Chamber Question/Education

[Jackie_Daytona]

I was hoping for a little education about chambers and bullet sizes, specific to these new “heavy for caliber” bullets. How does chamber cut influence performance with various sized bullets? Or is it not even a thing?

Specifically, I have a match chamber for a .300 PRC set for 225gr projectiles. Can anyone explain what to expect should I run slightly lighter or heavier bullets?

For example, 212 ELDX or 230 A-Tips. Would performance shifts be negligible or what?

 

[BPGuru]

I was hoping for a little education about chambers and bullet sizes, specific to these new “heavy for caliber” bullets. How does chamber cut influence performance with various sized bullets? Or is it not even a thing?

Specifically, I have a match chamber for a .300 PRC set for 225gr projectiles. Can anyone explain what to expect should I run slightly lighter or heavier bullets?

For example, 212 ELDX or 230 A-Tips. Would performance shifts be negligible or what?

The simplest answer is the heavier/longer bullet might have to be seated deeper in the case to chamber which reduces available powder capacity.

 

[roostercogburn98]

How does chamber cut influence performance with various sized bullets?

Would probably benefit you to measure your chamber/freebore/throat to see what kind of room you have to play with.

Some heavier bullets may be longer and close up your available space to seat longer to avoid pressure signs.

If your chamber is cut for the bullets you say, I’d imagine your build sheet for the barrel has the freebore dimensions listed

 

[Rocketmandb]

Chamber cut can mean a number of things - chamber diameter, free bore, etc.

Free bore will impact seating depth which can impact the effective case volume and chamber diameter directly impacts effective case volume. This will impact the case max powder charge before you hit pressure, which would dictate how heavy you can go with bullet weight for a given desired velocity.

Bottom line: you won't know until you try.

Oh, and can the Hornady shit and get some Berger 220 or 230 hybrids. Much easier to load for and far more consistent. I just started playing with the 220s after years with the 230s, and... yeah, they're good.

 

[Supersubes]

I was hoping for a little education about chambers and bullet sizes, specific to these new “heavy for caliber” bullets. How does chamber cut influence performance with various sized bullets? Or is it not even a thing?

Specifically, I have a match chamber for a .300 PRC set for 225gr projectiles. Can anyone explain what to expect should I run slightly lighter or heavier bullets?

For example, 212 ELDX or 230 A-Tips. Would performance shifts be negligible or what?

Who built the gun for you, and can they tell you what they mean by “match”? There is no strict definition of that word when it comes to chambers, but by all accounts the standard as designed hornady 300 PRC chamber is “match”. There’s really no improvement to be made to it to make it more “match”. The standard chamber has a minimal body clearance, minimal freebore diameter (.3088), a long freebore (.2328), and a 1.5 degree leade. Thats the garden variety “match” recipe for almost all cartridges. It will suit your two example bullets just fine, in fact I would say that it is perfectly “set” for the 225 ELD.