Dimension Difference in RC and L-N-L

[jgh4445]

I have a Rock Chucker WITH the L-N-L Quick Change Bushing system installed. Of course, to do this I had to remove the large insert that came with the RC and replace it with the L-N-L bushing insert. Now, I want to be able to move dies from one press to the other and not have to adjust the dies. I have taken a bunch of measurements and finally just decided to seat a .22-250 bullet in a case, first in the L-N-L and then in the RC and measure. I did. The round seated in the L-N-L measured 2.446. The round seated in the RC measured 2.443. Has any one else done any of these measurements? Should I now measure different cartridges including handgun? Is it time to make a shim of .003 for the RC? what do you guys think?

 

[rcmodel]

No I haven't.

But I think the .003" is still gonna be .003", regardless of what cartridge you try it with.

rc

 

[KansasSasquatch]

If everything is going to be .003" different I'd say there's no need to do anything. 2 presses from the same manufacturer are likely to be off that much. I'd call it good and use your time working on perfecting your shooting.

 

[rcmodel]

But, for the dies to switch back and forth without needing adjustment, both presses must be the same.

.003 is a lot for a rifle sizing die, if it's pushing the shoulder back that much further or not enough on one press then the other.

rc

 

[jgh4445]

My .22-250 shoots best at .004 off the lands. In this case, .003 is a lot. Now to add to the confusion, I measured the thickness of the top of the frames of each press. I measured from the point that the die bushing touches each die, to the bottom of the frame where the die would protrude. The LNL is 1.162 and the RC measures 1.219. The difference is .057. How can there be only .003 difference in seating depth? I must be doing something wrong here. Like the lady who got fired from the IRS, "math is not my strong suit"!

 

[rcmodel]

Slack or slop in the LnL quick-change threads??

The shell holder pushes it up when seating or sizing.

But you are pushing it down when you measured it??

Just a WAG!

rc

 

[Certaindeaf]

fguffey will tell you all about it.

Yea, if you swap dies between presses, you might have to adjust them.

 

[jgh4445]

rc...there was nothing to push up or down. I measure the seated rounds. Used the same case then pulled the bullet, re-seated with the same die in the different press. Again, measure the seated round. Ballistic tip so no bent lead points or anything. Then, just measured the top part of each frame. I guess there are just too may variables to be absolutely accurate. Cheap digital calipers, shell holder vs. shell plate thickness, etc. Scratch the cheap caliper theory. The digital and the nice set of dial calipers read the same.

 

[Blue68f100]

If you did not mind using the std threads you could have used a steel shim to make up the difference. Not a quick change but very doable. I have a several complete shim packs. I got them off Amazon for like $6/pk.

 

[jgh4445]

Well as I think more about it, the thickness of the frame is probably not relevant. If I remove the seating stem from the seating die, stand the calipers up on the die so the tail can go thru the die and touch the bottom of the shell older I would probably get a more meaningful measurement. Should that measurement not equal the difference in the OAL on the rounds I measured?

 

[rcmodel]

Forget the die.

Measure from the top of each press thread insert to the top of the shell holder with the ram at full stroke with the depth measurement on a dial caliper.

That is the actual distance from the bottom of a tight die lock ring to the top of the shell holder.

However, like I said in post #6.
If there is any slack or slop in the LnL insert the die is attached too?

You can only measure it when the ram is pushing all the slop out at the top of the stroke.

That's what you did when you seated bullets in both presses and came up with .003" difference.

rc

 

[KansasSasquatch]

Are you using the same shellholder with both presses? I assume you're using the same die bushing on the die when you switch presses.

Seeing as the die touches the shellholder I only see a couple options. Either the press insert on the Rock Chucker isn't as worn in as the insert on the LNL so the die bushing isn't moving up as much as it is in the LNL. This would cause a few thousanths variance. You could solve that with a shim (only using the shim with the LNL press) if you feel it's necessary. Using one press more than the other for sizing would likely cause the press bushing in the press to wear at an uneven rate over time so you'd want to keep an eye on your settings.

Or the stop for the ram lever on the LNL isn't allowing the ram to go up as far as it would on the Rock Chucker which would also leave the round a little long when using the LNL. I guess you could attempt to take .003 off of the stop on the LNL.

Or like rcmodel hinted at in post #6, the press bushing on the LNL may be slightly loose. Properly torquing it down and using some Loc Tite should help that. Or like he was saying in post #11, the height of the press bushing may be different, that could be solved by taking .003 off the top of the press bushing on the Rock Chucker.

There could be other options that I'm not seeing but I think those would be the most obvious and easiest to rule out first.

 

[jgh4445]

OK...Bushings and and LNL less than 6 months old, less than 2000 rds loaded. No slop or upward movement. RC (Rock Chucker not rcmodel ) is quite old but bushing conversion same age as LNL. Consistent measurement from LNL threaded bushing is 1.480. Measuring the RC the exact same way I get a repeatable 1.304. Both rams are as far up as possible, no dies in the presses. Difference is .076. BTW to answer Kansas, the same shell holders cannot be used. the LNL uses a rotating shell plate, while the RC has an RCBS shell holder in it.

 

[rcmodel]

Well, when I subtract 1.304" from 1.480"?

I continue to get .176", not .076".

Still, if you seated bullets in the same case on two different presses with the same die and came up with a .003" difference in OAL??

I just don't know what else to say to help you that I haven't already.

rc

 

[KansasSasquatch]

I see. I made the mistake of assuming you meant LNLSS and not LNLAP. That could pose some more challenges. Are you overcamming on the LNL? I've always had widely varying results doing so. Are you running it as a full progressive or are you sizing everything, trimming, and then finishing them out?

 

[jgh4445]

You are correct rc, meant to type .176. ( told you I was math challenged) Thanks a lot. Can't answer why or how the .03 came about but it did. I'll re-measure again tomorrow on a seated bullet and see what I get. No need to keep beating a dead horse here. I'm thinking there are just too many variables to contend with. Kansas..I do it both ways. On the .22-250 though, I've been sizing on the LNL, priming by hand, using the LNL powder measure or my Chargemaster, depending on the powder, and seating on the LNL.