How important is chamber to bullet length? 40sw

[soulbyte]

How important is chamber to bullet length?

 

The backstory: I'm getting a custom 6-inch barrel and the complete top end made for my 40sw. The current 5-inch barrel will only accept a cartridge OAL of 1.15 using extreme 180grn. The barrel maker informed me that they cut their chambers for a max length of 1.2. I want to be able to use these top assemblies interchangeably with my frame. Will the .05 difference in chamber length affect the accuracy of my load. This is assuming I don't ream out the factory chamber of my 5-inch top end. Thanks in advance.

[DsWright]

unfortunately the only real answer is to shoot it and see.  Same guns, made at the same place on the same day might react differently to different seating depths.  Typically it shouldn't be an issue.  But regardless, the only real way to know is go shoot it and find out. 

[drewbeck]

+1

shoot them and see, it probably won’t matter but if it does, having a local Gs throat it .005 should be a two minute job and cheap. 

 

If theyre building a topend for you, send one of your rounds and ask that they make sure it chambers fine. If they won’t, I’d be concerned

[jcc7x7]

BE very concerned !!!!!!!!!!!!!!!!!!!!

[Hi-Power Jack]

6 hours ago, soulbyte said:

Will the .05 difference in chamber length affect the accuracy of my load.

 

It most likely will have absolutely no impact on accuracy or safety,

 

BUT, as everyone above mentioned, only trying it out will tell you 100%     

[zzt]

I'm confused.  The chamber depth should be the Go Gauge, and not much, if any more.  If you want a longer OAL with a certain bullet, you throat your barrel, not lengthen the chamber.

[72stick]

I literally just had my STI Edge in .40 S&W throated last week. I'd been having trouble with .401 diameter lead powder coated and most .400 plated 180 grain bullets loaded anything over 1.145 OAL. It was a pain in the butt cause it wouldn't go into battery if I reloading anything longer than 1.145 OAL. My Edge now takes any bullet combo out to 1.200 OAL and the accuracy didn't change at 25 yrds.  

 

After fighting this issue for a long time it cost me $20 to fix it. 

Edited April 9, 2018 by 72stick

[soulbyte]

I'm confused.  The chamber depth should be the Go Gauge, and not much, if any more.  If you want a longer OAL with a certain bullet, you throat your barrel, not lengthen the chamber.

It’s probably me that’s confused having the terminology backwards. I’ll invest in a reamer and throat my 5 inch to match my new top end. Thanks guys!


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[zzt]

Don't bother s.  Any gunsmith with a Clymer reamer will do it for you for $15~$20.  Buying one, IMO, only makes sense if you have a lathe and you plan on doing additional barrels.

[Gomar83]

Wouldn’t this be a issue with free bore? Or am I mistaken?

[Furrly]

make one load length for 5 inc barrel and another load length for the 6 inch

[ltdmstr]

Yes, he's referring to freebore not chamber length.  It's easy to add and length is not critical (just needs to be enough to clear the loaded round).  You can do it yourself by hand with a piloted reamer.  If you want to check chamber/freebore dimensions, stuff with modeling clay, freeze, pop it out and measure.