Jambing a bullet into the lands, using Hornady OAL to find base to Ogive, Help me?

[cdherman]

OK,

I cannot really quite figure out what I am seeing today. I have Hornady's OAL Gauge, their bullet comparator, and headspace gauges as well. I am trying to work up a load in a Savage 7mm SAUM that I screwed together. Has a custom throated Shilen Select Match barrel. Bullet is Berger 180 VLD Hunting

I used the Hornady OAL gauge to determine the max OAL to the rifling. First round, measured 3x times and came up with 2.277" base to ogive. My headspace gauge says that the Hornady "dummy" cartridge is within .001" of my own casings.

My headspace is about .008" more than the dummy cartridge and my own casings. As determined with layers of scotch tape, each at .002". Bolt closes with effort at 4 layers, which I have verified adds .008" to the cartridge length, measured to the datum line with the Hornady Headspace gauges.

So:

I wanted to jamb the bullet just enough into the rifling so that I get that benefit, but not so much that I start having bullets stick in the barrel if I have to unload. Its a hunting rifle.

I start the loads light, and start at 2.285" (2.277" plus the .008" headspace) base to ogive. I have a Forster Ultra die set with the micrometer head. I chamber each round to be sure and no trouble at all closing bolt. Bullet does not stick in rifling.

So the next string, I take the bullet out .005", thinking perhaps I will feel a little resistance or perhaps the bullet will hang up. Base to ogive is now 2.290" No resistance to bolt close, no stuck bullet, and when cartridge is removed, Base to ogive still is at 2.290".

Next three rounds, I again seat .005" further out, expecting that I will start to either feel some resistance on bolt close, or at least see the bullet pushed back into the case. Neither occurs. No stuck bullet, Base to ogive remains at 2.295" We are now at .018" longer than the measured base to ogive using the Hornady OAL gauge.

I repeat this for each 3 shot string, each time extending the base to ogive by .005" increments. I end up at 2.345" base to ogive for the last string. This is a full .060" beyond where I thought the bullet was hitting the rifling. Never did the bullet stick in the barrel. Never did the bolt hesitate to close. Never did the bullets come out pushed any deeper into the neck.

I cannot understand. I *think* I am using the OAL gauge correctly. Tried my measurement one more time just now. Pushed the bullet into the rifling as hard as I could limited by fear of breaking the plastic plunger rod. Made sure the dummy cartridge was firmly against the shoulder. With all that effort, my measurement did go from 2.277" to 2.296" The bullet was firmly stuck in the barrel -- had to remove with a wood dowel.

But 2.296" plus the .008" headspace is still .041" less than the base to ogive of the last group of cartridges I loaded. They did not stick in the rifling, and did not push back into the case.

I am worried that I have a burr or other machining defect in the throat that I am unable to "push by" with the OAL gauge, but loaded rounds are pushing by. But I see no scratches or dings in the bullets, even at the 2.345" base to ogive. I think I can see some slight burnishing from the rifling.

I am thinking a borescope is in order to find out what is going on in there???? Ideas?? Am I missing something totally obvious?

 

[918v]

Take a fired case and f/l size it so you end up with .002" of headspace, just enough to close the bolt easily. Cut a slit through the neck and into the shoulder. Deburr the slit. Insert a bullet about .100" into the neck. Chamber and close the bolt. Carefully eject the dummy round. That's your max OAL assuming all your bullets are exactly alike. They're not.

 

[AIdog]

Take a fired case and f/l size it so you end up with .002" of headspace, just enough to close the bolt easily. Cut a slit through the neck and into the shoulder. Deburr the slit. Insert a bullet about .100" into the neck. Chamber and close the bolt. Carefully eject the dummy round. That's your max OAL assuming all your bullets are exactly alike. They're not.

+1 on the slotted case... Ive measured The riflings using the slotted cases with consistent results... I also used my friends hornady oal gauge and came up with a consistent .002" longer probably because I was using more force with my fingers than the slotted case. Dremel with a cut off disk 3 slots. Not my idea it was a recommendation from Larry Willis works great

 

[cdherman]

Take a fired case and f/l size it so you end up with .002" of headspace, just enough to close the bolt easily. Cut a slit through the neck and into the shoulder. Deburr the slit. Insert a bullet about .100" into the neck. Chamber and close the bolt. Carefully eject the dummy round. That's your max OAL assuming all your bullets are exactly alike. They're not.

Was working on a similar approach while you were posting. I remembered a old method that I used once years ago, or read about.

I just now slit a case, seated the bullet shallow, and then chambered it. I then slide my dowel down from the muzzle, till it hit the tip of the bullet. I made a fine mark on the dowel right at the crown. Then, I extracted the round (the bullet stuck in the barrel inspite of my careful ejection). Then I tapped out the bullet, and closed the action, with the gun cocked (make sure firing pin is not protruding). I re-inserted the dowel till it hit the face of the bolt. Made another mark.

Measured true max COAL to rifling -- 3.006" Now -- the overall COAL of my longest load is 3.055", .049" into the rifling as determined by this method as well. Yet the bullet does not stick when extracted, and there are scant marks on the bullet. And the bullet does not end up pushed back into the case.

I wonder if the very gradual curve of the VLD bullets ends up making the exact point of contact to the rifling a whole lot more "fuzzy".....

The cambing of the action is perhaps pushing the bullet into the lands, and likewise on extraction, the neck tension of an actual loaded round is sufficient to pull the bullet back out without changing the seating depth. All I am seeing is a little abrasion on the bullet, since the bullets curve is very gradual at this point anyhow?

OK, next step -- some soot on a bullet to see what that shows....

 

[cdherman]

OK, sooted up a dummy round. When extracted, it shows a .060" band, pretty evenly on the end of the straight part of the body of the bullet. No clear rifling marks. It seems as if the throat is narrowing before the bullet even hits the rifling.

 

[918v]

Do the slit case method, making sure you have plenty of neck tension, but with the bolt out. Use your finger to push the case against the chamber to seat the bullet, then use your dowel to push out the dummy round.

 

[Squid284]

There was recently another post on this sight about a method using a dummy round and closing the bolt without the firing pin assembly. It had a link to a youtube video. You could try that also.

 

[cdherman]

Lots of different methods. I get different numbers with each. I think the secant ogive of the Berger VLD, plus perhaps the specific characteristics of my throat from Shilen, seem to add up to a "fuzzy" stretch of throat.

I begin to see what some people advocate jamming the Berger VLDs in to the rifling. I can imagine that the engagement to the rifling of these bullets can be erratic.

I am going to go shot my loads and see what happens...

 

[1J04]

You too may wanna go this route. You can do this 'and' a little black color marker also on the bullet so you may see even better as you touch. Then measure away.

<iframe width="560" height="315" src="//www.youtube.com/embed/Jv-D1mEI514" frameborder="0" allowfullscreen></iframe>

 

[Fatelvis]

A good video, thanks!

 

[1J04]

I fucking knew you lived ! ! ! !

A good video, thanks!

 

[cdherman]

I am going to rephrase the issue a little bit to see if I can get some other ideas...

I have used literally every method described in this thread at some point in my 35 years of reloading. I have been using the Hornady system of late since it seemed easy and reliable.

What I have never done, before 2 nights ago, was to start purposely jamming the bullet further and further into the lands. I had always read that I would run the risk of leaving a bullet in the barrel and getting an action full of powder. I also assumed that at some measureable point, the bullet would push back into the case, as opposed to further movement into the throat.

I experienced neither of those events, even after jamming a bullet almost .050" into what was the longest base to ogive as determined my multiple methods.

I wonder if the worries about the bullet staying in the barrel when jamming are based on experiences from bench rest shooting, where neck tension is purposely left very low.

And I wonder if the modern secant ogive VLD bullets are putting such a gradual curve against the rifling, that the clear point at which the bullet is going to push back into the case, may be a LONG way from the point where it initially touches the rifling....

What I am certain about is that of 30 plus rounds loaded, all with either contact or varying degrees of jamm into the rifling, never did the bullet remain in the rifling. I never tried jamming before, as I hunt with my guns. Wondering if I have missed my golden chance all these years.

 

[sharpshooterbr]

I posted this in the other thread about finding base to ogive length. Hope it helps.

"I have tried about every method and tool out there to find the base to lands length on my rifles. The best way I have found to do it is to close the bolt on an empty chamber and insert a cleaning rod down the barrel until it contacts the bolt face. I have 2 rod stops on my cleaning rod at this point, and I slide them both up to touch the crown and lock them both down on the rod.

Next I take a long soda straw, acquired from the local convenient store, that holds the caliber bullet I'm working with very tightly. Remove the bolt. insert a bullet into the end of the straw, and then push the bullet up into the chamber until it touches the lands in the barrel. At this point you can feel exactly how much kiss or jam you are getting on the bullet by varying pressure on the straw.

Next, take your cleaning rod and again slide it down the barrel until you contact the tip of the bullet. I like to have one hand on the straw, and one hand on the cleaning rod so you can get a really good feel for everything.

Next, slide the rod stop closest to the crown down the rod until it contacts the crown, and lock it down.

Now just measure from the crown side of each rod stop to one another and you have your base to bullet tip length. I repeat this several times to get a consistent measurement.

I then take that bullet, and seat it into a case to the previously determined length. Then I measure with my comparator tool and find the base to ogive length. I now have a very precise measurement that I can use to know how far in or out of the lands my loads are for load development testing."

 

[cdherman]

I posted this in the other thread about finding base to ogive length. Hope it helps.

"I have tried about every method and tool out there to find the base to lands length on my rifles. The best way I have found to do it is to close the bolt on an empty chamber and insert a cleaning rod down the barrel until it contacts the bolt face. I have 2 rod stops on my cleaning rod at this point, and I slide them both up to touch the crown and lock them both down on the rod.

Next I take a long soda straw, acquired from the local convenient store, that holds the caliber bullet I'm working with very tightly. Remove the bolt. insert a bullet into the end of the straw, and then push the bullet up into the chamber until it touches the lands in the barrel. At this point you can feel exactly how much kiss or jam you are getting on the bullet by varying pressure on the straw.

Next, take your cleaning rod and again slide it down the barrel until you contact the tip of the bullet. I like to have one hand on the straw, and one hand on the cleaning rod so you can get a really good feel for everything.

Next, slide the rod stop closest to the crown down the rod until it contacts the crown, and lock it down.

Now just measure from the crown side of each rod stop to one another and you have your base to bullet tip length. I repeat this several times to get a consistent measurement.

I then take that bullet, and seat it into a case to the previously determined length. Then I measure with my comparator tool and find the base to ogive length. I now have a very precise measurement that I can use to know how far in or out of the lands my loads are for load development testing."

Yep, did that more or less in one of my attempts, albeit with less precision than you (don't have stops).

Like I said in my later post -- I have the distinct feeling that finding the exact base to ogive in a secant VLD bullet may be part of the issue here.... There seems to be some "fuzzy" there. Or at least the rumor that bullets pull out of cases when jambed into the rifling is over rated.

I was thinking more today -- I could imagine a scenario when you load a round into a hot barrel (few tenthou larger diameter) and jam the bullet into the rifling. And then let the barrel cool.

I wonder if that is the scenario where bullets get pulled......

 

[sharpshooterbr]

In my opinion, bullets get pulled from the case when two things occur: 1) the bullet is seated far enough into the lands to start the engraving process, thus "squeezing" the bullet, and 2) using too light of neck tension to overcome the resistance created from having the bullet jammed into the lands.

My personal experience has taught me that if I'm loading for competition where it is unlikely that I will need to extract a loaded round, then I can use far less neck tension on my loads. On the other hand, if I'm loading hunting rounds where I will most definitely be extracting loaded rounds, then I add quite a bit more neck tension to retain the bullet in the case. I have loaded rounds ranging from being able to pull the bullet out of the case with very little effort, to rounds that had to be pounded with a kinetic bullet puller to release the bullet. What I have learned is that consistent neck tension both around the circumference of the bullet and from round to round is far more important than light or heavy neck tension. Just my .02 cents.

 

[Geno C.]

you hit the nail on the head where you said it about concistancy more than light of heavy tension. I have tried both to the extreme and everything in between. As long as I have it consistent there is no visible difference. So, since in prone to accidents, I use fairly good next tension and have never pulled a bullet. Yet...

 

[stilts75]

Lol, I pulled a bullet in my -06 at the range, sighting in a new scope, at dusk, the day before leaving for a out of state to hunt. Not one of the prouder days of my life. O, and it makes a hot mess of lubed bolt and action.

 

[Fatelvis]

I followed the method shown on the video posted here. My bolt moved very free after the FP was removed, and "fell" into battery when no cartridge was present, but after I started working with the cartridge, there was much more drag. I FL sized the brass beforehand, and made sure I had between .002-.003" HS clearance before proceeding, and the bolt still did not drop like in the video. In fact, it was more of a "feeling game". Good idea, but did not work as definatively as in the video.

 

[clrems77]

You too may wanna go this route. You can do this 'and' a little black color marker also on the bullet so you may see even better as you touch. Then measure away.

<iframe width="560" height="315" src="//www.youtube.com/embed/Jv-D1mEI514" frameborder="0" allowfullscreen></iframe>

Awesome instructional video, thank you!!

 

[1J04]

I followed the method shown on the video posted here. My bolt moved very free after the FP was removed, and "fell" into battery when no cartridge was present, but after I started working with the cartridge, there was much more drag. I FL sized the brass beforehand, and made sure I had between .002-.003" HS clearance before proceeding, and the bolt still did not drop like in the video. In fact, it was more of a "feeling game". Good idea, but did not work as definatively as in the video.

Is your gun "Squeaky Clean"? Gotta be clear of grime build up. Good reason to clean the hell outta it

 

[Fatelvis]

I fucking knew you lived ! ! ! !

Are you saying you were one of many "Suspicious minds"? Lol
Yes, the chamber and bore are sweaky clean.

 

[1J04]

Are you saying you were one of many "Suspicious minds"? Lol
Yes, the chamber and bore are sweaky clean.

LMAO, ya that was me. Size the piece of brass for your dummy round more than you normally would. You don't want to feel any crush as you close the bolt on that piece. You will feel some very slight resistance but should not amount to squat. This way you can feel the bullet later touching instead of the case shoulder. You'll get it.