.470 Nitro Express Trim Length?

[deewayne2003]

Gentlemen,

Can someone tell me the proper length to trim .470 Nitro Express brass to?

The cartridge diagram I have shows 3.25" would be the correct length, but I am noticing different lengths shown depending on the publication.

Thanks,

 

[ve7poi]

Mine all trimmed to 3.24” after once fired brass arrived to make the whole batch same length.

 

[meigsbucks]

I checked a variety of manuals and got these lengths:
Hornady: 3.240“ trim / 3.250” max
Barnes: 3.250”
Swift: 3.240” trim / 3.250” max
A-Square: 3.250”
Norma: 3.250”
I hope this helps you.

 

[Rem700stw]

I am curious what tool you are using to trim the 470 brass.

 

[deewayne2003]

I am curious what tool you are using to trim the 470 brass.

I am using a Lee Deluxe Power Quick Trim with custom ordered trim die.

https://leeprecision.com/deluxe-power-quick-trim.html

Combined with a custom ordered quick trim die.
https://leeprecision.com/rifle-quick-trim-dies/index2.html

The custom quick trim die - you have to send them a sized casing & a dummy round(bullet seated to length with NO primer or powder)

You also have to fill out a diagram of a sized casing and then wait 8-12 weeks and they will send you the large 1&1/4" die.

 

[fourfive8]

Recommended trim length for any cart is about .010" shorter than chamber. NO matter what the manuals say, it is the rifle's chamber that determines best or critical trim length. Obviously most modern chambers should be within pretty tight standard specs but you never know. If you can determine YOUR rifle's chamber length, the most practical trim length, all around, is about .010" shorter than chamber length. Also, with single shots and doubles it's pretty easy to do a "plunk" test to check for adequate sizing and checking for being within length limit. The last thing you want to do is to shoot a max load with a case that is even a smidge too long! The other side of the case length coin is that if cases are too short, eventually a carbon ring can form in the freebore area just in front of the case. Not a very good condition either- not really dangerous but at some point can impede chambering and may hurt accuracy.

You can make your own chamber length gauge with even simple tools like a drill press, small length of brass or mild steel, hacksaw and file. All it is is a two diameter mild steel (or brass) plug that is placed in a partially sized case that has been trimmed back to accommodate the length + plug after it is inserted in chamber. The plug is snug but not overly tight in neck. The plug is pulled out well beyond normal chamber length. The plug gauge test case is carefully chambered and extracted. The chamber length is then directly measured from end of plug to base of case. The forward portion of the plug is turned to about the diameter of the case mouth with bullet. Here's a pic of a simple chamber length gauge inserted into a case.

 

[deewayne2003]

Thank you everyone for your help....

@fourfive8 ..... The chamber gauge is a great idea!

Do you know where I could go about getting those brass or steel plugs for .375 H&H, .416 Rigby & .470NE?

 

[fourfive8]

Thank you everyone for your help....

@fourfive8 ..... The chamber gauge is a great idea!

Do you know where I could go about getting those brass or steel plugs for .375 H&H, .416 Rigby & .470NE?

I have bought some from Sinclair and have made some. Quite a few choices at Sinclair Intl--- shows up to 50 cal but I don't see a 470. I think the neck diameter of the 470 is about .500". So a decent quality 1/2" diameter bolt or rod stock cut to about 1/2" long then the smaller diameter turned to about .475" diameter for a snug slip fit (not tight) in partially sized neck would work.
https://www.sinclairintl.com/reload...s/sinclair-chamber-length-gage-prod32925.aspx

Since these are one time use type dealeos (unless you have a dozen 470 doubles laying around ) most anything could be made to work. You could take (cut with a Dremel cutoff wheel) a 1/8" to 1/4" section off a 470 case neck and epoxy it to the base end of a 470 bullet. Make sure the diameter matches the loaded neck diameter of a regular round. File or turn the base end flat, true and flush for an accurate reading. Trim a 470 case to about 3/8" shorter than normal...and you already have a partially shortened case already that was the donor for the 1/8" - 1/4" ring. (Two birds with one stone!) Insert the bullet backwards into shortened case, chamber test round- measure length. Necessity is the mother of invention...

 

[limpopo]

Trim mine to 3.24" per Hornady manual. Use a Forster Classic 50 trimmer for a number of years, does the job and no complaints.