Armory Sponsor
Posted: 6/20/2009 10:24:30 AM EDT
| I was preparing a large batch of brass yesterday and had plenty of time to think about what I was doing on each step. The mystery is why trim to 1.75 when the spec is for 1.76. Why not trim to 1.76 each time? I suppose trimming to 1.75 could mean you could go two or three loadings without trimming, but I lke to trim both to length and to make sure the case mouth is square. Anyone know where the 1.75 came from? |
|
1.760" is max length.
If case length is 1.760" or shorter after sizing trimming is optional, if over 1.760" the case needs to be trimmed to 1.750". If the case is long it may cause problems with chambering. It's common practice to trim back .010" from max length, hence 1.750" trim to length. |
|
I have some once fired LC 5.56 brass that I trimmed to 1.757. I found that it didn't stretch that much after the 2nd firing. In fact it was still under the 1.76 max. This was with a 25.1 grn load of H335. Personally I like the longer trim length I feel it gives me a better crimp on the cannelure. But some of my ammo gets run in F/A guns so it all has to be up to par for that.
ETA I use a Dillon case gauge and to get good readings with it I have found that I'm getting 1.53 to 1.55 on my caliber. I think to get the cases back down to 1.75 I would run the risk of either falling below the low shelf on the head space end or going too short at the neck and having the crimp too low on the cannelure or below it. ETC sp |
Armory Sponsor