I'll preface this with the fact that I've only been reloading precision rifle for about 2 years now so as I dive deeper and deeper down the reloading rabbit hole, I find that I am wondering about every little detail. This one comes from the fact that I've been reading a lot lately about Neck clearance. This seems to be one of those subjects that everyone and their mother has a different opinion on. And I've seen people talk about order reamers or making their own custom reamer. I've seen that manufacturers for chamber reamers make several in the same caliber but with different neck clearances. I've been wondering lately and haven't found much in the regard to the question: does neck clearance (b/w loaded round and neck of chamber) affect MV any significant amount? Does it change MV nodes? How much does it affect ES/SD? Is there a difference between say 1 thou neck clearance, 3 thou, and 6 thou, etc.? Do you need more neck clearance for larger calibers (say any overbore magnum vs. a 6br or 6.5 creed)? I am mainly interested in PRS/field style shooting and just ringing steel at distance, so I've found that most believe that you need enough neck clearance so the round will chamber every time because you could get sand/dirt/debris in the action and with a really tight neck that could prevent you from being able to send the bolt home fully. This is simply a question of curiosity. Let me know your thoughts and experiences as I am fairly new to this whole thing.
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Reloading Nerds: MV and Neck Clearance?
- Thread starter cdeiglmeier
- Start date
To learn about the tight end, you could look at setups used by benchrest shooters. So some of those folks want at least 0.0015 and not more than 0.002". Others aim for ~0.003". On the other hand, talking with benchrest fanatics could screw your whole life up and you might develop a tic in your dominant eye.
I don't think it's all about just getting a round to chamber. With 2 or 3 thou, brass life will be good because you won't have to be sizing much but running tight means your brass has to be uniform. Next we'll be talking about turning necks and the whole discussion can then go to hell in a handbasket.
I don't think it's all about just getting a round to chamber. With 2 or 3 thou, brass life will be good because you won't have to be sizing much but running tight means your brass has to be uniform. Next we'll be talking about turning necks and the whole discussion can then go to hell in a handbasket.
Thanks for the info! Yea I’m not interested the whole neck turning thing lol but just more or less interested in if neck clearance plays a role in variations in MV, ES/SD, and/or the nodes, does it make them smaller/larger? Would you see a difference in a 3thou neck vs a 6thou? Maybe there hasn’t been an answer and 3-4 thou seems to work for PRS style rifles and I’m just wondering something pointless haha
If you are so tight that you get a pressure spike, it might have an effect on MV, ES and SD but that would be probably less of a concern than overpressure. I have seen neck tension consistency have an effect on ES and SD but not so much MV in my experience, but I only have ~1500 rounds through 3 guns with a chrono, so others may know more.
OP - I just want to make sure I understand d the area you're asking about.
Are you wondering about the dimension on the neck area of the brass, that holds the bullet, and how it interacts with the corresponding surfaces in the chamber?
Are you wondering about the dimension on the neck area of the brass, that holds the bullet, and how it interacts with the corresponding surfaces in the chamber?
Yup! I’m referring to the space between the neck of a loaded round when it is in the chamber and the wall of the neck of the chamber.
A good rifle can shoot .3 MOA with a standard chamber with .005”+ neck clearance and unturned necks.
Look up an article called shooting in a warehouse great info and very interesting. What it came down to is the barrel had to be good, the powder wasn't as critical as the preparation of the shell. Their record was .024 over bullet size for 5 shots.
If you've ever chambered rds into a carbon ring and fired them, you'd know not having proper clearance creates issues. Nothing good comes from too little clearance. On the other end of it, if your neck dia in the chamber too great, necks have a harder time sealing off, letting gas come back onto the shoulder or even farther down. Now your options are limited as to shutting it off.
I want .003" clearance on most cases 6.5 and under. I also believe necks thin as they grow and we end up trimming them.
Now if you are shooting magnums, 5-6 thou of clearance becomes the norm, maybe even 7 thou.
So if you are not pinching your necks off firing, or 99.9% of the gases produced are not going down the barrel, logic says no to your question.
I want .003" clearance on most cases 6.5 and under. I also believe necks thin as they grow and we end up trimming them.
Now if you are shooting magnums, 5-6 thou of clearance becomes the norm, maybe even 7 thou.
So if you are not pinching your necks off firing, or 99.9% of the gases produced are not going down the barrel, logic says no to your question.
Thank you! That was more or less what I'm interested in. For magnums needing more neck clearance as you say, is it mainly because they are using more powder? slower powders? than say a 6.5 creed or short action caliber which you say can be 3 thou neck clearance. Just curious as to why that is.
By giving an answer, I can only be speculate, more powder for one, thicker brass the other. If you were to neck down 284 Win brass to 6.5x284, or 7mm or 300 saum bras to 6.5, you will want more clearance than .003" too. I'd imagine neck lengths play too, where a shorter neck may do better in a tighter situation.
This could be one expensive thing to solve, 2 rifles, same case, differing neck diameters most likely wont tell you much as it's be hard to duplicate pressures generated.
I once made a tight neck reamer for myself thinking my brass would last longer, but all I got was pressure signs at 200 less FPS.
.003” neck clearance is stupid.
.003” neck clearance is stupid.
