Headspace question

LRshooter6mm

LRshooter6mm

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Minuteman
Oct 1, 2017
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#1
My custom 22 is giving me light primer strikes. I’ve tried a different trigger, sent the bolt back to the manufacturer and tried different ammo. Same story, light primer strikes. I’m now thinking it’s a headspace issue. I tried the tape method of checking headspace. Put 1, 2, and 3 layers on the back of a live round and it closed with ease and no resistance. Didn’t want to keep adding more because I don’t want to stress the extractor. I measured the layered tape and it was .014 inches. Does that sound right with it being a headspace issue? Also, is it unreasonable to ask the gunsmith who spun the barrel to pay for the shipping to get this fixed?

Gun is a Curtis Custom Valor 22lr conversion in a KRG Whiskey 3, with a trigger tech 2 stage special trigger.
 

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#4
Federal typically has thick rims and fairly sensitive primer. If you are getting light strikes and/or failures to fire, then either it’s a headspace issue, firing pin protrusion issue, or too light a strike issue (which could be mass or speed).
Measure rims of various ammo, and test with the thickest rim.
When testing, seat the round fully by hand (so the energy of the firing pin is fully expended on crushing the case, not seating it first).
Cases have different thickness of brass as well, and some compresses easier than others.
 
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#5
obx22 said:
Federal typically has thick rims and fairly sensitive primer. If you are getting light strikes and/or failures to fire, then either it’s a headspace issue, firing pin protrusion issue, or too light a strike issue (which could be mass or speed).
Measure rims of various ammo, and test with the thickest rim.
When testing, seat the round fully by hand (so the energy of the firing pin is fully expended on crushing the case, not seating it first).
Cases have different thickness of brass as well, and some compresses easier than others.
Click to expand...
Seating the bullet first won’t damage the extractors correct? It’s similar to a vudoo bolt. I know you can’t with Rimx without risking breaking the extractor
 
#12
BassNbrass said:
Do you have the cone style breech on that Curtis? I had the same issues with mine for a while.
Click to expand...
It’s a hybrid. It’s a cone breech with no extractor cuts but the 3 and 9 o’clock on the cone are kind of chamfered to make it easier for the extractor to catch. Don’t have a picture but I can provide on at a later date.

What the issue with yours?
 
#13
LRshooter6mm said:
It’s a hybrid. It’s a cone breech with no extractor cuts but the 3 and 9 o’clock on the cone are kind of chamfered to make it easier for the extractor to catch. Don’t have a picture but I can provide on at a later date.

What the issue with yours?
Click to expand...
With mine, also cone breech, once fired a couple hundred rounds the actual cone had been peened down enough to where the shoulder had to be set back another 8 thousandths to reset proper headspace. Once I set it back it has been working well and doesn't appear the cone is mushrooming further, I suspect the very end was just a little too thin on the cone. If yours hadn't been fired though that wouldn't be your issue. would be worth checking with a headspace gauge if you can find access to one.
 
#14
LRshooter6mm said:
Okay, so maybe I’ll try adding more tape
Click to expand...
SAAMI spec for .22LR chamber headspace is 0.043-0.051" min/max. Spec for the cartridge rim is 0.043-0.050" 0.036-0.043". Fwiw, the "rim thickness" of my Rim-X no-go gauge is exactly 0.050 inches.

If the cartridge rim is within SAAMI spec, the round should fire. Period. You need to confirm correct headspace. Without that confirmation, discussion of rim thickness is useless noise.

If I don't like the indentation "signature" of some brand/SKU of ammo in my Vudoo or Rim-X, I change the ammo - not the rifle*.

I suppose, in absence of a go or no-go gauge, if you measure a specific round's rim thickness, stack tape until the bolt won't close, and measure the depth of the stack, maybe you can get a rough idea as to whether excess headspace (> 0.050") exists - layers of tape being soft and not especially precise.
----

* I do, of course, pay attention to pin indentations in a new build. I've just never encountered a problem with misfires or light strikes in any of my .22s with ammo from CCI SV through several SKUs of Lapua, SK, Eley, and RWS. I do have a buddy whose new Rim-X misfired a lot, especially in cold weather, and accuracy was poor. Long story short, he screwed on a different (prefit) barrel and the problems went away. He sold the original barrel, and the new owner was reportedly very happy with it. [head shake] .22s be weird sometimes.
 
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