Bullet runout

Toddco · January 11, 2012, 05:19 PM

I have just recently checked some of my .243 reloads for runout. I am using the RCBS casemaster to do this. I am finding that most of them have around 5-6 thou of runout, consistently. I use a redding press, rcbs neck sizer die, and an rcbs bullet seater. The thing i never did was check the case mouths for runout before i reloaded this batch. Is is possible that either my shell holder, also rcbs, is out that much, dies? or possibly my action to barrell alignment is that bad? Any ideas?

dahermit · January 11, 2012, 05:32 PM

Quote:

I have just recently checked some of my .243 reloads for runout. I am using the RCBS casemaster to do this. I am finding that most of them have around 5-6 thou of runout, consistently. I use a redding press, rcbs neck sizer die, and an rcbs bullet seater. The thing i never did was check the case mouths for runout before i reloaded this batch. Is is possible that either my shell holder, also rcbs, is out that much, dies? or possibly my action to barrell alignment is that bad? Any ideas?

1) Use your casemaster to check the run-out on the neck of a case fired in your rifle. If there is any run-out, then you chamber is not concentric with the bore.

2) Get a Lee collet neck die. Neck size a case and check run-out. Seat a bullet in that case and check the run-out again. If there is more than .002 run-out, you should be able to figure out at what stage in the process it is coming from.

jepp2 · January 11, 2012, 06:41 PM

Couldn't agree more with the Lee Collet die suggestion. It will give you the lowest neck runout, period! A resource I found invaluable is Precision Shooting reloading guide.

It will give you excellent tips on improving the accuracy of your loads and provides data on what equipment works best (and why the expensive bullet seating dies don't necessarily lower runout of seated bullets).

flashhole · January 11, 2012, 07:38 PM

Measuring for runout in the case after it has been fired in your gun is a good start but you need to measure it after each step of the manufacturing process to determine where you might have a problem .... measure the fired case, sized case and seated bullet.

Some pointers:

1) I chuck my cases in a drill press using the Lee 3-Jaw chuck. I clean the inside of the case neck with a bore brush. This greatly reduces friction when the expander ball is pulled up through the case neck. I also put a minute amount of Imperial on the inside of the case neck too.

2) Align the sizing die - I run a lubed case up inside the FL sizing die before I lock down the die ring. This ensures the case/ram/die are in proper axial alignment and gives you the best chance of not inducing runout during this step.

3) Polish the expander ball.

4) Loosen the expander ball/decapping rod and let it center itself in the die with the decapping pin sticking through the flash hole. Once centered, tighten the rod.

Step 2 can also be applied to the Lee Collet Neck Die.

I'm a big fan of the Forster and Redding sliding sleeve bullet seat dies and I see a very positive benefit with these dies to keep runout to a minimum. It's rare that I get any measurable runout on my rifle loads. Details ... the devil is in the details. It's not hard to make highly concentric ammo unless one piece of equipent is totally out of whack but you would notice that pretty quickly.

jdillon · January 11, 2012, 10:46 PM

All good points mentioned in previous posts. Mostly use redding dies and with those in which I run expander, I use the Redding carbide expander ball that floats on the recapping rod providing better alignment. Also lubricate the inside of the necks

If you have the tools to check neck thickness, do so. Uneven neck thickness will tend to increase runout when used with an expander plug/ball. As mentioned above, check runout before and after sizing. This will help you identify the source of the problem.

Nnobby45 · January 11, 2012, 11:54 PM

Quote:

The thing i never did was check the case mouths for runout before i reloaded this batch. Is is possible that either my shell holder, also rcbs, is out that much, dies? or possibly my action to barrell alignment is that bad? Any ideas?

Check the runout before you size it. Then size it and compare. Runout shouldn't be worse. A good die set up will even improve it. This should be done with unfired factory brass, and brass fired in your rifle so you get a good picture of what's happening.

*Check the runout of the loaded round. That's really what counts.

I once loaded up a bunch and separated the ammo into batches with excellent runout and the worst runout. Went to the range. Didn't notice one wit of difference on paper from a good bench. Was once talking to one of the Sinclair Techs (all very experienced handloaders) and he just chuckled and said he had the same experience.

Now this was hunting ammo. Benchrest might be more sensitive in that regard.

mrawesome22 · January 12, 2012, 12:24 AM

Turn the necks down a couple thou and remove the expander ball altogether.

azar92 · January 16, 2012, 04:13 PM

Nnobby45,

Do you remember the numbers from the "best" and "worst" batches that you tested? I recently got the Hornady Lock-N-Load concentricity gauge and tested all my loaded ammo (both factory and handloads). From my handloads only 4 to 5 rounds measured 0.005", not one went over. Only a small sample measured 0.004". Most all my loaded ammo was 0.002" to 0.003" with some going 0.000" (or nearly so) and some at 0.001". I corrected all my ammo to be 0.003" or better.

And guess what? From a standard grade hunting rifle I couldn't tell a difference. It was a small sample, so it's nothing conclusive. But I have spoken with others who know more than I and they claim that most factory made hunting rifles won't show a real difference until run-out exceeds 0.005". Custom made and benchrest rifles held to higher tolerances and shot at long range are a different story...

As for the factory ammo... I couldn't believe how crooked some of that ammo was. A little more than 50% of the factory loaded ammo was 0.005" or worse! One partial box (15 rounds) of factory ammo had three rounds that measured 0.009". A different box and different caliber had one round go 0.010". Yikes! I'd like to test that factory ammo with no attempts to correct the run-out. I'll shoot 3 rounds with 0.002" and the 3 rounds with 0.009" and see if the groups vary significantly. It would be fun to see the results.

January 11, 2012, 05:19 PM	#1
Toddco Senior Member Join Date: August 7, 2009 Location: Stony Plain, Alberta Posts: 108	Bullet runout I have just recently checked some of my .243 reloads for runout. I am using the RCBS casemaster to do this. I am finding that most of them have around 5-6 thou of runout, consistently. I use a redding press, rcbs neck sizer die, and an rcbs bullet seater. The thing i never did was check the case mouths for runout before i reloaded this batch. Is is possible that either my shell holder, also rcbs, is out that much, dies? or possibly my action to barrell alignment is that bad? Any ideas? __________________ I fit in very nicely when i am completely alone!

January 11, 2012, 07:38 PM	#4
flashhole Senior Member Join Date: February 9, 2005 Location: Owego, NY Posts: 2,000	Measuring for runout in the case after it has been fired in your gun is a good start but you need to measure it after each step of the manufacturing process to determine where you might have a problem .... measure the fired case, sized case and seated bullet. Some pointers: 1) I chuck my cases in a drill press using the Lee 3-Jaw chuck. I clean the inside of the case neck with a bore brush. This greatly reduces friction when the expander ball is pulled up through the case neck. I also put a minute amount of Imperial on the inside of the case neck too. 2) Align the sizing die - I run a lubed case up inside the FL sizing die before I lock down the die ring. This ensures the case/ram/die are in proper axial alignment and gives you the best chance of not inducing runout during this step. 3) Polish the expander ball. 4) Loosen the expander ball/decapping rod and let it center itself in the die with the decapping pin sticking through the flash hole. Once centered, tighten the rod. Step 2 can also be applied to the Lee Collet Neck Die. I'm a big fan of the Forster and Redding sliding sleeve bullet seat dies and I see a very positive benefit with these dies to keep runout to a minimum. It's rare that I get any measurable runout on my rifle loads. Details ... the devil is in the details. It's not hard to make highly concentric ammo unless one piece of equipent is totally out of whack but you would notice that pretty quickly. __________________ ,,, stupidity comes to some people very easily. 8/22/2017 my wife in a discussion about Liberals. Are you ready for civil war?

January 11, 2012, 10:46 PM	#5
jdillon Senior Member Join Date: October 7, 2011 Location: Southern NM Posts: 141	All good points mentioned in previous posts. Mostly use redding dies and with those in which I run expander, I use the Redding carbide expander ball that floats on the recapping rod providing better alignment. Also lubricate the inside of the necks If you have the tools to check neck thickness, do so. Uneven neck thickness will tend to increase runout when used with an expander plug/ball. As mentioned above, check runout before and after sizing. This will help you identify the source of the problem. __________________ "Emergencies have always been the pretext on which the safeguards of individual liberty have been eroded" - F.A. Hayek

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January 11, 2012, 06:41 PM	#3
jepp2 Senior Member Join Date: December 24, 2008 Location: Loveland, CO Posts: 1,476	Couldn't agree more with the Lee Collet die suggestion. It will give you the lowest neck runout, period! A resource I found invaluable is Precision Shooting reloading guide. It will give you excellent tips on improving the accuracy of your loads and provides data on what equipment works best (and why the expensive bullet seating dies don't necessarily lower runout of seated bullets).

January 12, 2012, 12:24 AM	#7
mrawesome22 Senior Member Join Date: November 9, 2005 Location: Ohio, Appalachia's foothills. Posts: 3,779	Turn the necks down a couple thou and remove the expander ball altogether.

January 16, 2012, 04:13 PM	#8
azar92 Senior Member Join Date: April 16, 2009 Location: Utah Posts: 209	Nnobby45, Do you remember the numbers from the "best" and "worst" batches that you tested? I recently got the Hornady Lock-N-Load concentricity gauge and tested all my loaded ammo (both factory and handloads). From my handloads only 4 to 5 rounds measured 0.005", not one went over. Only a small sample measured 0.004". Most all my loaded ammo was 0.002" to 0.003" with some going 0.000" (or nearly so) and some at 0.001". I corrected all my ammo to be 0.003" or better. And guess what? From a standard grade hunting rifle I couldn't tell a difference. It was a small sample, so it's nothing conclusive. But I have spoken with others who know more than I and they claim that most factory made hunting rifles won't show a real difference until run-out exceeds 0.005". Custom made and benchrest rifles held to higher tolerances and shot at long range are a different story... As for the factory ammo... I couldn't believe how crooked some of that ammo was. A little more than 50% of the factory loaded ammo was 0.005" or worse! One partial box (15 rounds) of factory ammo had three rounds that measured 0.009". A different box and different caliber had one round go 0.010". Yikes! I'd like to test that factory ammo with no attempts to correct the run-out. I'll shoot 3 rounds with 0.002" and the 3 rounds with 0.009" and see if the groups vary significantly. It would be fun to see the results.