I came across a bunch of 168 Hornady match bullets. No Cannelure. Should I use these in a semi-auto? Will crimping them be enough to keep the cartridge from sliding back into the case when it's chambered?

My experience has been good enough with just the neck tension alone on your average RCBS dies and tun of the mill brass.

Have shot tons of Nosler, Hornady, Sierra bullets from an AR10 A4 over the years and never was worried about setback.

Only time I ever saw setback was when I had an exposed lead tip spire point jam itself into the corner below the feed ramp and the bolt decided to try to ram it home nice and hard.

I recently got some Hornady 168gr A-Max on clearance. I've loaded them for a M1A and a M1Garand. I didn't have any issues with either of these.

I don't believe it is even possible to increase neck tension on a non-canalure bullet with any form of crimp tool.

I've done some non scientific testing and was only able to prove that you have a much better chance of decreasing neck tension by over crimping and crushing the bullet than actually doing anything positive.

Non canalure bullets have been used for decades in rifles like the M1A and M1Garand in competition and nobody crimps.

If you want some re-assurance take a couple of your rounds and let them self load but don't fire them. Hand eject and measure then repeat this using the same round a few times and see if the bullet is moving.

A couple thousands of an inch is not unusual but most of the time you'll find they don't move at all.

Motor

If your semi auto is built right,  and you have the proper neck tension, which you probably do, no cannalure and no crimp is preferred.

I've shot lots of those bullets out of
M1 Garand
M1A's
AR10's

No crimp is needed or wanted in my book, neck tension is where it's at.
Crimping might screw up good neck tension. I never crimp and never will for any semi-auto.

Guess I'm in the minority..I prefer crimping into the cannelure.

There's a statement by GKR floating around about some LE agency ordering a special run of 64gr PP with cannelure due to the standard load suffering setback in their duty rifles which IMO proves it does indeed happen.

Theres a reason .mil ammo is all cannelured with a heavy crimp.

OP is asking about match bullets that have no cannelure


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I am by no means an expert when it comes to reloading however, I have loaded up 30-06 rounds with155 gr Nosler HPBTs with no cannelure to shoot in my M1 Garands’. I have shot close to 200 of them and had no issues with them.  I use the lee crimp die (that came in the Lee 4-die 30-06 set) to crimp the bullets.

I have also loaded some 77gr Noslers in 223 with no cannelure for use in an AR-15 and had no issues in at least 300 rounds.  I also crimped these rounds using the Lee 223 crimp die.

Just because you used the crimp die does not mean it actually did anything.

Neck tension is created by the brass being smaller than the bullet. Once the bullet is within the neck no amount of crimping is going to make the brass any smaller without crushing the bullet. If you crimp hard enough to crush the bullet the brass springs back and you end up with less neck tension.

This is of course pertains to bullets that do not have a crimp groove aka canalure.

When you displace brass into crimp groove you still are not increasing neck tension but you are creating a physical barrier that under normal circumstances won't let the bullet move beyond the limits of that barrier.

So it may give you some kind of piece of mind but in reality your Lee FCD is not actually doing anything when you use it on non canalure bullets and if you force it enough it will definitely decrease neck tension.

But it's footprint is pretty small so your not losing much.

Motor

I only crimp dummy rounds that will see dozens of cycles.

I use a Lee FCD

If it has a cannelure?  It gets crimped lightly.  This is generally blammo for me, so it if shoots under say 1.5" Im happy.

If it has no cannelure? I back the crimp off just enough to remove the minute flare I put on every case with the Lyman M-die when I load.

Neck tension on decent brass is enough.  However fatigued and hardened brass crimping does help.  YMMV

There is no need to crimp.
LE and Mil is a different story and reasoning.
Most have an extra measure of protection, neck sealant.  Those rounds are stout.

Most have shot OTM bullets with no crimps for years and years in all kinds of platforms.

The reloader is more the issue.  Not paying attention to brass # of firings, over working, etc....

Sure you can an increase neck tension without crimping.  Get a Type S Bushing die and use a smaller bushing!  But it if the brass is shot from the get go you can attempt to rejuvenate with annealing.

The neck is sealed to prevent moisture intrusion, right?  As a side effect, it also glues the bullet in place.

Why does the military also crimp?  Higher g-loads than simply firing the rifle?  Perhaps from firing a cannon and not want rifle bullet set back (<-- total guess here)?

Some rifles like a bit of crimp some do not. My  .308 gets no crimp. My Grendel likes a little crimp from the the Lee factory crimp die if I'm loading using the Lee dies. Now if I use the Hornady dies I don't crimp. Some of my  .223 loads get a light crimp especially with ball powder. You might try the load you choose crimped and none crimped. I would use the Lee factory crimp die and never turn the seating die down again.  

My 7mm mag likes a very light crimp on the 160gr accubond bullets. It tightens up the extreme spread a little. And that's in a bolt action. I say it never hurts to try.

My rule is "If it has a cannelure, I crimp into it.  If it doesn't, I don't."  I've loaded thousands of rounds of non-cannelure bullets relying only on neck tension to hold the bullet and have never had a problem.  And I've been reloading for 40 years.

If you pulled the bullets from military ammo, you'll find they are less consistent in diameter than most hunting and match bullets.  Before crimping, it is safe to assume the neck tension will not be that consistent either.

LE and Military ammo is definitely crimped for no other reason than durability. Remember most ammo is used in a variety of weapons from rifles to mini guns and everything in between.

Plus it has to withstand the rigors of some very rough handling from long airplane rides (just ask anyone familiar with vibration and air travel) not to mention air drops.

It's all about reliability and nothing more.

The sealant is to keep out moisture which can promote corrosion and frost expansion and is needed because like commercial ammo all of it is loaded into casings that have mouth flare and you simply can't make the brass hug the bullet after it's been flared. Especially true with auto pistol ammo.

Motor

No crimp needed if there is sufficient neck tension. I kiss the case mouth with a taper crimp die on all my match loads. I find it makes the transition from the bullet jacket to the case mouth a little smoother, and it looks better aesthetically.

My guesses to the military crimp is almost zero chance of ammo failure du to storage, transportation, handling, and abuse. If I was in military scenarios I would want crimped and sealed bullets and primers. For normal realistic civilian use I would not worry. I treat my handloads well enough to not worry.  I lightly crimp cannelured bullets. I don’t crimp my match ammo.

Full auto use.

Even an M16 is around 800 rounds/minute [over 13 rounds per second].

And if you need full auto (the mil guys I know all said it was usually limited to ONE person per patrol) the last thing you need is a jamb.

There are practical reasons for fluted chambers and oversize chambers on larger machine guns.
Asa chamber heats its diameter is reduced.

And firing till very hot is pretty common when SHTF.

Spare barrels are not uncommon.

I have found in my non-scientific, small batch testing, that crimping my 5.56/.223 rounds to be used in my ARs reduces SD enough that it should/could be conducive to better groups.

With that said, if the bullet does not have a cannelure I don't crimp as I think deforming the bullet is worse than not crimping.  But if the bullet has a cannelure, I will generally crimp that round.

I usually don't use bullets without a cannelure in my ARs.  Each to his own.

I think if you pay close attention to neck tension, crimping is not necessarily needed.  But I, and I'd bet most guys that reload 5.56/.223 range brass don't have a clue what the neck tension is throughout the group being loaded.  I think unless you anneal, even once fired cases will have very different amounts of neck tension.  I believe it is this widely differing tension that will increase SD and probably some malfunctions.

I prefer once fired LC brass or commercial once fired, (but you never know if commercial brass is once fired).  But I load whatever is in the batch, of course separated by head stamp.

I'm sure you have experienced different brass resizing harder than other.  That will effect brass prep through all steps including the end neck tension.

Sorry for the long post but I think many would benefit rethinking crimping in general.  YMMV

Open bolt machine guns and a requirement to last through decades of rough handling.

All the crimp in the world won’t correct poor neck tension.

You are correct that an asphaltic sealant is used to prevent contamination.  

The concern is not so much water as petroleum, penetrating oils and solvents.

The sealant is actually fairly brittle and doesn't contribute much to keeping the bullet in place.

But a pretty good guess.

The military specifies a crimp to hold the bullet in place against set-back when it is fired.

The crimp also helps keep the bullet in place when the ammunition is subjected to rough handling.  After all, your handloads or commercial ammunition are never going to be strapped to a pallet and then pushed out the back of a C-130 flying at 35 feet over a drop zone at 115 knots (a so-called Low Level Extraction or LoLEX - although I think the acronym has changed since VietNam).

I agree.  The point I wanted to get across is, neck tension of resized range brass, from head stamp to head stamp, year to year, case to case will be different unless you anneal your cases.  I do not anneal and as I said I doubt many do, and I know some do.

Crimping these cases with different neck tension should/could improve SD.  That is my experience from my personal limited testing.  YMMV

Whatever you can do to reduce differences in bullet pull/neck tension is a good thing.  Nothing will replace correct/consistent neck tension.

Gotcha, I guess misunderstood your post a little.



I have zero experience loading mixed brass. The only rifle reloading I do is for accuracy so it’s all matched cases with the same number of firings on them. I don’t anneal either, cases get tossed in batches same as they get loaded.

I have fired tens of thousands of rounds of match grade bullets and never crimped a single one of them.

You need .0025" to .003" of neck tension to hold a bullet firmly in place. Simply measure the resized neck prior to seating the bullet. Measure again after the bullet is in place.

The difference is your neck tension measurement.

I shoot M1 Garands, AR10's, M1A's and AR-15's using this formula. Never had a single problem doing it this way.