Q about K&M Arbor Press Features

[jccinohio]

Toying with the idea of getting an arbor press for .308 & .243 bullet seating. Don't want to spend any more than I need to.. My neck tension I'm shooting for is .0015-.002".

So the K&M has a low and standard force pack. I guess the 'force packs' are a sort of spring with a rod connected, so when you compress the spring the deflection of the rod is a measure of the force?

I see they recommend the low force pack for the neck tension I'm looking for. So with the low force pack a 1 pound force will cause a .002" deflection in the rod?

They say you have to buy the 'special indicator' for the low force pack. I assume all the dial does is do the math for you? So if there's a .020" deflection, then you had 10 pounds of force? I already have a good dial indicator.. can't I just use that and divide the measurement appropriately?

Does the K&M use a standard 3/8" diameter dial shaft?

Thanks!

 

[Forum Boss]

The OP first posted this Thread in another area. There was a useful response by member MikeRu:

Simpler than that. Let’s say your case neck expands by 0.002” when you seat a bullet (a micrometer and some pin gauges or expander mandrels can be on your list). You’ll see a corresponding reading on the dial such as 25, and you’ll try to get a consistent reading from case to case to case. It doesn’t really matter what the units are, low vs high force pack, etc. Thats about it. You should be fine with either low or high force pack. If you don’t get both you’ll be sorry someday, that’s how it goes for me anyway.

 

[jccinohio]

I know we're looking for consistency vs a specific reading, was just wondering if I had the theory of operation correct?

I guess I can revise my questions to:

- Is the low force pack more appropriate if I'm looking for around .002" 'neck tension'..
- If I do need the low force pack, can I just use my Accuracy 1 gauge and do the math appropriately, or do I REALLY need the special low force gauge?

 

[RegionRat]

The issue isn't very complicated as far as their parts and instruments.
What can be tricky is knowing your seating force ahead of time.

So, if you don't want to overshoot the issue and end up pegging the low force pack, then you get the standard one. The Standard Force Pack range is 0 - 150 lbs.

It is not difficult to get over 50 lbs seating force with NT values of 0.002" but some folks use very light NT with lube and those forces may stay below 50 lbs.

Use either the gages they recommend for each pack, or make sure yours is the equivalent. YMMV



The Low Force Pack is 1/3 the range of the standard, so 0 - 50 LBS.

 

[Ringostar]

I will recommend the standard force. The standard was out of stock when I was shopping, so went with the low force. It bottoms out on me while seating, and I use 0.002 smaller than bullet diameter.

 

[Chris Edmondson]

Does the K&M use a standard 3/8" diameter dial shaft?

Yes.

 

[JFrank]

I know we're looking for consistency vs a specific reading, was just wondering if I had the theory of operation correct?

I guess I can revise my questions to:

- Is the low force pack more appropriate if I'm looking for around .002" 'neck tension'..
- If I do need the low force pack, can I just use my Accuracy 1 gauge and do the math appropriately, or do I REALLY need the special low force gauge?

You don’t need a force pack to create a .002 dimensional difference between a loaded round and a sized round.

 

[PopCharlie]

I use the standard force pack. I use .003 tension on my 6br, with a neck turned to .009. I use .002 tension on my no turn 6.5x47L and .223. The standard force pack works well for all three. The idea is to get consistent readings for all of the bullets you seat in a batch. Any .001 dial indicator with a 3/8" shaft will work in the standard force pack.
As ReagionRat said, it is easy to exceed the limits of the standard force pack. If you are seating a bullet with a long bearing surface, such as Norma 6.5mm 130 Golden Target bullet, it can be problematic. I damaged a standard force pack trying to seat these bullets with .002 tension. I ended up using a Redding seater to finish this batch and subsequent batches.
I would recommend the standard force pack.

BTW: I quit trying to get the Norma bullets shooting in my 6.5x47 Lapua. I was never able to get any better than 1 MOA at 100 yards.

PopCharlie

 

[jccinohio]

I use the standard force pack. I use .003 tension on my 6br, with a neck turned to .009. I use .002 tension on my no turn 6.5x47L and .223. The standard force pack works well for all three. The idea is to get consistent readings for all of the bullets you seat in a batch. Any .001 dial indicator with a 3/8" shaft will work in the standard force pack.
As ReagionRat said, it is easy to exceed the limits of the standard force pack. If you are seating a bullet with a long bearing surface, such as Norma 6.5mm 130 Golden Target bullet, it can be problematic. I damaged a standard force pack trying to seat these bullets with .002 tension. I ended up using a Redding seater to finish this batch and subsequent batches.
I would recommend the standard force pack.

BTW: I quit trying to get the Norma bullets shooting in my 6.5x47 Lapua. I was never able to get any better than 1 MOA at 100 yards.

PopCharlie

Gotcha, thanks. I believe you meant you messed up a low force pack?. Sounds like the standard pack is for me

It's hard giving up a bullet with a good reputation.. I just had to call it quits on the 175smk for my .308. It just doesn't like them. Much as I tried I couldn't get better than a little over 1 moa. Got a batch of Hornady 178 bthps the other day. Found my jam.. loaded to jam - .020".. Did a few pressure tests from start load then +1gr up to 44gr.. Loaded up 5 at 44... and they we under .5moa (on steel so couldn't really measure too well) at 200yds. Waiting on a few things before I load more, but looking promising so far.

 

[PopCharlie]

Gotcha, thanks. I believe you meant you messed up a low force pack. Sounds like the standard pack is for me

It's hard giving up a bullet with a good reputation.. I just had to call it quits on the 175smk for my .308. It just doesn't like them. Much as I tried I couldn't get better than a little over 1 moa. Got a batch of Hornady 178 bthps the other day. Found my jam.. loaded to jam - .020".. Did a few pressure tests from start load then +1gr up to 44gr.. Loaded up 5 at 44... and they we under .5moa (on steel so couldn't really measure too well) at 200yds. Waiting on a few things before I load more, but looking promising so far.

I did damage a standard force pack by exceeding the 150 lb limit (several times). It would no longer seat any bullet. The "springs" would flex too much. I purchased a 2nd one, all good after that. I did not seat the Norma GT bullets using the arbor press/ force pack after I broke the first one.
Another nice feature of the arbor press is that it is small and stand-alone. You don't need to fix it to a bench. This comes in real handy if you like to seat bullets at the range.

PopCharlie

 

[jccinohio]

K&M with standard pack inbound

 

[Ccrider]

Ok. I’ll ask. What do you mean shooting for “.015 to .002” neck tension?

@SPJ suggested that if what you are referring to is sizing down to .015 to .002 under loaded round diameter, you do not need a force pack to do this. What he did not add is that this is a better and understandable way to talk about neck tension. Anything else and everyone (except maybe Guffey and a few others) get lost in the discussion.

Spend the money and time buying and testing different size neck bushings, rather than looking at the numbers showing on the force pack. You will quickly learn that the numbers on the force pack can be significantly impacted by many things, most of which do not show up on the target. Well, maybe not “quickly;” maybe not at all.

And yes, I have traveled up, down and all around this particular rabbit hole. Fortunately, my primary purpose was to experiment. I sold my k and m unit and bought a 21st Century.

Having said all of that, test this for yourself, like I did. You should learn some things along the way. Throw in testing with annealed and unannealed brass. You will find that annealing is not required-if you keep your brass on the same firing cycle. You will also see a difference in neck tension between annealed and unannealed brass. I think this matters. If you do not anneal, at some point you may have to change bushing sizes to maintain desired tension and accuracy. Again, my experience. Yours may vary.