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Posted: 3/31/2016 8:45:04 AM EDT
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OK, so it's my first time using the OCW method and I'm developing my first load for my .308 AR. I'm basically looking for verification that what I have planned looks to be a sound method. Rifle is an Aero M5 receiver set with an 18" barrel and mid length gas. Gas block is adjustable.
Brass is once fired Lake City. Primer is CCI-200. Powder is IMR-4064. Projectile is Hornady 168BTHP. After reading through my manuals and studying other field reported load data, I've decided on a maximum powder charge of 43.0gr. This is the loading group I'm planning on testing with: Max Charge 43.0 Down 10% Load 1 38.7 Up 2% Load 1 39.5 Up 2% Load 1 40.3 Up 2% Load 3 41.1 Up .7% Load 3 41.3 Up .7% Load 3 41.6 Up .7% Load 3 41.9 Up .7% Load 3 42.2 Up .7% Load 3 42.5 Up .7% Load 3 42.8 Up .7% Load 3 43.1 |
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Quoted:
Hodgdon website shows IMR 4064 with 168BTHP start charge of 41.5grs, max 45.9grs. Considering you're using a gas gun, I personally wouldn't go below Hodgdon minimum. I did reference that data, but they used a commercial case (Winchester) whereas I'm using a military case. Most recommendations stated a decrease of 2.0gr for loads using military cases. |
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In .308, there's a dramatic difference in capacity between Win brand and LC brass.
Your plan of .3gr increments should allow you to really see the nodes come and go. I don't use 4064 or 168gr so I can't comment on whether your min and max loads are appropriate. For reference, 43.0 gr Varget should be considered a max load with 175smk/178amax in LC brass, especially in a gas gun. I load at 42.5 with this combo and get some signs of pressure but not on every round. With a bolt gun and Win brass, the max load will be at least a couple of grains higher in my example. |
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Iconoclastic, curmudgeonly advice -
First thing to do - define your goals, in writing. Second - Skip the whole OCW thing for now. Load a bunch (~20 or more) with 42.0 gr and seated to mag length OAL Shoot them (over a chronograph) for group at the longest distance you have (200 yards preferred). Call every shot. Record the wind conditions for every shot (part of your call). Come back and report results. |
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Quoted:
Iconoclastic, curmudgeonly advice - First thing to do - define your goals, in writing. Second - Skip the whole OCW thing for now. Load a bunch (~20 or more) with 42.0 gr and seated to mag length OAL Shoot them (over a chronograph) for group at the longest distance you have (200 yards preferred). Call every shot. Record the wind conditions for every shot (part of your call). Come back and report results. While I appreciate the sage advice, I don't get a lot of opportunities to shoot these days, so I'm trying to collect as much data as I can in a single outing. While I'm sure that loading a moderate powder charge would result in a usable round, I'm really hoping to dial in the load to the rifle a bit more than that. I'm also hoping to find a powder charge that is resilient to the variations that a powder measure and long grain stick powder inevitably have. My distance goal doesn't exceed 600 yards as I really don't have any place to shoot that exceeds that, at least not here in IL. |
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Quoted:
While I appreciate the sage advice, I don't get a lot of opportunities to shoot these days, so I'm trying to collect as much data as I can in a single outing. While I'm sure that loading a moderate powder charge would result in a usable round, I'm really hoping to dial in the load to the rifle a bit more than that. I'm also hoping to find a powder charge that is resilient to the variations that a powder measure and long grain stick powder inevitably have. My distance goal doesn't exceed 600 yards as I really don't have any place to shoot that exceeds that, at least not here in IL. Quoted:
Quoted:
Iconoclastic, curmudgeonly advice - First thing to do - define your goals, in writing. Second - Skip the whole OCW thing for now. Load a bunch (~20 or more) with 42.0 gr and seated to mag length OAL Shoot them (over a chronograph) for group at the longest distance you have (200 yards preferred). Call every shot. Record the wind conditions for every shot (part of your call). Come back and report results. While I appreciate the sage advice, I don't get a lot of opportunities to shoot these days, so I'm trying to collect as much data as I can in a single outing. While I'm sure that loading a moderate powder charge would result in a usable round, I'm really hoping to dial in the load to the rifle a bit more than that. I'm also hoping to find a powder charge that is resilient to the variations that a powder measure and long grain stick powder inevitably have. My distance goal doesn't exceed 600 yards as I really don't have any place to shoot that exceeds that, at least not here in IL. The theme underlying the recommendation is that this has been done many, many times before. Too many. Your rifle is not unique. It will shoot this load better than you are able to shoot. At this charge, you will not have trouble with charge weight variations if using IMR4064. This, too, is known about this load. Still, it is a hobby. Be sure to follow up with a large sample test of your selected load. Is your bullet the A-Max? If not, why did you select the 168 versus the Sierra 175? If you are going to burn up your barrel developing a load, use the better bullet. |
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Quoted:
The theme underlying the recommendation is that this has been done many, many times before. Too many. Your rifle is not unique. It will shoot this load better than you are able to shoot. At this charge, you will not have trouble with charge weight variations if using IMR4064. This, too, is known about this load. Still, it is a hobby. Be sure to follow up with a large sample test of your selected load. Is your bullet the A-Max? If not, why did you select the 168 versus the Sierra 175? If you are going to burn up your barrel developing a load, use the better bullet. Quoted:
Quoted:
Quoted:
Iconoclastic, curmudgeonly advice - First thing to do - define your goals, in writing. Second - Skip the whole OCW thing for now. Load a bunch (~20 or more) with 42.0 gr and seated to mag length OAL Shoot them (over a chronograph) for group at the longest distance you have (200 yards preferred). Call every shot. Record the wind conditions for every shot (part of your call). Come back and report results. While I appreciate the sage advice, I don't get a lot of opportunities to shoot these days, so I'm trying to collect as much data as I can in a single outing. While I'm sure that loading a moderate powder charge would result in a usable round, I'm really hoping to dial in the load to the rifle a bit more than that. I'm also hoping to find a powder charge that is resilient to the variations that a powder measure and long grain stick powder inevitably have. My distance goal doesn't exceed 600 yards as I really don't have any place to shoot that exceeds that, at least not here in IL. The theme underlying the recommendation is that this has been done many, many times before. Too many. Your rifle is not unique. It will shoot this load better than you are able to shoot. At this charge, you will not have trouble with charge weight variations if using IMR4064. This, too, is known about this load. Still, it is a hobby. Be sure to follow up with a large sample test of your selected load. Is your bullet the A-Max? If not, why did you select the 168 versus the Sierra 175? If you are going to burn up your barrel developing a load, use the better bullet. I agree that out of the few load reports that I found that used LC cases, most all seemed to land at the 42.0 grain mark. Are you in agreement that this load would be suitable in a LC case as well? I went with the Hornady 168 HPBT mostly due to it's cost, availability in bulk, and my limited range. While I completely agree that the 175 Sierra is a better bullet, especially at even longer ranges, I just went with what I knew and could reliably obtain. |
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Quoted:
The old belief "military" brass has less capacity than commercial is not always true. Weigh cases, military and commercial, and you may find a surprise. Of course you're right. Especially with .223 or 5.56 brass - LC and Win are very similar. But in my experience, Win brand .308 brass has a lot more case capacity than LC 7.62 brass. |
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Quoted:
OK, so it's my first time using the OCW method and I'm developing my first load for my .308 AR. I'm basically looking for verification that what I have planned looks to be a sound method. Rifle is an Aero M5 receiver set with an 18" barrel and mid length gas. Gas block is adjustable. Brass is once fired Lake City. Primer is CCI-200. Powder is IMR-4064. Projectile is Hornady 168BTHP. After reading through my manuals and studying other field reported load data, I've decided on a maximum powder charge of 43.0gr. This is the loading group I'm planning on testing with: Max Charge 43.0 Down 10% Load 1 38.7 Up 2% Load 1 39.5 Up 2% Load 1 40.3 Up 2% Load 3 41.1 Up .7% Load 3 41.3 Up .7% Load 3 41.6 Up .7% Load 3 41.9 Up .7% Load 3 42.2 Up .7% Load 3 42.5 Up .7% Load 3 42.8 Up .7% Load 3 43.1 To return to the question asked, that range conforms to Dan's published methodology and should expose at least one accuracy node. It may well be a low speed node as others have pointed out, but that's not a bad thing either. I do see that you increased by only 0.2gr from 41.1 to 41.3 which is fine and I'd guess was done to avoid going to 43.2gr at the top end lol. And that you stuck with a 0.3gr thereafter which I think is a good thing. Having answered your question, I'd add my own observations as follows: In use, I've seen little point to the first 3 loads in the sequence. I begin instead with your first set of 3, a load actually being tested with a group. But preliminary sighters/foulers/conditioners are important. So without those first 3 loads in *my* workups, I make 3 extra rounds (IMPORTANT: or as many as I think I MIGHT need) of one of the loads I am actually going to test. Which load? Sometimes it's the one I want the most data from (a guess, SWAG, whatever you want to call it). Another is to set my zero so it's unlikely to cause bullets to fall directly on the POA, obscuring it, while hopefully allowing all tested loads to stay close to my little 2" targets, 8 to a sheet of 8.5"x11" paper. I don't think those changes affect the methodology in any way. My last change may, depending on your POV. I do not believe in round-robin firing the first round of each group, then the 2nd, then the third to spread the effects of heat and dirt build up "fairly". I fire each group as a group so that each round has the same conditions as its predecessor, as close as can be achieved, and as groups will actually be fired when in use. Have fun! Learning is great. |
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