To crimp or not to crimp?

[lokidansk]

To say I'm new to reloading would be a large understatemnt. I just recieved my first dies two days ago. I will be loading .223 for a 20" ar15 to bench and coyota hunt. I will also be loading for a Reminton 700 in 6mm Rem strickly for bench shooting. In yall,s oppinion should I crimp the rounds or not? If so, or if not please let me know why.

P.S.
This is only my first stupid question guys, more will surly follow.

Thanks

[Bart B.]

Top ranked competitive shooters winning rapid fire NRA matches and setting records with their ARs don't shoot ammo with crimped in bullets. Neither do the best bullet makers testing 22 caliber bullets for accuracy. They know crimping impairs accuracy. Normal case neck grip on bullets is good enough.

Standard full length sizing dies makes that happen. Set the standard seating die up about 1/16" above the shell holder when the press ram's at the top of its stroke so that die's crimping shoulder doesn't touch the case mouth. Competition grade seating dies for rifle cases don't have crimping shoulders. The die's neck is long enough to prevent the bottom of its bullet guide touching the case mouth.

Do what you believe is best and you're comfortable with.

[condor bravo]

There are two types of crimps, a roll crimp and a taper crimp and a proper crimp design for using each that is built into the seating die, a roll crimp that is intended to roll a crimp into a bullet's crimp groove on a lead bullet or the cannelure on a jacketed bullet (if the bullet has one or the other). A taper crimp is normally used just to remove the flare, if any, from the case after the bullet is seated. The roll crimp can be used to apply a taper crimp if used very lightly. In your case your seating dies are probably the roll crimp type and the bullets for those calibers may or may not have cannelures. If not, all that should be needed is to just remove any flare with the application of a light roll crimp acting as a taper. If the bullets have cannelures you again could just apply a light crimp or none at all.

You can determine if the seating die is the roll crimp type by removing the seating stem and looking into the base of the die. If you can see a shoulder ring some distance up the die, that is the roll crimp shoulder.

[firewrench044]

The only cartridges I crimp are for pistol and the ones for a tubular magazine

I ask the same question when I started loading, the answer I got was
NO, it is not needed and only adds another variable to the cartridge

the only stupid question is the one not ask !

[lokidansk]

Thanks guys, I was opting for the no crimp but wanted a bit of warm and fuzzy about it. I'm gunna do my first loads with no crimp. I fear this first inexpenceive jump into reloading will end up being one of the most expenceive things I've ever started.

[sawdustdad]

Lokidansk, I see we are nearly neighbors...(I'm in Hanover Co.). I have been using a very slight taper crimp on AR ammo because I had some issues with uncrimped ammo not chambering in my M&P 15. The bit of crimp takes the case mouth back to spec so the rounds chamber easily. It might have been something to do with my case prep, or my particular weapon, YMMV.

[gedenke]

The only cartridges I crimp are for pistol and the ones for a tubular magazine

I ask the same question when I started loading, the answer I got was
NO, it is not needed and only adds another variable to the cartridge

+1.

Exactly what I was told. I taper crimp for cast lead pistol bullets, but never for rifle. Just full length size and load.

[4runnerman]

One word---NO

[Jim243]

NO, it is not needed and only adds another variable to the cartridge

That is basically correct, however it will really depend on neck tension on the bullet. If the neck tension is insufficient for the load (Hot loads) then in a semi-automatic rifle the bullet will set back into the case from recoil of the rifle. When this happens it becomes a very dangerous thing and increases the pressure developed in the case and can cause a catastrophic failure that can blowup in your face. Too much of a crimp can also loosen the neck tension and do the same results. General crimps are best placed on a bullet that has a cannelure http://www.merriam-webster.com/dictionary/cannelure thus insuring a proper fit and good neck tension.

http://www.thehighroad.org/archive/i.../t-364894.html

In most cases a crimp will not be necessary and really does not affect accuracy as stated in other posts. There is no crimp you can obtained from your dies that will stop the 52,000 psi developed in your 223 from moving the bullet out your barrel straight and true to it's rifling.

You can have bullet set-back or lose bullets with or without a crimp. Usually the test for neck tension is to take a completed round, turn it upside down on a table and with your thumb press hard on the bottom (head) of the round. If the bullet pushes into the case doing this, then you need a crimp. If it does not push the bullet back into the case, you should be good to go and do not need a crimp.

Some crimp, some do not, I always put a slight crimp on every round just to make sure the case is sealed to the bullet.

But that's me, stay safe and shoot straight.
Jim

[Hook686]

I try not to 'Should' on people. I do crimp, using Lee FCD, my 30-06, 9mm, .357 & .44 magnum. I like to think the round is more uniform and consistent cartridge to cartrige. Whether it is, or not is not material. I like to think it is and it adds one more pull on the handle of my turret press. I have noted that my cases are not always perfectly round after seating a bullet. Perhaps the bullet is not perfectly centered as I pull the handle. I like to think they are after using the Lee FCD.

[Bart B.]

The industry method for measuring case neck tension or grip on bullets is determining the force in pounds needed to move the bullet out of the case neck. The amount of force needed to seat bullets is close to what it takes to pull or push one out except for military ammo. Crimping adds to that amount of force but it's not the same amount to each bullet. It varies with case length and case mouth wall thickness and those variables transfer to the uneven depression around bullet jackets without cannelured which unbalanced them.

Military rifle service ammo has bullets easily seated in case necks coated with sealant that when hardened, "glues" and seals the bullet in the neck with more grip than neck tension alone. Military match ammo used to have crimped in bullets until crimping was proved to degrade accuracy by increasing the spread of bullet release force.

If one cannot see any difference in accuracy, partially fixes a case sizing problem by crimping or fears problems will happen if they don't crimp, they will crimp.

[skizzums]

I personally so not have a choice when loading .224. I have to crimp, I have had a few roundswhere bullet jams all the way into the case when feeding. I know this means there is something going on with my neck tension and also my feed ramps need opened up a little more for my big 77gr bullets, but it was easier just to pit a slight crimp in it. I have very good accuracy with good handloaded and have done lots of personal tests on crimp or no crimp, at 100 and 200 yards, there is absolutely no difference. I have pulled lots of bullets and my crimping doesn't deform my bullets at all, so I feel better crimping.

I bought a box of 300b.o. from summit a few weeks back and those bullets also had MMO neck tension and the bullet would get pulled out if I ejected a loaded round out of tchamber, so I put a crimp on it and all good

[Bart B.]

Skizzums, you had other choices; you stated the problems you chose not to fix. But I understand your reasoning and it's fine by me that you made them. You're more aware of your objectives and priorities than anyone else. I also understand why you cannot see nor measure any difference.

[Mike38]

Give the Lee Factory Crimp die a try. You may find it doesn’t help a bit. But you may find it does what Lee claims, improves accuracy. I found in .223 an accuracy improvement of right around 10%. Some people claim that the LFC is a bandaid to cover up mistakes made reloading. Maybe that is true for some people, and maybe it will help you as a new reloader. Personally, I would never reload for a semi auto without a crimp.

[Jimro]

Don't crimp if you don't have to.

The rounds where you might have to crimp are heavy pistol loads, revolvers especially, where excessive recoil acts like an inertial bullet puller. Sometimes it will pull the bullets far enough out of the case to lock up the cylinder. In old hunting stories sometimes bullets would break loose inside the magazine of hard recoiling bolt action rifles and fail when the hunter needed it most, which is why a lot of hunting ammo should be crimped (especially if you plan on taking multiple shots and topping off the magazine without emptying it).

The only time I would consider crimping for a centerfire rifle for a semi automatic is when rough handling might compromise the safety of the load. The Mk262 load went through two iterations, Mod 0 with no crimp, and Mod 1 with crimp. Shooting lots of Mod 0 we experienced a lot of "bullet setback" where the 77gr pill was pushed back into the case because of misaligned feeding. This was deemed not acceptable for a combat round and so the crimp was added to prevent bullet setback (preventing some dumb private from blowing up his rifle by shoving a compromised round into the chamber and pulling the trigger).

So if it isn't a functionality or safety issue, no need to crimp, and I don't.

Jimro

[Bart B.]

Some would never reload for a semi auto without a crimp. Yet thousands have done it since the 1950's without a hitch in any getalong. The M1 and M14 rifles have a lot more force moving loaded rounds outside the chamber and their bullets are a lot heavier. The first AR's used in competition didn't shoot crimped in bullets and there were no issues whatsoever. Grade school physics shows smaller caliber bullets with lighter weights and less recoil forces compared to larger and heavier ones has to be an indicator of what's not needed. Arsenals quit crimping bullets in match cases and even removed the cannelure in the match bullets 'cause it also caused accuracy problems.

Sierra Bullets gets less accuracy with their cannelured 77-gr. 22 match bullets than the same ones without it when both are tested the same way; uncrimped. When they crimped those cannelured bullets even lightly, accuracy suffered even more. But they get the accuracy levels to prove it.

If these aren't the highest trumps in this card game, I don't know what is.

[mikld]

Good discussion. FWIW, I crimp all my revolver ammo and none of my rifle ammo. I sorta crimp my semi-auto rounds. I just straighten out the case with a taper crimp die, no crimp. I was fearful when loading my M1 Garand with "un-crimped" ammo, but I did a test. I loaded a full clip, fired the first round, ejected the second, fired the third, ejected the fourth, and so on. I measured the ejected rounds and found no difference in OAL, so there was no deep seating due to the fairly violent loading cycle...

[Bart B.]

Garand clips hold cases by their rib that goes into .30-06 case extractor grooves. That pulls rounds back in recoil. The bullet guide stops them from being slid too far out of a too loose neck not holding them in place. Bullet guides rarely, if ever, touch bullets when the rifle is fired.

I've heard of bullets slipping out of the last few clipped reloaded cases with little bullet grip used in 7.62 NATO Garands. They've got an extra half inch of space between clipped ammo and the bullet guide. There was a concern that when .3086" diameter bullets were pulled from 7.62 match ammo then .3082" diameter Sierra match bullets there wouldn't be enough grip by the sealant coated case mouth. While it was much less than before, 168, 180 and 190 grain bullets stayed in place for all clipped rounds subject to recoil jerking them back and none slid forward in case necks. The .001" to .002" thick asphaltum sealant bonded well to them. Same ammo was used in box magazine bolt guns and M14NM rifles withstanding magazine front wall smacking bullets' tips; they didn't push back into case necks.

Same thing with .30-06 M72 match ammo whose bullets were replaced with smaller diameter commercial match bullets for use in Garands and bolt guns.

[Gary L. Griffiths]

I did a test of crimped vs. non-crimped ammo this summer. You can probably search my posts for it if you're interested. Bottom line: Crimping has virtually no effect on OAL after being chambered in an AR-15. Bullets were neither set back nor moved forward significantly. Accuracy of non-crimped loads was, however, significantly better than that of identical crimped loads.

[steve4102]

Originally Posted by lokidansk

To say I'm new to reloading would be a large understatemnt. I just recieved my first dies two days ago. I will be loading .223 for a 20" ar15 to bench and coyota hunt. I will also be loading for a Reminton 700 in 6mm Rem strickly for bench shooting. In yall,s oppinion should I crimp the rounds or not? If so, or if not please let me know why.

What brand/type dies did you purchase? Some come with a built in taper crimp, some do not, some come with a dedicated crimp die, most do not.

My comments will be geared to your AR-15 loads and when I use the term crimp I amreferring to the rifle Lee Factory Crimp die.

Here is a good read on loading for semi-autos.

http://www.exteriorballistics.com/re...sgunreload.cfm

Note the section on Neck Tension.

There are two distinctly different forces that need to be considered: those that force the bullet deeper into the case, and those that pull it out of the case. When the round is stripped from the magazine and launched up the feed ramp, any resistance encountered by the bullet risks having it set back deeper into the case. Due to the abrupt stop the cartridge makes when the shoulder slams to a halt against the chamber, inertia dictates that the bullet will continue to move forward. This is exactly the same principle a kinetic bullet puller operates on, and it works within a chamber as well. Some years ago, we decided to examine this phenomenon more closely. During tests here at Sierra’s range, we chambered a variety of factory Match ammunition in an AR-15 rifle. This ammunition was from one of the most popular brands in use today, loaded with Sierra’s 69 grain MatchKing bullet. To conduct the test, we chambered individual rounds by inserting them into the magazines and manually releasing the bolt. We then repeated the tests by loading two rounds into the magazine, chambering and firing the first, and then extracting and measuring the second round. This eliminated any potential variation caused by the difference between a bolt that had been released from an open position (first round in the magazine) and those subsequent rounds that were chambered by the normal semi-automatic operation of the rifle. Measuring the rounds before chambering and then re-measuring after they were carefully extracted resulted in an average increase of three thousandths (0.003") of forward bullet movement. Some individual rounds showed up to seven thousandths (0.007") movement. Please bear in mind that these results were with factory ammunition, normally having a higher bullet pull than handloaded ammunition.


To counteract this tendency, the semi-auto shooter is left with basically two options: applying a crimp or increasing neck tension. The first option, crimping, brings up some other issues that can be troublesome. In general, crimping degrades accuracy. Most match bullets are not cannelured (which also seriously damages accuracy potential), a requirement for correct application of most crimps. Still, there are taper crimp dies available from most of the major manufacturers. Lee offers their “Factory Crimp” die as an alternative, which seems to be one of the better options for those bullets without a cannelure. That having been said, crimping is still, at best, an occasionally necessary evil. Avoid it if at all possible.

In my tests I have found that neck tension alone cannot stop a 6.5-30 cal. bullet from creeping forward when cycled through a semi-auto action. The light weight .224 bullets were much easier to hold in place then the heavies without a crimp.

Crimping with the Lee Factory Crimp die holds my bullets secure and Improves accuracy. That's right, it improves accuracy.
OH, and the use of the LFCD is no more of a crutch or a band-aid then any other technique, from adjusting OAL, to adjusting powder charge, to switching primer brands, to turning necks, to tweaking run-out, to jamming to the lands, to Bushing Dies.

lokidansk, one thing you should consider here, that many of the members here that preach the evils of crimping with the LFCD have never tried it and never will. Bart for example, will tell you over and over how the LFCD will degrade accuracy and cannot improve accuracy, yet he has no first hand experience with it and has never tried it. Go figure.

If you want to know about how crimping affects your loads ask those that have tried it or still use it, or better yet, do as I did and test it for yourself. You may find it helpful, then again you may not.

[Bart B.]

Steve, many folks know that cutting off their left arm impairs their functionality without ever doing it to prove it. I think the basis for that reasoning is something you cannot apply to crimping. Thousands of rifle competitors have never proved it either by trying it but they don't crimp because they've got the wherewithall to figure out it's bad for accuracy. Too bad everyone doesn't; such is the realities of life.

The fact that Sierra Bullets' has proved crimping impairs accuracy is obviously not good enough for those who insist it's a good thing to do.

[steve4102]

Testing a tool or technique, is a far cry from cutting off a limb.

Getcha a crimp die and test for yourself, them come back with Hard facts and evidence. You can keep your left arm in the possess.

Otherwise, what you have to offer is pure speculation and opinion without any supporting data.

[Bart B.]

I'll not waste my time doing what others with supporting data have already done. I even believe the earth is round in spite of the FES enthusiasts claiming otherwise, so I won't go into space to measure it for myself as there's other supporting data good enough to convince me.

Sierra Bullets has supporting data. Take your crimped cases to them. Prove them wrong. Shoot their bullets crimped in cases more accurate than they do without crimping them. Then challenge all the benchrest winners and record holders. Forget about anyone else who shoots rifles held firmly against their shoulders adding too many variables to the accuracy the get.

Steve, unless you've loaded crimped bullets that have shot sub half MOA 15 to 20 shot groups at 600 to 1000 yards as I and many others have with no crimping, you don't have much credibility. Crimp-ability? I've no interest in trying something that has yet to prove better by anyone than what I and others do for best accuracy.

[lokidansk]

thanks Steve
I will do enough to get comfortable with my loading and then I will try to crimp 20 rnds and not crimp 20 rnds of 223 and of the 6mm. I will post what I find and picture if possable. Thanks for the insight guys

[Jimro]

Bart B.,

Like most things in life, there are exceptions to any rule.

Competitors and Sierra don't crimp because it degrades accuracy. But, they are not using the absolute cheapest components they can find either, after all this is Sierra we are talking about.

There are times when crimping can improve accuracy, and that is mainly when the powder/primer interface is not optimal such as using a powder too slow for the bullet weight with a primer not strong enough to get good ignition. In this case, holding the bullet in longer can allow more uniform pressure curves between shots.

Obviously Sierra and match shooters aren't using suboptimal components. Someone trying to keep their reloads down to the absolute bare minimum of cost might be using suboptimal components, at least enough to use up a lot purchase and get a useable load out of it.

Jimro