VELOCITY QUESTION

[crouch41]

Since 7/1/06 I have kept close records regarding a Rem 700 in .243,factory barrel; the only changes have been a Timney trigger, and I fire lapped the barrel with Final FInish). I've only been reloading about 10 months chasing accuracy. Since then, I have fired 54 strings of various case, bullet, powder, charge and seating depth combinations. Of the 54 strings, 23 have grouped less than 1" at 100 yds. Of those 23, 7 have grouped less than 1/2" at 100 yds. Frankly the only pattern I can readily see in the data is that when the velocity spread is close, the group is tight, and even that isn't absolute. But it is a trend. What can be done to tight velocities? I use quality brass,Lapua), quality bullets,Hornady Amax 105; BC 500)and RCBS competition die. I have used QL to find density and burn combinations above 95%. And I am VERY careful in throwing charges.

Is the above data about as much as I can expect from a factory barrel/action?

Thanka for any insights, suggestions and wisdom.

 

[Hipshot]

I bought a new Savage in 243 to shoot 300 meter F class and was chasing accuracy for a year. The more I shot the harder it was to find accuracy, irrespective of velocity. What I discovered was that the 243 is hard on barrels and after 1500 rounds it was basically not going to be competitive. I just replaced the barrel and chambered to 6BR and now a year after that I'm still winning matches and even had a couple of perfect scores. I shot a state match yesterday and won F class with a 594 and can point to 3 shots that I flubbed.

You may be experiencing the barrel burn out that 243's are known for. From all the reading I've done on this board, and my experience so far, you can reach 243 velocities with greater accuracy and barrel life with a 6BR,which is based on the 243 case, so no bolt changes are necessary.)

 

[tightneck]

With a factory rifle in .243 win I woul expect to consistantly shoot .5-.75" groups. That being said, you can always get one that just wont shoot. In my experience, I can usually make them shoot pretty well. The very first thing I would do is to pillar bed the action. That alone can do wonders. Second, you say you are throwing your powder charges. While I throw charges for small cases and fine powders, I weigh all charges in larger cases and espescially with the coarser powders. I was throwing a semi-coarse powder the other day at 47 grs. and had variations of up to a full grain from one throw to the next. Get a good scale and weigh your charges.

 

[USAPatriot]

What are you doing to ensure each round is consistent? You aren't telling us much about what your velocities are. Are you weighing your cases? Weighing your slugs? What primers are you using? There are a lot of little things that conspire to make a rifle shoot worse than it could, even though for most of the ordinary hobby shooters what you're getting is perfectly within reason. To get more you usually have to do more. Whether or not you're getting the most accuracy that rifle can give, I couldn't say, but velocity spreads really aren't a function of a barrel unless it's getting gunked up between cleanings. The velocity spreads are wholly within your hands and dictated by the quality of your components and the quality of your work. -Rod-

 

[crouch41]

Hipshot: The rifle has less than 300 rds thru the barrel including the 50 rds to fire lap. I just joined the local clud,Palo Alto in BAton Rouge) and most of thse guys shoot 6BR. I am in the middle of a 30.06 project right now. As soon as that is finished, I will undertake the .243. Right now, am just trying to see what I can accmplish with it, and learn as much as I can.

Tightneck: The Rem stock is pillar bedded, but I assume you are talking about something more than that. Right? As for "throwing" I guess that has a meaning I did not intend. I CAREFULLY measure each and every load.

USA PAtriot: I am presently shooting new,4 rounds fired) LApua brass. No, I don't weigh the brass or the bullets. I use CCI 200 primers.

Re velocities, etc, I have attached a chart of the component combos involved in the tight groups. But all of these opened up to well over an inch on retest. Where the velocity indicates 0000, it measure the chrono didnt measure for whatever reason.

Thanks to all for the input.

 

[USAPatriot]

I think you need a larger data set. A couple of rounds is ok to check velocity but it isn't enough to really diagnose anything. At the least you should probably shoot 4-5 5 shot groups. More data = better feedback from us, better feedback from your rifle, better feedback on your shooting and loading techniques. You say you carefully measure each charge. What's that mean exactly? Are you weighing them out on a balance beam or using a digital scale? You should probably weigh your brass out and group them by weight. If you can get groups of 5-20 pieces that are all within .1 or .2gr of each other, that's a good thing. The same with slugs, but they should be grouped all alike if possible. Batches all weighing 104.9, 105.0, 105.1, etc. In Hornady's you'll probably end up with 5 or 6 piles out of every 100. With Bergers probably only 2 or 3 piles. The more accurate you are in your work, the more accurate your shooting will be within the limits of the rifle's capabilties. There is a point of diminishing returns though where the work simply can't produce any better results. That could be the rifle or it could be you. At any rate, strings of 20 for each load will give you much better data to work with and groups of 5 will tell you more about you and your rifle. -Rod-