Smoked necks on 308 cases- None on 338 Lapua

[armada]

Hello everyone, I recently fired my GAP build at my local range. I was doing a sight/break in and noticed that my spent cases had no carbon on the necks, or at least very little. So I decided to take my 308 and put a few rounds down range and that had the usual carbon deposites, on the neck, down toward the shoulder, that I'm used to.


I admit, I don't do the break in proceedure. I never do on a custom rifle. Not even a patch. They test fired it at GAP and I ran with it.


The components I'm using:

New Lapua brass
Winchester Large magnum primers
Reloader 22 - 90 grains
Sierra 250 grain SMK and SBT

Shot 20 total.

Rifle specs:

Surgeon XL
Rock barrel 1 in 10 5R
GAP built

I only necked sized the cases and on a separate step, used a Sinclair expander. Hand weighed each powder drop and made sure they were all 90 grains. AOL is magazine safe at 3.65 with no preasure signs. All cases, bolt closed like there was no case in the chamber. I did this before I started loading the cases.

I was just curious, why so little carbon or none at all on the necks? Does anyone have a clue? Is that unusual?

Thanks in advance.

 

[orkan]

Re: Smoked necks on 308 cases- None on 338 Lapua

Most likely the chamber is a little tighter, allowing the brass to get a good gas seal around the neck.

 

[ChrisGarrett]

Re: Smoked necks on 308 cases- None on 338 Lapua

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: armada</div><div class="ubbcode-body">Hello everyone, I recently fired my GAP build at my local range. I was doing a sight/break in and noticed that my spent cases had no carbon on the necks, or at least very little. So I decided to take my 308 and put a few rounds down range and that had the usual carbon deposites, on the neck, down toward the shoulder, that I'm used to.


I admit, I don't do the break in proceedure. I never do on a custom rifle. Not even a patch. They test fired it at GAP and I ran with it.


The components I'm using:

New Lapua brass
Winchester Large magnum primers
Reloader 22 - 90 grains
Sierra 250 grain SMK and SBT

Shot 20 total.

Rifle specs:

Surgeon XL
Rock barrel 1 in 10 5R
GAP built

I only necked sized the cases and on a separate step, used a Sinclair expander. Hand weighed each powder drop and made sure they were all 90 grains. AOL is magazine safe at 3.65 with no preasure signs. All cases, bolt closed like there was no case in the chamber. I did this before I started loading the cases.

I was just curious, why so little carbon or none at all on the necks? Does anyone have a clue? Is that unusual?

Thanks in advance. </div></div>

Let your 308 necks grow a bit, perhaps an extra .005" (2.810") is in order?

2.005" is for noobs.

Chris