Reloading for ar-10

[reynolds357]

I just bought an AR-10 308. Anyone have any tips on re-loading the .308 for the autoloading platform? I will be shooting Sierra 168 match kings. I guess my main question is do you use an ever so slight amount of roll crimp or not crimp at all? Without a cannalure, the neck would not be able to stand much crimp, but I definitely want the bullet tight in an autoloader but do not want to buckle shoulders. Conventional wisdom is never crimp without a cannalure, but conventional wisdom also is always crimp in an auto loader.

[grisbald]

I have 165 gr. Sierra's that I shoot out of my LR-308. I use the Lee factory crimp die.

[steve4102]

The first thing you do is set up your Full Length sizing dies according to the directions.

Then you FL size a few pieces of Fired brass and check to make sure they chamber and extract with ease. If not adjust your FL die into the press until they do.

Do this before you attempt to load any completed rounds.

Here is a good read.

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

[GWS]

RCBS sells a special "AR" die set that includes a seater that taper crimps. Or you can order just the taper crimp seater separately.

http://www.midwayusa.com/product/135...ProductFinding

[hodaka]

I've been reloading for a DPMS LR-308 for a long time. I bought one when they were first released, got bored with it and sold it, then bought another this past winter. I plan to add a .260 barrel soon and have a switch barrel rifle. I use standard Lee FL dies, no crimp and mine have both liked 4064 and SMK's, 155's and 168's both shoot great. I don't think either rifle ever, ever had any issue. A great rifle (especially with an aftermarket trigger) although very heavy. Nothing special is needed to successfully load for it.

[RNG]

Buy a case gauge and save yourself some grief. In fact, buy one for all rifle calibers you load.

[reynolds357]

I have never cared too much for case gauges. The only way a case gauge would be useful to me is if I cut it with the same reamer I cut the chamber with.

[Bart B.]

If best accuracy is important, don't crimp case mouths onto bullets; especially those without a crimping cannelure/groove.

Full length sizing fired cases from AR10's is best, but set the fired case shoulders back .003" and no more. Otherwise, case life will be one or two reloades before incipient head separation starts. Four to five reloads sizing the right way is about right for semiautos.

The US Army Rifle Team's shot their AR10's with ammo loaded this way and set records doing it. They know better than to crimp case mouths on bullets because such altered bullets don't shoot as accurate as those not crimped. Adequate neck tension's easily done with normal reloading tools and techniques. They and thousands of others have been shooting uncrimped cases in their M1 and M14 and M16 competition rifles for decades. Even arsenal and commercial match ammo for them doesn't have crimped case mouths on bullets. The arsenals quit crimping match ammo case mouths decades ago when they learned ammo was more accurate without crimped in bullets. Why so many people don't accept this as an OK thing to do for semiautos is..... well..... never mind.

You'll need a case headspace gauge of some sort to measure how much you're setting case shoulders back. A cheap but accurate way is to do what's shown in post #35 in:

http://thefiringline.com/forums/show...t=nylon&page=2

Or by an RCBS Precison Mic or Hornady LNL case headspace gauge.

[SWThomas]

Here's my experience handloading 308 for my AR-10 platform...

I never set a rifle die up in accordance with the instructions that come with it. Those instructions are to get the brass sized in a way that will fit any chamber and generally oversizes the brass. I ALWAYS measure 10-15 cases that have been fired in my chamber to get a baseline. I do this with a digital caliper, comparator body, and bump gauge insert. Then I set the sizing die to bump the shoulder back 0.005. This will give you brass that is more closely sized to your chamber and also extend case life.

As far as crimp goes, I don't do it. I was having issued with bullet set back when I first started loading for my AR-10. The way I fixed that was to polish 0.002 off the expander mandrel of my Lee sizing die. This effectively adds 0.002 neck tension and has worked great for me. I did the same thing with my .223 set up and don't crimp them either.

The best group I have fired is 0.172" at 100 yards. That was a 5 shot group fired from the magazine.

[reynolds357]

Thanks Bart, that what I needed to know. I have never crimped anything in a bolt gun, but I was not completely sure about the semi auto.

[Jim243]

Thanks Bart, that what I needed to know. I have never crimped anything in a bolt gun, but I was not completely sure about the semi auto.

Easy way to know is to load up a 19 round mag, fire off 10 rounds, then unload the mag and measure the last round in the mag, if it is still the OAL you original set you are OK to go, if the bullet has moved, then get the crimp die out and use it.

Jim

[Bart B.]

This crimp issue reminds me of a discussion the three military rifle teams (USMC, USA(rmy) and USN) had at the 1971 Nationals at Camp Perry when M16's were first allowed and used in high power competition. We all had a lot of laughs talking about all those upcomming thousands of folks reloading for their new Mickey Mouse rifles to shoot service rifle matches will want to crimp the bullets in case mouths. Didn't matter that none of us did making match ammo with new Remington and Winchester .223 Rem cases and primers, IMR4895 and Sierra 52-gr. HPBT match bullets. Our heavier bullets in 7.62 NATO, .308 Win and .30-06 cases shot in semiautos never needed crimped in bullets. And most of us had done enough tests with both types of reloading methods to know, as the arsenals and commercial factories making match ammo for us learned; crimping puts a crimp in the accuracy style of centerfire rifle ammo.

[GWS]

We all had a lot of laughs talking about all those upcomming thousands of folks reloading for their new Mickey Mouse rifles to shoot service rifle matches will want to crimp the bullets in case mouths.

That make us all warm and fuzzy inside. Making plans to educate those thousands, to prevent such uninformed stupidity would have been more admirable. And still it goes on doesn't it? Lots of laughs.

[Bart B.]

GWS, if you search this forum (web, for that matter) for crimping and me, you may lose track of the many times I've "educated" folks that crimping rifle case mouths onto bullets is not good for accuracy. As has all the top ranked people in all rifle competition disciplines I know of. All of the top military a civilian competitors had been educating folks about the pitfalls of crimping long before 1971.

I don't think it takes a lot of reasoning to figure out that crimping adds another variable to ammunition. And no centerfire commercial nor arsenal match ammo's had crimped in bullets for decades; that alone, is probably the best counter to crimping for accuracy. Nobody reloading their ammo used to produce the best results crimped case mouths. Sierra Bullets told Lee to stop telling folks to use their crimp die on their bullets; they proved it hurts accuracy. The list goes on and on.

If you're not aware of this, you've been traveling on roads that don't have billboards near them honestly advertising the pitfalls crimped in bullets have if accuracy's important. Meanwhile, I'll continue my decades old campaign against crimping if accuracy's at or near the top of ones list of goals and objectives for their reloaded rifle ammo. Yes; that still goes on. And on. And on.

We weren't laughing at anyone; just about how ironic things would be in spite of what proved best for accuracy. Most of us used to think crimping was good; we learned it wasn't.

[GWS]

What I think is ironic is the combination of things that encourage reloaders to do it "wrong".....still....40 years later! Such as brass standards that are so loose that neck wall thickness variation in different brands and maybe even batches influence die manufacturers to design one-for-all sizers that oversize necks so expanders can be pulled out to arrive at an inside diameter that allows "proper" seating. Add to that, expanders that expand more than ideal such that crimping in cannelures is encouraged to prevent bullet set back in tube loaders and gas guns....exemplified by factory ammo crimped into cannelures and bullet manufacturers who make cannelured bullets.

[Bart B.]

Every one I know of at all the places making crimped case mouths into bullet cannelures on center fire ammo isn't doing it for accuracy. They do it for at least one of these reasons:

* Ensures the bullet will remain seated at a functional depth surviving all sorts of handling and loading environments.

* The bullet will remain in place if there's no powder in the case so it can be extracted easily when only the primer fires.

All done because the ammo maker has no control over its use after they send it out for retail or issue. They exercise reasonable care.

Commercial match grade ammo, without such crimps and cannelured bullets is typically not expected to be used in harsh environments. Its primary objecitve is best accuracy.

Military match ammo with black asphaltum sealer "glueing" those 172-gr. FMJBT bullets in case necks oft times had such a grip on bullets with a wide range of release force needed to push them out So we brought Lyman 310 Tong Tools and a bullet seater to the matches where that ammo would be issued. After seating all the bullets about .010" deeper to break that seal, that added distance for jump to the lands had little effect on accuracy. But elevation shot stringing at 600 yards went from 12 to 18 inches to about 6 to 8 inches; twice that at 1000 yards.

Sierra makes specially cannelured 22 caliber match bullet because some customers want to crimp them in ammo used for competiton because they fear recoil will move them in case mouths:

https://www.sierrabullets.com/store/...HPBT-MatchKing

They don't crimp case mouths into them when a production lot's tested for accuracy; they know it won't be as good and they eliminate that variable in their quality control processes. None of their larger caliber rifle match bullets are offered with cannelures; very interesting as they're subject to more recoil than 22 caliber ones; expecially their 33 caliber 300 grain one.

[steve4102]

Originally Posted by reynolds357

Thanks Bart, that what I needed to know. I have never crimped anything in a bolt gun, but I was not completely sure about the semi auto.

I posted this above, but I'm not sure you took the time to read it. Might want to re-think the advice you have been given on crimping until you do. Pay particular attention to the section on Neck Tension.

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

Bart has his opinion, Sierra has facts. Your call who you wish to follow.

[GWS]

What part of the Sierra's neck tension section was opposed to what Bart is teaching? Totally missed that. They teach that the "best" scenario is no crimp, and bushing dies. I think Bart is in that camp with the option to replace bushings with whole sizers honed to do the same thing.......one requires a bushing for each batch of brass, the other requires a specially honed sizer for each batch of brass.

My issue was not that Bart is teaching something opposed to Sierra, but that 40 years has gone by and most people still load with one-for-all sizers with oversized expander buttons.....me included until recently. Just seems funny that nothing much has changed...the "knows" are few compared to the "thousands" of "don't knows." Too much literature on reloading skip this, and reloading manufacturers continue to easy sell the one-for-all sizers. I suppose the accuracy difference just isn't enough to alarm many "hunters".

The other issue is that often we are not specific enough in suggesting that a reloading method is only best for a particular purpose, such as competition, whereas if a person wants to load a few thousand for defense in a future time, the parameters change, then the "best" reloading method changes also.

Take Bart's comment on ammo that needs to be crimped:

* Ensures the bullet will remain seated at a functional depth surviving all sorts of handling and loading environments.

* The bullet will remain in place if there's no powder in the case so it can be extracted easily when only the primer fires.

That causes confusion, so reader beware, we'd better read in context, and have our minds right, that the ammo the writer or poster is making/proposing is for the same purpose as what you plan to make.

I was suggesting that RCBS's new "AR" taper-crimp seater may help those using expander buttons who are tempted to crimp ammo to be used in "violent" actions.....especially with non-cannelared bullets, but with cannelared too. Maybe that's a better choice than a Lee Factory Crimp Die for a particular purpose. Paper first, defense second? Maybe Lee's FCD is more Defense first, paper second. Where as non-crimped match ammo may not even be advisable for defense or survival.

[reynolds357]

Thanks Steve. I will take Barts word for it. With a bushing change I can put as much neck tension as I want on the bullet. I know for a fact crimping a match grade bullet will kill its accuracy. I accidentally did it on one batch of ammo. 1/4 minute rifle shot over a minute. Thought I had a bad scope.

[Bart B.]

GWS, all USA military sniper ammo used since the late 1950's has been non crimped ammo; mostly M72 .30-06 match or M118 and M852 7.62 NATO match stuff. 30 caliber magnum and .308 Win. ammo made commercially for sniper ammo never had crimped in bullets as far as I know.

[GWS]

Not one bit surprised. For that purpose, makes perfect sense to me.

When I said,

Where as non-crimped match ammo may not even be advisable for defense or survival.

There's always an exception. I wasn't thinking about snipers. Bet snipers are taught to handle and protect their specialty ammo carefully. Regular military ammo not only is crimped & sealed, the primers are too.

[Bart B.]

reynolds357, be careful about sizing fired case necks down too far in search of a stronger grip on the bullets. If the inside edge of the case mouth isn't both rounded and tapered smooth, it may scrape jacket material off bullets as they seat. When that happens, there's usually more scraped off one side than the other. An excellent way to unbalance a bullet before it's fired.

Check seated bullets at the case mouth point to see (with a loupe or magnifying glass) if there's tiny curls of copper peeled off of the bullet. If there is, I think you should do something to make the case "lip" better surfaced and shaped so bullet jacket material won't be scraped off.

[Slamfire]

Almost all our National Culture was created by corporate advertizing bureaus, and the crimp debate is no different. We have been taught by those selling crimp dies, that crimping is a good thing. This advertizing bureau has taught us crimping is an absolute necessity:






This bullet manufacturer does not think so, but you don’t see this ad very often.



In a shouting match the one who shouts loudest wins. We have a very loud shouter (Lee) who makes money selling crimp dies. The more Lee shouts, the more money Lee makes. So you will continue to see ads “educating” you to buy crimp dies. The bullet manufacturer does not make any money proving that accuracy improvements with crimp dies are a farce, and the sort of person who really knows they are a farce, will be buying bullets not crimp dies. So you won't see or read much paid copy against crimp dies.

The actual fact of the matter is that crimping bullets swages the soft lead inner core of a jacketed bullet. This moves the center of gravity outside the axis of rotation, does so inconsistently, and thus, crimped rifle bullets will always be less accurate than if they were not crimped.

[Bart B.]

Post #7 in the following:

http://thefiringline.com/forums/show...+crimp+die+fcd

Slamfire, it's easy to see how irregular a bullet's waist is squeezed in by the Lee crimping die unbalancing it. But that fact's not going to be believed by those thinking crimped in bullets are best for accuracy. I've done that myself as have others. But it takes a surface equal to a Johansen gauge block to see it as well as a bright light.

And while best accuracy has been with no crimps, someone will claim that's an opinion; not a fact.

[steve4102]

Originally Posted by reynolds357

Thanks Steve. I will take Barts word for it. With a bushing change I can put as much neck tension as I want on the bullet. I know for a fact crimping a match grade bullet will kill its accuracy. I accidentally did it on one batch of ammo. 1/4 minute rifle shot over a minute. Thought I had a bad scope.

In the article by Sierra, they explained why neck tension alone will not secure the bullet during the violent cycling of the action. They went on to say that "Factory" Ammo has a greater degree of neck tension /bullet pull then handloaded ammo and the bullet would still not stay secure.

They offered two solutions to the problem, increased Neck tension or crimping. They also said that crimping with the Lee Factory Crimp die mat be a "necessary evil".

"Necessary" to secure the bullet and "Evil" because they believe it degrades accuracy.

IMO they are correct in that the Lee Factory Crimp die does secure the bullet, but they are wrong when they say it degrades accuracy.

Making a blanket statement like that concerning accuracy is a kin to saying, you will never get a Nosler Partition to shoot MOA, or neck sizing is more accurate than FL sizing. It's true crimping can degrade accuracy, it is also true that it can improve it.