Quote Originally Posted by J.Baker View Post
Guess it's time to update this train wreck...

Got everything together and loaded up some initial development loads at 39.0, 39.5 and 40.0gr of IMR-4350 with Berger 105 Hybrids. Hit the range and got the scope bore sighted then sat down to zero it in. First round - click. Retry - click. Retry again - click. WTH? Grab another round - click. Retry - bang. Long story short, of the ten rounds I tried to fire only three went off and each of them needed multiple strikes. Firing pin strikes were notably light.

Seems I'm not the only one having this issue with the Nucleus action as there's a few threads of guys *****ing about it over on the SH forum. First suggested fix was to upgrade from the original 16# firing pin spring to a 19# spring, which is the spring that was being used in all the John Hancock rifles built on the Nucleus action. That still didn't resolve the issue for everyone so next they went to a 22# spring and it made thing better for a few more folks but still not 100%. Now they're up to a 25# spring, which is what they ended up sending me.

Interestingly enough, in messing around with mine while waiting for the new spring I did find part of the problem - though I still can't explain how it makes a difference.

Initial firing pin travel measurements off the back of the bolt shroud with the 16# spring were as follows:

Cocked (bolt up) = 0.128"
Cocked (bolt down) = 0.118" (decocking 0.010")
Decocked (fired) = 0.312"
Firing Pin Travel = 0.194" (way too short)

The discussion over at SH brought up the 0.035" gap between the bolt sleeve and bolt shroud and that if you screw the shroud all the way on until it stops against the bolt sleeve it stops about 1/4 turn short of being lined up where it needs to be. So, to get it lined up one has to unscrew it 3/4 turn resulting in that gap. Reassembling the bolt in that fashion - unscrewing the shroud 3/4 turn with the FP spring still compressed with the washer and screw, I would repeatedly get the numbers above.

Thens Is gots to thinkins (said in my best Curly Dan voice)...

With the shroud screwed all the way on and bottomed out on the bolt sleeve the one cocking lug and ramp are maybe just 15-20 thousands past lining up. What if rather than backing the shroud off the full 3/4 turn I just back it off enough to align the lug and ramp? So I tried that and naturally the shroud was about 270-degrees out of the orientation it needed to be in. I released the FP spring tension and then muscled the shroud around to it's proper orientation and took measurements again.

Cocked (bolt up) = 0.085"
Cocked (bolt down) = 0.075" (decocking 0.010")
Decocked (fired) = 0.295"
Firing Pin Travel = 0.220" (much better!)

So where did that 0.026" of extra firing pin travel magically come from? Assembling the bolt both ways the gap between the shroud and bolt sleeve is consistent at 0.035" so everything is in the same place, so explain that difference. I can't!

Took the rifle back to the range and of my 45 remaining rounds I had loaded up all of them fired on the first strike except two. Didn't get any pressure signs with any of the loads - not even from the 20 rounds loaded with 40.0 grains of powder, so I suspect I may have been getting cold fires with this rather light FP spring. My chrono is on the fritz so I have no velocity numbers to verify.

Naturally a 36% increase in spring rate in going to a 25# spring also means there will be a significant increase in bolt lift as well, and the light bolt lift with a 60-degree throw was the key selling points of the Nucleus action for myself and many others. Not real happy that I have $900 in an action that has a bolt lift almost as heavy as a factory Savage and far heavier than a T&T'd Savage that I could have been into for 1/3 to 1/2 the price.

Just to note, with the new 25# spring now in place the measurements are pretty much identical (+/- 0.001") to the second set above.

I may spend the $10 and order the 19# spring to lighten the bolt lift and hopefully still have 100% reliable ignition.

Weather has turned cold and nasty again so not sure when I'll get out to shoot it with the new spring. Loaded up another 50 rounds - 10 each at 38.0, 38.2, 38.4, 38.6 and 38.8 grains just to be on the safe side in case I was getting cold fires before.



On another note...

I've also come to the conclusion that all the people who rant and rave about how great the Greyboe stocks are wouldn't know a good synthetic stock if someone shoved one up their keister. Don't get me wrong, the Renegade I got isn't horrible, it just has a lot of flex in the forearm since there's no fabric shell or inner aluminum skeleton to give it any stiffness. When I first dropped the barreled action into the stock the barrel was free-floated. I left it on the workbench over night resting on a bipod and the next morning it was no longer floating. Sanded the barrel channel out a good bit and tried again - and again it sagged over night to the point it was touching again. Had to sand it out two more times before it finally stayed free-floated. Considering I only paid $400 for the stock and M5 bottom metal I can't complain too much. Cheapest M5 hardware is $160 so I'm only into the stock for $240. It's plenty suitable for a varmint gun, but definitely not something I would consider for a competition rifle.

I can also torque on the grip from the shooting position and cause enough flex to move the crosshair about 3.5-4 inches at 100 yards when on the bipod. Not good!
Very detailed write-up. I know you probably wouldn't like this, but have you contacted American Rifle Company to see what they can do?