Help understanding improveing my results please

[n2extrm]

I have been reloading for my .308 for about 6 years. I have a load that groups well in my 700 at 100 yards, about a quater sized group. I have a much looser group 2.5 or 3 inches at 200 yards. I have been blaming the shooter all along. I recently purchased a CED Mellinuem II chronograph and shot the load over it to see what was going on. My SD and ES are insane.

ES 148
SD 42.1
High 2492 FPS
Low 2344 FPS

My load is
Hornady match brass once fired and neck sized. 168G Sierra MK. 42 G RE15, and Fed Lrg rifle BR primers. seated to 2.945" Just off the lands, no signs of pressure.

My guess is I need to drive this load harder. It did seem to loosen up at 42.2 and 42.4 grains, so I stopped at 42.0. I also never uniformed primer pockets or flash holes. Please your thoughts. thank you.

 

[Rust]

Lower ES/SD numbers are dependant on uniformity of your loaded rounds. I haven't used Hornady brass in .308, but have some in 22-250 and figure the same steps would hold true for .308.


1. Visually inspect the brass for any defects like off center primer flash holes, deformed flash holes, extractor groove deformities, rim deformities etc.

2. Uniform the primer pockets. I prefer the Sinclair primer pocket uniformers, more expensive but cut well.

3. Deburr the primer flash holes. I only cut enough to remove the burrs. Some deburring tools can cut deep enough to leave a bit of a funnel shape which I prefer minimize as much as possible.

4. Measure brass length. Once fired brass shouldn't need trimming but look for the occasional oddball case.

5. Weight the cases and segregate. Some folks group in 1 gr increments, but I'd say for getting started 2 gr would be fine with a .308.

6. Weigh your powder charges to within .1 grain. If you have the time you can bump your loads in .5 grain increments, but 1 grain will do fine to get you in the ballpark.

Go out and shoot. Check your numbers. Check your numbers against the accuracy for each load. Try not to shoot your chrono, your buddys will ask you what it did to get you mad at it for the next month. Then they get huffy if you shoot one of their chronos.

Anyhow, some fine tuning can be done by varying seating depth of you come up with a load that looks promising, just keep in mind seating deeper bumps pressure up if you're working with an upper range load.

If the numbers still don't look to good, try a heavier or lighter bullet. If that still doesn't work out try a different powder.

In my case, the development of a match .308 load is still a work in progress.

 

[n2extrm]

Thank you rust.
I did laugh pretty hard at "don't shoot your chronograph.....what did it do to you." I kept tripple checking my position for just this reason. All loads are weighed and despensed on a charge master. I am within .1 grains. I never weight and sort cases, guess I should. I am going to order the primer pocket and flash hole tools today from Sinclair. I am ging to inspect and weigh cases and sort them out.

I will let you know how I do.

 

[Johnboy]

hey I give a pus 1 on the first gents reply.but just wanted to know what 700 you are shooting.the reason for asking is that you may need to set your bullets a little farther back.or you could bump the load up to around 43.5g.and if r15 doesn't get you the group you want then try varget/4064 if you have them.and if so try around 43-44 grains with one or the other.but for my I state my 308 likes 45g of varget and 43g of 4064 wihth a 168g smk.but I hope things work out for ya.

 

[n2extrm]

Johnboy

I am shooting a 700p 26" barrel, holland brake and a jewell trigger. Otherwise it is stock. I did use a fired case and a SMK to find the lands they are at 2.950. I was loading for a .005" jump.

I may have found 1 of my problems. I just went into the reloading room and took apart and meassured 10 unfired loads from this batch. All charges were within .1 grains. The seating depth was pretty consistent. I ordered a comparitor from Sinclair today so my meassurements should be more accurate, but COAL was reasonable. I do think my neck tension is way to low. The bushing I used was a .335 and my loaded is .333 to .334. I was using this bushing with my LC brass and never thought to recheck this when I switched brass. I did push them gainst the bench and they did not change with what I felt was moderate pressure. How ever I found I could pull the bullets by hand with a papper towel and a twisting pull. So I will now place order #2 with Sinclair and get some smaller bushings. My smallest is .334 I am guessing .330 and .331 would be in order here.

Thank you all again.

 

[Moderator]

Neck tension may be an issue.

But... before you go too far, make sure the chrono is at least 12' from the muzzle. And check the numbers with a second chrono.

 

[Rust]

Keep us posted.

I use a Millenium CED chrono and I set it up 10' from the muzzle, no problems so far. Well, excepting the one friendly fire incident...

If the neck thickness variations run too much and you don't have better brass available, and/or you are loading larger quantities of ammo, you may want to run a bushing sizing die and a carbide expander ball. You'll end up with a little more runout but if you work the numbers right for the size of the bushing insert, you should get pretty consistant neck tension. Works well for loading large quantities of ammo for a gas gun, something like a run and gun event where you can expect to fire a lot of ammo and not recover all the brass.

 

[n2extrm]

Thanks for all the replys.

The chrono is 12 feet away and I think with the holland brake a good amount of the blast is up and to the sides. I could be wrong. I do plan on shooting some good quality factory as a control next time out.

I know the brass seems to be simillar in loaded neck dementions, I loaded some with a full size die and checked it. Hornady is not my first choice, but I tried it. I will shoot it till it drops. I also have some once fired LC from the late 60's I can prep and I want to order some Laupa after the hollidays. I will post my test and results in a couple of weeks as soon as I get the bushings and a day warm enough to shoot.

Thank you all again!