Neck length for wildcat

[ShadowAviator]

I was considering making a wildcat in .375 caliber. I know the old rule of thumb was that the neck should be about one caliber length.

However, looking at my 375 Raptor, the neck length there is about .270" and I believe the 375 Ruger is around .300".

My wildcat will be on the shorter side so I was thinking of copying the 375 raptor's neck length, but was worried that was too short.

So would a little over .270 be enough or would it be better to go .300 or maybe even longer?

The bullets I am wanting to use are anything from the 235gr Speer to the 270gr LRX. The cartridge OAL will be kept similar to the 308 and 6.5 CM, meaning about 2.825".

Any help is appreciated.

 

[tobnpr]

Suggest you contact Manson, JGS, or whomever is going to grind your reamer.
That's what these guys do for a living.
Custom reamer should also be designed around your intended brass/loaded neck diameter as well as freebore based on your loaded rounds. Since you're going custom- consider all the variables so you get it right the first time; it's a significant investment in both reamer and dies.

 

[FEENIX]

I was considering making a wildcat in .375 caliber. I know the old rule of thumb was that the neck should be about one caliber length.

However, looking at my 375 Raptor, the neck length there is about .270" and I believe the 375 Ruger is around .300".

My wildcat will be on the shorter side so I was thinking of copying the 375 raptor's neck length, but was worried that was too short.

So would a little over .270 be enough or would it be better to go .300 or maybe even longer?

The bullets I am wanting to use are anything from the 235gr Speer to the 270gr LRX. The cartridge OAL will be kept similar to the 308 and 6.5 CM, meaning about 2.825".

Any help is appreciated.

You should be fine with the .270" neck length.

 

[ShadowAviator]

Thanks for the info. I figured I would be okay with the .270" neck, but since I want this to run in a semi-auto, I want to make sure it will hold the bullet securely.

 

[Harry Knutz]

You want to be sure the boat-tail is at the shoulder neck junction when the bullet you use is seated and make sure the bullet is not seated past that area so as to avoid that area where the donuts form. Like this drawing.

 

[glock24]

Amen. Avoid the dreaded donut . . . and since avoiding it means loading the bullet up into the neck, a longer neck is really nice to have for both alignment and consistent neck tension.

I think the 6.5x47 Lapua case is a great example of this . . .

 

[tobnpr]

You want to be sure the boat-tail is at the shoulder neck junction when the bullet you use is seated and make sure the bullet is not seated past that area so as to avoid that area where the donuts form. Like this drawing.
View attachment 411749

Agree with the verbiage, but not necessarily the diagram. Easy for heavy VLD's to be seated to correct minimum depth, and still exceed SAAMI COAL. Depends on the bullet, and the chambering...

 

[ARlife4me]

If designed around 1 specific bullet then it's easy. I like loading beginning of bearing surface at the neck/shoulder conjunction when possible. Might as well use case capacity for powder instead of bullet. I like the caliber - 5 to10% for length, unless designing for heaviest/longest per caliber. Longer necks will keep up chamber pressure peaking earlier per same throat dimensions (free bore) when seating at same coal.