Shoulder bumping

[6.5 shooter]

Hi all,

up until now I have been solely a neck sizer but I want to bump the shoulders back a little. 
I have all redding type s competition die sets and the only way possible with these die sets to bump the shoulder back is to use the FL sizer die and adjust it accordingly but I dont want to size the body. 
I dont want to have to buy forster shoulder bump dies for all my calibres so im thinking I will have to get a machinist to ream the walls of my FL dies out a little?

unless im missing something does anyone else have a different idea or how does everyone else carryout this task without full length sizing?

thanks

[Popsbengo]

27 minutes ago, 6.5 shooter said:

Hi all,

up until now I have been solely a neck sizer but I want to bump the shoulders back a little. 
I have all redding type s competition die sets and the only way possible with these die sets to bump the shoulder back is to use the FL sizer die and adjust it accordingly but I dont want to size the body. 
I dont want to have to buy forster shoulder bump dies for all my calibres so im thinking I will have to get a machinist to ream the walls of my FL dies out a little?

unless im missing something does anyone else have a different idea or how does everyone else carryout this task without full length sizing?

thanks

If you set back the die to bump back the shoulder to a size larger than SAAMI spec it won't be resizing the body to full-length spec.  The case is tapered and won't be going fully into the die.

Obviously if you intend to bump back to SAAMI then you will be full-length sizing the whole case.

[terryh]

6.5 Shooter,

Just set up the FL dies to only bump the shoulder back by your desired amount 1-2 thou.

As PbG said, you will be doing the minimum amount of sizing on the body of the brass, a FL sizer is to 'smash' a case back to the minimum spec. to fit into any rifle, not specifically yours.

T

[n8ess]

Is this in 6.5x47? I have a Redding s type bushing die set with a body bump die if your interested in a part exchange. They are virtually unused as I bought them with a blaser barrel that had only 20 shots fired though it. I would be happy to send you some pictures if you are interested.

[onehole]

Comp shell holders another way to go and no need for over centre positioning.Once you arrive at the correct holder just select it every time then neck size and job done.

[Big Al]

8 hours ago, 6.5 shooter said:

Hi all,

up until now I have been solely a neck sizer but I want to bump the shoulders back a little. 
I have all redding type s competition die sets and the only way possible with these die sets to bump the shoulder back is to use the FL sizer die and adjust it accordingly but I dont want to size the body. 
I dont want to have to buy forster shoulder bump dies for all my calibres so im thinking I will have to get a machinist to ream the walls of my FL dies out a little?

unless im missing something does anyone else have a different idea or how does everyone else carryout this task without full length sizing?

thanks

Have you measured the difference between a fired case and a resized case at the .200" mark? thats .200" up from the bolt face.

Dont get hung up on what you might have read, its not always accurate. Why not just full length them with the shoulders bumped a couple of thou and go shoot the gun, I doubt you will see any difference in your accuracy and you will benefit from easier bolt close and nicer extraction.

[No i deer]

BigAl has built and shot rifles that hold 600yds and 1000yds Uk benchrest records so I'd say he has given you sound advice and knows better 👍

[6.5 shooter]

Thanks for the replies guys!

I have been doing that for a few reloads with the FL resizing die but im just conscious of working the brass alot. 
an issue I cane across was I had a dud primer and the powder did not ignite and the case obviously moved forward enough to jam the bullet in the lands. When I opened the bolt it pulled the case out but the bullet stayed put and I had powder everywhere! Not ideal!

I think it was bumped 2 thou but maybe 1 thou will be enough. The calibre that this happened with was a 223. 

[onehole]

Hi ,,,,Sorry not wish to be rude but I,m assuming you are actually measuring the amount of bumping your acheiving using a comparator of some design? In my experience bumping a couple of thou never seems like overworking to me and sometimes wonder if the case has moved at all given the ease of press leverage.Measurement confirms though.Also assuming you are lubing your cases during the process?,,,,O

[No i deer]

I always pump the ram twice these just incase there's a bit too much spring back to make sure they've bump it back..

If it's set up for 2 thousanths it may only bump it 1 thousandths and could make it a a pinch to close the bolt..

A double pump makes sure it gets the full 2 thousanths.

I have measured and checked my theory 👍

[DaveT]

The same result can usually be had by letting the case 'dwell' for a second or two at the compression stage in order to have the brass set at the required bump.....depends on the state of the brass re work hardening.

Either way FL Sizing should be a steady process in both press directions and not a snatch which additionally risks skewing the neck or even stretching out some of the bump on a rough up stroke of the expanded ball (if you use one)

[onehole]

Here,s an old method I used to use to control repetative shoulder bumping.Get some shim steel cut out  make shift washers of various thickness ie 4,6,8 and 10 thou suitably  drilled to clear your case size.Place washer as shown in the picture and  work the press.You will soon arrive at the desired amount of bump and just make note of what size shim was correct for future bumping,,,,easy. You do not have to position die anyway near over centre just far enough to work press easily.

[stephentri]

56 minutes ago, onehole said:

Here,s an old method I used to use to control repetative shoulder bumping.Get some shim steel cut out  make shift washers of various thickness ie 4,6,8 and 10 thou suitably  drilled to clear your case size.Place washer as shown in the picture and  work the press.You will soon arrive at the desired amount of bump and just make note of what size shim was correct for future bumping,,,,easy. You do not have to position die anyway near over centre just far enough to work press easily.

This works the same way as Redding comp shell holder's 👍

[Big Al]

On 2/12/2020 at 12:08 PM, 6.5 shooter said:

I have been doing that for a few reloads with the FL resizing die but im just conscious of working the brass alot. 

Like I said earlier, dont believe everything you read.

0.002" is nothing in terms of case growth on your brass in any area, stretching and pushing it back every firing wont do your brass any harm and will make your bolt closing and extraction much nicer and more efficient. Measuring your brass resizing when it comes out of the die and then and then its growth after firing is what you need to do, then armed with this knowledge you can make appropriate decisions.

Growth and resizing at the .200" mark on a case is well worth measuring as well as shoulder bump, its easy enough to do with a relatively simple tool.

 

 

[Big Al]

Something I found from my own experiences both shooting and building competition rifles is there is so much dogma out there. A guy wins and so everyone hangs on his every word, his thoughts become Gospel and those who are afraid or to lazy to explore outside of these 'devine principles' just believe it and then do it and repeat it for the rest of their lives.

Im only interested in the truth, not 'my own made up truth' or 'someone else's truth' but the real truth, stuff I can see and measure with my own eyes and verify with a level of testing that takes chance and coincidence out of the equation.

I did well at long range benchrest for the short while I competed, I made my own dies to resize my brass. In the beginning everything I read revolved around concentricity in both the rifle chamber, the resized brass and the closeness of the fit between cartridge and chamber. The idea being that it introduced the bullet to the lands in the most concentric way possible. With my own dies I was able to control brass sizes consistently to within half a thou easily and from 60 resized pieces I could easily select 40 for the competition that were identical, the other 20 were +/- half to a thou of my desired shoulder bump length and so I used them as foulers.

What I found from my own thorough testing at both 100 and 600 yards as well as in competition was that my rifle much preferred a slacker case in the chamber, if my shoulder was pushed 3 thou back and my .200" size was 2 thou under fired case size my rifle shot better than if I was stuffing closely fitting and 'lightly worked' cases in.

Of the things a shooter has control of (after he has taken delivery of a rifle that has all the hardware aspects closely controlled for him in the build) without any doubt proper load development is the most significant factor, yet I see it taken far too lightly far too often. Proper load development that is properly verified (not just shooting a screamer and calling things good because you must have pulled the others yourself) paying close attention to your barrels harmonics with powder charge and seating depth are the keys to accuracy, I would say they are 90% of what the shooter can control with the other 10% being brass prep.

Remember, once everything is done ultimate accuracy depends on how good/consistently the shooter himself can shoot.

If you take what I call the 5% rule (that only 5% of people who try to do anything truly excel at it) then thats 95% of shooters who look for reasons other than themselves as to why they are not winning and thats why this dogma spreads faster than an Australian bush fire.

[Popsbengo]

30 minutes ago, Big Al said:

Something I found from my own experiences both shooting and building competition rifles is there is so much dogma out there. A guy wins and so everyone hangs on his every word, his thoughts become Gospel and those who are afraid or to lazy to explore outside of these 'devine principles' just believe it and then do it and repeat it for the rest of their lives.

Im only interested in the truth, not 'my own made up truth' or 'someone else's truth' but the real truth, stuff I can see and measure with my own eyes and verify with a level of testing that takes chance and coincidence out of the equation.

Big Al, 100% agree, thank you for saying it as you have way more credibility than many (including me) that post on here.  I'm heartily fed up with the bull-shine that get's trotted out as gospel without any real understanding of what's being touted as this week's 'Big Idea'.

[onehole]

Thanks for sharing some hard facts with us Alan much appreciated and understood.A friend of mine has a rifle built by you and dies to suit where stunning and repeatable accuracy is a joy to watch but only on days when the shooter can match the potential himself.Those days come and go as we all know.Outside the world of true custom built toolery I think some of us struggle a little and conern here for overworking brass to which you have somewhat helped. Most of us are working with mass produced dies of varying quality and certainly dimensionally to that of our rifles chambers hence the need to very carefully take measurements and note whats happening to our brass..I run mostly factory rifles that have been rebarrelled over the years and generally have tight chambers etc but when it comes to bumping cases this is done in  redding body dies and without doubt totally unrepresentative of the chamber the case was shot in! so apart from bumping a little am not always sure of what else may be on the move.However and as you say 90% is then down to the shooters control and generally works.......O

[Big Al]

11 hours ago, onehole said:

Most of us are working with mass produced dies of varying quality and certainly dimensionally to that of our rifles chambers hence the need to very carefully take measurements and note whats happening to our brass.

I think this last bit hits the nail on the head Dave.

Any reloader with a mind to can measure their fired and then resized brass and get a very good idea of how effectively their dies are working. Neck diameter, shoulder bump length (headspace) body diameter just after the shoulder and then at the .200" mark are all easily measured, with a few tweaks here and there with their factory dies they can make good ammo. Its not uncommon to see a factory die that is too long to bump a shoulder and that squeezes the life out of the base, Ive many times removed as much as 40 thou from the bottom of a factory die and its made a world of difference. Usually its more in the 10-30 thou range and the inside can often be polished out as much as 5 thou in certain parts.

Anyone who has proven through measurement that their factory die is squashing their brass way too much compared to its fired (chamber) dimensions can quite easily polish/open up the inside of their die with as simple a tool as an electric drill and a piece of 8mm or 10mm dowel and some emery paper. Polish a bit, resize and measure, repeat as required.

Something that has made me smile when it comes to case to chamber fit is the number of times Ive seen seen simply amazing groups while fire forming. Cases like the 6BR get blown way out of shape when pushing a Dasher shoulder forward 0.100" or the 6BRA and all other Ackley Improved designs that push the shoulder forward to 40 degrees. Ive shot consistently tiny groups while fire forming my own 6BRA brass that Ive never improved upon in load development. One barrel during fire forming shot 29.5gr of N150 under a 105VLD into remarkably small groups, by pure chance I must have hit on very close to the harmonic the sweet spot for powder and seating depth.

As for what exactly constitutes overworking in terms of our brass, the effect it would have on brass life and also accuracy I honestly dont know, but in truth I also wonder if anyone else really knows? If Im sizing my brass 3 thou here and there I wouldn't be unduly worried.

 

[Big Al]

I think something else worth bearing in mind is exactly how much a thousandth of an inch is in terms of measurement and movement.

I do believe there are a lot of people who understandably dont work in measurement increments like this on a daily basis and so can get overly concerned with what they see. I remember a chat I had with a well regarded shooter about the tenths that his digital caliper would show, the fourth decimal ie 0.0005" which is half of one thou.

He had no idea it was as about one twelfth of the thickness of the hair on his head. I think he was quite relieved to find that the last column of his calibers didnt really matter as much as he thought it did, it had been driving him mad for years.  😄

[No i deer]

See I told you 😉

Fl size 👍

[flyingfisherman]

@Big Al thank you for some really informative and unbiased, fact based information. It’s really good. I’ve not heard about measuring the .200 bit before and wondered if you could explain some logic behind it? I bump my shoulders in a Forster die and do it for chambering more than anything but really keen to learn more about what I should be looking for apart from the basic headspace measurement,

 

TIA, FFM

[Big Al]

On 4/22/2020 at 12:01 AM, flyingfisherman said:

@Big Al thank you for some really informative and unbiased, fact based information. It’s really good. I’ve not heard about measuring the .200 bit before and wondered if you could explain some logic behind it? I bump my shoulders in a Forster die and do it for chambering more than anything but really keen to learn more about what I should be looking for apart from the basic headspace measurement,

 

TIA, FFM

The .200 mark is a nominal distance up the case from the bolt face where case body diameter and in turn chamber fit can be measured and then controlled by resizing. People can make their own measuring tools like the one I showed quite easily, even a flat bottom hole in a block of wood or plastic will do, it doesnt have to be exactly .200" just thereabouts. The important factor is having a flat surface to reference your calipers on to provide repeatable measurements.

The main issue with undersizing a case in the .200" region is poor primary extraction sometimes referred to as clicking or the cases become known as clickers. Clickers can even be a false indication of pressure as the initial bolt lift is stiff and sometimes sticks at a point towards the top where a little jolt of the bolt handle upwards is needed to break free the case from the chamber. The problem is in fact that the case in the .200 area is too close a fit in the chamber and so when it expands it doesnt expand much so in turn contracts less than is required, has too tight a grip on the chamber walls and doesnt extract easily without the 'click'. A properly sized case should expand under firing and then contract enough to be easily extracted with no 'grip' on the chamber walls.

In a fire once field/hunting rifle scenario its not as big an issue as a quick fire benchrest rifle where minimum disturbance of the gun on the bags is critical but because we can control these things I would say why not?

It only takes a little measuring to see whats going on with your brass. The problem that can occur though is factory made dies are sometimes too sloppy to size your brass enough in the .200" region. On the other hand if it is sizing too much you should feel it on the press and if you measure the dimensional changes you could polish out your die with some quite basic tools or get someone with a lathe to do it for you.

None of this is rocket science and it can all be done with quite basic tools and a bit of common sense.

 

 

[Popsbengo]

Thanks Big Al, very informative.   Is there any benefit from measuring the case at, say 0.500" too ? Will it held any useful info that's not apparent at 0.200"?

Also is 0.200" about right for a .338 case too please?

I purchased some "once fired" .338 brass and F/L sized in a Redding Type S die only to find the brass was tight as you described.  A Hornady comp die did F/L resize for an acceptable fit in my rifle.  I've found though, that after that initial problem, the Redding die sizes back the same brass fired in my chamber to an acceptable fit.  I'm thinking this is down to the once fired brass having been stretched in a 'slack chamber' (my rifle is a custom CIP standard) and not returning to size fully in the Redding die but the Hornady die being ever so slightly tighter?

[Big Al]

57 minutes ago, Popsbengo said:

Thanks Big Al, very informative.   Is there any benefit from measuring the case at, say 0.500" too ? Will it held any useful info that's not apparent at 0.200"?

Also is 0.200" about right for a .338 case too please?

I purchased some "once fired" .338 brass and F/L sized in a Redding Type S die only to find the brass was tight as you described.  A Hornady comp die did F/L resize for an acceptable fit in my rifle.  I've found though, that after that initial problem, the Redding die sizes back the same brass fired in my chamber to an acceptable fit.  I'm thinking this is down to the once fired brass having been stretched in a 'slack chamber' (my rifle is a custom CIP standard) and not returning to size fully in the Redding die but the Hornady die being ever so slightly tighter?

You could have datum points in as many places as you want Pops, each is just giving you an accurate means of comparing your internal chamber dimensions with the resized dimensions of your brass. From a practical point of view on a taper if you knew the measurements in three places at say .200" from the bolt face and maybe 0.050" back from the body/shoulder junction and again one in between the two you will then be able to see how your sizing die is shaping your brass relative to your chamber.

Sounds like as you say the Hornady die brought your brass back to a place where the Redding die could then control it. 👍

[Popsbengo]

thanks mate, I've just made a 0.20" flat bottomed hole tool. now off to make a 0.50"