Reloading all copper?

[73Jim]

Do you have to load differently for an all copper projectile vs a copper jacketed lead bullet? I've read some information stating that the copper round needs more twist...anyone have an experience? I bought these copper 55g blems from American Marksman and wow...not on paper @ 100 and in the far upper right corner @ 50 (20-24" from center).

Here is my plinking load for my ar with 18" 1:7 twist and Rem 700 1:12 twist:
case length = 1.75"
COL = 2.20"
primer = CCI 41
powder = W748 23.5g
projectile = Xtreme .224 55g (0.740" long)

For these copper projectiles (0.800") I used the same brass prep and primer but varied the COL from 2.27 to 2.20" and powder grains from 22.0 to 25.5. I've only tried these in the Rem 700 but they were ugly.

Is the problem that the 700's twist is too slow (didn't try them in the ar) or the blems THAT bad or do copper round need "special" handling?

[ducky_0811]

It's the twist rate, they should shoot much better out of your AR

[elk hunter]

No, nothing special about copper. Get the reloading manual for them and load accordingly. Copper is no different than any other bullet in most cases, you have to find the right combination of bullet powder primer seating depth. All different makers bullets are going to shoot different in all guns. You can not (except by dumb luck) go out and buy .224 50 grain slugs of Sierra, Hornady, Nosler or any other of the same weight load them all up and expect them to shoot the same, it just don't work. The rate of twist in production barrels is not in most cases specific to one weight bullet they are made to cover and use a larger area. Say from 55 gr. to 62 grain as a example. If your shooting Barns blems use the Barns book same for any other makers bullet.HTH

[CSACANNONEER]

Of course your POI will be different with different bullets, powder or even primers. You need to use the proper load data for the bullets you are loading. Not all 55 grain bullets are the same even if they are made from the same material(s). I can't believe that you are a reloader and don't understand these simple and basic concepts.

[73Jim]

Of course your POI will be different with different bullets, powder or even primers. You need to use the proper load data for the bullets you are loading. Not all 55 grain bullets are the same even if they are made from the same material(s). I can't believe that you are a reloader and don't understand these simple and basic concepts.

I guess I haven't reloaded enough to see a two foot delta at 50 yards, it seemed extreme. Other combinations of bullets/powder/depth have had variations measured in inches rather than feet at that short of a distance...but thanks for the help!

[JMP]

Yes, it is quite different. I shoot mostly solids for ELR and lead jacketed for short action. Copper and zinc, which compose solids are much less dense metals than lead, which gives them more volume for the weight. This reduces their rotational inertia to remain stable in flight. Hence, for the weight, you generally need a faster twist than lead. Also, for the weight, they generally require less powder since they have more volume so they will act like heavier leads in terms of building pressure.

[Fjold]

The 55 grain copper bullets are about as long as a 70 grain cup and core bullet. Check the holes in your target, they're probably not round. They should work fine in your 1:7" twist AR.

[CSACANNONEER]

I guess I haven't reloaded enough to see a two foot delta at 50 yards, it seemed extreme. Other combinations of bullets/powder/depth have had variations measured in inches rather than feet at that short of a distance...but thanks for the help!

I guess I should have asked if the POI was consistent?

[LynnJr]

2 feet at 50 yards is beyond extreme.
The main difference with copper is seating depth.

[JagerDog]

That 1:12 was made for very light bullets...more specifically, very short bullets. My Kimber of Oregon wasn't fond of 50gr Varmint grenades (which mfg specs as requiring 1:10 or faster). Your 1:7 should be fine if the bullets are decent. I'm not surprised the Rem 700 isn't happy with them.

You didn't really ask, but copper generally requires shorter OAL's as well. The bullet profile is different in order to help make up for the lack of density. At typical lead OAL's they can jam up against the rifling. As well, copper tends to like a bit of "jump" or high pressures will occur.

[ultracovert]

I had the same problem with my rem 700 25-06. I tried everything, finally i called Barnes and asked wtf is wrong with their bullets. They suggested seating them 25 thousandths off the lands and move back from there. Im still not happy, but at least i can measure groups in inches instead of feet. if i find a combo that works i will share it.

[Wrangler John]

I shoot all copper bullets exclusively now. As some have mentioned, there are some factors to remember when shooting copper aka 'lead free' bullets:

There are two basic types of copper bullets: Monolithic copper expanding bullets, either hollow points or plastic tipped; the second type is compressed powdered metal core jacketed bullets. This latter type may have a core of atomized copper, or a blend of copper and tin, compressed with a binder into a thin copper jacket.

The monolithic copper bullets for big game are usually the most problematic for some rifles in heavier weights as they are longer than jacketed lead core bullets. Many copper bullet manufacturers now list the recommended MINIMUM twist rate for their bullets:

http://www.barnesbullets.com/bullets/tsx/

http://www.barnesbullets.com/bullets/ttsx/

I suggest selecting the stable twist rate or faster for the heaviest weight bullet of a given caliber, as this will shoot the lighter weight bullets as well. In the case the manufacturer does not list a recommended twist rate, as the Barnes example below, it is possible to calculate a twist that will stabilize all bullets in a class:

http://www.barnesbullets.com/bullets/varmint-grenade/

First go to a twist or stability calculator and plug in the numbers:

http://www.jbmballistics.com/cgi-bin/jbmstab-5.1.cgi

Barnes 50 grain Varmint Grenade is 0.858" long, so we enter those parameters, then in my .22-250 Remington they will attain a 3,500 + fps velocity, so enter that number, and accept the default elevation and temperatures. In a standard 1:12" twist the bullet is UNSTABLE with a Stability Factor of 0.835 - we want something ideally around 1.5 or above.

A 1:10" twist is marginally stable at SF 1.202, close but still not good enough.

A 1:9" twist is stable at a SF of 1.484, just shy of 1.5, this is the minimum twist rate I would recommend for this bullet. Now we check the 1:8" twist and find a SF of 1.878 - most likely able to handle even longer and heavier copper bullets as will the 1:7" twist.

If we look at that 62 grain 6mm Varmint Grenade, we find it to be 0.978" long. When I tried it in a Sako 6mm PPC 1:14" twist rifle, it wouldn't hit the target at 100 yards. This rifle shoots 70 grain Sierra bullets into .3" groups. When I finally did get one to hit it was completely sideways. Using the calculator it was discovered that the Varmint Grenade required a 1:8" twist to stabilize.

Because these bullets have no lead core, or a separate core at all, we don't have to worry about driving them too fast or with too much spin, even the powdered metal core variety, as they won't disintegrate in flight. I have experimented with a 26 grain Barnes Varmint Grenade in a 1:8.5" twist at 4,110 fps which shot little bug hole groups that hit squirrels at 250 yards or more easily.

Some manufacturers don't list a minimum twist rate for the lightest (and shortest) bullets because these will generally stabilize in the "industry standard twist" accepted for that caliber. Don't let this fool you, while in most cases it will work, some older rifles with slower twist rates will not deliver acceptable accuracy, a 1:14" twist .224" such as older .22-250 Remingtons for example. Besides, ballistic engineers are human and make compromises and mistakes too. The .204 Ruger being an example with a 1:12" twist adopted as standard. I found that twist too slow for some popular bullets, and have settled on the 1:9" twist as ideal, with the 1:8" twist better for Berger's 55 grain HPBT (although not a copper bullet). You'll have to measure your twist to make accurate calculations using the cleaning rod method, http://www.accurateshooter.com/techn...el-twist-rate/, because twist rates of factory barrels can be all over the place.

The final factor is seating depth. Most will have to be seated at least 0.020" off the lands, with Barnes TTSX bullets being somewhere around 0.050" off, or more. Even 0.070" is a sweet spot for these somewhat rigid bullets. This requires a lot of either guess work, or using a seating depth gauge to determine where the rifling begins and allow one to make graduated seating depth samples.

[LynnJr]

Wrangler John
Great post but stability factor could be changed to Sg for gyroscopic stability.

[Divernhunter]

I have a 1-10 barrel on my rem700 223 and it is great with 36 or 50gr Barnes VG bullets. My son in laws Howa with factory barrel(I thing 1-14 or 1-12 twist) shoots the 36gr bullets just fine but the 50gr bullets are like a shotgun pattern.
For what it is worth.

[73Jim]

Wrangler John...good read, thanks!

Quick update...out of the faster turn ar barrel they behaved like I thought a blem should. A far cry from a match load but with relativity rapid fire (every 3 seconds or so) I maintained 6" group at 100 yards. Plinking loads they shall become.

One thing still bothers me, I saw no appreciable difference between any of the loads (varied COL and powder charge). Perhaps my cadence was too fast.