Cast Bullets in an AR-15

[klw]

I always thought that this wasn't a good idea because the alloy and grease would build up in the gas tube and plug it up. But I've seen a couple threads elsewhere that suggest that that doesn't happen. That the pressure is such that the crude just gets blown out. Anyone try this? If so, does it work?

[Larry Gibson]

I've shot lots of cast bullets through ARs and several thousand .22LRs myself through M16s with the M221 adaptor. Never had a problem with the gas tubes getting plugged and used Javelina lube on the cast bullets. Any load with enough pressure to function the bolt will keep the gas tube blown clear. The manual for the M221 advised just to shoot regular M193 ball ammo through the M16 to clear any lube build up. It works fine. I use 225415 and 225462 in the ARs without problems. The ARs I used them in had 12" twists so I got very decent accuracy and functional reliability at 2000 fps. The 225462 was the better bullet in the 10" twist Mini14 I had.

Larry Gibson

[NickSS]

Dito for me I have used the same bullets in my AR 15 with a 9 twist and got decent accuracy. Do not know what velocity was as I never chronoed the loads but I would gess in the 1900 to 2000 fps range. I also have a conversion unit that lets me shoot 22 RF from mine and have shot hundreds of rounds. never had any problems.

[corvette8n]

will gc cast work with a pinned on compensator?

[xfire]

i have a 22 conversion kit thats mil spec called a M260 had it for years but now it stopped working i been trying to find a new firing pin & new rail guide for it but nobody knows who made itor where i can get parts from. i have all the nsa numbers for parts too any information would be a great help.

[nicholst55]

will gc cast work with a pinned on compensator?

What's different between a pinned compensator and an unpinned one? No reason why they shouldn't work.

[Outpost75]

My neighbor has been shooting cast in his M4 for several years. His has a 16" barrel with military 5.56 chamber, which is larger in neck and throat diameter than a SAAMI .223 Remington. The gas port measuress 8" from the bolt face. Quick Load, the interior ballistic computer program estimates port pressure at ~ 12000 PSI. with 15 grains of RL7, which as low as you can go and still work the action reliably.

Accuracy is equal to FMJ ball ammo, the gas system after 100+ rounds shows no issues. The gun runs as clean with the cast bullet reloads as with the cheap, imported milsurp ball ammo. He uses the cast loads is to conserve his stash of arsenal or factory stuff for serious work.... They work OK for practice and casual shooting.

He casts bullets blending linotype from Roto Metals and wheelweights 50-50, running the mold hot enough so that bullets drop uniformly frosted, quenching in water direct from the mold. Gaschecks are crimped on in a .225” sizing die so that the driving bands of the bullet are not sized at all. Bullets are seated as far out as they can be and still load into and feed from the magazine. His barrel twist is 1 in 9". Until recently he hadn’t tried any other powder than RL 7, because we both keep that around as our best go-to powder for .30-30 and 7.62x39, which we use a lot of.

Velocity with 15 grs. of RL7 and the RCBS 22-55 bullet is 2150 fps. This load performs very well considering the generous military chamber dimensions. The major problem with shooting cast lead in AR's is their fast twist barrels in current rifles and their sloppy military chambers. Most folks who give up on cast in their ARs do so because they don't understand that the bullet surface which engraves ~ .002" deep simply does not have adequate shear strength to spin the bullet up in such a short acceleration distance without slipping the lands and damaging the bullet's integrity. Slow the load down to the minimum which cycles reliably, about 2100-2200 fps and they shoot even better than the steel cased Russian ball!

Computer modelling of slower powders such as Varget through Quick Load, with bullets lighter than about 70 grains, they don't develop enough port pressure at suitable velocities normally useable with cast bullets. Harder quenched bullets can be driven over 2400 fps without leading, but their accuracy is best in older 2-inch twist barrels, and by limiting yourself to flatbased bullets no heavier than about 65 grains. In 9" and faster twists stay below 2200 fps.

In our experience RL7 shows the best characteristics to adequately function the action and its efficiency is almost 100% of the powder being burned in a 16 inch barrel. A standard 20" length AR barrel is harder to make "work" as its gas port is further down the barrel than it is on the M4. Before the weather turned cold we shot some groups in his M4 with 15 grs. of RL7 and the 55 gr. RCBS bullet, putting a 10X scope on the rifle. Three, 5 shot groups off sandbags at 100 yards averaged 1.67." Similarly, three five shot groups with AKA 55-grain FMJs shot 1.75" groups.

A fed buddy visiting our range from VA brought his Colt Miliitary/law enforcement model with 7-inch twist barrel. It shot a one-hole 10-shot group of about 3/4 inch at 25 yards. Our load of 15 grains RL7 wouldn't reliably cycle his action and occasionally would short recoil, ejecting the spent casing but without feeding another round. Additional experiments later with bullets cast from a 60-grain Saeco mold with 18 grains of H322 clocked 2150 fps and cycled the Colt gun with no signs of leading. We are lubricating bullets with Lee 50/50 Alox-beeswax.

Adequate bullet diameter, not less than .225" is critical to accuracy. Load the largest bullet diameter that will chamber/function. Bullets must be of adequate hardness, not less than commercial 92-6-2 “hardball” alloy or 50-50 linotype and wheelweights, especially above 2200 fps, and with heavier loads of slower powders such as Varget or 4895, which may be needed to boost port pressure in full-length 20-inch ARs.

To load cast bullets without damage you must chamfer the case mouths with a shallow-angle Lyman "VLD" deburring tool, and also slightly bell the case mouths with a Lyman "M" die. This is necessary so that the bullet can be hand started into the case mouth up to the top of its gascheck and seated smoothly into the neck without risk of shaving lead. Then, during the seating operation apply a light taper crimp to remove all mouth flare, but not a heavy crimp which could deform the bullet. Also drop-check all rounds 100% in a max. cartridge gage to ensure that they will chamber and extract freely. The same as required for any cast bullet load to be used in any semi-auto, AK, Garand, M1 carbine, M1911A1, etc.

There are heavier custom molds available up to 75 grains, optimized for the 5.56mm military chamber, but I have no personal experience with them. Users on other forums report reliable functioning with 18 grains of IMR4895 or Varget for about 2000 fps with the MiHec 75-grain NATO bullet. The HM2 225-62-1 design is a good choice for either the .223 Remington with 12" twist, or in the faster twists, with appropriate loads. Their six-cavity gang mold is great for quantity production and is VERY affordable at $125, fitting RCBS handles. I have several of their .30 cal. molds which are top drawer!

[Jailer]

klw, you're not going to get much better advice then what you just got right there. ^^^^^^^^

FWIW, it takes a minimum charge of 19gr of H4895 or 20gr of IMR 4895 to reliably cycle my mid length and rifle gas system guns. If you have a carbine length follow Outpost75 advice above.

[35remington]

Strangely, my mid length 16" RRA functions with lighter loads than my two WW 16" carbine type barrels, probably a matter of gas port diameter. The RRA will function and lock back on empty with as light as 17/H4895 and a 55 grain bullet while the two other rifles require 18 grains to cycle and 19 grains to lock back on an empty magazine.

Since these are 1-9 twist and accuracy is better the slower I go, 18 grains is what they all see when using H4895. I find IMR/H4198 (preferably H due to shorter granule length) to be about similar to 75's post above lauding the similar Reloder 7 in the same approximate (14.5-15) grain charge area.

I also have had dismal results with ACWW's in the longer 55 grain and up cast bullets in my AR's and prefer them of linotype or some similar hard lead. Since lino fills out so well and gives a smaller percentage of rejects from the mould this is what my rifles see. I can cut it at most about 25% with wheelweights before poorer casting quality becomes evident and since the bullets are already small and give good return in bullets per pound I usually don't bother.

Casting a higher percentage of more nearly perfect bullets is saving time, and time is money. The gascheck is most of the bullet expense anyway.

[walltube]

Outpost75,

Thank you and thumbs up to you for your post, number 7.

Cheers,
Wt.

[garym1a2]

I looked into it and from what I read about 2000 fps is what you get from cast with those tiny boolits, i decided to go the blackout round instead for my ar. With the lee 155gr running at 1720fps I get much more energy to the target than the 55 gr at 2000fps.

[lksmith]

if you are shooting anything supersonic in an AR make for dang sure you use a gas check or you will have lead build up in the bolt.
The last un checked boolit I shot was WCWW that tested at 22 BHN with my lee tester.
I have seen no issues with subsonic or gas checked boolits in my AR's

[Moonie]

if you are shooting anything supersonic in an AR make for dang sure you use a gas check or you will have lead build up in the bolt.
The last un checked boolit I shot was WCWW that tested at 22 BHN with my lee tester.
I have seen no issues with subsonic or gas checked boolits in my AR's

I've not had any trouble with boolits under 1,500fps unchecked in my 300BO upper. I've run several hundred between cleanings and had no buildup of any kind. I run WDWW.

[xacex]

Several thousand through one 300BO with cast with no issues. I did find I had better accuracy without a muzzle brake or flash hider with mine. Also, with the 5.56 rifle and pistol there have been thousand of .22lr shot through a M261, along with lots of cast Mihec 5.56 boolits, and Bator boolits. No issue with gas tube.