30\30 - Shrinking o.a.l.

[rp85]

hello;

shrinking o.a.l. of 30/30. rifle is a marlin 30as, 30-30 cal. every time a loaded round is cycled into the rifle, .o.a.l. is reduced @.024”.

3 molds, 2 lee molds and 1 rcbs. makes no difference to which bullet is used. gas checked bullet, sized to .309". neck outside diameter of loaded round is .3285”, spec is .330". bullet nose diameter .300", steel wool works wonders. tried 2 different sizing and seating dies, lyman and a c-h, no difference. roll cripped as much as possible. still same problem. Tried a lee FCD, it did not work.

At a loss, any suggestions?? thx .for any input.

rp

thx for input. possible fix. when a case is trimmed a slight flange is left on the inside and outside of case neck. a chamfer tool is used to remove this slight flange. was aggressively using the tool on the inside of the case which gave a significant bevel on inside of neck. stopped the using the chamfer tool to remove any residual material on inside of the case neck. problem went away. thx again.

[jimkim]

Have you checked the brass, to see if it's being collapsed instead of the bullet being pushed back? I'd try triming the brass 0.010" under too.

I'd also have the chamber and lead checked to see if it's in spec. You can lengthen the lead a bit with the correct reamer, if it's needed.

Sent from my VS880 using Tapatalk

[FredBuddy]

rp:

I posted recently that my 30AS micro-groove was difficult to chamber the Lee 150 RNFP
first, because the nose was engraving heavily on one side of the boolit, but second,
because the boolit seemed to be seating crocked.

What I do now is select those rounds that don't have a 'bulge' on one side of the case neck, and they are not powdercoated, and they chamber with even engraving,

So, does it take lots of squeeze of the lever to chamber ? How does the nose look?
.309 diameter is probably not the problem, mine are .310. As jimkim says, mine seems to have a short leade.

I continue to work on this rifle, its one of six, but the most fussy for boolits.

[FredBuddy]

rp:

Is your roll crimp too heavy and causing the case to bulge at the mouth causing difficult chambering
thereby causing setback?

[jcourson]

rp:

Is your roll crimp too heavy and causing the case to bulge at the mouth causing difficult chambering
thereby causing setback?

I had a similar thought: brass will spring back and lead won't (or not enough to notice). Maybe you are effectively resizing your bullet during your crimping process and rendering your crimp inneffective.

[Taterhead]

Do you have correct neck tension prior to crimping? I'd check that first. The next thought that comes to mind is seating depth. Boolits seated too far that contact the lands will want to seat deeper.

[HangFireW8]

Measure shoulder height before and after. You don't need a Hornady Headspace Comparator per se, but you'll need something like it that slips over the neck, sits on the shoulder, and lets you use calipers to read the same spot with repeatability.

https://www.midwayusa.com/product/479704/hornady-lock-n-load-headspace-gauge-5-bushing-set-with-comparator

[rp85]

thx for input. knew it was likely operator error, just didn't know what it was. note fix in org. post thx again for input.