Actually, there are none. I thought there was for a bit, but there wasn't, and there isn't. There never was.
A short while back
sabotloader wrote about installing a vent liner in his Triumph breech plug. He wrote about perhaps working the headspace end, but noted that he had zero problem with blow by, and i believe he mentioned the primers only grew a couple of thousandths, when popped; he did nothing with the headspace. At that time i measured some primers from my Triumph, and just like him, i found the spent primers grew one or two thousandths is all. Like him, i decided my Triumph had no headspace issues.
A week ago, i checked some primers from my Triumph, and they had grown over 0.010". This was a surprise to me; i thought i had previously measured 0.001" or 0.002". Attributing this discrepancy to 'old brain', i set out to work the headspace of my breech plug. What i did was drill out the primer pocket and install a 3/8" x 24 grade bolt just like i had for an Omega plug, and the QRBP.
A new primer pocket was created to give a slight crush to STS primer. When the flash hole was measured, it was found that it had grown from 0.029" to 0.032". It seemed i may as well install a vent liner at this time, so i did. The flame channel was also drilled out from stem to stern to a little more than 5/32".
Previously whilst cleaning this plug, i had damaged the compression rings. I was able to get them to work again, but they are not like new. Also the o-ring had begun to split, so i replaced it with one from our local ACE store. It seems that these repairs made it so i could not install this plug with my fingers, so i fabricated a tool that allows me to install the plug. The scope on this rifle, prevents the tool TC sent with the rifle from installing the refurbished plug. The tool..........
At this point, i thought i was done, and was ready to call it a job. I had even tested the plug in the Triumph, and it had worked fine. Then
sabotloader asked a question about the firing pin bushing on the Accura V2. My V2 was out in the truck, and i wondered if i could come up with some help by looking at the firing pin bushing in the Triumph. That is when i found it was
loose. This was a real shock. In the time i have owned this rifle, i never looked at the bushing, let alone check to see if it was tight. So i tightened it, and now my newly modified plug would no longer work. Then i had more work ahead of me making the modification right for the rifle.
After the firing pin bushing was tightened, i checked the headspace on an OEM plug, and found the rifle closed tightly on the W209 primer, i had always used. Actually the rifle now crushes W209 primer 0.005" just like my scoped Omega does with the OEM plug.
There was no headspace issue, ever. These rifles, as they come from TC, can use CCIm, 209A, and W209 primer without allowing them to expand when fired.
The plug i modified, allows the use of STS, and CCI primer, and gives them a little 'crush'.
This morning i did some shooting with this Triumph and the V2. Both plugs i removed without tools. Both plugs were installed without any grease or anti-seize, or teflon tape.
This concludes my examination of headspace in my rifles. Two of my TC rifles had nice tight headspace. The other TC rifle allowed W209 primer to grow a couple thousandths or so, which i could have lived with just fine. It has a peep sight, so a small amount of blow by wouldn't matter at all. It was fixed by modifying it to use STS primer with a slight crush. The two CVA rifles had excessive headspace of 0.015" when using W209 primer. These i fixed by making and/or modifying their breech plugs. The easiest fix for these rifles is to use the
metric o-ring identified by
Busta. The use of these o-ring requires no modification of anything in my CVA rifles.
Triumph Headspace Issues
