Taper crimping the .308win.

[Redhook]

I just started loading for .308 win match. I know that there are a lot of you who do not crimp the .308, but I feel better doing so. At least with my first batch of test rounds.

My question revolves around how much to crimp. I've got a redding taper crimp die, but most of the instructions that I've found out there talk about how important it is to crimp "just enough" or "the proper amount" without crimping "too much." So my question is, how much is enough without being too much? Is there an guide or way of measuring by which I should follow? Any other methods or suggestions would be appreciated.

-Red-

[MADISON]

If you want to taper crimp the.308win. or any bottle neck case you need to start with NO CRIMP on the case and work up in VERY SLOW/LITTLE turns of the die. I have crushed bottle neck cases with too much crimp.
MADISON

[Redhook]

MADISON,

Are you saying that I should keep turning the die down until I crush the neck and then turn it back to the last setting? That sounds a bit excessive.

-Red-

[Fatelvis]

No Red, just the opposite. Start with no crimp, slowly screw the die down, a little at a time (I`d say 1/16th turn) between each pull of the handle, until you get the desired amount of crimp. Although, if you have enough neck tension, you wont need a crimp. Good luck!

[MADISON]

Fatelvis is correct! Start with no crimp and tighten down 1/16th of an inch or less.

[Redhook]

I know that you guys are just doing this to mess with me!

Fatelvis,
How much is the "desired amount of crimp?" Is there some measure of the crimp that tells me that I have enough, but not too much?

I understand MADISON's instructions which are the same for resizing, seating, etc. Basically, start long and work down. The only difference is that I know when to stop with the other steps.

Let's put it this way. As the cartridges sit right now, I can push on the bullet and get it to move. I assume that I want to crimp tight enough to stop the bullet from moving. But, is that too tight? And how do I know when I've crimped it too much? I DON'T want to blow my rifle up.

The only other thing I can think of is to turn the expander ball of my RCBS comp die down .001" to .002" to make the bullet seat tighter. I'm just afraid to take off too much and the bullet gets scraped during seating.

Thanks
-Red-

[Poodleshooter]

How much is the "desired amount of crimp?" Is there some measure of the crimp that tells me that I have enough, but not too much?

That's why most of us would tell you that crimping isn't necessary with rifle rounds. The desired amount of crimp is reached when you can push a seated bullet against a hard surface with plenty of force, and see no change in the OAL afterwards. Crimp just keeps it from seating deeper in the case. If no crimp (just neck tension) achieves this goal, then you're ok!

[Jim Watson]

No amount of crimp can really make up for a bullet loose in the case neck. You need enough interference fit for 50 or 60 pounds of bullet pull. Crimp is just added protection against an automatic driving a bullet back.

Check your expander balls. My RCBS '06 is .3070", the .30-30 is .3068". So a thousandth under bullet diameter is about right. If yours are similar, maybe your sizing die is not taking the necks small enough. Try seating a bullet in a case sized but not expanded. Will it move under heavy thumb pressure? Or maybe you have some thin brass.

[Redhook]

Thanks guys,

If all I need to do is crimp it untill the bullet stops moving, and I'm not crimping too much, then I should be good to go.

-Red-

[Bogie]

First, what rifle are you loading for? Why do you need to crimp the rounds? For semi-auto stuff, I crimp using Lee's "factory crimp" dies. They work very well.

My .308, .243, and .22-250 critter guns don't get crimps. They have enough neck tension.

For match ammo, I adjust the neck tension using the various size bushings in my "Redding style" dies.

[Jim Watson]

Red, read my previous post. You are not good to go. You have a problem that cannot be solved by crimp. You need enough friction to keep that bullet from moving by hand pressure.

[Redhook]

Jim,

So what you are saying is that I should be able to put a 50-60lb weight on top of my bullet and they should not change OAL? That seems like a pretty tight fit. Do you experience copper shaving off of the jacket when you seat the bullet?

Don't get me wrong, the bullets are fairly tight in the case, but I plan to test this either tonight or this weekend by making up a couple of dummies. I will also check the diameter of the expander ball.

-Red-

[Bogie]

You don't HAVE to have bullet grip at all... I know folks who drop powder in a case, stick a bullet on top of it by hand, and then stuff the sucker into the rifle, and let the bolt and lands "seat" and align the bullet.

What sort of rifle is it?

[Bogie]

Also, unless you've got a REALLY GOOD die, you're not going to get match quality ammo with a die that uses an expander ball.

[Jim Watson]

Well, Bogie, you may be right. If Red is shooting a tight-neck benchrest rifle with fitted brass, he can certainly do that. And not need dies at all. I may have made a rash assumption that he was shooting a repeating sporting or military rifle and needed the bullet to stay in place for handling and action cycling, plus give a little resistance to help the powder get lit. That is my application and I may have mistakenly applied it to him. I have loaded decent ammo with a conventional expander ball, but an M expander is a big help and bushing dies are probably better.

But since I do load ammo for repeating sporting and military rifles, also pistols, I want the bullet to be there for good. My usual test is to load a round and put the bullet nose against the edge of the bench and push. I better get a good roll back in my swivel chair without moving the bullet. Not very scientific, but it is good enough for my use.

[Redhook]

Sorry guys, I should have given some reference. This is for a Rem 700PSS. I'm using RCBS COMP die set with a FL resizing die and a Comp seater.

I know, I know, Bolt Gun! Doesn't require a crimp! But it makes logical sense to me that a consistent crimp should allow for a consistent release as well as better powder ignition. At least that's what I'm going to start with and I'm sure I'll try it without a crimp at some time.

BTW, I did measure the expander ball at .3097" tonight. I will give RCBS a call in the morning to confirm if this is to spec. You have to consider a little spring back in the neck, but I would agree that this will vary depending on conditions.

-Red-

[labgrade]

I'd say that a .3097" expander ball is about .002" too large - it's defeating the whole neck sizing operation & allow your bullets to "float" in the neck = not what you want. See if you can get one that's about .307, or just a tad under. Chucking your expander ball in a drill & polishing with ScotchBrite, etc. may bring you into your desired range.

I agree that neck tension should be all you'll need for bolt gun. IMNSHO, adding a crimp when "not needed" is only adding another thing that could adversely affect accuracy.

Coupla other things thread-related - if your shaving bullet material, chamfer the inside of your brass necks a tad more to facilitate bullet seating w/o shaving.

Too, make certain that all your cases are w/in .001-.002" in length. Otherwise your crimps will be inconsistant & you'll be causing more problems than you're trying to "solve."

Still, I see no need to even attempt crimping for bolt gun use.

[Redhook]

O.K., RCBS is sending out a new decapping rod with a new expander ball. The CS rep didn't even question it and threw a new one in UPS so I should have it by Monday. He also agreed that, if properly seated, I shouldn't be able to move the bullet by hand or by pushing it into my bench.

Depending on the size of the new ball, I'll probably turn down the one I already have. If the new one is .308, I'll turn the old one down to .307 and give it a try.

I already have 50rds ready to go, so I'll probably still crimp these anyway. Thanks for your help guys and feel free to add any other suggestions.

-Red-

[yankytrash]

Depending on what range you're talking about shooting, do yourself a favor - leave a batch set aside with no crimp. You'll see what we mean by saying not to crimp too much.

The difference in accuracy will be sub moa, but at the longer ranges, that gets pretty big.

I'm a firm believer in not crimping unless I have to, which means I never crimp until the gun causes problems with the non-crimped loads.

Crimping harms accuracy. Causes friction and gouges the bullet, inevitable uneven crimping causes uneven pressures. Makes some occasional wierd trajectories like whirly-birds and lops.

FYI - I recently bought 1000rds of 55gr 223 FMJ from Georgia Arms. Most accurate reloads I've tried yet (except for mine!! ). They used no crimp. I had one or two rounds out of 500 that FTF (because of a few new mags I picked up, not the round), and close inspection showed that the bullet dropped right inside the casing.

[Bogie]

What causes the greatest group dispersion (assuming a tuned load, good barrel, etc.) is damage done to the bullet's base - Just like a dinged crown. Shotgun patterns.

Call Ron Hoehn (get the number from www.benchrest.com) and tell him that you want a K&M inside chamfer tool - It does a very nice and repeatable chamfer on the inside of the case necks.

You may also want to consider eventually getting a Redding bushing die. That way you can use different sized bushings to vary the neck tension.

Loading my .262 neck 6PPC, I use anywhere from .260 down to .256 bushings, depending on how much neck tension I want.

My .308 gets loaded with a Lee collet die and a Wilson straight-line seater. The only RCBS dies I own are for the .223.

[Patrick Graham]

I know this is a taper crimp thread but ..... you can adjust a Lee Factory crimp to squeeze the case neck just enough to hold the bullet in.

[Redhook]

I got the new decapping/expanding rod today, which was timely. So far RCBS has had pretty good customer service. Anyway, the new expander ball is just under .307, so I'll run a few samples to test. Thanks again guys!

-Red-