While researching various 338ctgs for my next long range build I am interested in something like this. There exists already a 338 on a 505Gibbs, but I fear too much modification to the action I have in mind(sako m995).

Andy

Basically it depends on the application...

Ask youself to what extent do you want to modify your prefered receiver, then work through the problems...if you want to wildcat then you want to exclude all the obvious and documented problems the pick the easiest(less costly) solution...or just throw money at the project to get what you think is the "optimum"...or ANYWHERE IN BETWEEN.

Feeding problems with the rebated rim of the Jeffery is well documented in DG rifles...no problems with push feed/single shot rifles...so it might not be a problem at all.

The point of diminishing returns raises it's ugly head...bigger cartridges(larger volumes) requires an escalating amount of slower and slower burning powder which causes more recoil and less velocity, percentage wise...velocity increases very slowly while powder amounts increase very quickly.

AND...you might just end up with very little added velocity but require a larger powder amount just to equal the velo of the smaller, more efficient and powder friendly round.

Stepping up in caliber also increases the BC of the longer, heavier bullets but also has it's attendent problems...which means requiring a lower velocity to have the same drop over distance.

That 375 cal 370 gr RMB G1 at .926 is mighty tempting. If you need to rebarrel to get the length, you might as well go up in caliber. (Just a thought)

Personally, I have no problems with using the Jeffery case as the bolt face enlarging is/might be the least of your problems.

I would pick the 500 AHR case over the Jeffery case tho'.

I'm guessing you're at looking/have a TRG-42 in 338 Lapua or 338 WM. In eigher case I would go with the Lapua round based action as either the AHR, Jeffery or the Gibbs rim sizes don't require much of a bolt face regrind. Yes/No??

Use a 30 plus inch barrel for certain...to get every last bit of velo out of your powder load.

And BEFORE you do much in the way of tossing money around...get yourself QL and spend a few weeks crunching numbers and putting together a dossier of data.

Lots of people like to dream about their "Ultimate Wildcat" but very few spend the time to actually work out the details and costs...I need to hit the Lotto to put all my dreams into reality...

Luck

The rifle is currently chambered for 375H&H. I have explored the options of 338 RUM, Edge,Lapua, Allen, and Extrema. I find the Gibbs case way beyond ridiculous. Barrel I was thinking Broughton 32-34in. I have copious amounts of H1000. Honestly I hadn't given much thought to the .375 caliber, but that may well be an option worth pursuing. Thanks FB

Andy

This is a big one. The same case capacity as the 338/378 Wby.

The Gibbs was developed back in the day with the available powders to get the biggest with the mostest...no different than today's 600 and 700 offerings.

The AHR has about 145 gr plus H2O volume and the Gibbs has about 175 gr H2O volume with a 0.635" rim...slightly larger than the Rigby and AHR.

One thing about using the Gibbs case, full length or shortened, is you get equal to or larger case volumes for equal case lengths than the smaller cases and it is relatively easy to accomplish...same thing as engine...no substitute for cubic inches.

I designed my 510 Makatak around BOTH the Rigby and Gibbs cases for my tang Ruger(cut the Gibbs rim down to Rigby rim size) and had no problems feeding two down...but to get 3 Gibbs down made for a much larger coffin box addition...plus the dies were about 30 bucks more not to mention the brass cost and availability.

There's something deep down in my gut that stirs when I hold a large cal, large case cartridge that doesn't happen with the "little stuff".

Luck

This has been done.
Look up 338 Voschol.
http://www.sabirifles.co.za/calibers.htm

There it is...in todays world and with todays CNC machinery, wildcats proliferate faster than viruses.

Many of them never get added into data bases of any kind.

Luck