9.53 Saturn, 375-416 Rigby Imp anyone shooting them?

Looking into a new build - I want to try a .375 without getting into the Cheytac/505 Gibbs family of cases.

Is there anyone shooting a 9.53 Saturn, 375-416 Rigby Imp or 375 AX? Any info on these cartridges would be appreciated.....thanks

I'm working on one but haven't got all the parts yet. I ordered a Stiller TAC338 and a Krieger 10 twist .375 barrel. Mine will be a .375 based on a .338 Lapua Imp. with a 35* shoulder.

IdahoCTD said:

I'm working on one but haven't got all the parts yet. I ordered a Stiller TAC338 and a Krieger 10 twist .375 barrel. Mine will be a .375 based on a .338 Lapua Imp. with a 35* shoulder.

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So it'll be like the 338 Allen Xpress? What bullet are you planning on shooting?

Like the 375 Allen I guess. I don't know what Kirby uses for a shoulder angle or shoulder diameter. I talked to Dave Kiff at PTG and he recommended a 33-35*shoulder and a .562 shoulder diameter. So I'm going to go 35* and .562. He said the 33-35* shoulder angle has been proven to be more accurate when he tested them than the 40*. I'll do a .338 version later too as I have 2 Stiller actions coming.

I intend to try the CE copper bullets between 300 and 330gr and I have 260gr Accubonds I can try also. It depends on how much CE wants to do a custom order but I might have them make me brass bullets designed after the copper bullets. So high BC but lower weight and higher velocity.

What twist and barrel length are you looking at running?

I just got my barrel Thursday. It's Krieger 10" twist 1.350" shank for 5.5" straight taper to a 1.1" muzzle at 28". It should make the rifle just under 16lbs. It has to be under 16lbs to hunt with here.

What velocity do you think you'll get out of the 330?

Hopefully around 3000fps or a hair more.

Just get a 378 wby. Same performance as the 375-416 in a factory cartridge. My 378 wby shoots the 350 grain smk's right at 3000 fps. It is a long range hammer. I am trying the new cutting edge bullets in it with the huge bc this summer to see what it does. The CE bc at 3000 fps with that heavy a bullet would make about as good a long range elk cartridge as there is in a carry rifle weight. With the new 375 bullets on the market the past few years this caliber is taking over the 338's as the best extreme long range elk caliber.

Weatherby brass can't hold a candle to Lapua or I'd build a .378 Weatherby Imp. like I did for my .30-378 Imp. years ago. I even have a decent amount of .338-.378 brass I could use but I'd rather buy Lapua. It's considerably cheaper and better. The cost difference just with the first 100 rounds of brass pays for the custom dies.

Doesn't Norma make 378 Weatherby brass?

From what I've seen the Weatherby brass can take a lot more pressure than the Rigby brass. Is this a concern? Does the 378 Weatherby have to have that extra pressure to keep up with the 375-416 Rigby Imp?

Hornady make 416 rigby brass which will take more pressure than the norma if your building a 375-416 imp

Norma makes Weatherby brass. It's rather soft though compared to Lapua. The .416 Rigby brass isn't designed to be pushed hard as it was a rather low pressure round when introduced. The brass today is tougher than the older stuff but it still won't compare to Lapua. The 338 Lapua is based off of the Rigby but with much stouter brass. So if your going to build off of something I'd use the .338 Lapua case rather than the Rigby. If you don't alter the shoulder/neck junction you can shoot the standard Lapua case necked up to fireform. The standard .378 Weatherby will compare well with the .375-338 Lapua Imp. but you won't get the case life (from what I've seen with my .30-378 Imp.) and brass is about 4.00 each compared to 2.50 for 338 Lapua.

Durak, Norma does make Weatherby brass. The Rigby imp in 338 and 375 holds slightly more powder than the 378 case but performance is very close. The rigby imp is slightly faster on average. For me not worth all the extra effort of forming the 416 Rigby brass when you can just get a 378 wby that you probably will not notice the performance diference with. I am having good success with mine at long range. At safe operating pressures the Norma/wby brass has worked well for 60+ years to set numerous 1000 yard world records and win untold numbers of matches. It has been tested succesfully on probably millions of big game animals worldwide during that period. Amazing now new keyboard comando kids come along with limited knowledge/experience trying to tell everyone Norma/Wby brass is no good.

The Lapua brass can perform at higher pressures allowing the lapua cartridges to perform slightly better than equal case capacity cartridges. However you must look at staying within the safe operating pressures of the rifle which haven't changed for the lapua. The 338-300 RUM vs the 338 Lapua is an example where the 338 Lapua may be the best choice with 338 lapua brass. However that does not mean norma/wby brass or remington brass for the 338-300 RUM is no good. I shoot well over 150 rifles from my collection with brass and bullets from all manufactures and when shooting I can not tell a difference which brass is in the chamber. Results and performance are what matter.

The 338-378 wby and 378 wby will outperform the 338 and 375 Lapuas at reduced loads with extremely safe pressures with excellent brass life. Some try to hot load the lapuas to unsafe pressures trying to get within 100-150 fps or so of the 378 case cartridges lessening the life of the brass. I prefer to shoot safe pressures with the 378 case. I have shot norma/wby brass since the 70's at safe pressures with good success. The safe pressures still allowed me to shoot faster and outperform lesser cartridges at higher unsafe pressures.

I guess it all boils down to performance when you get that once in a lifetime chance at an animal. I want the top performance and put every odd in my favor. I have taken hundreds of trophy animals by putting every odd in my favor. All through the years as people have admired my many trophy animals not one person has ever cared what brass I shot them with. Also as I was preparing for the shot for each never once was I concerned that I was shooting worthless wby/norma brass instead of the fantasticly great supperior superperformnce lapua brass.