factory ammo adhesive between bullet and case

[kobus]

i pulled some bullets from factory ammo to look for crimp marks on the bullets. i pulled one of each Winchester 115gr fmj rn and PMP 115gr fmj rn.
i usually takes 2 or 3 good whacks with the kinetic hammer to pull my own reloads and when the Winchester bullet popped out after 4 hits i thought it was normal when i saw the deep crimp mark and could actually feel the groove with my fingers.
here is a pic of the Winchester bullet


it took 7 solid smacks to pull the bullet from the PMP round and i thought these must have a very tight crimp ...... but no, there was no crimp mark to speak of and i could not feel any indentation on the bullet but there was some sort of black adhesive or sealer between the bullet and the case as can be seen in the pics below.






this stuff does not feel sticky and is fairly easy to rub off between my fingers.
i was wondering if this is used to seal the round from moisture and/or to hold the bullet firmer in the case to prevent it from being pushed back into the case when the rounds are cycled. 
has anyone seen this before and know what it is and why it is used on this ammo?

[jwc007]

Sealer, Yes!  Adhesive, No.  Primers may also be sealed against Moisture.

[DenStinett]

You find that with a lot of MilSpec rounds too
Think about storage and/or where it could be used
There are a lot of very humid locals in the world
?Keep your powder dry boys !?

[1SOW]

You can buy bullet/primer moisture sealants for your reloads too.

[kobus]

thanks everyone.

You can buy bullet/primer moisture sealants for your reloads too.

are there any specific brand names you know of?
i shoot my reloads all the time and they do not need to have a long 'shelf life' but i may want to experiment with some sealant for my sd reloads.

Sealer, Yes!  Adhesive, No.  Primers may also be sealed against Moisture.

i must say this sealant does make the bullet difficult to pull from the case.
i have seen that S&B ammo have some kind of red sealant on the primers.

You find that with a lot of MilSpec rounds too
Think about storage and/or where it could be used
There are a lot of very humid locals in the world
?Keep your powder dry boys !?

this does make sense because PMP supplies to the military and law enforcement.

[Wobbly]

Loctite product #290 might work. This is "wicking" grade thread locker. In this application, it's not going to "glue" the pieces together, but it will wick into the minor porosities and seal any leaks. Apply it with a cotton swab, like a "Q-tip". NAPA auto stores sell this as "after torque".




Any excess you apply will remain liquid on the exterior and can be easily removed hours later.

 


PS. The taper crimp DOES NOT hold the bullet. In that sense, TC is not truly a "crimp". It's the press-fit between the bullet outside diameter and the smaller case inside diameter that does all the holding. The case is sized smaller than the bullet. That's why the case has to be "belled" to get the bullet started. That's why some reloads have the "coke bottle" or "wasp waist" look.

If you want to hold your bullet tighter, chuck the expander in a drill press and polish .0005" (1/2 thou) off the case expander with 600 grit emery cloth. This way you can dial in the exact fit you want.

[kobus]

thanks Wobbly. i will see if i can get some of this 290 to experiment with. 

i do not want want to crimp my bullets any tighter. my press is set up nicely to give a nice tc on the .355 bullets. i was just looking for the correct sealant to improve the "shelf life" for my sd ammo.

[FF1063]

Use the proper product.

There are two basic types of sealant. The black asphalt type that can be thinned/cleaned with mineral spirits, and the (usually) red lacquer based sealants that can be cleaned using lacquer thinner/acetone.

Fingernail polish is the primary choice for DIY. Midway sells Markron sealant.http://www.midwayusa.com/product/954332/markron-custom-bullet-and-primer-sealer-1-2-oz-liquid

[kobus]

thanks for the link FF1063.     do you know if the Markron can be used inside the rim of the case while the bullet is seated or can it only be applied afterwards?
if i read the description correctly it seemd like it is applied after assembly.

i would ideally like to use something like the black sealant that PMP uses. (see pics above) it looks like it's applied to the bottom edge of the bullet base before seating.

[FF1063]

There's no need for the asphalt sealant. That's for factory use.
You're more likely to ruin the ammo by applying sealant inside the case than not using it at all.

If you want to use sealant, get the Markron. I don't use the included brush, I use a small artists brush with a pointed tip and do a quick, light pass around the primer while they're upside down in the loading block after priming. Then a quick pass around the case mouth after the ammo is finished.

Less is better than more. It is thin and will wick it's way around the bullet, like sweating (soldering) copper pipes together.

IMO, the primer sealant is as important or more important than the case mouth sealant. I had some commercial .40 ammo go bad after it spent a week in a wet plastic bag. I got caught in a downpour, spilled a box of ammo on the bench, swore a bit, scooped them into a plastic bag and threw them into my truck. Found them a week later and about half of the first ten failed to ignite. The ones that did fire, fired normally, so the powder was still dry. I threw the rest away because I didn't want to risk lodging a bullet in the bore if the primer fired, but the powder failed (squib).

Markron is basically thin fingernail polish with a little green pigment. Same as the commercial red sealant. It cleans up with acetone/lacquer thinner even after it is dried.

[kobus]

@ FF1063.   thanks very much for you input and advice.