My hornady reloading manual (7th ed.) says: min and max is 1.260 (180gr bullet)? Bought some ammo yesterday and measured them and the col is at 1.277?
I'm gonna start to reload 10mm soon, and was wondering why the min col is the same as the max?
Thanks
For reloading a manual will specify a minimum length. You should not load shorter as it can cause a spike in pressure. Longer is OK as long as it doesn't impede function.
One of my 10mm's doesn't like certain kinds of bullets seated out longer than 1.250". And I am not sure my mags would fit a 1.277" COAL.
My reloading manuals have COAL's as low as 1.240" for some loads and as long as 1.260" for others.
The Minimum can be shorter than or longer than the normal 1.2500" which is the SAAMI standard. 10mm was designed as a taperd flat nose design (Turncated Cone bullet) (also think of round nose bullets and Hollow Point designs where the nose is cut off). I work to get a the 1.250" for all of my 10mm loadings.
Bullets are seated long to allow the maximum amout of powder space when using heavy charges of slower burning powders that take up so much case volume. The magazines and feeding properties will also determine the longest COAL of a particular load. If using powders that can generate the maximum pressures/velocities without filling the total space the standard COAL is easily attained.
I will test some of my loads at longer COAL (1.260") as I work close to maximum loadings, then adjust the COAL closer to 1.250" looking to see if the pressure is increasing too much. As you shove bullets deeper into the casing, the pressure is greater due to the occupied volume. If pressures are acceptable I will work with the COAL at 1.250" for that bullet & load combination.
Some bullets like those Hard Cast, Wide Nose Flat Point bullets are being loaded shorter than 1.250", to about 1.240"-1.242" because of the short forcing cone transisition of some barrels(where if left long the bullets touch the forcing cone before they are fully chambered), also the tipping over angle as the cartidge enters the chamber can affect feeding, thus the shorter COAL improves feeding.
When used in revolvers there is usually more room for longer COAL, and less issues of feeding. Maximum length there is only hampered by cylinder designs.
Thanks for replying guys, I appreciate it. Also I'm a bit concerned about crimping. I pulled one of the bullets, and damn, I smacked the hell outta my puller. I damned near lost my breath trying to pull the bullet out. When it finally came out, I thought it was glued in or something but maybe it was just crimped a little too much???
(http://i45.tinypic.com/rvaeqs.jpg)
What ammo?
Wow that is a lot of crimp.
Quote from: Steve4102 on December 20 2012 04:25:29 PM MSTWhat ammo?
I'm curious to know what ammo maker and the specific load too.
When I did the commercial ammo pull downs, I did notice some crimped almost that bad, they were noted in the descriptions.
Over crimping can also raise pressures, damage the bullet or actually buckle the casing which can affect full chambering.
Plated bullets can suffer poor performance and the jacket can be shed in flight!
That is about what the Double Tap loads I have pulled looked like. Way over crimped IMHO.
Crimp on a 10mm should just flatten the flare back out, not swage the bullet.
Quote from: Steve4102 on December 20 2012 04:25:29 PM MST
What ammo?
Its actually reloads from a shop down the road from me. It was cheap, so I figured I buy a box and dissect them.
Quote from: sqlbullet on December 21 2012 03:58:12 PM MSTThat is about what the Double Tap loads I have pulled looked like. Way over crimped IMHO.
Crimp on a 10mm should just flatten the flare back out, not swage the bullet.
I've seen the same. Can't imagine why anyone is applying so much crimp to 10mm either.