...and now for something a little bit different.
- Thread starter robin2y
- Start date
I'm taking this project pretty slowly and any advice along the way is greatly appreciated. McCaan has done 458 win mag, so not at all worried about receiver strength, especially with post war italian. The op rod is the only real concern, especially since the one I'm using at the moment is the first generation small cut and don't want to open it up to the later diameter for history's sake.
I do have one of Pocketfisherman's adjustable gas cyl screws on right now (hence the older slot pattern); however, I've been wrestling with the math. The bullet weight is about 85% more; however, the cross sectional bore area is 40% more. Peak chamber pressures is similar. Powder weight will be a bit higher, perhaps 20-25% (from memory, so reserve the right to be off on this one). I've forgotten what the gas port diameter size is, but just have to pull the gas cylinder off to measure that one again. What will the pulse look like by the time the gas gets to the port? Might not be too far off in the end. Anyone running a 35 whelan? Oddly, I did talk to one barrel rebore guy, before getting this Walther barrel, and he was fine with 358 but did draw the line before tackling 366.
The tooling took a while to get in, more than the barrel itself!
I've got an unfinished forest laminate stock to go with this one and metal still needs to be park'd.
I do have one of Pocketfisherman's adjustable gas cyl screws on right now (hence the older slot pattern); however, I've been wrestling with the math. The bullet weight is about 85% more; however, the cross sectional bore area is 40% more. Peak chamber pressures is similar. Powder weight will be a bit higher, perhaps 20-25% (from memory, so reserve the right to be off on this one). I've forgotten what the gas port diameter size is, but just have to pull the gas cylinder off to measure that one again. What will the pulse look like by the time the gas gets to the port? Might not be too far off in the end. Anyone running a 35 whelan? Oddly, I did talk to one barrel rebore guy, before getting this Walther barrel, and he was fine with 358 but did draw the line before tackling 366.
The tooling took a while to get in, more than the barrel itself!
I've got an unfinished forest laminate stock to go with this one and metal still needs to be park'd.
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First AR barrel I made, I researched gas port diameters, then drilled the port smaller. Proceeded to open the port gradually, step by step with numbered drills until I had achieved proper function. When the rifle initially started working, it would not open enough to feed; then it would not open far enough to lock open on the empty magazine; finally it ran like a clock.
You might try the same. If the port is too small, there will be insufficient gas. Keep opening the port until you have function. If you go too far, the screw could be used to bleed off pressure.
You might try the same. If the port is too small, there will be insufficient gas. Keep opening the port until you have function. If you go too far, the screw could be used to bleed off pressure.
- Location
- Aaaaaadmontin AB
I guess my question is 'why'?
A Garand in .35 Whelan would be a useful baseline for reference. Shuff's Parkerizing offers a .35 Whelan conversion and they might give you some info on gas port size for it. The .35 Whelan works well with the well established Garand propellants (IMR4064, IMR4895, H4895) which generate the correct port pressure in a standard .30-06 Garand. From what I see on the 9.3x62 the ctg works OK with these propellants as well.
The larger diameter bore would allow a greater accumulation of propellant gas prior to the bullet exiting the barrel and create a different pressure pulse at the gas port, so the port size would need to be varied to some extent. Even the comparatively simpler .308/7.62 conversion needs a larger gas port. Setting up an adjustable gas plug to vent gases and get proper functioning with heavier bullets is always an experimental proposition.
I wonder if the ctg case radial dimensions will require any internal modification to the receiver to get proper feeding? As you mention, the strength of the receiver will not be a problem as long as chamber pressures are kept within parameters. The Garand receiver ring is quite massive compared to bolt guns which are adapted for the 9.3x62. The weak point is the operating rod. They can take a beating with heavier bullets in a standard .30-06 rifle. You are pretty much off in the blue on this project and it will be interesting to hear how it works out.
The larger diameter bore would allow a greater accumulation of propellant gas prior to the bullet exiting the barrel and create a different pressure pulse at the gas port, so the port size would need to be varied to some extent. Even the comparatively simpler .308/7.62 conversion needs a larger gas port. Setting up an adjustable gas plug to vent gases and get proper functioning with heavier bullets is always an experimental proposition.
I wonder if the ctg case radial dimensions will require any internal modification to the receiver to get proper feeding? As you mention, the strength of the receiver will not be a problem as long as chamber pressures are kept within parameters. The Garand receiver ring is quite massive compared to bolt guns which are adapted for the 9.3x62. The weak point is the operating rod. They can take a beating with heavier bullets in a standard .30-06 rifle. You are pretty much off in the blue on this project and it will be interesting to hear how it works out.
Of course. It's still a Garand.
will it physically fit 9.3x62 rounds? lol
why not
Exactly!
Looking forward to following this project.
Ted
