necking 404 Jeff to 375 Ultra

Ray Boone

May 21, 2015 20:08

Seems 404 brass is easier to get than 375 Ultra. Since the Ultra is a necked/blown out/rebated 404, what problems should I expect, or equipment other than Ultra dies are involved in the change.

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  COMCHIEF

  May 22, 2015 05:00

  May need to turn the case necks depending on how close your chamber tolerances are. Had issues shooting 284 win necked down to 6.5 and using them in a match/target chambering. Case neck was bit too thick on several cases and had no place to go when the round was touched off. Blew out the primer pocket. Pretty scary. Now I measure and turn all my "necked down" brass and turn the necks.
  
  Cheers,

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  charliemeyer007

  May 22, 2015 05:57

  http://en.wikipedia.org/wiki/.375_Remington_Ultra_Magnum
  http://en.wikipedia.org/wiki/.404_Jeffery
  http://en.wikipedia.org/wiki/.300_Remington_Ultra_Magnum
  
  Wow I looked at like 20 places for 375 RUM brass, nothing.
  
  Midway shows Doubletap loaded ammo $90 a box of 20 in stock vs say $110 box of 100
  
  2 boxes here http://www.GunBroker.com/Auction/ViewItem.aspx?Item=483910753

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  nononsense

  May 23, 2015 15:05

  Ray B,
  
  These folks have bulk 300 RUM PRIMED brass in stock:
  
  http://www.dlsports.com/fed_300_rum_brass.html
  
  $2.00/pc with a 500 piece minimum purchase. Get some buddies together who shoot the RUMs and buy some of these.
  
  Otherwise:
  
  Neck the brass down in two steps
  
  Resize up to .375 and measure the diameter of the neck
  
  Turn necks to clearance diameter of your chamber
  
  Load with fireforming loads and shoot.
  
  Best.

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  Ray Boone

  May 27, 2015 22:24

  I've found sources for 300 Ultra, but need 375 Ultra. If I get 300 Ultra it's a two step necking process. the 404 can be reduced to 375 in one step but then needs fire forming. either way it means case forming with occasional loss of case due to splits or collapse. I guess when the ammo companies get caught up with all the govt contracts and 22 lr, they may run a batch of 375s- at least that's the hope.

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  Ray Boone

  June 07, 2015 11:33

  UPDATE:
  
  
  
  In photo are L to R:
  1. R-P 375 RUM Sized
  2. R-P 375 RUM loaded with Sierra 350 gr MatchKing
  3. Norma 404 sized/Fireformed to 375 RUM with Sierra 250 gr GameKing
  4. Norma 404 with shoulder collapsed while sizing to 375
  5. Norma 404 factory brass
  
  Forming from 404 to 375 followed normal expectations/processes with following exceptions.
  1. the shoulder angle of the RUM case, 30 degrees was too sharp to neck the case down- the result was the collapsed shoulder. An less sharp angled die was needed. With the shoulder angle reduced to 15 degrees the cases formed to 375 without problem.
  
  2. Reduction of the necks from .423 to .375 resulted in neck thickness too tight for the chamber and inside reaming of a few thousandths was needed.
  
  3. The 404 rim is not rebated (as is the 375 RUM) so if you are using a rifle with a claw type extractor (I was using a Winchester Model 70) make sure that when loading the rifle that the rim is engaged with the extractor and not being pushed in front of it. There is insufficient clearance for the extractor to snap over the rim when chambered- the result is a broken extractor.
  
  4. I'm not sure of the tolerances on enclosed bolt face actions- there may not be room for the full sized rim and it may need to be turned to fit.
  
  5. And lastly, the diameter of the 404 case ahead of the extractor groove is minutely narrower than the RUM case. The result is a slight bulging ahead of the web. The bulge seems to be more of a cosmetic issue than safety since if the pressure is sufficient to degrade the integrity of the case the primer pocket will have also opened with similar results.
  
  So while the results are mixed, at least we 375 RUM shooters are not subject to the whim of market attorneys and cost accountants at Remington.

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  charliemeyer007

  June 07, 2015 13:27

  Nice report. Perhaps opening up 300 RUM cases would fit better with less work. An 8mm and a 357 buttons would be 2 easier transition steps.

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  Ray Boone

  June 07, 2015 20:18

  And as soon as Nosler has a run on the 300 RUM, I'll place an order. I'm on their list to notify when they are available. I have two tapered expanders for them, one goes from .3 to .33, the other is from .33 to .375. Agreed it will be less trouble; but then the 404 does provide another means of getting working cases when the original manufacturer reneges on their obligations.

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