309 Euro-bullets, AFIK.

The only real advantage I've ever *heard* of is making it a bit easier to get good accuracy as the throat wears. Big bullets for worn bores, tight bores for regular bullets.

The pressure and velocity effects are fringe "benefits", if you think that way.

 

[memilanuk]

Re: Any benefits of tight bore barrels for reloaders?

The primary reason for the tight bore was for the undersized Radway Green ammo used in the UK @ Bisley back when international Palma still used 'issue' ammo from the host country. For whatever reason, the RG ammo had undersized bullets, and the .298 bore is the US answer to the problem.

Now that issue ammo is no longer standard practice... the question of whether the .298 bore is worth it is not uncommon. Basically it works, and works well, with the short bullets used in Palma. Not sure it'd be my first choice for use with a long heavy VLD with a longer bearing surface. The Palma shooters I've spoken with about the .298 bore indicated that it didn't really seem any more accurate (with domestic US projectiles) but seemed to *maybe* hang on a little longer as far as barrel life, or at least degrade a little more gracefully.

HTH,

Monte

 

[kombayotch]

Re: Any benefits of tight bore barrels for reloaders?

The 308 barrel I just ordered from Bartlein is .298 bore with 0.3075 grove. I did this partly because a lot of .308 bullets I've measured have been 0.3078 or less. The barrel will be cut short and the tighter tube will help raise pressure and velocity. Frank was also of the opinion that it would be more efficient, that the velocity gain is a greater (percent) than the pressure gain.

I couldn't find any info about anyone trying it with a short-barreled tactical rifle, so I figured "what the heck?". It will be an interesting experiment at the very least.

 

[BLAWTON]

Re: Any benefits of tight bore barrels for reloaders?

There is no need for a tight bore unless your running a shorter barrel that needs the extra pressure to get the FPS back up. Yes Palma barrels are usually run tighter because of the size difference in the lighter bullets they shoot along with the slower twist and a 30" barrel.

kombayotch. One thing that is not understood alot is that there is for one a pressure ring on the back of most bullets. Two that a bullet expands a bit when put under those kind of pressures and its not needed to make the barrel tighter because your just getting more copper fouling in your barrel. But thats just my experience. I have found that using a barrel that is really close to the standard bore and groove size and doing a 3 groove with a special ratio will get pressures and speeds up but not give you the extra problems that are associated with the tight bore barrels.

 

[kombayotch]

Re: Any benefits of tight bore barrels for reloaders?

Have you actually tried it?

 

[BLAWTON]

Re: Any benefits of tight bore barrels for reloaders?

what? I have been making rifle barrels for 8 years now if thats what your wondering.

 

[C.K]

Re: Any benefits of tight bore barrels for reloaders?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: kombayotch</div><div class="ubbcode-body">The 308 barrel I just ordered from Bartlein is .298 bore with 0.3075 grove. I did this partly because a lot of .308 bullets I've measured have been 0.3078 or less. The barrel will be cut short and the tighter tube will help raise pressure and velocity. Frank was also of the opinion that it would be more efficient, that the velocity gain is a greater (percent) than the pressure gain.

I couldn't find any info about anyone trying it with a short-barreled tactical rifle, so I figured "what the heck?". It will be an interesting experiment at the very least.</div></div>

Ive been running Obeymeyer barrels which are tight bore barrels for the last 15+ years.. Ive found that with 155 to 175 the manuals are pretty close. If you are going to use a long bearing surface bullet watch your pressure close as they spike faster. I found this out when i started using bib 187gn bulets.

 

[Grump]

Re: Any benefits of tight bore barrels for reloaders?

Hmmm...the really good experiences back in the really old days with 2-groove Springfield bolt guns makes me interested in this 3-groove phenomenon reported above.

I'm more interested in accuracy with a wide range of bullets, and longer bore life.

Any insights?

 

[kombayotch]

Re: Any benefits of tight bore barrels for reloaders?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: NotAGuru</div><div class="ubbcode-body">what? I have been making rifle barrels for 8 years now if thats what your wondering. </div></div>

Oh lordy! My bad... I didn't realize.

lol!

 

[PKelley]

Re: Any benefits of tight bore barrels for reloaders?

Can any of you tell me if the 300gr .338 Scenar is .339 in diameter? I heard it was and was not sure if it would work in my barrel.

 

[BLAWTON]

Re: Any benefits of tight bore barrels for reloade

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Grump</div><div class="ubbcode-body">Hmmm...the really good experiences back in the really old days with 2-groove Springfield bolt guns makes me interested in this 3-groove phenomenon reported above.

I'm more interested in accuracy with a wide range of bullets, and longer bore life.

Any insights? </div></div>

Yes ask a few people like Sendar_Man how his 300 wsm works with the 3 groove barrel. From what i have done they shoot a wider range of bullets much better then anything else i have found. Later's Little Shield and other 18" 308 i we have built lately just shoot up about any type of ammo you can shove through them.