reloading question

[Hunt7112]

I have been playing around with my 7 RUM loads I believe I am close to what I am looking for. I have 85.6 grains of IMR 7828 topped with a 150 grain scirocco the average mv 3370 with a .75 group at 200 yds my coal is 3.60. My question I have loaded several more rounds but have changed the coal to see if this improves my accuracy. Does lengthening my coal create more pressure or less.

 

Thanks for the help.

[rclouse79]

I actually just bought all of my reloading stuff and have not even loaded a cartrige yet so I am definately not an expert. From what I have read if you increase the length of the bullet to where it touches the lands pressure goes up. I would get a second opinion before you take my word for it.

[jeffro]

The preasures go up as you seat the bullet deeper into the case. You can see this on a crony as your coal gets shorter you will see the fps go up even with the same powder charge. Thus increasing preasure. The preasure goes up due to the decreaseing capacity of the case. If you jam into the lands you will also see the preasures go up. I would stay at least .005 off the lands for a hunting/tactical rifle.

[308Nut]

It is going to depend on how much bullet jump you have currently and how far you move the bullets in or out.

 

In a factory remington there is a ton of freebore. If you increase the coal by .020" you wouldnt even see it on the crony regardless of your freebore. Now if you had .100" of bullet jump and you seated some on the lands, you will definatley see it in the crony and probably your brass. However, the difference between .010 off the lands and .010 into the lands isnt decernable.

 

In short, if you go from alot of jump to no jump you can get into trouble. Moving bullets in or out a little bit, regardless of how much jump you started out with is no big deal even if you are close to or on the lands.

[jeffro]

I have done load development many times, and on various calibers with a set powder charge and only changing the OAL. When I do this I would change the setting depth by .010 each time. I can see the vel change right away as you start to seat the bullets deeper. IE: COAL 2.850 then 2.840, and so on. You will also see the vel go down as you seat longer. Thus allowing you to add more powder and increase your vel even more if you have room in your mag box, or if you want to single load them. Seat a bullet .010 off the lands then seat one touching the lands you will most definatly get a preasure spike if you are already on the hot side of your loading data. An example of this is on a 308WIN load shooting the 208 Amax @ 2640fps. The OAL is 2.950. If you were to seat the bullet at box lenght 2.820 you would never be able to get enough slow burning powder ( RL-17 ) in the case to get that vel before you started to see preasure signs. Seat long- increase capacity.

[.270]

from everything i've ever read and have been taught, the longer the col, the more pressure and velocity you'll see. seating the bullet deeper should drop pressure and velocity. you might see some pressure increase from a compressed load, but nothing like you'll see by having the bullet right on the lands. the closer the bullet is to the lands, the less time their is for expansion of gas before the bullet gets squeezed down the barrel. i won't go as far as to say you're wrong, but it goes against everything i've ever heard about reloading. i reload a bunch. thousands of rounds a year. i use a chronograph a bunch. i've never seen pressure or velocity go up by seating the bullet deeper. when barnes first came up with the x bullet they had special instructions for them that required seating them deeper and using reduced loads from what you would use for a like weight lead bullet, because the longer bullet caused so much more pressure. what cartridge are you seeing these results in? i'm more than a little interested. like .308 said, when you're seating bullets somewhere shorter than where the lands start, you shouldn't see a lot off difference in velocity or pressure. you can see some dramatic differences in accuracy tho. but again, from everything i've ever been learned up on, the closer the bullet is to the lands, in other words, the longer the col, more pressure and velocity is the rule. Lark.

[catclaw]

WOW- You better find a better source to get reloading advice than what you have gotten here, both 270 and 308 nut have both given you erroneous information. Lark did say "from everything i've ever read and have been taught," so he may well have heard and been taught this, but as you seat the bullet out further, the volume of the case increases and gives you lower pressures. Velocity may or may not be affected enough to notice. This is common sense as it is the same thing that distinguishes a magnum from a non-magnum in the same caliber- ie. a 300 H&H has a little bit more volume that the otherwise, very similar 30-06 so you can achieve somewhat higher velocities, everything else being equal.

 

As for 308nut's assertation that "the difference between .010 off the lands and .010 into the lands isnt decernable." is also wrong. My reloading experience as well as the professional treatises I had read on it show a MARKED difference between .010 off and .010 into the lands. The difference is usually very discernible.

 

Now, even though the increased cartridge overall length (COL) increase creates more volume and hence, lower pressures, seating into the land will usually spike your pressures back up again. If you have plenty of freebore, you can go with my first paragraph. If you don't, you will have to rely on your pressure testing to tell you.

 

Reloading is one place where you should exercise extreme caution as you can get seriously hurt if things go too wrong. A friend of mine lost a finger when his reloading practices turned out to be unsafe. Luckily, most of the time, you will only damage your rifle and the built in safety mechanisms will often spare you injuries.

 

You shouldn't take my word for all this either- it is worth just as much as it cost you. Get yourself a few reloaded guides and actually read through them. If I came off as arrogant, forgive me, I am only trying to spare you some frustration and bad experiences.

[Hunt7112]

Thanks for the info I bought a oal guage from hornady and found with my remington 700 xcr that there is so much free bore that when the bullet touches the lands it is completely out of the shell case. So I wont be seating very close to the lands at all. I feel comfortable with the group so far I think by tweaking the coal in small increments I should be able to find what the gun likes best. If my pressures are fine at my shortest coal of 3.60 then do you think my pressures will be fine at 3.650 which is the longest round I have loaded

[.270]

yep, that's what i said and if i'm wrong then so is joyce hornady and about every other reloader of any repute. i'm real astounded by your reply. but what do i know? i have a rifle that doesn't have a fat barrel, therefore, i don't know anything. i looked a little for something on the net i could post real easy, but couldn't find anything, so i'll hand type a couple paragraphs out my trusty ol' hornady reloading manual. 3rd edition. found the same info in sierra, hogdon and speer books. didn't look at any of the other ones.

 

now you're sure that stuffing the bullet in farther makes more pressure and velocity? positive? there are some variables and i fullly agree with what 308 said because as long as you keep the shoulder of the bullet in the freebore area of the throat, it doesn't change things a lot. they change and measurably, but not to a great extent. at least not dangerously. and i think that's what he said. but i'll let him explain his thinking. i've talked with him enough to know he is extremely knowledgable and experienced and would trust him. now when you let the shoulder get close to the lands, you really see some changes.

 

when a bullet is seated deep, it has farther to jump before it engages the lands. when the shoulder of the bullet engages the rifling is when pressure really sky rockets. and mean it gets high. 50 to 60 thousand psi in some cases. take it from a guy who built and maintaned steam boilers for a lotta years, that is a lotta pressure. no power plant sees more than maybe three thousand psi, and that will rip you into hamburger instantly. this isn't stuff to be foolish with. i never give anyone reloading data. but i will share experience. instead of just saying i'm right and someone is wrong, i'm gonna spend a few minutes on this, because i don't want anyone getting hurt.

 

this is what the 3rd edition of the hornady reloading manual says. pages 18 and 19. it has some illustrations, but i don't have a way to post them.

 

"to illustrate the effects of variations in bullet travel before the bullet enters the rifling, we'll compare a standard load with adjustments made only in the bullet's seating depth.

 

in a "normal" load with the bullet seated to allow about a 32nd of an inch gap between the bullet and the intitial contact with the rifling, pressure builds very smoothly and steadily even as the bullet takes the riflings. pressure remains safe throughout the powder burning period, and the velocity obtained--3500 fps-- is normal for this load in this rifle.

 

seating the bullet deeper to allow more travel before it takes the rifling, as in the next 2 illustrations, permits the bullet to get a good running start. (this is the real important part so pay attention everbuddy) 'POWDER GASES QUICKLY HAVE MORE ROOM IN WHICH TO EXPAND WITHOUT RESISTANCE', AND THEIR PRESSURE THUS NEVER REACHES THE 'NORMAL' LEVEL'. nor does the velocity, with same powder charge it only comes to 3400 fps.

 

when the bullet is seated to touch the rifling, as in the accompanying illustrations, it does not move when the pressure is low and not having a good run at the rifling as did the other bullets, it greatly increases pressure to force it into the rifling. as the now rapidly expanding gases now find less room than should have at this time in their burning, the pressure rise under these conditions are both rapid and excessive. velocity is high at 3650 fps-- but at the expense of rather dangerous pressure."

 

this is verbatim from the hornady manual. word for word. if i'm wrong, then so are buncha other folks that have a lot more experience than i do, and i didn't start reloading last week.

 

a compressed load, with the bullet touching, or very close to the rifles, will create more pressure and velocity than a noncompressed load that is touching the rifling. because it has more powder. if it didn't it wouldn't be compressed. but we aren't talking about compressed loads. we're talking about c.o.l. in equal powder loads, the bullet seated deeper will not achieve the pressure or velocity of the bullet that is not seated as deep and is closer to the rifling. i don't know what more i can say on the subject. like i said earlier, unless the guys at hornady, nosler, sierra, speer and hogdon are all wrong, what i said in the earlier post is true. again, there are many variables; chambers tolerances, throat length, rifling integrity immediatly after the throat, differences in case wall thickness in different brands of brass, and especially in military brass, bullet jacket thickness, bullet composition, especially pure copper bullets, all have very defined and measurable affect on pressure and velocity. if you're going to reload, be careful. make sure you're doing it right and then check again.

 

there's my rebuttal, refute if it you want. but i'm not wrong. and to anyone just starting to reload, please be careful and consult folks who have some experience at what they're doing. read up on it a bunch. modern rifles will take a lot of abuse, but when they reach critical pressure, things blow up. you're holding a contained explosion in your hands, next to your face, at pressures 20 times greter than a power plant makes. as long as things are done correctly, you shouldn't have a problem. be postivie you are correct. Lark.

 

 

[jeffro]

What Catclaw and I are saying are on the same lines, and are true. I have done this testing with a lot of large rifle loads that I have delt with. 7-08, 308, 7mm, 300WM, and many more.

 

Quote- If my pressures are fine at my shortest coal of 3.60 then do you think my pressures will be fine at 3.650 which is the longest round I have loaded?

 

I cant say that they would be fine as I have not watched your load development take place. I have also not watched all the trends that happen while working up a load. If your 3.650 load is not jamming into the lands then you should be fine. Note- should be fine

[jeffro]

I did a little looking around to see if I could find some credible info. Here is some great info from a person who makes the bullets. This is an artical from Erik Stecker of Berger bullets talking about this issue. Half way down in the bold is the good info. I think this pretty much sums it up. Enjoy

 

What 270 is saying about a bullet touching the lands and getting a preasure spike is true. Im not talking about the bullet touching the lands, Im talking about seating the bullet out long, but still at least .005-.010 off the lands.

Seating long, and seating to touch the lands at two different things.

 

 

AccurateShooter.com Bulletin

March 14, 2009

Berger Tips for Loading VLD Bullets

Filed under: Bullets, Brass, Ammo,Reloading — Tags: bullet, Reloading, VLD — Editor @ 7 am

The folks at Berger Bullets have just released an interesting technical bulletin that describes methods for optimizing bullet seating depths with Berger VLDs. The document explains how to find the OAL “sweet spot” for VLDs in your rifle. Interestingly, while VLDs commonly work best seated into the rifling .010″ or more, Berger’s research indicates that, in some rifles, VLDs perform well jumped .040″ or more. This is a significant finding, one that’s backed-up by real-world testing by many shooters.

 

The key point in Berger’s report is that: “VLD bullets shoot best when loaded to a Cartridge Overall Length (COAL) that puts the bullet in a ‘sweet spot’. This sweet spot is a band .030″ to .040″ wide and is located anywhere between jamming the bullets into the lands and .150″ jump off the lands.”

 

CLICK HERE to download Berger VLD Tuning Tips

 

Writing in the report, Berger’s Eric Stecker observes: “Many reloaders feel (and I tend to agree) that meaningful COAL adjustments are .002 to .005. Every once in a while I might adjust the COAL by .010 but this seems like I am moving the bullet the length of a football field. The only way a shooter will be able to benefit from this situation is to let go of this opinion that more than .010 change is too much (me included).”

 

For target competition shooters (for whom it is practical to seat into the lands), Berger recommends the following test to find your rifle’s VLD sweet spot.

 

Load 24 rounds at the following COAL:

1. .010″ into (touching) the lands (jam) 6 rounds

2. .040″ off the lands (jump) 6 rounds

3. .080″ off the lands (jump) 6 rounds

4. .120″ off the lands (jump) 6 rounds

 

Berger predicts that: “One of these 4 COALs will outperform the other three by a considerable margin. Once you know which one of these 4 COAL shoots best then you can tweak the COAL +/- .002 or .005.”

 

OBSERVATION and WARNING

Berger may definitely be on to something here, and we applaud Berger’s testers for testing a very broad range of seating depths. However, we want to issue a STRONG WARNING to reloaders who may be inclined to try the 4-step method listed above.

 

Be aware that, as you load your cartridge progressively shorter, putting the bullet deeper into the case, you will be reducing the effective case capacity dramatically. With smaller cases, such as the .223 Rem and 6mmBR, moving from .010″ into the lands to .080″ and .120″ off the lands can CAUSE a dramatic pressure rise. So, a load .010″ into the lands that may be safe can be WAY OVERPRESSURE with the bullet seated .120″ off the lands (i.e. .130″ deeper in the case, the difference between .010″ in and .120″ out).

 

To illustrate, using a QuickLOAD simulation for the 6mmBR cartridge, moving the bullet 0.130″ deeper into the case can raise pressures dramatically. With the Berger 105 VLD seated .010″ in the lands (with 0.220 of bearing surface in the neck), and a charge of 30.0 grains of Varget, QuickLOAD predicts 60,887 psi. (This is using ADI 2208 data, and a 5500 psi start initiation value). If we move the bullet back 0.130″ further into the case, QuickLOAD predicts 64,420 psi (even after we drop start initiation pressure to the “default” non-jammed 3625 psi value). The 64,420 psi level is way higher!

 

Cartridge & Load COAL Jam/Jump* Start Pressure Max Pressure

6mmBR, 30.0 Varget

Berger 105 VLD 2.354″ +0.010″ in lands 5500 psi 60,887 psi

6mmBR, 30.0 Varget

Berger 105 VLD 2.324″ -0.20″ JUMP 3625 psi 59,645 psi

6mmBR, 30.0 Varget

Berger 105 VLD 2.264″ -0.80″ JUMP 3625 psi 62,413 psi

6mmBR, 30.0 Varget

Berger 105 VLD 2.224″ -0.120″ JUMP 3625 psi 64,420 psi

* As used here, this is the variance in OAL from a load length where the bullet ogive just touches the lands (first jacket to barrel contact). Loading bullets to an OAL beyond that point is “jamming” (seating bullet into lands), while loading to an OAL shorter than that is “jumping” (seating bullet away from lands).

 

NOTE: This is only a software simulation, and the real pressures you encounter may be different. But, the point is that moving the bullet 0.130″ further down in a 6mmBR case can raise pressures more than 3,000 psi! Therefore, you must employ EXTREME CAUTION when moving your bullets that much in a relatively small case. Remember that going from .010″ jam to a very long jump will probably increase pressures in your cartridge so you MUST adjust your load accordingly.

[catclaw]

Lark is talking about two completely DIFFERENT things. He stated that as the COL increases, the pressure increases which is FALSE and I stand by that. What he is doing is making and assumption that by seating the bullet out longer, you are getting it into the lands which WILL increase pressure. I am not talking about getting it into the lands.

 

If you seat the bullet out longer, you create more volume which in turn, creates a load with LESS pressure. Thus, as you INCREASE the COL (make more volume) the pressure decreases up until the point where you get into the rifling. This changes everything- it will create a pressure spike and this is likely be measurably higher.

 

I am talking about regular jacketed bullets made with gilding metal and lead cores. IF you want to talk about homogenous alloy monolithic bullets we have to be careful to give them more room to get a running start at the rifling. Generally .040" is plenty. For a typical lead jacketed bullet, .005" is plenty.

 

 

So, Lark, if you increase the COL to the point where it engages the rifling it will create an artificial pressure spike but in most factory rifles, you can't get close enough to the rifling and still fit the loaded rounds into the magazine to do this. I think you were misinterpreting what you read in the reloading manual.

 

As for what 308nut said about the plus/minus .010, and talking about standard hunting bullets, I feel that he is wrong. I have had too many loads that were marginally safe pressure-wise flow brass or pop primers, give hard bolt lift as soon as I seated the bullets into the rifling. If we are talking about secant ogive VLD bullets. I think what he said is probably true. I think you just need a little more info given to make that statement. Also, f you have a low pressure load, he would be right, you would never notice the difference but since most handloader play with the ragged edge of pressure, this is not something to indiscriminately try.

 

Hunt 7112, if you increase your COL by .005"-.010" and you are not into the rifling, your load will be safe, assuming it is safe the way it is.

[.270]

a guy asked a question about c.o.l. jeffro said something that sounded real contrary to everything i've ever done, read, been taught, etc. i asked him to explain. instead i get catclaw calling me a liar, like he likes to do, because i don't have a fat barrel on my .300. nobody said or asked anything about compressed loads. when i get a load close to the desired velocity i usually get it where i want by tinkering with the overall length. seat it deeper to slow it down, longer to speed it up. as long as i'm within what the rifle likes as far as the distance from the bullet shoulder to the lands. the info i posted was the simplest description i could find of what i was saying. the less "jump" a bullet makes, the more pressure and velocity it makes, with equal powder charges. that's the rule. to everyone on this site, please disregard anything i've ever said about reloading. it ain't worth it being called a liar, when i'm trying to loan someone some experience. and again, with like loads, the less jump a bullet has, the more pressure it builds and the more velocity. and there ain't anything artificial about a pressure spike. pressure is pressure. it doesn't go away until it's relieved. Lark.

[catclaw]

a guy asked a question about c.o.l. jeffro said something that sounded real contrary to everything i've ever done, read, been taught, etc. i asked him to explain. instead i get catclaw calling me a liar, like he likes to do, because i don't have a fat barrel on my .300. nobody said or asked anything about compressed loads. when i get a load close to the desired velocity i usually get it where i want by tinkering with the overall length. seat it deeper to slow it down, longer to speed it up. as long as i'm within what the rifle likes as far as the distance from the bullet shoulder to the lands. the info i posted was the simplest description i could find of what i was saying. the less "jump" a bullet makes, the more pressure and velocity it makes, with equal powder charges. that's the rule. to everyone on this site, please disregard anything i've ever said about reloading. it ain't worth it being called a liar, when i'm trying to loan someone some experience. and again, with like loads, the less jump a bullet has, the more pressure it builds and the more velocity. and there ain't anything artificial about a pressure spike. pressure is pressure. it doesn't go away until it's relieved. Lark.

 

 

Lark, I never said you were a liar, you simply don't understand internal ballistics. I guess there is no point beating this anymore because you know what they say about teaching old dogs new tricks... I'll bet you have never playing with a Oehler Mod 43 ballistics lab, I have. It has a strain-gauge feature where you can actual measure the pressure your favorite loads are making. I have incrementally seated bullets in and out, measured pressure and velocity to see correlations etc. You are simply misinformed if you believe that seating a bullet out creates higher pressure; it doesn't. An easy test is to find a load that is near max pressure with your rifle and using a fairly heavy bullet(lets use a 200 grain bullet in your 300 mag for example) seated close to the max COL for your magazine box. Then seat the bullet about 1/4" deeper and watch your bolt lift and every other pressure indicator spike!

 

In this example, we will take a 200 grain Nosler Partition and seat it so that you have the COL of 3.340, the SAAMI max for this cartridge. In this load, the bullet is seated .614" into the case. If we load it with 77.25 grains of H4831SC (I picked this powder at random as a likely candidate for this load) we will get (according to Quickload) 62,321 PSI. This is right at the top of SAAMI pressure for the 300 Winny. If we then seat the bullet .250" deeper and leave everything else alone. The pressure will rise to 71,849 PSI. This is a 9528 PSI INCREASE in pressure. A 15.2% increase and enough pressure to flatten the primer, cause brass to flow in the head and surely make for hard bolt lift. The primer pocket will probably be toast etc.

 

This info jives with what was posted by Eric Stecker of Berger bullets. I don't know if you have Quickload software (souds like not) but you can easily run any scenario you can imagine and see how pressure changes. The pressure spike created by jamming into the lands wont be as great as the spike caused by seating the bullet .250 deeper and displacing an additional .305 cubic centimeters of case capacity as you do with seating the bullet 1/4".

 

Sorry we don't see eye-to-eye on this but it sounds like maybe I have more experience, education and knowledge in the theory and practice of internal ballistics than you do. I would never tell you how to operate a power plant as I am sure you know far more about that than me.

 

I won't post on this subject again.

 

It is like mud wrestling with a pig, you can't win and the pig likes the mud.