Green Dot in .45 Colt effected by level of crimp?

[Southern Shooter]

I am just starting to explore using Green Dot in .45 Colt. Today, I loaded 7 grains under a 255 grain boolit. Out of my 5 1/2" Uberti velocities were in the very low 800's FPS. From reading of other's experiences with Green Dot and .45 caliber boolits of this weight I predicted hitting around 900 FPS from this gun.

My question is: Using Green Dot, does a weak/light crimp cause any issues like loss of velocity or erratic velocity?

Thanks

[DougGuy]

Well, anything that is inconsistent will cause changes in pressure, velocity, and also point of impact. This could be varying case lengths which would give varying COA measurements, or cause the crimp not to align with the crimp groove, and all these little changes will have an effect. Consistent neck tension is probably the greatest aid to good ignition, simply by virtue of it giving the burning gases time to ignite well before there is enough pressure to overcome the force of inertia and cause the boolit to start moving. Crimp works WITH neck tenson, and unless you are crimping heavy for caliber boolits over large charges of slow burning powder in magnum loadings, a moderate roll crimp should work well but not enough crimp can cause inconsistent ignition because it makes it easier for the boolit to pull crimp and start moving which increases the case volume under the boolit and there you have a major culprit right there, that causes extreme spread to be excessive.

This would be true no matter what powder you use. I guess some powders would be more affected by small changes in how the boolits are assembled than other powders but I would expect the faster burning a powder is, the more the inconsistencies in how the ammo is assembled would affect it.

[bouncer50]

My question is the load of green dot your using accurate. Then i would not really worry if it not going 900 fps. I have 5 pounds of green dot a guy gave me. The load i am using i not sure how fast it going but it very accurate. I also use it in my 45 acp and i happy.

[shooting on a shoestring]

SS Green Dot is a pretty good choice for your application.
Fas as crimp affecting your velocity, yes it can have some affect. I doubt 100 fps worth though.
Some guns are faster some are slower due to deminsions of the guns.
Also a big factor is how much case volume there is under the loaded boolit. This can be controlled somewhat by seating depth. The less space, the more velocity all else being equal.

like DougGuy, I wouldn't worry about velocity so long as it's not approaching either extreme. If the load shoots well, well I'd shoot it. If you really want to hit 900, work up to it. Probably won't take much more powder to get there. Or play with seating depth. Often decreasing case space makes extreme spread of velocity get smaller.

Also so uniform neck tension is a big player in uniform velocity.

Enjoy. Green Dot should work well for you.

[C. Latch]

What's your cylinder gap? I actually shoot a fair bit of GD in my .45 colt but I haven't chronographed most of those loads.