Push Test

[gdawgs56]

Hey guys. Finally getting to setting everything up and decided I should do the push test with Berrys 124 HBRN

What is your guy's "procedure" In doing this? Even after flaring the case, the bullet only slides in ever so slightly and if I try and do the push test (with bbl out) I have to SHOVE the round in the chamber.

Edit: Maybe I mean "Plunk Test", Not sure what to call it. I'm trying to determine Max OAL



-Jason

[SMSgt]

Being that you have to "shove" the round into the chamber tells you your COL is too long. You can probably see rifling marks on the bullet. Continue to seat the bullet slightly deeper until the round drops freely into the chamber and will rotate freely (Not binding on the rifling).

That will establish the COL for that bullet for that gun. If you're loading for more than one gun, you'll have to establish a COL that works in all of them. My 9mm reloads will work fine in my 6906 at 1.100 but have to be 1.095 to fit my Sig 226. So now I set all my reloads for the .1095 COL.

[gdawgs56]

I actually figured it out. The cartridge is not finished, I'm just doing the test where you slide a bullet in the case and then push it into the chamber and slide it out carefully to determine the absolute max OAL.

I figured out your not supposed to do anything to the case, no flare or sizing, just pick up a spent case and slide a bullet in.


-Jason

[vwpieces]

Push test & plunk test are different. For the push test I use a Fired cracked case. It holds the bullet tight enough for removal from the chamber but easy enough to push in.

An alternate method may be to just shorten the COAL a couple thousandths at a time till you loose the drag on the bullet to rifling in barrel. Insert an empty case & get a feel for how it spins in the chamber & the depth it is. Now continually shorten the COAL till it feels the same when you spin it & it sits at the same depth. Once you tink you got it load a few more & see if they also fit. Measure that COAL & write it down in your notes regarding that particular bullet & weight.

Just out of curiosity what bullet are you loading?

[tdogg]

I actually figured it out. The cartridge is not finished, I'm just doing the test where you slide a bullet in the case and then push it into the chamber and slide it out carefully to determine the absolute max OAL.

I figured out your not supposed to do anything to the case, no flare or sizing, just pick up a spent case and slide a bullet in.


-Jason

Yeah and not all fired cases are equal.  I like to find one that has some moderate resistance to hold the bullet well when inserting into the chamber.  That way when you pull it out it doesn't stick in the rifling and pull itself out of the case and give you a longer max OAL reading.  I use a case with enough gripping resistance to have to use a bullet puller to remove the bullet when done, but not so much that I can't comfortably push the case into the chamber.

I also usually try to find a two bullets that are either the heaviest and lightest or are the longest and shortest of a random sample of ~25-50 tested.  I then find a case that holds the bullets with a moderate grip and perform the push test on both (several times each) and pick the shortest overall length to use as the max OAL for that bullet barrel combo.  Then subtract your ~0.015-0.030 inch for extra safety.

That way you have attempted to find the extremes of the distribution of the bullets.  Maybe a little overkill but it gives me piece of mind knowing I tried to capture more variability.

Cheers,
Toby

[1SOW]

I find the same as tdogg about the fired UNsized cases.   It may take 10-20 to find three or four that are expanded enough but still provide a little tension to hold the bullet lightly.   I save those cases as they often can be used again for another push test,  and I'm lazy.

I personally don't always subtract a full .015" and make that my oal.  I may use less or more depending on the seating depth that gives with that bullet. Some bullets may test to 1.193"  and some to 1.062 and minus .015" isn't where I'll load them.  Like load data,  it's a good guide to be fully aware of.  "YMMV

[Wobbly]

In addition, you may want to use some cases with lengths around .742-.743".  That way, when you hit a case at .748 you're not pushing the bullet back into what you just worked so hard to miss.

 

[ShadowGuy2014]

Hello Everyone,

First of all I apologize for my grammar, english is my second language.

I've been reading about the push test and how to find your MAX O.A.L. post. Couple of questions.

What's the difference between using a fired case or a sized case for the test? I actually used re-sized cases, flare them, seat the bullet, no crimp, for the test but the C.O.L seems to short. 1.048 in., this is without taking the respected .015 for the rifling.

Is the O.A.L. to short?

Recently I'm using mix ranged brass, 9mm 147gr Lead FP (didn't cast them my self), Dillon SDB, CZ SP-01 Shadow (Factory New).

Problems:
1. Some bullets get stuck on the barrel and when I clean the malfunction the ogive gets separated form the case inside the handgun.
2. Some cases don't let the slide to go into battery.

I appreciate all the help in Advance

Greeting from Guatemala

Rafa

[vwpieces]

Hello Rafa,
What are the specifications of the bullet or if cast, the mold used.
Some profiles are not as CZ friendly as others and will give a short OAL push test.

I am sure that flaring the case will not give an accurate reading as the case needs to easily fit the chamber but still hold the bullet snug enough to accomplish the task without getting stuck in the rifling. That is why I use a fired, cracked case from the recycle bin. You can "out side size" the cracked case & still be able to slip a bullet snugly through it. 

[ShadowGuy2014]

Hello Rafa,
What are the specifications of the bullet or if cast, the mold used.
Some profiles are not as CZ friendly as others and will give a short OAL push test.

I am sure that flaring the case will not give an accurate reading as the case needs to easily fit the chamber but still hold the bullet snug enough to accomplish the task without getting stuck in the rifling. That is why I use a fired, cracked case from the recycle bin. You can "out side size" the cracked case & still be able to slip a bullet snugly through it.

Thanks for the reply vwpieces.

I currently don't know the mold used (Cast Bullets), but I just e-mailed the guy who sold them to me, but i will take a picture later and post it so maybe you can identify it.

[1SOW]

Shadow Guy,  your grammar is excellent and likely better than mine.
For the 'Push Test' to be accurate,  a fired case that has been expanded due to the firing pressure is needed.    Not all will work.  Find a few that are expanded enough to to be able to push the bullet into the case BY HAND.  Just push it in enough to hold the bullet  and no more.
Then with the bbl out of the pistol,  gently push the cartridge into the chamber until the case mouth seats fully.

Turn the bbl over and "gently" remove the cartridge and measure the length.  Do this a few times with other spent cases until you find a consistent maximum length.   That is the length that is touching the rifling or chamber wall.   Subtract .015" from that length,  and the cartridge will feed and fire reliably.

I keep the cases that worked for this test to use again the time.

I hope this makes sense and helps.

[ShadowGuy2014]

Thanks for all the help guys, will try finding fired cases and do the test the way 1SOW mentioned it.

For the moment here is a pic of the bullet I'm using. 9mm 145 gr, .356.

[Matt O]

Turn the bbl over and "gently" remove the cartridge and measure the length.  Do this a few times with other spent cases until you find a consistent maximum length.   That is the length that is touching the rifling or chamber wall.   Subtract .015" from that length,  and the cartridge will feed and fire reliably.

Yeah, when I was working up my first load, I read the description of this process on this forum and it was extraordinarily helpful in determining max oal for a given chamber and bullet profile.

[1SOW]

One last consideration:  Lets say that coated bullet has an oversized diameter---maybe .357/.358".   With a "THICK-walled" brass case,  It may never fit your CZ chamber properly.   It is possible to have too large of a bullet diameter for a CZ chamber with thick-walled  cases.  If they measure within SAAMI diameter checks after they are loaded using the push test,  they should run fine.

This is where the "Plunk Test" comes into play.  With tha cartridge loaded drop THIS into the chamber and it should FALL in with a clink/plunk and seat on the casemouth.  THEN,  when you turn the bbl over, it shouild fall out into your hand.  If it doesn't do this 100%,  the cartridge is not fitting properly into the chamber ,  and it "could" cause feed and or extraction probles.
The plunk test is jus a quick final  go-no-go test.

[ShadowGuy2014]

Thanks all for the help.

Just did the test 10 times the average OAL was 1.052, (1.052 - .015 = 1.037). Gonna reload some test rounds and hit the range on saturday. I will tell you how it went.

Cheers