Belted Vs Non Belted Cartridges

[PA Deer Hunter]

I own a Weatherby 338-378 RC rifle that I purchased 2 years ago.  I had a gunsmith remount the scope and clean the bolt, barrel, etc.  He has won many awards at long range shooting competitions.  He told me that a belted cartridge is not as accurate as ones without a belt.  Is this true?  Is the 338-378 accurate out beyond 1000 or even 1500 yards?

Also, even though the 338-378 has a belt, is the headspace determined by the belt or the shoulders.  I only ask this as I have read conflicting reports on this question.

Thank you for any thoughts.

[dubyam]

I hear this fairly frequently. My experience is that this entire idea is founded upon a potential minuscule difference, and relates far more to brass consistency than any other factor. What does this mean? It means that quality brass, in a carefully cut chamber, with or without a belt, is capable of excellent accuracy.  If everything is kept equal (which would be nearly impossible) a beltless round might have a very minuscule (think in terms of less than a tenth of a minute of angle) better accuracy potential, but even that is suspect. That the military has used and still uses the 300WinMag for sniper use confirms for me the idea is without much merit.

For all belted rounds, headspace occurs at the belt, technically. But that's for folks using factory ammo. For handloaders, we can adjust the sizing dies (using neck dies, shoulder bump dies, and FL size dies) to move the shoulder back .001-.002" from fired case measurements, creating a shoulder headspacing situation. At that point, in my specific rifle, with my specific handloads, headspacong occurs at the shoulder, not the belt.

[GrandeJuan]

When I rebarreled my 270 and 340 Bees I had my Smith cut the belt -.002 since the brass manufacturers don't hold to SAAMI specs on the belted cartridge cases very well. I adjusted my sizing dies to headspace on the belt and the shoulder (took a few tries to achieve this). I know it's overkill but what the heck. GJ

[HuskyMusky]

Probably.

Will a belt-less make you personally shoot way better? doubtful.

I think I'd take a quality rifle with a belt any day over a junk rifle in a belt-less cartridge.

[HighDesertHunter]

+1 on dubyam's post.

[257 Shooter]

Ditto on what was already said. Cases fired in your rifle and properly sized will headspace on the shoulder.

If you get a chance, have a look at 1000 yard benchrest results. Still a lot of belted cartridges used: 300 Winchester, 300 Weatherby, 300 Ackley, 308 Baer etc.

[.257]

The belted case was designed to head space on the belt. That way the case body can be full length sized for easy are reliable clambering
Does this make the belted case less accurate, that's open for debate. Some benchrest shooters neck size only and some full length size. lMO it depends on the chamber which works best in that gun

[257 Shooter]

I stand by what I said.

[HighDesertHunter]

My .02 for whatever that's worth.


When you fire a round for the first time, it's supposed to be head spaced off the belt. Typically, head space is .002-.004 with .005 being a no go or .007 being no go for a field gauge. Head space is the distance from the head of the round to the face of the bolt.


Once it's fired, the case becomes fire formed to the chamber minus about .001 due to spring back. The case expands in diameter normally and rarely lengthens. If you can still chamber the case easily then it's still head spaced off the belt but it is now a better case from an accuracy standpoint because its dimensions are typically within .001 of the actual chamber.



You should only need to neck size a case that still chambers easily in your rifle. You have to do that because if you didn't the bullet would fall out due to lack of neck tension. I have found that after about 5 firings the case gets a little difficult to chamber. This is because the case has become work hardened and lost it's ability to spring back the needed .001. To avoid this and prevent a case from sticking in the chamber, I anneal the case and then do a full resize after 3 neck sizing's and firings. A full resize will add length to the case so I trim them back to trim length. You don't really need to trim them until they exceed max case length. Typically after the 4th full resize and subsequent firings, I begin to see signs of stress near the belt so I've come to discard cases after the 3rd resize and subsequent 3 neck resizes and firings.


So why add a belt to a round. In theory, unless your brass is work hardened, your head space should never change which should improve consistency and accuracy.

[buffybr]

It's above my reloading/shooting ability to see any difference in accuracy between belted and non belted caratridges.

[dubyam]

So why add a belt to a round. In theory, unless your brass is work hardened, your head space should never change which should improve consistency and accuracy.

Well, why indeed? You may already know this, but fir those who don't, the belt originated on the 375H&H, way back when. Why did H&H add a belt to that cartridge case? Because they wanted a reliable bolt action feeding round with a rim for headspace. Why a rim? Because the shoulder on the 375 was so thin they were concerned it would not provide viable, repeatable, safe headspacing in all firearms. The belt solved that. And hence all those rounds wildcatter off the 375 & 300H&H rounds also wear a belt, despite it being unnecessary for any with sufficient shoulder to reliably and repeatably headspace on the shoulder.

[dubyam]

The cartridge design may have revolved around coresite, but the addition of the belt was due to the lack of sufficient shoulder for headspacing. Otherwise, it would have been like all the other cordite-driven cases of that era.

[257 Shooter]

Agree with last post. The 416 Rigby and 404 Jeffery are beltless cases and were originally loaded with Cordite.

[Creekstone]

I agree with the .375H&H being difficult to head space on the shoulder do to the shallow angle.  In my mind the best situation is a once fired standard case with a reasonable shoulder angle, something like Ackley is perfect.

[African Leadwood]

I hear this fairly frequently. My experience is that this entire idea is founded upon a potential minuscule difference, and relates far more to brass consistency than any other factor. What does this mean? It means that quality brass, in a carefully cut chamber, with or without a belt, is capable of excellent accuracy.  If everything is kept equal (which would be nearly impossible) a beltless round might have a very minuscule (think in terms of less than a tenth of a minute of angle) better accuracy potential, but even that is suspect. That the military has used and still uses the 300WinMag for sniper use confirms for me the idea is without much merit.

For all belted rounds, headspace occurs at the belt, technically. But that's for folks using factory ammo. For handloaders, we can adjust the sizing dies (using neck dies, shoulder bump dies, and FL size dies) to move the shoulder back .001-.002" from fired case measurements, creating a shoulder headspacing situation. At that point, in my specific rifle, with my specific handloads, headspacong occurs at the shoulder, not the belt.

Excellent reply.