Modification TC Speed Breech
 

The process started out to simple make a modification in the Triumph breech plug, by opening the flash channel to 0.159” from 0.125” and to exchange the 0.028 flash hole with a Lehigh Vent Liner. Sounds simple, then I decided I should find out more about the gun.

I took all the measurements off the Speed Breech that I thought might be of importance. I also decided I would try to see what the Head Space might be and how all of this came together when the gun was closed.

The Speed Breech may be the longest breech plug on the market, measuring 2.073” inches long + or – a couple of thousands. This length aids in reducing the blow back pressures felt on the nose of the primer after firing. It also might create a problem in getting heat and pressure to the powder in very cold temperature.

When the Speed Breech is inserted and turned into place and the gun is closed, I thought for sure there would be a gap between the top of the breech and the receiver block. I could close the action with a 0.0015 feeler in between the block and BP but I could not pull it out after the receiver and barrel were closed. It really surprised me how close that tolerance was.

As I looked at the block I also noted the firing pin bushing does stands out approximately 0.014” longer than the block. I measured the primer pocket depth at 0.230”. I inserted some Teflon tape in the bottom of the primer pocket pushed a w209 down onto top of the tape and closed the action. The primer rubbed the pin bushing upon being closed and it did press fit the primer onto the Teflon tape. Opened the gun and pulled the primer and re-measured the primer pocket at 0.224”. That works to be a 0.006” difference. TC got this one very close to being perfect. Because of this measurement there was no sense in worrying about head space.

I also found out that over time the slotted head in the pin bushing on the hammer side can and will work loose allowing the bushing on the breech side to push its way back out and increase the head space. It this has been going on for some time you may now have a hard deposit built up in that area that will not allow the bushing on the block side to protrude as far as it should. Make sure you are cleaning and doing the maintenance on the firing pin.

Finally this morning I did get to the shop to work on the modification of the breech plug. One thing I would like to say is that I am not a machinist – not even close… There is no doubt in my mind that there is probably a better way to accomplish what it did and the manner that I did it. One thing keeping everything ‘plum’ in a simple drill press like I have is a challenge (for me at least). There is also no doubt that a machinist with a lathe could and would do a better job.

Here is a pictorial of what I accomplished. The job is complete and the breech plug is installed and ready to go shoot. Should get that done Thursday or Friday.




One last point… the TC Speed Breech is the hardest breech plug I have ever drilled out. I believe it is a quality metal and it probably been through a hardening process. So if other are going to attempt this make sure you have sharp bits, cutting oil to help keep the temperature down and work at it slowly… Keep the temp to a minimum.

Shuck's, that was too easy. What are you going to do now? Shoot it, of course!

ronlaughlin

Easy for you to say - you are a machinist.... I was sweating great big sweat beads to whole time... You know how much a Speed Breech costs????

But all in all I am glad i to took the time to do it and to disect the the way the gun works in itself... Things I do not know before I began the project...

I have to make a run to Kennewick tomorrow or I would shoot it tomorrow - Oh! wait a minute I do not go till Wednesday - so i can shoot tomorrow... Great Day in the Morning.....

mike

I am not a machinist; just an old retired carpenter is all. They cost about $33. The dissection of your rifle was instructional for me too. I wondered why i have zero blow by around the primer in my Triumph, when i use W209.

Getting the plug perfectly centered is what makes the job be good. I don't have a spot drill; use a 3/8" 82 degree counter sink as the final step before tapping. Here is a plug headed to Michigan i guess. It was worked this afternoon after returning home from a hunting trip in bitter cold wind.







I laid that vent liner along side, in case you couldn't tell i am using them Lehigh.

Great day in the morning!

ronlaughlin

Your customer will appreciate the Lehigh vent liner. We have one guy that has 325 shots of BH through his liner and it shows no signs of flash hole wear.

got 22 cans of BH209 between 4 of our rifles without any breech plug flash holes wearing out "enlarging".

Mike I have been using this simple modification ever since I started trying to make my own vent liners. I did not have the necessary equipment for a good heat treat but had good luck with the Savage vent liners then switched to Lehigh when I found out about them. I am using the first Lehigh that I got still in the Triumph. The idea you gave us for enlarging the flame channel really made a big difference in the flame channel combustion area because it made a major reduction in the carbon deposit.
I did mine with the touch hole in the same position that the original was in. I don't try to count shoots but 2 cases of BH have gone through the Triumph since I put the Lehigh liner in and with the loads I use I would normally had to replace the BP in about one case.

lemoyne

Thanks for the comments Lee... This last year or so has really been an exciting time for us in the positive modifications and changes that have come about.

You know it is dang handy to have someone with your knowledge and no-how hanging around to bounce things of.

I am having fun even when i am shooting your ding dang favorite powder.