Maximum case length.

[ssphunter]

Good day.
Just wondering if anyone can tell me how to figure out the maximum case length a person should trim their brass to in a wildcat cartridge like the 7mm/300 win mag.

Thanks in advance
Mike

 

[jimbires]

here you go . I use these . you have to take a piece of brass and trim the neck way short . so if you have a piece of brass ready for the scrap bucket save it for this tool .

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[ssphunter]

here you go . I use these . you have to take a piece of brass and trim the neck way short . so if you have a piece of brass ready for the scrap bucket save it for this tool .

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237 SINCLAIR INTERNATIONAL Products For Sale Up To 91% Off including Reloading, Tools & Cleaning, and Gear.

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Thank you

 

[fguffey]

Just wondering if anyone can tell me how to figure out the maximum case length a person should trim their brass to in a wildcat cartridge like the 7mm/300 win mag.

Necking the 300 Win MAG neck down to 7MM will lengthen the neck, I know, reloaders claim the neck gets thicker and or thinner when necked up and or down. And then there is the 'think about it', the neck on the 300 Win Mag is short, there is no disadvantage to a longer neck.

SO? I suggest you make an attempt to determine the length of the chamber from the end of the neck to the bolt face. there has to be something wrong with my method and or technique because no one does it. I would take a longer case like the 300 Weatherby and form the case to 7mm300 Win Mag. I am lucky because I can not move the shoulder back meaning all of that extra case/brass has to go out the front. when that happens the newly formed case neck gets longer, when I want to know the length of the chamber I start trimming the neck of the newly formed case until it chambers without turning the mouth of the case in to a crimp.

And then there is the length of the chamber from the beginning of the rifling to the bolt face. I want to know where the rifling is located because I am the fan of the bullet jump, I want my bullets to have that running start. It makes me nervous when the bullet is setting against the rifling when I pull the trigger.

F. Guffey

 

[MagnumManiac]

I run 4 300WM's, all have .040"-.045" longer than 2.620" from the boltface.
When trimming a wildcat, general rule of thumb is to use the parent cases max case length and trim back .010" from this.
I do it differently, I measure the chamber length, then allow the cases to grow and trim .010" shorter than that measurement in my hunting rigs and, in my comp guns I run them .005" shorter to try and eliminate the dreaded carbon ring.

Cheers.

 

[Mram10us]

I ran 2.610" (saami minus .010") in my 7-300win mags. Both shot well. Good luck. To answer your question, go with saami and adjust based on the shortest piece as long as you understand what you're doing

 

[ssphunter]

Thanks for all the replys.

 

[25WSM]

The Sinclair guages work great. I make my own but they look the same. Not all reamers make the neck Sammi spec. It's good to know exactly how long it is. My 30br reamer had a shorter neck by .020 so that after forming you can trim them all the same length. If you don't verify your length it's just a guess. A little too long will cause all kinds of accuracy issues as well as higher pressure. The guages are inexpensive and can be used over and over.
Shep

 

[ssphunter]

Thanks again
one more question if I may,
Everyone mentions SAAMI specs but I can not find anything on their site that relates to the 7mm/300 win
what am I missing?

 

[243winxb]

http://bulletin.accurateshooter.com...-chamber-length-with-home-made-modified-case/ This method works. Deduct .010" from the maximum chamber length, for safety, when trimming brass.

Wildcat (7mm/300 win) are not on SAAMI, only adopted rounds made from USA factories.

 

[Mram10us]

http://bulletin.accurateshooter.com...-chamber-length-with-home-made-modified-case/ This method works. Deduct .010" from the maximum chamber length, for safety, when trimming brass.

Wildcat (7mm/300 win) are not on SAAMI, only adopted rounds made from USA factories.

I meant saami for the parent round

 

[ssphunter]

I meant saami for the parent round

Thanks again everyone.

 

[J E Custom]

I would recommend that brass should be trimmed a minimum of .010 thousandths shorter that your chamber, and a maximum of .030 shorter than the chamber. Sammi gives you the recommended trim length of SAMMI cartridges but that doesn't mean that your chamber is that length, so first measure the chamber length for case length and decide where you want to be and trim. Some case designs grow in length each time they are fired so in those cases .015 would be a good start,

Remember, the bigger the gap between the case and the the actual chamber the better chances of
carbon build up so keep an eye on those case lengths that are near to the chamber dimension to prevent problems later.

J E CUSTOM

 

[jimbires]

the only way to know for sure is to measure it . for as cheap as the tool is , and how easy they are to use , it's a no brainer for me .