I recently started using a Wilson bushing type full length sizing die along with their bullet seater. I also used the KM arbor press with force measurement. Loading 6.5 CM it took 150 lbs. to seat the bullet. Also, the bullet press was not smooth. I would pull the handle down and the bullet would not move until I got to 150 lbs. & then the press would jam the bullet fully in w/ no additional movement on the press handle. Is this normal? I am not used to this as all my traditional single stage presses would smoothly insert the bullet w/ no jarring.
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Wilson Arbor Press w/ Force Measurement
- Thread starter MMH
- Start date
OUCH!
No, that's not "normal". There's no way you should have that much seating pressure. It sounds to me like the case necks have not been expanded enough to a good "neck tension" . . . like .002".Take a measurement of the OD of one of you sized case necks and compare it to a measurement of the neck with a bullet seated in it. The difference should tell you what "neck tension" you're actually dealing with.
The diameter of a loaded round is 0.292". I used a 0.290" bushing figuring that would give me 0.002" neck tension.OUCH!
Take a measurement of the OD of one of you sized case necks and compare it to a measurement of the neck with a bullet seated in it. The difference should tell you what "neck tension" you're actually dealing with.
I measured a fired case and the diameter is 0.295". After sizing the diameter is 0.290" so there is no spring back
I am using Alpha brass. The brass thickness is 0.0155". If the case is 0.290" after sizing, then subtracting twice the thickness gives me 0.259" which means that there is 0.005" of neck tension.
Not sure why there is a disconnect between measuring a loaded round and the brass thickness calculation. I've tripple checked my measurements and think that my numbers are accurate.
Have you tried sliding a bullet into a fired case? It looks to me like the fired case OD of .295" gives you an ID of .264. It makes me think you might need or want to turn those case necks for the chamber that you have???
This is how I'm looking at the numbers:
2 x .0155 = .031 .290 - .031 = .259 .264 - .259 = .006
I'd say you're going to need a .294 bushing to get the .002 neck tension you're after.
Agreed. Just do not understand why measuring the loaded round does not yield the same answer.
Hmmm??? Something going on with your measurements??? Like. . . you say the neck of a loaded round measured .292". If you subtract the bullet diameter from that you get .028, then divide that by 2 it tells me .014" is actually the thickness of the case neck, not .0155".
If the case necks are .0140" in thickness, then yes . . . you'd want an OD of .290", which is what'll give you your .002" neck tension.
Going back to the problem of so much force to seat a bullet. This is virgin Alpha brass I take it? An issue I had with my Alpha brass was that the case mouth's were not chamfered or deburred. They had a nice square cut to a very uniform length. There can be enough of a burr on the ID of the mouth of any case to cause that much resistance. I highly suspect you hadn't chamfered the neck. . .is that right?
I agree w/ the 0.294 being the bushing I need to try. The Alpha brass was once fired & I did chamfer the inside of the case mouth. I purchased loaded ammo from Eagle Eye as I did not have any 6.5 CM brass.
Just bothers me why measuring the OD of a loaded round and measuring brass thickness do not reconcile. I measured 15 each:
- loaded rounds: 0.2915" (all were exactly this dimension)
- wall thickness: 0.0165" (six were this dim, two were 0.017 & two were .0155)
- Measured ID of sized cases: 0.259" (a lot of variation (0.257" to 0.260" w/ two cases being down to 0.257")
- measure the bullet: 0.2635" (not sure why not 0.264" - bullet is a 147 gr. ELD-M)
So so with a 0.290 bushing:
- based on loaded round OD: 0.2915" - 0.290" = 0.0015"
- based on brass thickness: 0.2635" + (2 X 0.0165") - 0.290" = 0.0065" - TOO MUCH need 0.2945" bushing!!!
- based on bulled OD & ID of sized case: 0.2635" - 0.259" = 0.0045" - TOO MUCH need .2925" bushing!!! (based on ID w/0.290 bush)
Comparing bottom two calcs I will go to 0.294" bushing
Also, I measure the bushing. The top was 0.2885" & the bottom was 0.289. Wilson says that there is 0.003" taper top to bottom but I am measuring only 0.0005" taper. The bushing is marked as "290" so if it is off by 0.001" then I probably need to order 295 & not a 294.
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I cleaned wet w/ dawn using southern shine stainless media (does not dent like SS pins). I did not anneal. I usually anneal every third firing as I flame anneal and not induction anneal.
Squeaky clean necks= a ton of friction.
Annealed squeaky clean necks = even more friction.
Try dry tumbling a batch and looking at seating force.
Only way I found to make a clean (virgin) neck work like it’s been fired before is to run a wet lube mandrel through it and tumble to bust down the anneal scale.
I do not think making your hole bigger is going to help this at all.
I tried lubbing the bullets w/ Hornady one shot, but apparently that did not do much. Maybe will run a brush inside case mouth w/ lube on it.
Try the Redding Graphite.
I use the same press set up as you. I see about 30-35lbs max iirc. I anneal eveytime. I also use a mandrel instead of relying on a bushing.
Calipers aren't a great tool for measuring diameters like neck thickness. A ball mic is better.
What caliper are you using? Is this what you used to measure neck wall thickness?
Using a caliper to measure your bullet to get .2635 instead of .264 is not unusual, depending on how good the caliper is and this could be an indication of how accurate it is. And if you're using a caliper to measure directly for neck thickness, that too can be way off. Better to use a micrometer to measure the neck thickness directly. Without a micrometer, it's better to take a measurement of a loaded round's neck and subtract the bullet's diameter, which is more accurate than trying to do the former.
Also, you're likely to know, the neck wall thicknesses will vary from on area to another and can vary as much as .0015.
If you go to a .294 bushing, be sure to test one before doing all the cases and see if the bullet resists going in at all.
Squeaky clean neck wall will certainly add to the interference fit making for a little harder seating and often requires some kind of addition of some lube for take care of that.
Agreed. But its not like I'm going to get a 3-point ID mic like I use on bearing bores.
