Good Forum to Ask a Question About Jacketed Bullets

[Reed]

I don't want to taint this forum with a question about a jacketed bullet problem. Since I don't get out much and rarely load jacketed ammunition, I don't have a feel for where to get reliable information about the other side. Could anyone recommend a forum they feel has some knowledgeable shooters in the jacketed world? I know this forum has folks who dabble in both, but I wouldn't want to get any eggs and rotten fruit thrown at me by presenting the question here.

 

[Brad]

Present away. We may enjoy casting but it doesn't mean we totally shun the jacketed bullet. I know fiver even makes his own.

 

[Reed]

Cool-thanks Brad! When I fired some full resized brass in my 30-06, the brass grew in length anywhere from .005 to .008". The groups weren't spectacular, although in one group 3 out of 5 were touching at 100 yd and the other two were next door in separate rooms at the Jones', making that group a bit over 2". Those were Sierra 150 gr sptz boat tails with 50.0 gr IMR 4064, average velocity 2880 fps. I Also fired a couple groups of Hornady 165 gr SP Interlock with 48.0 gr IMR 4064, average velocity 2743 fps. Those groups were larger yet. The headspace in this rifle is very tight. In fact, a Lee FL sizing die wouldn't push the shoulder back far enough to chamber. I have an old C-H die that does the trick, though, but I can't imagine there's much room for stretch between the bolt face to the shoulder. Unless--if the angle between the shoulder of the case and the shoulder of the chamber were different I suppose brass could flow there??????? Maybe that helps explain why all rounds chambered easily, yet a select few were a bit tight when lifting the bolt--and not necessarily the longest ones! Even at the stretched length, there's still good clearance inside the case mouth. The fired cases measure .310" there. I'm pondering the timing of the stretching vs the release of the bullet. What do you suppose happens first? Could the stretching steer the bullet a bit if the two things are happening simultaneously? Are they even happening at the same time? If this is a possibility, then it might make sense that the boat tails, being tapered fired better groups than the straight Hornadys, since part of the boat tail could be avoiding contact with the neck at least for the last part of the time as expanding and stretching are going on. A hundred yards shouldn't normally be enough to make much difference between designs, should it? I'd really like to hear some opinions.

 

[Brad]

Ok, this is MY understanding of how this all works.

If there is any space between case shoulder and case on ignition it happens like this. The firing pin drives the case forward until the should stops against inside of chamber. Primer ignites powder and bullet begins to move forward. The pressure builds and the front of the case is now held firmly against the chamber by that pressure. The rear end of the case is now slightly off the bolt face. The case head moves rearward to meet the bolt face. This stretches the case in the one area where pressure doesn't have the case held tight to the chamber walls-the web of the case. This is why head separations occur- the brass is stretched in that location due to the size/fire, repeat sequence.

Case stretch is not the issue. It is mostly a factor in case life.

I would get a runout gauge. Measure a fired case, a case after sizing, and a loaded round. Is the loading process taking a straight neck and bending it?

I would also get a Hornady Stoney Point headspace gauge. With that gauge and a set of calipers you can push the shoulder back a known amount. I like .001 for a bolt rifle. More than that just means case life suffers.

Also make sure cases are trimmed and not too long. If too long the case mouth MAY hit the end of the chamber and this can lead to the bullet being held tightly and pressure rises.

If bolt lift is stiff with some rounds it may be a pressure issue. It can also be dry bolt lugs, make sure they are lightly lubed.

Grouping issues are usually a load development problem or a loading process issue. Look at each step, measure with runout gauge, and see where the process is going astray.

 

[Reed]

Maybe I need some perspective. Is .008 an excessive amount of stretch after a FL size in a high pressure load? Most of my brass is neck sized and fired at moderate cast pressure, and I have rarely been concerned about stretch. Thanks for the suggestions, Brad.

 

[Ian]

Usually there's a spring loaded ejector on the bolt face which puts a hard forward pressure on the cartridge. Also the primer explosion jams the case head away from the bolt initially until the case stretches and shoves it back home. If the case body is sized significantly smaller than the chamber, the ejector plunger will also push the case CROOKED in the chamber. What's needed with full-power jacketed loads (this goes for full-power cast bullets, too) is enough room between case head and bolt face that the case body can expand and grab the chamber walls BEFORE it stretches to the limit of the bolt face. If the chamber/case fit is sloppy in diameter, it will need more headspace room, and vice-versa. If you EVER get hard bolt lift, bump those shoulders back another couple of thousandths and see if that takes care of it. Hard bolt lift is due to too much bolt thrust load, which is in turn due to insufficient headspace or too much pressure. If the case doesn't grab the walls or have room to stretch, it transfers too much force to the bolt, which flexes the bolt face, lugs, and action, and then when it contracts it binds up the case between shoulder and bolt face, causing hard lift.

 

[Brad]

Shooting low pressure cast then full power loads can lead to massive case stretch.
Low pressure loads can allow the case to drive forward and over time push the shoulder back a bit. The pressure is never enough to let the case stretch so this action can be cumulative.

.008 stretch is a ton. It is less a matter of the brass stretching on firing than why was it sized that short in the first place?

 

[Ian]

Maybe I need some perspective. Is .008 an excessive amount of stretch after a FL size in a high pressure load? Most of my brass is neck sized and fired at moderate cast pressure, and I have rarely been concerned about stretch. Thanks for the suggestions, Brad.

That's well into head separation territory if you do it more than once.

 

[yodogsandman]

It would be helpful to know which rifle you're using. Cases trimmed?

Sounds like you're pushing the case shoulder back too much when sizing.

I almost never use cases that were used for cast in full power, jacketed loads.

What kind of load work up was done? IMR 4064 might be the best for 150 gr but, too fast of a power for 165 gr for best accuracy at max velocities.

 

[freebullet]

I think your loads a bit stout.

I helped a new loader work a load for his model 70 in '06.
150 hornady soft point over 48gr 4064 was best accuracy
165 smk over 46.5gr 4064 was best accuracy.

To push the bullet faster AND keep it accurate a slower powder was needed.

 

[JSH]

Your sure it was a shoulder issue and not a body issue of the once fired brass?
I am guessing it was fired in another rifle?
What kind of brass?

From what you describe I would check the action screws.

A mixture or even same case brand, fired in another rifle or rifles is not a good recipe for high expectations for good groups, cast or jacketed.

I have a commercial Mauser that was built in the 60's. It will drop the first and second shot into a group. All bets are off after that.
After a lot of tinkering and really wanting to wrap it around a tree and fling it down range, I found it was all in the bedding.
I have no idea who or whom fooled with the inletting. It is going to have to be bedded front to back or restocked.
Luft, out of Washington state was the original builder. I have seen one other example of their work and I just don't think this is even their stock.
After firing two rounds, let it set over the week and it will repeat the same result. Group may move a bit left or right,but the first two will always touch if I do my part.
Dangdest thing I ever ran across.
Jeff

 

[fiver]

that .310 case mouth sounds like a clue to me.

your IMR-4064 load is just .4grs higher than my pet load with a plain base sierra 150 [or my copy of the sierra]

 

[yodogsandman]

That IMR4064 warms my barrels up quick. Could you be shooting them too fast, heating the barrel up too much?

I have a Remington 7400 30-06 semi, 18 1/2" barrel that will shoot the first 3 shots touching and then one at 5 o'clock, a half inch away and then the last shot is at 7 o'clock, an inch away and to the left of shot #4. The group opens up to 1 1/2" but will repeat over and over again. The barrel gets heated up too much. The load used is a Hornady 165 gr btsp over a full case of IMR4831. (BTW, this rifle shot 5"+ groups before Remington replaced the barrel.)

 

[Ian]

That IMR4064 warms my barrels up quick. Could you be shooting them too fast, heating the barrel up too much?

I have a Remington 7400 30-06 semi, 18 1/2" barrel that will shoot the first 3 shots touching and then one at 5 o'clock, a half inch away and then the last shot is at 7 o'clock, an inch away and to the left of shot #4. The group opens up to 1 1/2" but will repeat over and over again. The barrel gets heated up too much. The load used is a Hornady 165 gr btsp over a full case of IMR4831. (BTW, this rifle shot 5"+ groups before Remington replaced the barrel.)

I know someone who had that exact same rifle that did the exact same thing yours did before you had the barrel replaced. He fought it for years and finally traded it off.

 

[Josh]

Do yourself a favor and try 57 gr of IMR 4350 with a 150 gr bullet seated to that bullets recommended OAL per the manufacturer. The max load is 60 gr, but has never shot well for me. In 12 different 30-06's I've tried it in, 57 gr of IMR 4350 always produces good groups. If that is too slow for you then use the same charge with a 165 gr bullet, 57 gr being a max load for the 165.

I have nevet got IMR 4064 to shoot as well as IMR 4350 in my 30-06's

I have also had good luck with 49 gr of IMR 7383 behind a 150 gr bullet of your choice.

 

[Reed]

Wow. Many good ideas here. Thanks all. Will do some digesting and try again. Will post some results of the next trial and try to respond to some individual comments.

 

[Reed]

That's well into head separation territory if you do it more than once.

Sure enough-good call. With my little bent wire I've just rejected 3 out of the 20 pieces I was using. I need to be more careful with that sizing die. Most of the remaining cases can now be just neck sized with the exception of a few where the bolt was hard to lift. BTW, it's a Mauser 98 bolt. No spring loaded ejector.

 

[Ian]

Full power loads NEED headspace, meaning space between case head and bolt face. Mausers have a firing pin from he-double-L and they drive the case forward against the chamber shoulder (or bullet if it's seated out too far, bad juju with jacketed) as Brad described. Either way, the case needs to be all the way forward in the chamber with a little headspace when the powder ignites, this is the mechanism which makes the action safely take thousands of rounds because the case itself soaks up a lot of the bolt thrust by grabbing the chamber walls and then stretching a LITTLE BIT back to the bolt face. Bolt thrust load is tripled if the headspace is zero, which is fine if you're shooting 1/3 pressure cast bullet loads like 14.5 grains of 2400 but NOT ok with 55K PSI loads. The action can take full power loads with zero headspace, but it is technically well into the "abuse" category of use.

Just get used to the fact that you'll be replacing brass ever 3-5 firings when using full power loads and setting the shoulder back correctly each time you load.

 

[RBHarter]

I had three 06's that would not share any cases short of a full length , half turn past touching , 15 second hold all the way up in any of the 9 possible combinations .

I still have the Savage that is super touchy about case volume and matched brass . That rifle drove me nuts at first I had a pile of loaded GI M2 LC 43 , I'd shot 30-40 rounds of it and I'd get a nice 3" 4/5 group and then one tossed off ,using your description , over in the next zip code maybe county . Like 12" out .
Bedding , mounts , scope , all of it ! No change even when working loads for it in 40° and taking an hour to shoot 5 .

In a fit like temper tantrum I went and shot the entire remaining 80 odd rounds ........ Breathing , trigger control , no sense wasting range time even if you're just emptying brass . What showed up on the target backer ? 8 really wild shots nowhere near the three neat little 3" groups placed at 4:00,8:00&10:00 about 14" ctc . I didn't know what else to do so I weighed the cases ........ 178-207 gr with 12 that didn't fit into 3 groups of 2gr (ie 180-182 gr) for the whole lot of 125 rounds .

I went back and loaded 50-55 gr of 4350 in half gr steps in the largest lot under a Hornady 3033 spbt with a CCI LRP and had 12" patterns at 55 and .670 at 50 gr . 50.3 left me just over an inch and happy . Later with a Chrony at hand I found that with that combination 2600fps was a better group than I could hold on the bench . 2675 moved out to 5 clear holes for a 5 shot and 2710 was 3" , 2750 is just bad .

I have 2 FL sizers set up 1 only sizes down to about the last .07 of the neck , remember to 3 rifles it's all in the shoulders . The other is set up to make the fit of most brass fit the tightest of the 3 rifles . Which is a just touch holder to die firm cam over with a case in the holder . I'd guess about dead stop plus thread slop gets it done .

In 35 yr of handloads I've had 1 head separation and 2 cartridges show almost head failure . 1 of the cartridges was 110% my fault who knew a 27-130 could throw a 142 gr bullet ? ( Weigh a sample every time anything changes) the other was factory 22-250 and a heat issue , apparently 90°+ and a 1 min cycle in a heavy bbl 98' don't work well together .

 

[Reed]

OK, I've been reading (and re-reading) and thinking about the suggestions you all have given. Having rarely ever loaded high pressure ammunition, and having to deal with some rather generous .303 British chambers, I've achieved a mindset that head space is bad, period, and causes cases to stretch. In cast bullet forums, there's lots of discussion of guys going to great lengths to mitigate the effects of long military chambers, such as o-rings on the case head to take up space, greasing cases so they slide back against the bolt before gripping the chamber, etc. Ian's explanation in particular has helped me understand the difference when it comes to high pressure loads: expand the case against the chamber before the full force of all that pressure has to be handled by the bolt. For that you need a little cushion of space, and you have to accept some case stretch. Do I have that about right, now? Brad asked a key question. It was, why did those cases get sized so short to begin with? The answer to that is another dumb mindset that I fell into. I mentioned that my Lee sizer wouldn't move the shoulder enough to even chamber a round, no matter how hard I cranked it down. I found that an old C-H sizer would. I simply adjusted the C-H die the same way I did the Lee (all the way down), it moved the shoulder, I could chamber the round, and I thought life was good. I never stopped to consider how far I had just moved all those shoulders. After my experiment I've described below, I've found that according to my feeler gauges, my die is at least .004" higher than where it was when I sized all that brass the first time. Possibly even a little higher, because I really cranked that C-H die down the first time, just as I had the Lee. I have yet to address my accuracy issue, and there are many more suggestions above that deal with that, but I need to first address the headspace issue. Below is my attempt to achieve .001-.002 headspace. Your expert opinions, as always, are appreciated.


Brad said: "I would also get a Hornady Stoney Point headspace gauge. With that gauge and a set of calipers you can push the shoulder back a known amount."

Being retired and poor, and lacking a Stoney Point headspace gauge for now, here’s what I did:

1. Select a fired case that caused resistance to lifting the bolt.
2. Use a dry-erase marker to color the neck and shoulder of the case, then gradually adjust the FL sizing die ≃ .001” at a time until the ink shows that the shoulder of the case is just touching the shoulder portion of the die.
3. Turn in the die ≃ .001” and size the case again.
4. Color the shoulder of the case, then chamber it in the rifle. (After extracting the case, use a chamber swab to remove any ink from the chamber so it’s clean for the next test.)
5. If there is resistance to lifting the bolt or if the ink shows that the shoulder of the case is touching the shoulder of the chamber, repeat steps 3-4. I found that I couldn’t detect resistance to lifting the bolt several steps before the ink showed that the shoulder of the case actually stopped touching the chamber.
6. Push the shoulder back an additional .001”.

Finding Approximate .001” Graduations on the Resizing Die
The die has 14 threads per inch. That means it would take .014 of a turn to move the die up or down .001”. Since turning is measured in degrees, I needed to know how many degrees of rotation would equal .014 of a turn. Using a ratio, if one turn equals 360°, then .014 turns equals x°. Solving for x gives 5.04°. So, ≃ 5° to the right is .014 of a turn to the right, which will move the die down .001”. There’s no sense worrying about the decimal portion, since this method is a bit crude. I’m interested in marking approximately 5° increments on the die so I can see when I’ve moved the die down approximately .001” at a time. I eyeballed the following steps:

1. Use a permanent marker to mark the die lined up with a reference point that does not rotate.
2. Make a second mark on the die 90° counter-clockwise of this mark.
3. Make a mark halfway between the two 90° marks. There are now two spaces that are each ≃ 45° (depending on the accuracy of your eyeball and hand).
4. Divide each of the two 45° spaces in half with marks. There are now four spaces that are each ≃ 22 ½°.
5. Divide each of the four 22 ½° spaces in half with marks. There are now eight spaces that are each ≃ 11 ¼°.
6. Divide each of the eight 11 ¼° spaces in half with marks. There are now sixteen spaces that are each ≃ 5 ⅝°. That’s close enough to 5°, considering the error I’ll introduce marking and reading my homemade scale, and is far better than guessing.