Building a 505 Gibbs on a PH action. 22" barrel, barrel band front sight and sling swivel (NECG). Action size is 1.505 at the barrel face. What dimension shank and muzzle size would you guys recommend?

I was thinking 1.450 shank with .830 muzzle in a sporter contour

If you want to save yourself some time, here's a 505 Gibbs on an MRC PH action, ready to go.

http://forums.accuratereloadin...1078981/m/6391067622

Already have the action and dies. Thanks anyway.

Biebs,
Do you have any info on the barrel on your gun? Like maker, twist, contour, etc?

Thanks

A no. 5 Douglas contour...I like a heavy 505, real heavy..even a bull barrel turned to specs.

Yes, it's a Lilja.

My factory MRC 505 is 1.325 ahead of the receiver for about 2.25 and sweeps to .810 at the muzzle, 24". It seems comfortable. Heavy enough for the ctg. without feeling like a fence post.

Thanks, Dan. That is what I was needing

This is what you need, a Dan Lilja No. 7 Sporter Contour with 1.350" breech diameter.

http://riflebarrels.com/barrel-contour-data/

The uncut cylindrical knoxform is 3.5" long.

Order it to finish at 26" so you have plenty to play with.
It will come 28" long with a saw cut about 1/2" back from the muzzle end.
It is .820" diameter at 28".
It is .850" diameter at 26" length of the blank: My measurements.





Of course, you will not want to flute the .505 Gibbs barrel, nor could it be done by Lilja unless the contour was much heavier.

But the weight of the barrels will be about identical for this contour in nonfluted .505 Gibbs and fluted .408 Chey-Tac:

The 28", uncut Lija No.7 Sporter barrel blank will weigh about 4.5 pounds for a nonfluted .505 Gibbs.
That is my prediction.

Chambering and cutting it shorter, taking off a little at both ends, crown and finish by turning/sanding/bead-blasting,
and you might end up with a 4-pound barrel as small as .830" diameter at the muzzle.
That is how my .408CT fluted barrel finished up, at 26" length and .830" muzzle diameter.
Leave more knoxform if you want it heavier.

Add extra weight for any barrel hardware add-ons (iron sights) and adjust for stock weight different from the walnut supplied by MRC.
At 2#10oz my stock came from Boyds/MRC with the visible crossbolts and Pachmayr Decelerator pad.
I added a 1/2" steel rod in the grip and pillar bedding.

The action weight is supposed to be 64 ounces, 4 pounds, according to MRC. I cannot remember actually weighing mine. Here is some old info:





4-pound barrel.
4-pound action.
3-pound stock.
About 11 pounds will be a good estimate for a functional, iron-sighted .505 Gibbs MRC PH.





This is the Boyd's walnut stock supplied by MRC to fit the PH, 2#10oz, before beddding and further reinforcement (pillars and grip bolt):



Wrist bolt, no limp wrist here:



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RIP,
Great info. Thank you very much. I'm going to run a laminate stock with an ebony tip. I'm guessing that the laminate will be somewhat heavier than the walnut. One of the forum members here is turning the stock for me from a blank.
I will be using the NECG barrel band front sight and sling stud, as well as the rear sight.

Which scope mount set-up did you run for the 408?

I looked at Dan's website and he does not list a .505 barrel groove diameter. Pac-Nor only lists a 16" twist on their .505 blank. I'm planning on running 600 grain bullets and I think I might want a little faster twist.

Forgot to add: My MRC 505 weighs 10.75 lbs.
Aftermarket irons only. I like it.

quote:

Originally posted by boltgun308:
RIP,
Great info. Thank you very much. I'm going to run a laminate stock with an ebony tip. I'm guessing that the laminate will be somewhat heavier than the walnut. One of the forum members here is turning the stock for me from a blank.
I will be using the NECG barrel band front sight and sling stud, as well as the rear sight.

Which scope mount set-up did you run for the 408?

I looked at Dan's website and he does not list a .505 barrel groove diameter. Pac-Nor only lists a 16" twist on their .505 blank. I'm planning on running 600 grain bullets and I think I might want a little faster twist.

Hello boltgun308,

WHAT! BIEBS IS CONFUSED ABOUT BARREL MAKE?
I would not have posted my Lilja .408 barrel fitted on an MRC PH if I knew Lilja didn't make .505 barrels.
Oh well, I cannot keep up with everything.

If PAC-NOR makes a .505 with 1:16" twist and a 1.350" diameter breech cylinder/knoxform, that would be great!
I see they also make a 1:20" twist .505 at PAC-NOR. Don't get that one.
Love those PAC-NOR's too!

Sounds like a good recipe for a .505 Gibbs you are cooking up.

Twist:

My CZ-USA factory .505 Gibbs has a McGowen barrel with 1:10" twist, the only twist McGowen offers in .505-caliber. Worked fine.
The McGowen 1.200" diameter breech cylinder/knoxform, however, is not what you need on a PH.
McGowen bore and groove:



C.I.P. standard twist for the .505 Gibbs is 1:406mm = 1:16"

Surely whatever you like between 10" and 16" would be fine for twist rate.

C.I.P. bore/land diameter is .494" (12.55mm), groove diameter is .504" (12.80mm)


Scope Rings:

The standard CZ 550 Magnum rings work fine if you just use a "front ring" on both the front and the rear integral base of the PH.
Slide the rear ring fully forward so that the end of the MRC integral dovetail groove acts as the recoil stop.
You will figure the finer points out when you have them in hand.
Use two CZ front rings on the rifle (one on rear base, one on front base) for a not-too-heavy, 1"-tubed scope.
Or you can use 3 rings for a heavy and long 30mm-tubed scope.
That long PH requires a long span of scope tube, not hard to find:



Here are two front rings on the front base, which is long enough to fit both.
Pushed all the way forward they act as a recoil stop in the groove too.
Torque those main mounting screws to 65 inch-pounds and the rings ain't goin' anywhere.
I replace the slotted-head main mounting screws with metric socket-head automotive screws.
Hex wrench in pocket, will travel, always tight:





Above is a scope-joke, but that HUGE 10-50X scope is easily replaceable with a Sightron 1-7x24mm Illuminated reticle, 30mm-tubed, straight-tubed scope, in 3 rings also.

Or use two 1-inch rings for the Zeiss 3-9x40mm:



It worked well, really, I just started flinching after the first three shots with .408/370-grain GSC HV's.
Notice how I yanked the trigger worse on the fifth shot than on the 4th shot:



Sub-eleven pounds dry weight is pretty light for a .408 Chey-Tac!
Muzzle brake coming up!

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I appreciate the huge amount of info along with the pictures. You answered a lot of my questions.

Thanks again

boltgun308,

My pleasure.
I see that I had the ringtop on the rear ring above incorrectly installed.
No worries, I never shot it with that monstrosity on it.
That scope now resides on a 6.5 Creedmoor Ruger American Predator, still accurate.

Back to barrels:

PAC-Nor will make you a 1.35"-diameter barrel, instead of their usual 1.2" diameter, for a mere $25 extra, IIRC.
They can contour it however you like.
They have some nifty muzzle brakes there too ...









Their thread protector is different too, not unpleasant in appearance:



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