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M1a crimp or not

3K views 34 replies 11 participants last post by  soundguy 
#1 ·
seen different opinions on whether or not to crimp for M1a.is it necessary or a waste of time.
 
#2 ·
the only stuff you really don't have to crimp for are single cartridges hand fed into a bolt gun, or otherwise, single shot manual loaded firearm.

Everything else gets it's appropriate crimp IMHO.

Having a repeatable crimp gives you repeatable results.

ANY autoloader that strips a cartridge from a mag, noses it up a feed ramp and slams it into a chamber needs a robust crimp, or you may find it setting your projectile back into the cartridge at chambering, and if not then, during recoil. either, leading to dangerous pressures and other problems.
 
#5 · (Edited)
After close to 5000 rounds of my reloaded ammo fired thru my M1A, not one of them ever had a crimp. With enough neck tension, the bullet won't be moving. Factory dies have LOTS of neck tension!! Custom dies? That's another animal.
Try pulling a few bullets and see for yourself how much neck tension you actually have? My bet is more than you would ever expect. YMMV, Mike.
 
#6 ·
neck tension is going to be a product of the expander button. And if you are shooting flat base bullets, if you can start them by hand.. you don't have enought neck tension.

If you are using boat tails, and a sufficiently small expander, then yeah.. neck tension alone may just do it.

I rarely only shoot boat tails... and I like consistent neck tension across the board on my hand loads, reguardless of bullet type... they way you 100% ensure that is applying a crimp. No guessing about what bullet you use as to whether it will have enough neck tension load to load. dependable repeatable ammo is what I like.
 
#10 ·
When I got my Garand 8 years ago I crimped all rounds (light collet crimp). Once I forgot the final step on some reloads so when I got to the range, I loaded up and fired one round and hand ejected the following round. Measured it an saw no difference in length. Did this several times; fired one, hand ejected the round fed into the chamber, measured the unfired but fed round. No push-back. I use mostly Hornady and HXP brass, RCBS F/L sizing die and .308" bullets....

My 7.63x39 SKS is not crimped either, as are none of my other bolt guns...
 
#11 · (Edited)
I do not crimp any of my cases for my M1 Garand, AR15s or SKS.
I simply polish the expander until it is .002 to .003 smaller than bullet diameter for more bullet grip.
At the Whidden custom die website the sell expander kits with five expanders. They are from bullet diameter to .004 smaller than bullet diameter.

The average expander is .001 smaller than bullet diameter. "BUT" nothing is written in stone, annealing, neck thickness and expander diameter govern bullet grip.

The link below shows variations in .223 dies and how it could effect bullet grip.

Are Your Sizing Dies Overworking Your Rifle Brass?
http://www.massreloading.com/dies_overworking_brass.html

 
#14 ·
Impressive. That's a whole lot of work to go thru to avoid a single set and crimp step, or a seat and then crimp step. I like taking my dies apart like the next guy.. but not that much. I much prefer just rotating the tool head a click and pulling the lever again. :)
 
#12 ·
Being as the M1A is the direct descendant of the M14, and the M14 is a battle rifle, absolute performance and reliability is essential. My rifle only sees M-80 Ball and M-118 Match ammo. The M80s are a boat tail 147 grain FMJ with a cannelure, so they get a crimp. The M-118s are either Sierra 168 grain Match boat tail hollow tip or 173 grain FMJ boat tails (getting so rare I hardly shoot them anymore) - and neither have a cannelure - so neck tension only.
 
#16 · (Edited)
I'm referring to your referenced erector set expander buttons that you change out per bullet diameter variation, in order to avoid a simple crimp step. ;)

Not the polish job.

I'm well aware of what various brands expanders look like I've got 4 shelves stacked top to bottom of die kits, plus a large box of more kits that get less use beside my bench.

Is my brass getting over worked ? Maybee. I still have almost a couple thousand 60's? Era Greek 30-06 cases I've been loading for years. I started with about 2000. Most of my bagged sets are at 5-7 reloadings. I've averaged less than 1% culling loss due to neck splits, shoulder fissures and primer pocket issues.

I guess I'm over working them.. Think of how many I could have saved! ;)
 
#18 ·
I know what the point of your posts were, I'm not a house cat or 4yr old. Like I told you, for me, its less work to simply crimp during seating, or as a separate step, vs changing out expanders all the time. Besides, most of what I shoot is cast lead now. I'm not fond of shaving bullet bases down trying to cram them into tight necks in order to save another handle pull. ;)

Like LD says, we all get to choose what works for us.
 
#19 ·
Of course you get to choose but safety should be first. I agree that any gun that carries its ammo in a magazine on the gun during firing and the ammo has to be man-handled to feed into the chamber needs a crimp whether the bullet has a cannelure or not. The unsafe part is excessive pressure possibilities that could damage the gun, damage the shooter, and maybe damage those around the gun during firing. While not crimping may work, it also may not, neck tension or not. It is safer to crimp than not to crimp. BE SAFE.

As much as I hate LEE products normally, I highly recommend the LEE Rifle Factory Crimp Die. It is a collet die that squeezes the case to the bullet to get uniform neck tension between all the ammo made using the same components. It works on a horizontal force, not a vertical force like regular crimp dies and will not semi-collapse the shoulder with over crimping. But don't over do the crimp with the FCD as you can distort the bullet.

Do choose safety over theories claimed by others.

LDBennett
 
#20 ·
but safety should be first. ..I agree that any gun that carries its ammo in a magazine on the gun during firing and the ammo has to be man-handled to feed into the chamber needs a crimp whether the bullet has a cannelure or not. ...It is safer to crimp than not to crimp. BE SAFE....Do choose safety over theories claimed by others.

LDBennett
Very much agreed sir. I'm in the 'crimp' camp myself. I like uniformity on my ammo.
 
#21 ·
Deciding to tune your dies to get a specific amount of neck tension instead of using a crimp isn't being done because we're unaware how easy it is to use a crimp die or we're trying to save a handle pull. Avoiding the use of a crimp is actually going to produce MORE uniform ammo, even compared to the LEE FCD unless you turn your necks to a uniform thickness before crimping.

This is a topic bordering on a religious war (and was an advertising war at one point) so I'm perfectly content to let the crimpers crimp and the neck tensioners tension as long as we can all be nice and respectful.
 
#22 ·
Ok, so answer this one. Looking at the recommendation of polishing ones neck expander to .002 to .003 under the projectile diameter...

How does that work for you on a cast bullet that is going to shave lead when seated if the case mouth is not opened larger than the bullet base/skirt diameter?

And do that with no crimp?

Somewhere in there, the no crimp, and undersized expander logic goes non linear and nosedives' into the flight deck. ;)

Friendly question of course. :)
 
#27 ·
Ok, here are my M1A crimping suggestions inclusive of the troublesome cast boolit that I heretofore thought no one was using.

147-150gr FMJ or other cannelured non-match jacketed bullets - Crimp.
Non-cannelured non-match jacketed bullets (eg. some hunting bullets) - Crimp or don't crimp based on your religion and existing tooling.
168-175gr SMK or similar jacketed match bullets - Don't crimp.
Lyman cast data - Doesn't matter because you'll have a single shot rifle.
Experimental cast loads that cycle the action - You're already running off the seat of your pants so do what you want.

Now when I say "don't crimp" that doesn't mean you get to skip a step, it means you are seeking match winning accuracy. I'm not a competitor so I rely on their advice when pursuing match quality loads and the source I have says don't crimp plus do a whole lot of other expensive and time intensive tasks.

There might be someone out there winning service rifle matches with the M1A and lead bullets, but I'm going to risk it and say such a person doesn't exist. Thus my apathy for a discussion of trying to load cast lead bullets without a crimp, it is pointless.
 
#33 ·
Some here are too anal about not crimping, claiming accuracy impacts with crimping. But:

The M1A is a semi-auto clone of a Military rifle, not a bench rest gun

Nine out of ten users will be satisfied with one inch groups at a 100 yards which crimped ammo will do nicely (at least my guns using the LEE FCD on many different calibers will do)

It is a known fact that if you crimp at all it is better to do it as a separate step and my experience is the LEE FCD gives much more uniform crimps than most other crimp dies, separate or in combo with the seating die, with zero chance of collapsing the case shoulder with too much crimp

Trying to stick a big bullet in a too small case neck is a recipe for disaster for the case, whether the bullet is cast or jacketed, regardless of the bullet's base shape

Reloading manuals RECOMMEND crimping ammo that is used in semi-autos, pumps, levers, or any rifle that carries the ammo in a magazine during firing and they even suggest hunting ammo be crimped as it may be carried in pockets in the field.

Factory rifle ammo is crimped and some is so good as to be hard to hand load to the same accuracy level

Do as you please, its your choice, but a safety minded shooter would follow the manual recommendations.

LDBennett
 
#35 ·
I think alot get confused in nomenclature.

De flare

Crimp

Neck tension, etc

I'm in the crimp crowd. I can't afford even one of my rounds having a projectile migrate.

At best it will lock an action, at worst it coil blow an action.

Given that different age and thickness cases will provide different neck tension sans a mechanical squeeze of some sort, I lil to err on safety and follow the basic rules.

Will that hurt me on a 1000 yard bench shot? Maybee.. But I dont do those.. ;)
 
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