Reduced loads for AR-10

[L308]

I am working to develop a reduced recoil load for my Armalite AR-10. The Hodgdon on-line reloading manual says that you can use H4895 powder at 60% of the maximum load listed in their manual to make reduced loads. The max load for a 150 grain bullet in 0.308 is listed as 45.5 grains. Since I would like to use 150 grain bullets I was thinking to start at 27.5 grains (45.5 grains X 0.6 = 27.3 grains) and work up to the minimum load of 43.0 grains. I imagine the action won't cycle at the lower loads; but I am hoping that at some point the gun will start cycling.

My question is this: Does anyone know if there are any safety concerns with this idea?

Thanks much in advance for your help.

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[Member 5605]

Make sure the bullet leaves the barrel every time.

Other than that.... Nope. Have fun.

 

[OutlawHoss]

I wouldn't start that low at all, just at the minimum listed load. I think what should be said is they are recommending 60% reduction in power, as expressed best by pressure, not literally the amount of powder (and I would get this data from an actual reloading book; they'll have much more load development info about the pressures involved than most online loads, and less likely to be someone's pet load that got posted widely). I've never seen any load recommendation show that dropping the grains by 60% produces any kind of viable round; the pressure drops off exponentially at such low loads and 27 grains won't do much at all. In fact, at that small of a charge in a case that lists at 56 gr capacity/water, you're getting close to detonation issues. More likely is having a bullet stuck in the barrel; it would be an exercise in futility at best, and a re-arraignment of your face at worst. If you want a low and slow round, try a different cartridge, like the AAC Blackout.
Gas guns need a minimum of pressure to operate as it is. What is your twist rate, and length of barrel? Lower end bullet weight means a faster load to get usable performance. For reference, a M80 round, 147gr at 2733 fps, is designed for a 1:12 twist; the M118LR is 175gr at 2580 fps, which is in a 1:10 barrel. I think you'll have better success at reduced power loads with heavier bullets, or at least one suited to your barrel's twist. I recently found the lowest power load that performs well (ballistically) in my DPMS LR308 is a 168gr at 2420fps. It was very accurate, but at that load it started to not fully cycle the action, and threw the brass to about 1:30 from the port, a diagnostically under-powered (under-gassed) load. 3 to 4 o'clock is 'the zone' for a properly gassed load.
Hope this is helpful!
Hoss

 

[Roop]

My pet load is 39grs of H4895 under a 150 gr hornady fmj. this load cycles in my bushmaster lr308, but this rifle is a bit overgassed. The listed starting load of 43grs wouldn't shoot accurately, and the full power loads were all over the place. I too have read the bit about using reduced loads with H4895, the Lee reloading manual has an extensive section on reduced loads, especially as they relate to cast bullets in cartridges like the 30-06.

As an alternative to H4895, you can try out accurate 5744. I played around with loads in the low 20s range a few years ago and had really good luck. I only quit using it because of the powder shortages. http://www.accuratepowder.com/wp-content/uploads/2010/09/WesternLoadGuide1-2016_Web.pdf

 

[OutlawHoss]

My pet load is 39grs of H4895 under a 150 gr hornady fmj. this load cycles in my bushmaster lr308, but this rifle is a bit overgassed. The listed starting load of 43grs wouldn't shoot accurately, and the full power loads were all over the place. I too have read the bit about using reduced loads with H4895, the Lee reloading manual has an extensive section on reduced loads, especially as they relate to cast bullets in cartridges like the 30-06.

As an alternative to H4895, you can try out accurate 5744. I played around with loads in the low 20s range a few years ago and had really good luck. I only quit using it because of the powder shortages. http://www.accuratepowder.com/wp-content/uploads/2010/09/WesternLoadGuide1-2016_Web.pdf

Yes, using cast is way different than copper plated, so there's that too.
I'm not familiar with the 5744. I had no idea there was a powder for 308 in such small charges. If you can adjust your gas block than that's a huge advantage, one I haven't experimented with myself.
Such small charges in a 308 case makes me a little nervous, but if they're listing it as such for that particular powder, it's could be a good round. I just wouldn't use a powder at a load that's so reduced beyond what's listed.

 

[AMProducts]

I've shot EH-LOT of .308 handloads over the years from various bolt-guns I owned. One of my personal favorites was a 150gr M80 over top of about 35grs of H335, it was a bit dirty, and I would be skeptical that it would cycle the AR-10, but it was an accurate fun load. I developed it for a 4-lb .308 pack rifle I had that was just brutal on the shoulder without something a bit lighter. IIRC MV was about 2100FPS from a 20".

Another powder you might try that responds really well to these types of situations is IMR3031, which is often used as a smokeless replacement in black powder cartridges. A buddy of mine has an 11mm mouser that he loads with paper-patched bullets and 3031. I think I'm using ~41gr of 3031 in my .308 match loads (168gr SMK) but don't quote me. My normal preferred powder is Varget, but while that was in short supply I bought a few drums of 3031, which maybe some day I will finish using.

In all, I'm not really sure exactly what you're trying to achieve here, recoil reduction or cost savings are the two obvious, at which point I would say "shoot your AR-15 more" to both. I actually barely shoot my .308 rifles any more, I can push .223 out to nearly 1000yards with my bolt gun and 75gr SMK's, and anything less than 600 I can beat up nicely with any of my AR-15's. Unless you really need something really big, really dead, really far away, shoot .223, and if you do need that, buy a .50 cal upper

Another thing you may consider, if you're looking for something easier on the shoulder long term, but still want to reach out and touch... think about rebarreling to 6.5 creedmoor.

 

[BonesD]

I am working to develop a reduced recoil load for my Armalite AR-10. The Hodgdon on-line reloading manual says that you can use H4895 powder at 60% of the maximum load listed in their manual to make reduced loads. The max load for a 150 grain bullet in 0.308 is listed as 45.5 grains. Since I would like to use 150 grain bullets I was thinking to start at 27.5 grains (45.5 grains X 0.6 = 27.3 grains) and work up to the minimum load of 43.0 grains. I imagine the action won't cycle at the lower loads; but I am hoping that at some point the gun will start cycling.

My question is this: Does anyone know if there are any safety concerns with this idea?

Thanks much in advance for your help.

I have a stOck DPMS AR10 that runs fine on Hornady Custom Lite 125 grain SST ammo. It was almost new when I started trying the lite loads and it would fire and eject but not pick up a fresh round. After several boxes of 160 grain ammo I tried again an would get two rounds to run and then again fail to pick up. So I oiled the stink out of it and now runs flawlessly on the lighter loads.
My daughter loves it compared to the bolt action 243 I had bought her. The recoil is much reduced and shooting about a half box of ammo she was still drilling the target and not flinching. Shooting off of sand bags but started the hits started walking up. Shooting every minute or so so I guess it was warming up or it could have been her. Great combination.

 

[Caveman Jim]

Make sure the bullet leaves the barrel every time.

Other than that.... Nope. Have fun.

Just Say NO to SQUIBS...

 

[BonesD]

You betcha!

 

[gmerkt]

While it's true that both 4895's are versatile and will successfully tolerate significant charge reductions, this is a general statement that pertains in the main to bolt guns and other rifles that aren't semi-autos.

For one thing, the AR-10 doesn't impart all that much recoil since it's a gas operated design. I've got an Armalite AR-10, never considered it a bruiser.

For another, the reduction in charge that you are considering may not be reliable in the action of the rifle. If it matters to you. But one reason I have an AR-10 is because it loads itself. I have several rifles chambered in .308; I have them all zeroed to the same loads using 150 and 165/168 gr. bullet loads. Depending upon which bullet weight I'm using, I'm very happy with charges of IMR 4895 in the 40.0 to 41.5. gr. range.

I've just looked at the Hodgdon online load data. You've got to bear in mind this data is published largely with the idea that such loads are going to be fired in sporting rifles mostly of a bolt action nature. Typical loads constructed for service type rifles are loaded at reduced min/max levels from what Hodgdon has provided. In my view, the AR-10 falls under the service rifle category and does best with loads such as would be used in an M1A or an M1 Rifle chambered in .308. Also note that Hodgdon provides different charge amounts for the two different 150 grain bullet designs specified so this is also a variable.

 

[L308]

There have been several replies to this thread so I thought I'd give you an update: I have used the reduced loads and much to my surprise, they do cycle reliably in my AR-10. They are fairly accurate (one inch groups) in my 0.308 bolt action rifle. However, so far these loads haven't been very accurate in the AR-10. I believe that may be because I have trouble getting consistent crimps. Since the recoil is very mild I am going to try shooting some cartridges that have not been crimped to see if the bullet will stay in place under recoil.

 

[Member 5605]

There have been several replies to this thread so I thought I'd give you an update: I have used the reduced loads and much to my surprise, they do cycle reliably in my AR-10. They are fairly accurate (one inch groups) in my 0.308 bolt action rifle. However, so far these loads haven't been very accurate in the AR-10. I believe that may be because I have trouble getting consistent crimps. Since the recoil is very mild I am going to try shooting some cartridges that have not been crimped to see if the bullet will stay in place under recoil.

Do you have different twist rates in the two rifles?

 

[gmerkt]

You might bear in mind the position of the powder in the cartridge case at the time of firing. Your reduced charge doesn't come near to filling the case. If your powder is lying predominantly in the forward end of the case and away from the primer, erratic ignition may result. It's easy enough to raise the muzzle end of the rifle prior to each shot to be sure the powder charge is oriented to the back of the case and therefore over the primer. Erratic ignition can cause groups to open up. Powder away from the primer also results in reduced velocity.

Note: If you're shooting on an organized range, don't go crazy with elevating the muzzle of your rifle between shots. You may draw negative attention from the range master to yourself. Moderate elevation, say, 15 or 20 degrees and a little shake will usual settle the powder in the rear of the case.

My guess is when shooting the AR10 semi-auto with reduced charges, you're shooting shot after shot without regard to powder orientation. Moreso than a bolt action, the semi auto action tends to snap the rifle back forward again after recoil and guess which end of the cartridge case the powder wants to congregate in?

This is why some shooters in years gone by have used fillers to ensure powder position inside the cartridge case when loading reduced charges. I've done it a few times myself over the years but I find it's more trouble than it's worth and can introduce problems of its own.

 

[oli700]

There have been several replies to this thread so I thought I'd give you an update: I have used the reduced loads and much to my surprise, they do cycle reliably in my AR-10. They are fairly accurate (one inch groups) in my 0.308 bolt action rifle. However, so far these loads haven't been very accurate in the AR-10. I believe that may be because I have trouble getting consistent crimps. Since the recoil is very mild I am going to try shooting some cartridges that have not been crimped to see if the bullet will stay in place under recoil.

don't forget to single load those rounds in the AR , it might be closer to your bolt action grouping but so many variables in just barrels alone you may never see the same results . In fact I would bet not .......usually you cant get ammo to act the same through "identical" barrels

 

[arakboss]

I am working to develop a reduced recoil load for my Armalite AR-10. The Hodgdon on-line reloading manual says that you can use H4895 powder at 60% of the maximum load listed in their manual to make reduced loads. The max load for a 150 grain bullet in 0.308 is listed as 45.5 grains. Since I would like to use 150 grain bullets I was thinking to start at 27.5 grains (45.5 grains X 0.6 = 27.3 grains) and work up to the minimum load of 43.0 grains. I imagine the action won't cycle at the lower loads; but I am hoping that at some point the gun will start cycling.

My question is this: Does anyone know if there are any safety concerns with this idea?

Thanks much in advance for your help.

Here are a couple of other ideas. To be fair I have not tried either of these in 308 but I have used "the load" in my Remington 740 Woodsmaster and it did not cycle the action, very mild shooting load but enough accuracy and power to knock down the silhouette targets at 100yds. Do I need to say play with these ideas at your own risk and read all the info carefully!

THE LOAD BY C E HARRIS

https://rifleshooter.com/2017/09/reduced-308-winchester-loads-with-trail-boss/

 

[gmerkt]

In years gone by, I've experimented with Harris's "The Load" using 2400 powder. There are enough differences in high powder centerfire case design and actual chamber dimensions from one rifle to the next that his recommendations really aren't "universal." Some you have to bump his charge up to get the case neck to seal, then you find that accuracy goes to heck and begone.

I've also fiddled with the "Cat Sneeze" loads using Red Dot that were propounded by the cyber hand loader in Finland, now deceased. I've forgotten his name now. It was fun for a while, you can make some stealthy loads. You can make what is an ordinary high power rifle more versatile. But it's specialized stuff and requires lots of care, caution and experimentation.