Wouldn't longer OAL leave more room for powder and less pressure? Wouldn't longer OAL allow heavier .270 bullets to be used?

Jim

 

Wouldn't longer OAL leave more room for powder and less pressure? Wouldn't longer OAL allow heavier .270 bullets to be used?

Jim

That is true, but I have no way of measuring the pressure difference to know exactly how much of a pressure difference there is, if any.

 

Nice Paulo.

It would be interesting seeing the same test done with Barnes 85 and 110 tsx. And the Accubonds.

We just moved and I have all my books packed. What does the ft/lbs work out to in the different yardeges. Sorry being lazy because I am tired from the weekend.

 

Nice Paulo.

It would be interesting seeing the same test done with Barnes 85 and 110 tsx. And the Accubonds.

We just moved and I have all my books packed. What does the ft/lbs work out to in the different yardeges. Sorry being lazy because I am tired from the weekend.

For which loads? I'll check it when I get home.

 

very interesting, maybe consitency is more the key? I was planning on doing a similiar test once my Forester seating die shows up since it has the micromiter built in.

 

Good info Paulo.

I don't know if you believe in Optimal Barrel Time or not, but have you run the OBT numbers for these loads to see where you're at?

According to the theory, if you're in the node, variations such as seating depth should not affect the accuracy very much,

 

I've done the ORT Test in the past and it works great. I've found that the relaoding info is universal and works in most barrels, such as the Pro-Hunters with 28.5-30 Gr of H322 and the Speer 90 GR TNT with 28.6 GR of H4198. I did a thread on it a while ago, but I don't know if it made it to the new site.

 

If you use the JBM ballistics trajectory calculator you can plug in the information and it will give you back the different velocites and foot pouinds of energy. The formula for calculating energy is:

Velocity X Velocity / 450400 X grain weight of bullet.

 

Thanks Paulo and rcrandall. I know I had the formula writtn down. But they are packed away and I was to lazy to google last night. Thanks for the testing Paulo.

 

Wow Tim,
It looks like you just landed the runner-up spot for the longest post ever, held by you, of course.:a31:

But seriously, you make many good points, especially the small/large group sizes in the longer load averaging out.

 

Tim, look at the picture above. Those were the Sierra 115 GR SMK when I did the primer testing. Look at the first four and you will see that 3 out of the 4 are .5"-.7" groups. Those were with the Wolf Primers. The bottom two are witht he CCI Primers. I think the erratic accuracy was due to the CCI Primers, which I used for the testing. When I used the Wolf Primers the accuracy was much more consistant, as you can see above. And in the targets above, all of the OAL was 2.245". That is why I have stated and I tink that the OAL doesn't really make that much of a difference. Look at the magazine article in which the Stag & shot that .1??" group with the SSA 110 GR Accubonds. That OAL is app 2.245". Look at the accuracy guys are getting with the SSA Pro-Hunters. That is also loaded to 2.245" or shorter.

Now, loading longer won't hurt anything, so that is a good thing. Loading longer will also reduce pressure, especially when you are at the very max loads, and produce sligtly (10 FPS) more. But from a pure accuracy standpoint, I don't see the benefit.

Edit to add:
I went into this testing with the mindset that loading longer would significantly improve the accuracy. So my testing was to prove that the longer OAL would help. After the testing, I don't see any significant differences in accuracy. Loading longer has benefits, but for practical accuracy, I don't see it. Now does loading longer hurt anything? That is like going to the Doctor and after he prescribes you some medicine, you ask him if the medicine will help, and he replies with, "it won't hurt.":a21::a01::a31:

 

I believe bullet seating depth is critical to good accuracy. We are hindered in the AR platform by magazine length. I have shot alot of rounds over the last month. When I switched to PRI magazines going from 2.285" to 2.305" OAL my accuracy greatly improved. Also I was able to increase my powder charge in my max loads by 0.9gr. So 0.02" in extra length reduced alot of pressure.

Seating depth can have a great impact on accuracy. Seating depth is one factors hand loaders can vary to tailor the load to your rifle. Unlike factory loads that have to fit in all rifles. There are lots of other variables that also affect accuracy. COAL is one of the easiest to control. My experience has been that larger caliber rifles shoot the best with the bullets just touching the rifling. 6mm to 6.5mm touching to .010" off the rifling. 22 caliber .010" to.020" off the rifling.

We are stuck with the length of the magazine. Why would you not seat them to magazine length? Lower pressure and better accuracy (definitely not any worse).

 

Hi Paul,

I think I missed something since I'm not sure if the targets you show are from this testing or were a previous test. Are you saying that the results you reported at the top of this thread were shot with a combination of Wolf and CCI primers? If so, do you know which groups were which? If not, which primers did you use for these groups?

 

I think what he meant was other variables play a roll in how accurate a load is. This is a true statement. He is also saying that, for the most part, varying COAL will not affect most folks' accuracies to satisfactory levels, those levels beign good enough to shoot such and such from here to there.

However, once you start stretching distance, 44% (as Tim noted as the improvement in groups from Paulo's tests) begins to become more of a deal. 44% improvement of a 1.5MOA rifle isn't that profound at 100yds, but it gets more significant at distance. At 400yds, you can only guarantee the rifle could hit in an area 6" in diameter. 44% improvement would translate into a 3.0675" definite shot pattern instead of 6". That's a fairly large chunk of real estate in bullet terms. To continue the analogy, it'd be like the doctor prescribing a broad spectrum antibiotic for a bacteria that a specific antibiotic works better for. When you ask why the doctor says "it'll do it about the same."

For most, varying the COAL in their handloads will not bring them a warm and tingly feeling when their groups thighten up by .25" at 100yds, but to some it makes a difference. In my book, if you're already handloading, why not make it to the greatest potential of your rifle (or the best potential of your rifles). If you spend your time getting your powder, primer, bullet and case all evened out to produce the tightest group of the combo, why not take it the extra step by tailoring the legnth of the round to your rifle.

 

The OAL Testing was done with CCI #41 primers, which I think is the reason for the couple of erratic shots. In the picture above, that was the primer testing and you can see that with the wolf primers, the accuracy was more consistant.

There is no doubt that loading longer has advantages such as loading the longer bullets like the Barnes 110 GR TTSX, and also you can get slightly more powder. So if you have PRI mags, then do whatever you want. As already indicated, loading longer won't hurt anything.

If you have Barrett mags, then you are stuck with 2.245" OAL. Also, with the SPCII Chambers, even at 2.305", the bullets are not close to the lands.

 

The OAL Testing was done with CCI #41 primers, which I think is the reason for the couple of erratic shots. In the picture above, that was the primer testing and you can see that with the wolf primers, the accuracy was more consistant.

There is no doubt that loading longer has advantages such as loading the longer bullets like the Barnes 110 GR TTSX, and also you can get slightly more powder. So if you have PRI mags, then do whatever you want. As already indicated, loading longer won't hurt anything.

If you have Barrett mags, then you are stuck with 2.245" OAL. Also, with the SPCII Chambers, even at 2.305", the bullets are not close to the lands.

I agree it is only a slight improvement in an AR because of the magazine. When I tested to see what was my max load. I used 2.285" the first time. My max load was 30.1gr of 10x and 110 pro. I shot the round robin and found my best load. I then changed to PRI magazines to hunt with. I loaded them to 2.305" and now can load 31gr max. So my load that I found the first time has to be running at lower pressure. These are for strictly accuracy and hunting. For self defense I don't use hand loads. So it's not an issue for me. For the best performance in max loads longer OAL helps alot with pressure. So I agree it only helps slightly in 100 yard accuracy.

On the primer testing. Different primers work better with different powders. There are so many variables you can play with during load development. I'm glad to see that the Wolf primers are as good as they are. Seems like Wolf has got them right. I'm impressed with their 22 ammo and large pistol primers.

Paulo, thanks for testing. I would like to see how your Bison shoots at longer ranges. It looks like they are going to be nice shooting uppers.

Would you mind testing your new super sniper scope at dusk compared to another scope for light transmission? I'm curios how much light they let in compared to other scopes in their price range.

 

Have you tried the heavier .270 Win bullets while loading the cartridges longer? Like 140-150gr bullets?

Jim

 

Have you tried the heavier .270 Win bullets while loading the cartridges longer? Like 140-150gr bullets?

Jim

Actually when breaking the barrel in with the Tubbs Final Finish bullets (Sierra 130 GR BTSP), I was getting phenominal accuracy at 50 yards using TAC powder, but the velocities were in the 2250 FPS Range. I've tried the Sierra 135 GR SMK and the accuracy and velocity wasn't that great. I won't go any higher than the 115 GR bullets.

 

I guess I should have put this in the first post, so I will edit the first post because some guys are taking this test/conclusion in a negative way.

This test was not to convince everyone that they should start loading their ammo to 2.245". If you are trying to maximize your load, then get the PRI mags so you can load the bullets out as long as you can so you can stuff more powder in there as it reduces pressure, produces slightly more velocity, and in some cases, helps in accuracy. Just like anything else, learn the advantages and disadvantages of loading shorter and longer and decide what is best for YOU.

 

I've been loading my blemished V-max's out to 2.28'' and getting pretty good accuracy out to 100 yards while standing and shooting. Used a small 6'' target and dumped the whole mag on it. Not bad for blemished bullets.

 

For shits and giggles, I think it would be a fun little test if the guys with the PRI mags would be willing to do a fun little test.

Load up one of your favorite loads in the following manner and test it out.

Load #1: Load up 15 rounds of your favorite load to 2.245".
Load #2: Load up 15 rounds of your favorite load to 2.295".

Shoot 3, 5 round shot groups with each load and take the 2 best ones and average them out. Remember, everything has to be the same, except the OAL. You also have to shoot them on the same day to take the variables out.

 

Paulo, I think when i get my Reloading equipment, i shall have to give that a try. But Ill prolly find the best accuracy node for the 2.245 and the best for 2.295, then try to advance the distance to 500 yards or so. The way I see it, if its a .5 MOA difference at 100 yards, thats at least a 2.5 inch differencea t 500

 

Sounds like fun. When I get everything unpacked. I will try and run it.But that might be a while.:a33:

 

The way I see it, what do we got to loose? Either we find out nothing or we may actually learn something totally new. Maybe we can even develope a patternof which bullets like what OAL

 

Paulo,

I've loaded about 100 rounds of Hornady 110 grain hollowpoint to 2.260 as stated in my Lyman manual. Hornady's manual say's to load to 2.245. What gives? is 2.260 safe?


Kip

 

Paulo,

I've loaded about 100 rounds of Hornady 110 grain hollowpoint to 2.260 as stated in my Lyman manual. Hornady's manual say's to load to 2.245. What gives? is 2.260 safe?

Kip

Is it the Hornady 110 GR BTHP with cannelures, or the Hornady 110 GR Flat Base HP?
If it is the 110 GR BTHP with cannelures, then the cannelures are set-up to be loaded at 2.245" for the crimp.

Either way, you can load them to whatever length you want as long as your magazine will allow. If you have Barrett mags, I wouldn't load anything longer than 2.245". If you have the PRI mags, I would stick around 2.295". For the C-Products mags, you have to check them as some you can load to 2.285" and some you can only load to 2.260".

 

I've chambered and ejected 20 rounds, with no problem.

 

You can load them all the way out to magazine length.

 

I have looked at it as you load the hunting accuracy rounds to the longest you can. and load competition/plinking rounds to be able to fit into any mag.

But it would be interesting to shoot the round robins to see if a correlation between the bullet and powder mixtures can create different accuracies with the different OAL's.

In bolts the longest OAL's have been the norm to get the most velocity and accuracy but these are new types of bullets and some new powders and something could come from it.

If anything at a minimum it is a great idea just because you get some trigger time:a31:

 

I have looked at it as you load the hunting accuracy rounds to the longest you can. and load competition/plinking rounds to be able to fit into any mag.

But it would be interesting to shoot the round robins to see if a correlation between the bullet and powder mixtures can create different accuracies with the different OAL's.

In bolts the longest OAL's have been the norm to get the most velocity and accuracy but these are new types of bullets and some new powders and something could come from it.

If anything at a minimum it is a great idea just because you get some trigger time:a31:

Exactly. This is a combat cartridge,. not a Benchrest Cartridge. The techniques that work in the Benchrest calibers may also work for the 6.8SPC, and they may not. As I said before, I had always thought that loading longer would really help, but after shooting several 1/2 - 3/4 MOA groups using an OAL of 2.245", that kind of made me think twice.

 

I'm having issues right now with my oal. I'm using the hornady headspace guage and these are my readings.
110gr vmax = 2.360
90gr tnt = 2.440
All the info in my reload books is a max oal of 2.260
So what do i load my oal to ? Also i'm using c products mags.

 

Measure the inside of your mags and load a little under that reading.Also if you want to stick strictly to what the manu's say then you need to follow the data from Hornady for Hornady bullets and the data from Speer for Speer bullets. Etc..etc.. for the rest.
Different bullets will give you different OAL's to the type and design. That is why if you load the two different ypes to the OAL of your mags you will adjust the seating die accordingly.

HTH

 

So its agreed that longer COAL such as 2.29 gives significantly better accuracy than short COALs 2.26 and under

 

I want to do some more testing, but even if loading longer helps with accuracy, it sure isn't SIGNIFICANT. I'd say minor at best so far. And for most practical purposes, I don't see the need for it.

 

It seems to me that most of the guys on this site are hunting with their 6.8s so accuracy and velocity is important to those that wish to hit what they aim at, especially when at unknown distances.
Almost every reloading manual says accuracy is increased when bullets are loaded .010-.020 from the lands unless they are VLDs which shoot better loaded into the lands which is not recommended in auto loaders.
Anyone interested in loading for the best accuracy should read "Precision Shootings Reloading Guide"
Dave Brennan edited the book but received contributions from everyone that is anyone in the shooting world and contains much information compiled from decades of competitive shooting, and articles found in the monthly publication "Precision Shooting"----http://www.precisionshooting.com/

Noslers reloading guide, 5th edition on P.43 says .015-.030 that pretty much surrounds .020.

My Precision Shooting guide is the 95 edition and John Feamster wrote the reloading for gas gun section.
He says for gas gun it is best to seat bullets to .010 to .015 off the lands and "do not crimp the bullets, it causes a whole lot more problems than it solves"
PS RG deals with extreme accuracy in highpower, benchrest and varmint hunting and does not address reloading for combat
The .223/5.56 and 308 are also "combat" cartridges but they have won a lot of competitions.

 

Most 224 bullets, including the 77 GR SMK, are nowhere near the lands when loaded to magazine length at 2.245" when loaded in the 556 chamber, yet they are still very accurate. The 6.8SPC bullets are not really close to the lands even when loaded to 2.295" in the SPCII Chamber.

 

Lots of variables

Not trying to get in the middle of anything but every barrel is a little different and some may be more finicky than others on the OAL for accuracy than others. The only way to find this out is to do exactly what you are doing. Hands on field testing with different variables, 1 at a time. To find out what is affecting accuracy.

Paulo your testing is saving alot of people time and money, keep up the good work. After reading your primer testing thread I am now going to have to try some of the wolf primers. So I guess you are not saving me $$$. LOL!!! But I guess if my gas money is going to some shiek in the middle east buying Russian primers is merely a drop in the bucket