Question for the Wizards

[Retired shooter]

In regards to bullet seating depth, what is the consensus on how much bullet shank to be inside the case. What is the rule of thumb, be it left handed, or right handed thumb.

Hope everyone had a great holiday weekend.!

Thank you.!

 

[Homerange]

1 bore diameter is considered minimum/optimum.

 

[leakeyjohn]

I use one diameter of the bullet as a limit roughly.

 

[Webster]

In regards to bullet seating depth, what is the consensus on how much bullet shank to be inside the case. What is the rule of thumb, be it left handed, or right handed thumb.

Hope everyone had a great holiday weekend.!

Thank you.!

I don't think there is any real/modern rule of thumb. My 6BRX with a 55 or 58 gr bullet with 0.010",jump, the bullet is not near a 1/4" inch in the neck. It shoots under .400" or less in a varmint hunting rifle. Guys will tell you that some famous ballistician that wrote books in 1940 & 1950 will tell you 1/2 way in the neck minimum. I think we have learned more since 1950. A 55 gr bullet half way down the neck is almost up to the ogive in my case. Of course a 6BRX has a short neck. I don't care how far a bullet is in the case as long as the gun shoots small groups. I would guess that a light wt. bullet in any cartridge with a normal looking length neck woud be about half way in. I will not read any books by guys like Powell. They did a great job for the time they lived, but I don't like to read 50-70 year old opinions. I just seat my bullets 0.010-0.020"
off the rifling and accept however it's the neck. Just looked at a loaded 6BR cartridge for my other rifle. With about 0.010" jump with a 58 gr Hornady it looks like the bullet just makes half way in the neck. I would think a 22 cal bullet would have a very short bearing length. Cannot imagine how half way in the neck relates to accuracy. Someone probably thought the bullet was held straighter. Dies and bullet making tooling are probably made with CNC tooling now Much more accurate than dies made 50 years ago.

 

[jackieschmidt]

Your throat or freebore length determines how much of the bullet is in the neck after finding your ideal seating depth.

 

[mgunderson]

As much as you need to keep the bullet in place. That requirement might be different for a bench gun or a hunting rifle with rounds in magazine. Will a gun work with very little neck contact..... I bet it will. There is more to this question.... I expect.

 

[K22]

One bullet diameter, not counting the boat tail portion as a minimum has always worked for me. As mentioned, some require deeper depending on magazine, throat, and bullet ogives.

 

[6MMsteve]

there are wildcat cases that have a tiny nk like .050 or a little more I think I seen it on here somewhere

 

[Fast14riot]

Anything less than about 0.120" I start to look into longer jumps. But if seating hard jam, as long as its in the case!

 

[C.E.Smith043]

I've always heard a minimum of .125"

 

[Deleted member fkimble@charter.net]

It's got to be in enough to close the bolt and it's got to be in enough to not fall out. These vary depending on use. A BR gun can have more out than a dangerous game gun.

Frank

 

[JEFFPPC]

Like Webster above as a 6BRX shooter for many years I have the chamber throated for my bullet of choice so when just touching the lands the pressure ring is halfway up the neck. My necks are .210 so that leaves me at .105. I usually end up from there 0 to .015 in the lands after tuning. So I am usually less than .100 in the case neck and never have any donut concerns. This has worked well for me with about 20 barrels.

 

[LCazador]

If you're shooting a repeater where the round will be worked from the magazine it's best practice to have more bullet shank in the case to prevent the bullet concentricity from being upset. Neck tension also plays a role. In a single shot where the round is inserted or started into the chamber it will make little difference.

 

[Retired shooter]

Thank you all for your replies, and yes mgunderson it was and is leading to another question, you are very good at reading between the lines. Actually several questions

Short quick trip to local range last Thurs. to help my son zero a scope , to go for attempt at one mile plus today.
I was experimenting with seating depth. I know everyone will tell me I did this wrong, however from my racing days we always said if you did not know for sure which way to go and needed to make a change, make it a big one. I was experimenting with seating bullet depth, and changing .020 a a time 3 rounds ea all same components. 6 ARC gas gun. Single round loading Starting at 2.330. COAL put me @.075 off the lands,moving .020 EA time 5 groups of 3 EA. ended up @.015 off the lands with the COAL length of 2.390 with no major differences, grouping was basically the same. New Starline first time fired , 6.5 Grendel brass shoulder bumped back, case length trimmed, necks bushing sized and neck tension of about .002 with mandrel 29.7 grains Leverevolution ( worked up to slowly per Hornady 11th edition gas gun) with Hornady 110 A tips, 2750 ft ps. 26 in Bartlein barrel 1 / 7.25 twist

Pictures to me anyway, lots of carbon on the outside of the brass. Have not seen this on any factory ammo. ( primers appear good , no signs of case problems, shoulders moved forward .003 to .005 )

Question 1 Why so much carbon on the cases.?

Question 2 for Jackie , ( or someone )would you be so kind to research the Sammi spec for cartridge, and reamer and explain the freebore dim to me. I have looked at both , however having a difficult time understanding the freebore dim. OLD AGE guess.

As a final note just back from an extremely windy day here in middle of everywhere Ks, my son did connect with the steel targets @ one mile and 2165 yards multiple times with his 338 La pua.

Thank you all.!

 

[jepp2]

New Starline first time fired , 6.5 Grendel brass shoulder bumped back

Curious why you needed to bump the shoulder back on new brass? I have only ever encountered 1 particular instance where I needed to adjust the shoulder bump on new brass. And you state the shoulder moved forward 3-5 thousandths on firing. I record for each rifle:
- case head to datum length where I can feel bolt contact
- case head to datum length I size to
I always measure the case head to datum length on new lots of brass record and compare. I also check for proper chambering then proceed with my brass prep.

Regarding your question about carbon on case exterior. Leading causes of carbon on case exterior for me:
1. my DI gas gun leave carbon on the case exterior due to the ejection operation
2. a low pressure load that doesn't adequately seal the case neck/shoulder to the chamber wall can result in dirty case exterior and in some cases dents in the case
3. some powders just tend to leave more residue on the case exterior - I found Hodgon Superformance rifle powder was particularly bad for this when I used it
4. Recently I was shooting some Accurate 4350 for the first time, and it left the case exteriors similar to the Superformance. My ES and SD were excellent and I was near max on the loads. The next time I tried the 4350 I used cases with LRP, and the case exteriors were clean. So I attributed the difference to the SRP were not adequate for lighting the powder, even though the ES and SD had me thinking otherwise.

 

[Retired shooter]

New Starline first time fired , 6.5 Grendel brass shoulder bumped back

Shoulder bumped back to reform case to 6 ARC specs, due to brass unavailability.

The powder charge is max load per Hornady 11th edition for gas gun. First thought was due to fire forming to chamber, realized factory brass does not show the carbon, however factory rounds probably are not loaded as hot.

Thank you.