Can't get consistent #s using OAL and a modified case

[mj52]

I've tried and tried to get anything approaching consistent #s. Ain't working for me.

I decided to build a couple of dummy rounds and work my way around this particular user error.

AR15, 77gr Sierra, case trimmed to 1.760, Redding precision seating die (this tool I like a lot).

With upper removed I started with the shortest (+/-) of the OAL guage #s, built dummy, placed in chamber and pushed BCG with 1 finger. This sounded different so I backed seating up a few and tried again.

Kept this up till this got me to what I thought was a good place. bolt went home easily, sounded the same, and bolt was flush with back of upper (??).

Using bullet comparator and 77gr Sierra I got 1.938"

These are going to be single loaded so Magazine length is not an issue.

I came across a lb of IMR 4007 SSC and Sierra's web site says 22.0 - 25.0C I built 3 rounds each from
22.0, .5, 23.0, .5, 24.0, .5 Total of 18 rounds

This is going to be the 1st step in using Erik C's thread on long range set up at 100 yards.

I didn't think this question belonged in that thread.

Opinions please, mj52

 

[Raythemanroe]

Try making a modified case from one of your fired formed brass

 

[stool]

speaking of which...is the thread 5/16-36 ?? or ???
i lost my stuff in a fire...got to start over.

thanks

 

[amamnn]

One problem with doing the dummy round thing is that bullets can become slightly stuck in the chamber and be pulled out to some degree on extraction. This is one reason I use the RCBS precision mic when I can. The "bullet" features an ogive that is somewhere in the middle of most standard and match bullets and is hard enough to resist being stuck in the throat of your chamber.

These tools also perform other necessary (IMHO) tasks.

 

[letronshootit]

The modified case tool I don't like, too much inconsistency. Resize a fired case, unprimed of course and no powder, seat your bullet long and lube the end good with case lube. Chamber that and close bolt, extract and take a reading, do the whole sequence 3x and see if readings look better. Use the same bullet too. Removing the firing pin on bolt will help also. Works for me.

 

[Area Man]

I've gone to just making JB Welded dummy rounds.

 

[stool]

it's a tool..learn to use the tool.

it takes practice
but
like any tool its only as good as the user

everything you guys have described so far is like cutting your wedding cake with a chainsaw...

 

[Irv Benzion]

I had the same problem. I solved it by holding the firearm with the barrel pointed up. Insert tool and feel for rifling. Using this method the readings obtained were repeatable. My thought is that the case and bullet were in better alignment with the bore. Try it.

Irv Benzion

 

[chapstix97]

I had the curved version and found it was not consistent BC it had too much play in it. I replaced it with the Sinclair's tool. Its much more sturdier and does not need modified cases and is more consistant

 

[Raythemanroe]

Stool, I'll check to see what tap fits today..

I would like to hear from folks that have used the Stoney creek (Hornady) OAL gauge with fire formed brass that they made into a modified case..

Ray

 

[Raythemanroe]

Stool, My 5/16NF24 tap looks to course, I am guessing because I can't find one now that it is a 5/16x36 thread.. I am gonna order a couple so I can find them..lol

Ray

 

[stool]

it is 5/15-36 with no drill bit that is a perfect fit. so i will go small. taper ream a little and then use a taper tap..
( i started a second thread on the thread question, got an answer)
put the rifle in a cleaning cradle..what ever you use for cleaning, pull the bolt, back up the bullet pushing stem so the bullet is almost fully in the case. insert the case in the chamber and while pushing forward, rotate the casse to ensure it is all the way in, shoulder to shoulder.
now loosen the set screw and slowly push the bullet forward till it stops at the lands....this is the FEEL portion. it is like using a micrometer, there is a FEEL to the correct measurement, no force, but not sloppy loose.
do not be surprised if the bullet sticks in the lands...but if it takes more than a slight drop of the butt on the floor for it to come loose..it should not be counted as a valid measurement....you want just the lightest touch...the point where it touches, but does not jam....
take your time , learn to use the tool...do not let it be the boss....
if you cannot learn to use the tool...all the band aid methods will be much less accurate than doing this right.

 

[Raythemanroe]

I have used the Stoney Point (Hornady) OAL gauge for a while now. I use to take the firing pin Assembly out of my bolt and close or try to on a seated round..I would adjust the die until I felt the slightest tension on the bolt as it closed and figured that to be just touching..

Ray

 

['Freak]

Try the Sinclair tool. It’s more accurate and easy if you understand the why of how it’s used.

 

[letronshootit]

I watched and followed German Salazaar with the hornady set up, no bumping stock on floor was involved he pushed it out with a cleaning rod, so I followed, it worked but after too many hours I had many readings that were not consistent. So I used Erik Cortina's method which works....for me consistently. Thanks Erik for the Band Aid Method.

 

[bow shot]

'And the band aid method is...?

 

[stool]

just go up a couple of posts and read the silly things some use...

'And the band aid method is...?

 

[mj52]

With all due respect

Disassemble tool, sand rough edges off gray plunger because it is a 2 piece construction. Reassemble tool.

Attach modified case snugly and insert bullet of your choice, making sure plunger is loose and bullet quite far into modified case so as to not prematurely contact lands.

Gently press case into chamber until solid contact made.

With minimal pressure push plunger till bullet meets lands.

Tighten set screw.

Remove OAL guage and if needed use dowel to unseat bullet. Since case has no neck tension even the least bit of pressure on plunger will cause bullet to stick.

Once bullet out look to see if excess pressure applied, if not place in tool and measure using either OAL or comparator.

This is my system and I get different #s. I've tried this many times and continue to see the same results. I also understand the term "Gently".

As far as learning to use "The Tool". If I hadn't run into the same problem on a regular basis I would not have asked the question.

Respectfully mj52

 

[stool]

i do not put the case in gently..it goes in firmly and held in place while moving the bullet forward.

i guess you need to get together with another shooter and see if he can spot any issues....

bottom line is i have been using the tool for years, make my cases now, do not buy them, but can always get a solid set of readings from every rifle......

so, if the tool works, and it does, and others can use it, the variable left in the picture is you.

so find a buddy and try again

 

[M-61]

5/16 x 36 is the tap. Drill is letter "L"