OCW !!!

chambered221 · Posted: Tue Jul 13, 2010 4:00 pm Post subject: Re: OCW !!!

Dawgdad, Thanks for your comments !!!

I assure you I'm not trying to apply any snake oil just trying to get others to understand the system has some forgiveness built in.
I truly don't mean to make it sound like a end all, greatest thing since sliced bread.
I apologize if it's sounding that way.

I also agree (as mentioned in opening post) that seating depth changes should be made to fine tune or at least check to see if one can do better.

Stovey, You got it !!!
The 3 loads will obviously generate different amounts of pressure that translate to a difference in velocity but all 3 bullets will exit the barrel in the same harmonic node and share a common POI on target.
Understanding how the barrel reacts when a bullet is fired down it helps in understanding this better.

Gil Martin · Posted: Tue Jul 13, 2010 4:21 pm Post subject: Re: OCW !!!

All this sounds much too complicated for me. For several decades, I have relied upon the suggested Lyman accuracy loads and have been well pleased with the results. Then again, I am just a recreational shooter and cannot get too mired down in all the finer details. All the best...
Gil

chambered221 · Posted: Tue Jul 13, 2010 4:34 pm Post subject: Re: OCW !!!

Gil, the mechanics behind it can be.......the process itself is simple !!!

For the most part you start your testing as usual, the difference is how you shoot it and interpret the results.

Dawgdad · Posted: Wed Jul 14, 2010 4:52 am Post subject: Re: OCW !!!

Gil - it is not really that complicated. I made an Excel spread sheet where I enter the maximum safe load value and it spits out 6-8 charges to test with 5 shots each. In 30-40 shots you will have the answer.

If any one wants the spreadsheet send me a pm and I will e-mail it to you.

stovepipe · Posted: Wed Jul 14, 2010 7:10 am Post subject: Re: OCW !!!

Gil Martin wrote:

All this sounds much too complicated for me. For several decades, I have relied upon the suggested Lyman accuracy loads and have been well pleased with the results. Then again, I am just a recreational shooter and cannot get too mired down in all the finer details. All the best...
Gil

Good point ....Sierra sent me some accuracy loads and such. Pretty neat stuff and same are the next loads I'll be trying. Their recipes are different than loading manuals and powder company's.

Gil Martin · Posted: Sun Jul 18, 2010 7:43 am Post subject: Re: OCW !!!

I am convinced to give this a try. Thanks for the informative posts. All the best...
Gil

chambered221 · Posted: Sun Jul 18, 2010 2:22 pm Post subject: Re: OCW !!!

Gil, Glad to see your gonna give it a try !!!
Please report back with your findings and any general comments or thoughts on the process.

slimjim · Posted: Fri Jul 23, 2010 1:28 pm Post subject: Re: OCW !!!

Got to the range today and shot five 3-shot loads for my .270 Win using 150gr Berger VLD bulelts and Ramshot Hunter powder. Which load should I consider my Optimum Charge Weight?

slimjim · Posted: Fri Jul 23, 2010 1:32 pm Post subject: Re: OCW !!!

Wind was 10 mph with gusts to 20 mph mostly from the rear with a component that was slightly left to right. I think the 3rd shot with 53gr of powder may have been a gust (edge of paper). still if you move it back to the left some, it had the lowest POI. Before you say the groups are not very tight, this was at 200 yards (too many people on the 100 yd range).

slimjim · Posted: Fri Jul 23, 2010 1:43 pm Post subject: Re: OCW !!!

There are some things recommended with OCW that I don't do. I don't shoot one bullet then move to the next load. I already have 30+ rounds down the barrel since the last cleaning so I don't see mixing the shots as important. The primary reason I don't do this is it increase my chance for human error, e.g., placing the a bullet in the wrong group or fogetting to get up and change the string on my chronograph. Here is the velocity data

_52.0 _ 52.5 _ 53.0 _ 53.5 __ 54.0
2666 _ 2772 _ 2715 _ 2777 _ 2824
2836 _ 2677 _ 2766 _ 2807 _ 2824
2732 _ 2766 _ 2772 _ 2807 _ 2850
2744 _ 2738 _ 2751 _ 2797 _ 2833 _ Average

stovepipe · Posted: Fri Jul 23, 2010 2:15 pm Post subject: Re: OCW !!!

53.5 if yer intended POI was the X/center.

chambered221 · Posted: Fri Jul 23, 2010 3:05 pm Post subject: Re: OCW !!!

I'd be interested in seeing where 54.5 would have landed !!! (If a safe load)

Slim, the shoot one load one target thing is more about heat distribution than a clean or dirty barrel.

What's your procedure for dealing with barrel heat ???

slimjim · Posted: Fri Jul 23, 2010 3:51 pm Post subject: Re: OCW !!!

chambered221 wrote:

I'd be interested in seeing where 54.5 would have landed !!! (If a safe load)

My thoughts exactly. It looks like the POI is descending from 52.0 then starts rising again up to 54.0. I looks like the top of the node is between 51.5 - 52.0 and 54.0 - 54.5. I will try 54.5 next time out.

Note, 53.7 is listed as max, however, I had no overpressure signs at 54.0 other than the primers starting to flatten but not as flat as some of my other .270 loads. Nor did my other max loads with the same bullet but other powders show pressure signs.

I was really pleased with the velocity. I was getting almost 200 fps more than with IMR4350.

slimjim · Posted: Fri Jul 23, 2010 4:08 pm Post subject: Re: OCW !!!

chambered221 wrote:

What's your procedure for dealing with barrel heat ???

My barrel will only take 2 shots when cold before it heats up enough to affect accuracy. After 2 shots, I leave the action open and the barrel pointing up in the rack to cool. Since weather and temps vary, I use wait until the barrel doesn't feel warm any more. In the winter that may only be 3-5 minutes. In the summer and temps are above 90, it may take 7 to 10 minutes.

44marty · Posted: Fri Jul 23, 2010 4:24 pm Post subject: Re: OCW !!!

chambered221 wrote:

I'd be interested in seeing where 54.5 would have landed !!! (If a safe load)

Slim, the shoot one load one target thing is more about heat distribution than a clean or dirty barrel.

What's your procedure for dealing with barrel heat ???

Firing round robin (one of each charge weight) also helps take out other variables like change in the wind value and changing light conditions, etc.