[greenwell369]

I have never hand loaded for a semi-auto rifle before, I usally only have to be concerned with the jump distance from the OGIVE to the lands and grooves. Because of this I have always measured the length from the OGIVE. because I will be useing a Magazine (PRI) I have a maxium length (from tip to base) of 2.295 so they will fit and cycle in the rifle/mag. When I seat the bullets, the die (smallbase RCBS) seats the bullets on the OGIVE not the tip of the bullet giving me different a diferent OAL each time. I am useing a Sierra MK 115 gr. Sierra makes a good product but I,m not happy with the consistancy of there lenghts. I guess my question is, is there a simple fix for consistancy or am I just over thinking this and I just need to seat deeper? Thanks in advance Greenwell

 

[HTR]

I use the RCBS full-length dies, and my OAL may vary by about .001 to .003. this does not seem to affect accuracy as much as I would have expected, as long as the powder charge is consistent and there is little runout on the bullet.

Some bullets seem to seat more uniformly than others. Bullets with a broad shoulder, like the SMK seem to have the most variation whereas the tnagent shaped ogives are more likely to seat consistently, but this is a generalization.

Try seating the bullet once, rotate it 90 degrees in the die and re-seat with steady but moderate pressure on the ball. this seems to reduce runout and give a more consistent OAL for me.

There is a Hornady seating die ( I have not used it), that has a sleeve to guide the bullet during seating. This might give more consistent OAL. Also Forster makes precision dies which are designed to improve upon such tolerances.

In an AR platform, if you have good technique in prepping brass, and a good match grade barrel, you can get away with a little difference in the OAL and still have extremely tight groups.

I have fired one-holers with my AR Performance stainless 12 / 3, using ammo we loaded on a Dillon, and that is anything but high-precision.

I also recommend the Lee factory crimp die, because I believe it improves neck tension differences a little and probably also reduces run out. It surely reduces the chances of bullet setback which changes the OAL drastically. I apply a very light factory crimp to everything except subsonics and the GS bullets whose manufacturer recommends against them.

 

[greenwell369]

HTR, thanks I'm so used to exact tolerances it threw me of a little. Turning the bullet in the die is a good idea will try with the fifty I loaded up . thanks

 

[HTR]

You're welcome. Please let us know what your results look like. We are always trying to see if we have corroborated results among the reloaders here.

 

[ccoker]

I use the Hornday seating die and the 110TTSX
I load at 2.30 and did 20 rounds the other day and measured it round, all were exactly right
and I use a cheap Lee press

 

[Test_User]

What you are seeing is fairly typical. The issue is very likely not your seating die at all. Most seating dies work fine other than some Lee and Lymans. Not saying Those can't be good just that I have personally seen these have issues. The issue is likely your bullets. Most bullets other than plastic and poly tips will have irregular OAL that are from variations in the tip. It is for this reason that if you are really concerned with setting you COAL to a specific length in realtion to your barrels lands you need to use/purchase a Bullet comparator kit from Hornady. It has bushings of differnet caliber sizes that fit on the bullet at its neck's ogive. This way you are measuring the actual COAL from the bullet ogive to the cartidge base, which is the first part of the bullet to contact the lands. This measurement is technically the one that matters for performance. The only reason from measuring to the tip is for fit into the mags. The best thing is to measure a few to see that the true OAL is short enough to fit the mag then for checking the consistency of your loads measure with the bushing from the ogive.

 

[HTR]

What you are seeing is fairly typical. The issue is very likely not your seating die at all. Most seating dies work fine other than some Lee and Lymans. Not saying Those can't be good just that I have personally seen these have issues. The issue is likely your bullets. Most bullets other than plastic and poly tips will have irregular OAL that are from variations in the tip. It is for this reason that if you are really concerned with setting you COAL to a specific length in realtion to your barrels lands you need to use/purchase a Bullet comparator kit from Hornady. It has bushings of differnet caliber sizes that fit on the bullet at its neck's ogive. This way you are measuring the actual COAL from the bullet ogive to the cartidge base, which is the first part of the bullet to contact the lands. This measurement is technically the one that matters for performance. The only reason from measuring to the tip is for fit into the mags. The best thing is to measure a few to see that the true OAL is short enough to fit the mag then for checking the consistency of your loads measure with the bushing from the ogive.

This is an excellent point. One of the reasons I measure to the tip, is that I almost always load out to 2.30". Thus, I have to be conscious of loads that end up 2.305" or even 2.310". These all still fit in my PRI mags, too.

Tim, what are your thoughts on runout and turning the bullet in the seating die to help this? I have been doing it lately, but without a runout gauge, and while highly unscientific, the bullets do seem like they have less visible wobble when rolled on polished piece of granite. The most noticeable were the 135 grain SMK subsonics. The reason is that the bullet will seat right to the start of the ogive and the shank of the bullet sits just below the mouth of the case. Brass was perfect before laoding them.

When being very careful to seat and measure, with 7.2 grains of Trail Boss, I was getting .75" groups from these at 50 yards.

 

[greenwell369]

Thanks

Tim and HTR I have the hornady bullet comparator, but it measures length from the base to the OGIVE, I did measure several of the SMK's and they are not consistant. so I can not load this round to get minamal jump. I'm assuming now that since I,m firing from a magazine and I am limited to the mags max length that this is a sligth loss in accuracy that is part of semiauto shooting. (this is my first AR). I appresiated the help. And as far as the ballistic tip bullets are there any recomendations for brand weight and powder + charge! thanks again and in advance for the info. Greenwell

 

[HTR]

Tim and HTR I have the hornady bullet comparator, but it measures length from the base to the OGIVE, I did measure several of the SMK's and they are not consistant. so I can not load this round to get minamal jump. I'm assuming now that since I,m firing from a magazine and I am limited to the mags max length that this is a sligth loss in accuracy that is part of semiauto shooting. (this is my first AR). I appresiated the help. And as far as the ballistic tip bullets are there any recomendations for brand weight and powder + charge! thanks again and in advance for the info. Greenwell

You are absolutely correct that you cannot load to a COAL which approaches the land for "minimal jump" simply because the magazine dictates the OAL. The Freebore of the SPCII is .100" so the lands are pretty far away, like .030", IIRC.

Here is a picture of the GS bullet and the 135 grain SMK. You can see that, while they are the same OAL, there are definite differences in the way the ogive is shaped, and the way it lies adjacent to the case mouth.

I have a very light ( Lee Factory) crimp on the 135 SMK, because, as I mnetioned earlier, I found that this was making the runout less. This stands to reason because that bullet is sitting right at the takeoff of the ogive, and if not placed concentrically into the case, will "wobble" about the moment or axis of the cartridge.

Left is the 80 grain GS at 2.305" COAL, and right is the 135 grain SMK with Wolf Primer / SSA brass / and 7.2 grains of Trail Boss also 2.305"....subsonic.

 

[HTR]

As for Ballistic tips, the only ones I like are the Barnes TTSX and Nosler Accubonds. The TTSX is by far the # 1 ballistic tipped bullet on the market for 6.8, but its not the tip that gives it the balls. It is the all copper design and large cavity in the nose. It is a very long 110 grain bullet though, and takes a little practice to master the loading.

I load it to 2.305" also, with SSA brass, CCI BR 4 primers and 29.5 grains of RE10X. The Accubond is loaded to 2.29" (it was actually more accurate there) and uses 29.5 grains of RE10X as well.

Here is a picture of the loads. The TTSX is second from left, VMAX is third ( I don't use it ) and the Accubond is 4th from left. I also have been using the Harrell's Turret press lately. You guys should check it out. You can mount the sizing, bullet seating and Lee Factory Crimp die on the turret and spin it right into place. It really speeds things up.

Harrell's Turret Press

 

[Desert_AIP]

I can't believe what a difference OAL makes!


I finally got some PRI magazines to try a longer OAL.
I just came back from the range.
I had handloads of Barnes 85 TSX and Hornady 110 HPBT.

I loaded 5 rounds of each at 2.26 and 2.30 OAL, 20 total.

The 2.26 rounds patterend about 1.5" at 100 yards for the TSXs and 1" for the BTHP.

The 2.30 85 TSX shot a 1/2" group at 100 yards and the 110 BTHP made a cloverleaf from my 16" lightweight barrel!
I couldn't believe it.

Thanks to Paulo, HTR, Tim, others and this board for recommendations.

 

[jasonpeterson]

It also reduces pressure. It makes a world of difference in my uppers.

 

[HTR]

Longer OAL = less compression of larger powder charges

larger powder charges

better accuaracy, in my experience

closer proximity of the ogive / bullet tip to the lands, ergo, likely one reason
for better accuracy.


The only thing you have to watch is with bullets that have an ogvie whcih is takes off a little farther back toward the base of the bullet. The Nosler accubond has a little higher BC than other .277 bullets, so the ogive is a little longer, and thus we had to pull it back to 2.29" to make it most accurate. I did not find it to be as accurate at 2.30".

 

[Test_User]

Yep it sure does. IT a no brianer once you test it objectively. Its fairly universal through the precision shooting community and in jsut about every loading book dealing with accuracy that most tanget bullets give their best accuracy .02 off the lands or as clsoe as you can get tot that.. It also has the same reliability as loading shorter in the mags like the barretts. A round loaded to 2.29 in a PRi mag as the same amount of clearance in the mag that a Barrett mag has loaded at 2.25 OR a CP loaded to 2.28. So from a tactical perspective there is not difference in reliablity as far as feeding from the mags goes. As long as your upper has M4 ramps from that end any length will feed fine. With the old Pri mags I was able to actually load to 2.31 in a couple and they all worked with out ever a hicupp.

 

[paulosantos]

Sorry, but suggesting that it is a good idea to load longer in a Tactical Situation is not something I I would recommend. The more space you have to allow the bullet to go past the feedramps the better. Loading longer and Barrett mags don't go together.
IIRC, a couple of months ago someone was having feeding issues with the Sierra 90 GR HP and shortened the COAL and it helped.

 

[Jamesb74]

Sorry, but suggesting that it is a good idea to load longer in a Tactical Situation is not something I I would recommend. The more space you have to allow the bullet to go past the feedramps the better. Loading longer and Barrett mags don't go together.
IIRC, a couple of months ago someone was having feeding issues with the Sierra 90 GR HP and shortened the COAL and it helped.

I would agree with this on the tactical,defensive,competition side. A couple of months ago I was in competition this happened in two different competitions at two different times. My rounds were loaded to the longest with PRI mags both times I had problems with feeding. Both of them were mag issues and I was stuck because I could not use C-prod,orBarrett mags due to the OAL.

Now with loading it is true that loading to lands reduces pressure and increases velocity and accuracy so from that is why my practice has become for competition,and such to load to the ability of all the mags. For hunting and accuracy load to the longest.

I know this is not an objective test but just some musings and a case of "what happened to me"

 

[paulosantos]

I would agree with this on the tactical,defensive,competition side. A couple of months ago I was in competition this happened in two different competitions at two different times. My rounds were loaded to the longest with PRI mags both times I had problems with feeding. Both of them were mag issues and I was stuck because I could not use C-prod,orBarrett mags due to the OAL.

Now with loading it is true that loading to lands reduces pressure and increases velocity and accuracy so from that is why my practice has become for competition,and such to load to the ability of all the mags. For hunting and accuracy load to the longest.

I know this is not an objective test but just some musings and a case of "what happened to me"

And the velocity increase is very minimal at approximately 10 FPS from my testing and according to Sierra and Hornady per my conversation with them. And even the pressure difference is minimal at approximately 1K, again, this is according to Sierra and Hornady.

 

[HTR]

For those of you that haven't loaded the 6.8 much yet, after reading all of the posts above, I suggest you take this from them:

1) loading to 2.30" is the maximum that can be achieved with PRI mags, and this COAL will not fit in all mags. That's very important. Don't take away form this the idea that you can load to 2.30 and use these rounds in all mags.....you can't. Its a shame, but you can't.

2) Loading close to the lands is a technique which can increase accuracy. It makes perfect sense, because if the bullet is not perfectly aligned with the axis of the cartridge, then it will tend to "knock around" against the sides of the forcing cone( throat) as it enters the rifling, and could be malformed slightly. This could lead to a loss of bullet to bullet consistency, i.e accuracy.

3) However, in AR style rifles, these principles are mitigated by a few things. First, the mag issue, as mentioned. If you are in combat, accuracy is moot if you rifle will not fire. You could get dead in a hurry that way. Second, not all rifles will feed the longer rounds the same way. So, Paulo has a good point, in that, until you have tested every rifle you own, thoroughly, with rounds of this length, you cannot be 100% sure that they will feed like rounds which are slightly shorter.

4) the shape of the bullet will also determine whether "loading long" is a good thing or not. I already mentioned that the Nosler Accubond was not accurate for me loaded all the way to 2.30. It had to be taken back to 2.29". Also, contrarily, you cannot load the Barnes TTSX to any length other than 2.30" ....it is just too long. That is the only length that allows adequate case capacity and for the bands and ogvie to be oriented properly in the case for accuracy and good seating.

Having said all the above, JamesB has hit on something. Since we are in a time when many of you has to depend upon the anecdotal evidence that some of us "experts" post about the 6.8 and loading it, you must also test for yourselves, to find what works best for you. You must also decide what situations are going to determine the priorities you set for loading ammo.

I hunt with my AR's so, loading to 2.30 or even 2.305" works fine, gives what I perceive to be better accuracy and allows me to get max velocity with the least compression %. Anecdotally, I will also say, that with PRI mags, I have never, ever had feeding issues with any of my 6.8 rfles. In fact, I am astounded at the utter 100% reliiability, even with hand loads.

 

[HTR]

And the velocity increase is very minimal at approximately 10 FPS from my testing and according to Sierra and Hornady per my conversation with them. And even the pressure difference is minimal at approximately 1K, again, this is according to Sierra and Hornady.

I don't want to be misconstrued as saying that loading to 2.30 somehow "increases" velocity. We all know that one of the quirks of the 6.8 is the .277 bullets are short and fat, as a generalization. To get better BC bullets you have to find longer bullets. To get longer bullets in the case, you sometimes have to compress powder to get the cartridge to fit in the mag at all.

So, I believe that loading to the max restricted mag length simply allows me to get the most powder in the case, without having to resort to compressions of 105% or more, which I don't think many of us are comfortable with.

Here's a great example. The Barnes TTSX loaded to 2.26" will compress a charge of 29.5 grains of RE 10 X about 105%, but when loaded to 2.305" it only goes to about 100% and the pressure is very manageable. 10X does tend to show a significant increase in pressure when compression reaches the 103% mark, in my experience. It happens with the 110 Accubonds at that powder charge, and only my ARP 12 / 3 handles that load well. All my other rifles show swipes with it. I think that's becuase the charge is compressed, and there are no pressure-reducing driving bands on the bullet.

All my rifles handle the TTSX load very well, and it was surprisingly fast.....2698 FPS from a 16" barrel. This gives me versatiliy with a bullet I LOVE, whcih menas more dead pigs :a06:

At max charges the 1000 PSI is a benefit, though I agree it is a small difference.

 

[Jamesb74]

For those of you that haven't loaded the 6.8 much yet, after reading all of the posts above, I suggest you take this from them:

1) loading to 2.30" is the maximum that can be achieved with PRI mags, and this COAL will not fit in all mags. That's very important. Don't take away form this the idea that you can load to 2.30 and use these rounds in all mags.....you can't. Its a shame, but you can't.

2) Loading close to the lands is a technique which can increase accuracy. It makes perfect sense, because if the bullet is not perfectly aligned with the axis of the cartridge, then it will tend to "knock around" against the sides of the forcing cone( throat) as it enters the rifling, and could be malformed slightly. This could lead to a loss of bullet to bullet consistency, i.e accuracy.

3) However, in AR style rifles, these principles are mitigated by a few things. First, the mag issue, as mentioned. If you are in combat, accuracy is moot if you rifle will not fire. You could get dead in a hurry that way. Second, not all rifles will feed the longer rounds the same way. So, Paulo has a good point, in that, until you have tested every rifle you own, thoroughly, with rounds of this length, you cannot be 100% sure that they will feed like rounds which are slightly shorter.

4) the shape of the bullet will also determine whether "loading long" is a good thing or not. I already mentioned that the Nosler Accubond was not accurate for me loaded all the way to 2.30. It had to be taken back to 2.29". Also, contrarily, you cannot load the Barnes TTSX to any length other than 2.30" ....it is just too long. That is the only length that allows adequate case capacity and for the bands and ogvie to be oriented properly in the case for accuracy and good seating.

Having said all the above, JamesB has hit on something. Since we are in a time when many of you has to depend upon the anecdotal evidence that some of us "experts" post about the 6.8 and loading it, you must also test for yourselves, to find what works best for you. You must also decide what situations are going to determine the priorities you set for loading ammo.

I hunt with my AR's so, loading to 2.30 or even 2.305" works fine, gives what I perceive to be better accuracy and allows me to get max velocity with the least compression %. Anecdotally, I will also say, that with PRI mags, I have never, ever had feeding issues with any of my 6.8 rfles. In fact, I am astounded at the utter 100% reliiability, even with hand loads.

Very good points.

To use a golf analogy. I have always agreed with Ben Hogan when he said you have to dig the secrets out of the dirt. Thank God the secrets to handloading arent as complicated as the secrets to a repeatable swing.:a40: