run out question

[MildBill]

I have been tangling with a 243 I had re-barreled here recently trying to get it to shoot to it's potential. So far it is been a losing fight. I need/ want to check into the potential problems before I chuck and get another barrel put on it.

The next variable I am going to get checked out here is bullet and case concentricity. A guy I know has a run out measuring tool and I am going to take some fired cases, once fired neck sized cases and once fired, neck sized, loaded rounds over when I see him next time to see what it up with them

What would be a reasonable amount of run out to tolerate, that should not have significant effect on groups?

My press is a forster co-ax and I have forster dies, the seater is the ultra-micrometer version.

thanks

 

[rg1]

The often quoted rule on run-out is .004" or less for hunting and .002" and less for target shooting. Need to check each step of the loading process to find which if any is causing the run-out. Also checking the neck walls to see if the thickness is close to the same all the way around.

 

[Shynloco]

Also. might I suggest you take a close look at the dial face and make sure you are getting what reading you "THINK" you are. A friend just mentioned the other day that he's been having concentricity problems recently after getting a new gauge and a friend of his pointed out that the gauge face/dial has an increment change half way down from .001 to 0001. The increments for .001 are label on the bottom of the dial face, while the .0001 are at the top of the gauge face in smaller letters. What problems he thought he had actually didn't exist at all, all because he's misread the dial face. Just something to consider. BTW, my runout tolerance for target shooting is .002 max and preferably .001 and less.

 

[BoydAllen]

Has the action been bedded?

 

[MildBill]

Has the action been bedded?

Not to this point.

the barrel is a heavy sporter contour

The regular stock is a stockys laminated HART aluminum v-block stock

also have put an HS precision sendaro style short action stock on it.

get the same results with both stocks as far a performance.

the gun builder asked that I check run out on the ammo and cases next.

he is not satisfied with the performance either

 

[FeMan]

For bullet runout on sized and loaded cases, I would agree with 0.002" as a max.goal if you are striving for accuracy. Fired cases should be less than 0.001". If the brass is quality, they should be almost zero. I like to have my sized case necks at 1/2 or less of my goal for bullet runout.

 

[338 Mollett]

I agree with FeMan on preference as to runout ,but let me throw a wrench in the works buy a box of federal gold 308 ammo and see how it shoots then measure the runout it will make scratch your head or sick.

 

[Lapua40X]

Don't know what run out gauge you're intending to use but take care to understand its idiosyncrasies before you list the run out results. I have a RCBS run out setup and it works just fine but, if I get in a hurry and put too much pressure (or not enough) on the case, it can produce some alarming readings.
I love that adrenaline rush

 

[tenring]

Don't know what run out gauge you're intending to use but take care to understand its idiosyncrasies before you list the run out results. I have a RCBS run out setup and it works just fine but, if I get in a hurry and put too much pressure (or not enough) on the case, it can produce some alarming readings.
I love that adrenaline rush

I use a Holland guage and I get accurate readings by rolling each case with a 6" x 1/2" x 1/8" composite fingernail file. It produces consistent results.

 

[Raythemanroe]

I

I just bought a Hart bedded laminate and went a head with some devcon! I thought that the contact surface was slight and could be much better! I would reccomend bedding the rifle.

 

[Erik Cortina]

I agree with FeMan on preference as to runout ,but let me throw a wrench in the works buy a box of federal gold 308 ammo and see how it shoots then measure the runout it will make scratch your head or sick.

He has a .243, not a .308

 

[Erik Cortina]

What size groups have you been getting?

 

[BoydAllen]

A couple of points: Factory actions are machined soft and then heat treated, This results in some warpage, and lack of fit with bedding blocks. This is why it is a good idea to at least skim bed stocks with blocks. If you go to Erniethegunsmith.com and look around on the site, you will see some good ideas on skim bedding over blocks. Secondly, we have no idea what your load development process has been, and it is very likely that this may be a big factor. Another issue that I ran into recently, when trying to help a fellow in a similar situation is action screw torque. How tight are your action screws? On the subject of concentricity gauges, if you want to be able to gauge brass, the Sinclair unit has the best case contact surface. If you can live with only being able to gauge loaded ammunition, and you would like the option of playing with straightening, the H&H works very well, and is extremely versatile and easy to use. I do not like a couple of the gauges that have been mentioned because cases do not roll as easily on the surfaces provided.

 

[338 Mollett]

Let me clarify, I was using federal 308 as an example as to how well it shoots with bad runout .I thought the topic was runout thus as we try to make the straightest ammo we can what is the answer to federal shooting so well ?

 

[MildBill]

What size groups have you been getting?

anywhere from around 2" to down to around 0.75", I have been working up groups according to published recipes in 0.5 grain increments.

on some of the 0.75" groups my extreme spread has been 8 fps for the group, and the sd 4. other decent groups have extreme spread of around 15 to 20 fps in the groups.

I have tried different powders, different primers with stuff that does better, and different bullets.

been changing one thing at a time.

I have been working fairly close with the gunsmith who is a very good shooter himself.

just asking questions to get other perspectives and experiences.

 

[338 Mollett]

What kind of bullets have you tried and powders ?

 

[MildBill]

87 grain v-max.... did good not great

87 grain bthp.... did lousy

85 grain sierra. #1520... showed potential

80 grain sierra #1515... showed potential

70 grain nosler ballistic tip.... terrible

95 grain nosler ballistic tip.... showed potential

powders

varget with the 2 light ones, not fooling with it anymore

H4350 showed potential

IMR4007ssc showed potential

IMR 4320 shoed potential

IMR 7828ssc with the 95 showed potential

 

[338 Mollett]

I am surprised at the 7828 load with the 95g bullet ,7828 burns close to h 1000 a little slow.I would think the h4350 and h 4831 are your best bets.If you have an 8 twist barrel the berger 105 hybrids have been shooting well for some friends of mine.I'm building a 6xc and gonna give them a try.Or maybe try some of the heavier sierra's with those two powders,Good Luck ! hope that helps.

 

[MildBill]

I will probably not use the 7828 with the bullet, but the groups, with the charges near the top, were starting to tighten up somewhat well.

when I do some re-test with those bullets it will be with H4350 and H4831sc.

 

[MildBill]

measured some case necks and loaded rounds today..... disappointing...

rem brass, not neck turned

case necks were consistent about 0.003 to 0.004, probably tolerable

loaded round with 85 grain sierra bullets, measured 6 of them

2 were 0.003 to 0.004

2 were 0.005 to 0.006

and 2 were 0.007 to 0.008

using a forster co-ax press and forster micrometer top seater die

now to figure out what to do to fix the problem... grrrr