The age old crimp or not to crimp dilemma

[User00056]

Not a question really, more an observation. I recently bought a taper die and thought I'd give a few of my .308 reloads a light crimp to see how they perform. Hardly an exhaustive report, but I found it interesting to see how the group immediately tightened up when I fired the crimped rounds.

I was happy enough with the first group (rifle is a .308 Stutzen I use as my woodland rifle), but for the sake of an additional step that takes mere seconds I think it's well worth doing.

As I say, I just found it interesting.

 

[webley701]

Individual groups vary in size relative to the long run mean group size. For instance when using extreme spread as the measure, with exactly the same load / conditions you can expect individual 5 shot groups to vary by plus or minus 50% of that long run 5 shot group average. With 3 shot groups it’s more like plus/minus 75%.

Those two groups are sufficiently close to each other in size that it can’t be determined if the slight difference is anything more than normal variation.

You’d need to fire quite a few more groups before you can say with any reasonable confidence that crimping makes any difference. That’s not to say it doesn’t have an effect - you just can’t be sure yet.

 

[User00056]

You’d need to fire quite a few more groups before you can say with any reasonable confidence that crimping makes any difference. That’s not to say it doesn’t have an effect - you just can’t be sure yet.

That's valid, thanks. I was happy enough with the first group, and the second one is enough to give me confidence in the rifle for what I need it for in this case. Might be interesting to load a few more and repeat the exercise though, as you say

 

[stubear]

I like to crimp just for consistent neck tension and to hold the bullets firm - just a habit now really!

I also do a really hard crimp on .45-70 to stop the bullets getting pushed back into the case on a tube fed magazine.

 

[Heym SR20]

I like to crimp just for consistent neck tension and to hold the bullets firm - just a habit now really!

I also do a really hard crimp on .45-70 to stop the bullets getting pushed back into the case on a tube fed magazine.

ditto - a crimp makes the ammunition far more durable for everyday use.

 

[Acm]

I like to crimp just for consistent neck tension and to hold the bullets firm - just a habit now really!

I also do a really hard crimp on .45-70 to stop the bullets getting pushed back into the case on a tube fed magazine.

If i measure Coal on my 175grn .30-06 reloads when off the press that are a very consistent 3.38 inches. If I measure them after some have been in the magazine while I fire on the range or out stalking, I get 20-50 thou movement sometimes. I’ve never actually found it really affected group size but it sure as hell can’t be a good thing. A nice heavy crimp solves this. Guess it’s the same but even more so with your .45

 

[Jelen]

I tried crimping for my 6.5x55 some time ago and have to agree with the comments by Wesley 701 about group size. It did make obturation a bit better though.
The die i used was a Lee Crimp die and i was never certain as to how the die was set and how much crimp to apply, plus components were getting harder to source, so I gave up crimping.
I wonder if there is a better Crimp die out there?

 

[kenbro]

Individual groups vary in size relative to the long run mean group size. For instance when using extreme spread as the measure, with exactly the same load / conditions you can expect individual 5 shot groups to vary by plus or minus 50% of that long run 5 shot group average. With 3 shot groups it’s more like plus/minus 75%.

Those two groups are sufficiently close to each other in size that it can’t be determined if the slight difference is anything more than normal variation.

You’d need to fire quite a few more groups before you can say with any reasonable confidence that crimping makes any difference. That’s not to say it doesn’t have an effect - you just can’t be sure yet.

He pulled the one on the left, to be sure .
Ken.

 

[kenbro]

I like to crimp just for consistent neck tension and to hold the bullets firm - just a habit now really!

I also do a really hard crimp on .45-70 to stop the bullets getting pushed back into the case on a tube fed magazine.

You can get consistent neck tension if you use mandrels of the correct size for the tension you require.
Kb.

 

[kenbro]

An American’s perspective on crimping would interest me…….
Ken.

 

[Border]

I tried crimping for my 6.5x55 some time ago and have to agree with the comments by Wesley 701 about group size. It did make obturation a bit better though.
The die i used was a Lee Crimp die and i was never certain as to how the die was set and how much crimp to apply, plus components were getting harder to source, so I gave up crimping.
I wonder if there is a better Crimp die out there?

I think the Lee factory crimp die is the gold standard. Alot of FL sizing dies have a crimp feature although not as good as the Lee FCD. I have one for .308w but havent used it much so far.

 

[VSS]

He pulled the one on the left, to be sure .
Ken.

And there's probably at least another one under the strategically placed thumb.....

 

[Foxyboy43]

An American’s perspective on crimping would interest me…….
Ken.

An american has already expressed his opinion - “I crimp everything” - the late Dr Richard Lee, author of one of the best reloading books written and the founder of Lee itself. I follow his advice with every bullet.

 

[User00056]

And there's probably at least another one under the strategically placed thumb.....

You bunch of cynical buggers

 

[kenbro]

And there's probably at least another one under the strategically placed thumb.....

Yep, a 5 shot “group” would make sense.
Kb.

 

[User00056]

Yep, a 5 shot “group” would make sense.
Kb.

Not for a rifle that holds 4-rounds

 

[VSS]

Not for a rifle that holds 4-rounds

4 in the mag and one up the spout.

 

[User00056]

4 in the mag and one up the spout.

Why? What purpose would that serve?

Anyway, I'm not seeking anyone's approbation regarding the groups, so it really is a moot point as far as I'm concerned.

 

[kenbro]

Not for a rifle that holds 4-rounds

Mine only holds 1 round but I still shoot 5 if I’m testing.
I find my one shot groups are too good!
Kb.

 

[User00056]

Whatever. You two can argue black is white for all I care