The UK's Finest Independent Forum for Shooters and Gun Owners. Est 2010.

Hi!

How many of you regularly use a crimp die (Lee or otherwise) and if you do have you done any testing to see what difference it makes to group size or muzzle velocity (Speed and consistency) ?

I never use crimp unless it is for tube magazine fed guns or revolvers. Taper crimps can help feeding in some auto rounds

If you need to crimp for consistency then there are other problems in your load that the crimp is but a bandage for.

With good consistent case neck thickness/tension and consistent bullet diameter then crimps are an unnecessary evil that will just over work your brass.

Crimps have their place in things that will get hard usage like military rounds and automatic feed firearms but for the majority of our shooting fortunately does not need it.

Thanks for that, I did wonder what it would do to the brass.

I have done a fair amount of testing with crimped and not as I was curious. My results showed no appreciable difference in velocity or consistency, but then all I was doing was crimping "quality" ammunition anyway. There was however, a slight difference in accuracy, which worsened when using the Lee die on bullets that didn't have a cannelure.

I don't bother crimping unless as Adam says a tube magazine or an LBR. However, I would crimp in a straight pull. Even though that type of rifle is a "bolt action" ostensibly, the manual action is still replicating the semi auto movement and the action can be quite violent because of the return springs and the feed angle from a box magazine.

I use the crimp die on all my hunting ammo, and as it is sub MOA at 100m I am happy enough,
I have read a lot about the Lee FCD and it would appear that people fall into 2 main camps, those that wouldn't crimp anyway, and those that claim the crimp reduces the speed variation in their rounds.
I cant say I've bothered to chrono that many rounds, just enough to confirm velocity of a charge, on the other hand I crimp my hunting ammo based on the grounds that it is likely to be loaded/unloaded several times in its life and a crimp to my mind is a way of reducing the chance of the bullet being seated deeper in the process (may not be necessary but as I say accurracy is fine so what the hell )

I always use a Lee F/C die when loading cast bullets.

I adjust it to just take out the case neck flare, which is necessary to create a lead for flat based cast bullets to seat.

ukrifleman

ukrifleman wrote:I always use a Lee F/C die when loading cast bullets.

I adjust it to just take out the case neck flare, which is necessary to create a lead for flat based cast bullets to seat.

ukrifleman

So do I, I'm still new to cast bullets and found my loads for my smle were all over the place vertically, the crimp shrank the group appreciably.

I use the Lee FCD on all my rifle ammunition, though the crimp applied is a light one.
I've seen a slight but consistent increase in accuracy viz the vertical component in groups.
I really need to dig out the chronograph & see if there is any real reduction in velocity spread.

As I have said if the crimp "improves" your groups it is because of other issues in your load, get your components, loading process and dimensions right and there is no need to crimp for accuracy.

dromia wrote:As I have said if the crimp "improves" your groups it is because of other issues in your load, get your components, loading process and dimensions right and there is no need to crimp for accuracy.

Or perhaps for all but super critical applications it saves on going to the extremes of case neck turning.

My components are fine, as is my loading process & the only variables I'm addressing using the Lee FCD are neck tension & concentricity.
Empirical evidence has demonstrated an improvement without major expense & for my applications (hunting mostly), that'll do just fine.