Nosler 77 crimp vs non crimp

[masan]

Molon's excellent thread about Nosler 77 Custom Comps ( https://www.m4carbine.net/showthread.php?176382-Nosler-77-Grain-Custom-Competition ) spawned some discussion about crimping match bullets and effects on accuracy, so I decided to do a small and informal test to see how crimping 77 Nosler CC's affected a load that I use regularly.

Load Data:

Nosler 77gr Custom Comp
22.0gr Hodgon H322
Federal Brass
CCI 400
2.255 OAL

I do not crimp these, they are only used in one rifle. I do use a Lee Factory Crimp die to crimp loads for my other ARs.

For the test, I ran 10 rounds of this particular load through my Lee Factory Crimp Die and then fired two 10 shot groups at 200 yards using the rifle this load is always fired from. One ten shot group was the standard load, the other group was that same load but with a crimp.

The setup:
36073

Standard Load (no crimp):
36075

Crimped Load:
36076

Like I said, this was a quick and dirty informal test, mostly to scratch an itch caused by the discussion in Molon's thread. I thought that you all may be interested in the results.

note* I called one shot on both groups as a flyer, the one on the crimped target is pretty obvious, the one on the non crimped target is anyones guess

[HKGuns]

Thanks, as a participant in that thread I thank you for this data point. Good shootin' by the way too! When I have the time I will do something similar to this as well.

[rjacobs]

My guess as to why the un-crimped vs. crimped looks the way they do is that the un-crimped loads had fairly consistent neck tension and thus were a very consistent round. The crimped rounds had inconsistent neck tension which lead to inconsistent speeds which lead to your vertical stringing.

Group sizes appear to be fairly similar discounting the flyer from the crimped group, but its the shape of the group that interests me. At further distances the un-crimped rounds would probably still impact the target because of their consistency, where as the crimped rounds might miss high or low of the target as the vertical stringing becomes more dramatic.

[Molon]

Molon's excellent thread about Nosler 77 Custom Comps ( https://www.m4carbine.net/showthread.php?176382-Nosler-77-Grain-Custom-Competition ) spawned some discussion about crimping match bullets and effects on accuracy, so I decided to do a small and informal test to see how crimping 77 Nosler CC's affected a load that I use regularly.

Load Data:

Nosler 77gr Custom Comp
22.0gr Hodgon H322
Federal Brass
CCI 400
2.255 OAL

I do not crimp these, they are only used in one rifle. I do use a Lee Factory Crimp die to crimp loads for my other ARs.

For the test, I ran 10 rounds of this particular load through my Lee Factory Crimp Die and then fired two 10 shot groups at 200 yards using the rifle this load is always fired from. One ten shot group was the standard load, the other group was that same load but with a crimp.

The setup:
36073

Standard Load (no crimp):
36075

Crimped Load:
36076

Like I said, this was a quick and dirty informal test, mostly to scratch an itch caused by the discussion in Molon's thread. I thought that you all may be interested in the results.

note* I called one shot on both groups as a flyer, the one on the crimped target is pretty obvious, the one on the non crimped target is anyones guess



It's nice to see someone actually post pics of their 10-shot groups! https://app.box.com/shared/static/th42yciic1.gif








....

[rjacobs]

@Molon

Re-do those at 200 yards. Or I guess we can just divide those numbers in half.

Its dang good shooting at 200 yards.

[Molon]

@Molon

Re-do those at 200 yards. Or I guess we can just divide those numbers in half.

Its dang good shooting at 200 yards.

Crap! Stand by.

[Molon]

https://app.box.com/shared/static/fw4yj7oz2r3trbr926c2nxu9h9lbzqjv.jpg




https://app.box.com/shared/static/t7z3auufide5sl53g0sv85n6or17pf4m.jpg



....

[masan]

I am liking the positive responses, thanks all!

I will try to do some more of this at further distances to get some more data, if the wind dies down some time soon anyways (before deer season and deep snow anyways :))

[waveslayer]

I don't crimp my precision loads. tough to get perfect neck tension, unless you have the right brass thickness, etc. do you turn your necks

[markm]

I'd love to see what some Wolf/TULA primers would do in this equation.

[HKGuns]

I received, set up my crimp and crimped a few hundred rounds last night. We shall see how mine perform.

Do the rest of you have yours set up per the instructions of touching the plate + 1/2 turn?

[markm]

Do the rest of you have yours set up per the instructions of touching the plate + 1/2 turn?

I just watch the collet jaws from the top of the die when I run a round through to get it initially set. Then I look to see how much visible crimp is on the brass. I like just a very slightly visible crimp mark on the neck.

[HKGuns]

I just watch the collet jaws from the top of the die when I run a round through to get it initially set. Then I look to see how much visible crimp is on the brass. I like just a very slightly visible crimp mark on the neck.

Thank-you.

[Auto-X Fil]

I do it just like Mark.

Remember that you can set it to crimp a bit more of the case mouth than a normal crimp. This can help if your brass isn't all exactly the same length.