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Discussion Starter #1 (Edited by Moderator)
Because this thread has become long, I've added an index to the first post.

Drop-Tube Benefits
https://68forums.com/forums/showthread.php?44542-Longer-than-Magazine-COALs&p=508826&viewfull=1#post508826

Case Expansion as a pressure indicators
https://68forums.com/forums/showthread.php?44542-Longer-than-Magazine-COALs&p=516590&viewfull=1#post516590
https://68forums.com/forums/showthread.php?44542-Longer-than-Magazine-COALs&p=519747&viewfull=1#post519747

Pressure vs COAL
https://68forums.com/forums/showthread.php?44542-Longer-than-Magazine-COALs&p=560296&viewfull=1#post560296

110 AB and 110 TSX Powder vs Velocity
https://68forums.com/forums/showthread.php?44542-Longer-than-Magazine-COALs&p=560975&viewfull=1#post560975

130 ProHunter Powder vs Velocity - 1200R, CFE223, H335, R10x, TAC
https://68forums.com/forums/showthread.php?44542-Longer-than-Magazine-COALs&p=565410&viewfull=1#post565410

Additional 130gr Bullets with CFE223 - Barnes TTSX, Berger VLD, Hornady SST, Nosler Silver Tip (BT), Sierra GameKing (SGK)
https://68forums.com/forums/showthread.php?44542-Longer-than-Magazine-COALs&p=575693&viewfull=1#post575693

130gr Bullets Longer-than-mag COAL Lessons Learned
https://68forums.com/forums/showthread.php?44542-Longer-than-Magazine-COALs&p=590673&viewfull=1#post590673

jwthrape's AR Comp Results
https://68forums.com/forums/showthread.php?44542-Longer-than-Magazine-COALs&p=604016&viewfull=1#post604016

AR Comp add to Powder vs Velocity Ladder Chart
https://68forums.com/forums/showthread.php?44542-Longer-than-Magazine-COALs&p=711216&viewfull=1#post711216

130gr Bullets Powder vs Velocity - AA2200, 8208XBR, Varget, LeveRevolution + CFE with 150 VLD and ABLR
https://68forums.com/forums/showthread.php?44542-Longer-than-Magazine-COALs&p=606988&viewfull=1#post606988

100 AB and 100 GMX with AA2200 and R1200R
https://68forums.com/forums/showthread.php?44542-Longer-than-Magazine-COALs&p=609107&viewfull=1#post609107

120 SST w/ 8208 XBR and CFE223
https://68forums.com/forums/showthread.php?44542-Longer-than-Magazine-COALs&p=613023&viewfull=1#post613023

Powder Capacity Analysis w/ bullet line-up
https://68forums.com/forums/showthread.php?44542-Longer-than-Magazine-COALs&p=613026&viewfull=1#post613026

Benefits of Adjusting COAL during Load Development
https://68forums.com/forums/showthread.php?44542-Longer-than-Magazine-COALs&p=613740&viewfull=1#post613740
https://68forums.com/forums/showthread.php?44542-Longer-than-Magazine-COALs&p=665109&viewfull=1#post665109

Magazine Lip Mod to promote more reliable feeding
https://68forums.com/forums/showthread.php?44542-Longer-than-Magazine-COALs&p=643823&viewfull=1#post643823

150gr Federal Round Nose at Mag Length COAL
https://68forums.com/forums/showthread.php?44542-Longer-than-Magazine-COALs&p=650050&viewfull=1#post650050

Enduron IMR 4166
https://68forums.com/forums/showthread.php?44542-Longer-than-Magazine-COALs&p=654349&viewfull=1#post654349

Measuring Distance to the Lands - Hornady's new tool
https://68forums.com/forums/showthread.php?44542-Longer-than-Magazine-COALs&p=662073&viewfull=1#post662073

Changing COAL with 100 AB and H322
https://68forums.com/forums/showthread.php?44542-Longer-than-Magazine-COALs&p=665109&viewfull=1#post665109

Bullet Stability and On-line Calculators
https://68forums.com/forums/showthread.php?44542-Longer-than-Magazine-COALs&p=720063&viewfull=1#post720063

Link to Testing of Power Temperature Sensitivity
https://68forums.com/forums/showthread.php?53653-Powder-Temperature-Sensitivity&highlight=temperature


Original post
__________________________________________

This information may be useful for handloaders with bolt guns or those who load longer than 2.3" COAL. I've been checking distance to the lands for several 6.8mm bullets. Here are cartridge length measurements for when different 6.8 rounds touched the lands in an ARP barrel. Note, the ARP chamber has 0.015" less freebore than typical SPC II chambers.

95 Barnes TTSX___2.375”
100 Nosler AB_____2.390"
110 Nosler AB_____2.390"
110 Barnes TSX___2.438”
110 Hornady BTHP_2.335”
115 Nosler Custom_2.325”
120 Fusion MSR____2.475”
120 Hornady SST__2.358”
130 Berger VLD_____2.475”
130 Hornady SST___2.485”
130 Nosler BT______2.505”
130 Nosler Partition_2.450"
130 Rem Corelokt___2.420" (sigficiant variation between bullets)
130 Sierra ProHunter 2.420"
130 Speer Hot Core 2.380"
130 Speer BTSP___2.400"
150 Nosler AB LR___2.560”

It was interesting that the 110 TSX measurement was 2.428" which seemed rather long compared to the 95 TTSX which was 2.375". This measurement checked the same in 16" and 18" ARP barrels, as it should. Further investigation showed that the 110gr TSX ogive, unlike the 95 TTSX, doesn't reach 0.278" before the first band. The 110gr TSX ogive measures 0.272" at the widest point before the first band. The 110 TSX is touching the lands after the first groove. The 85gr TSX is like this too but all the other .277 Barnes bullets I have reach full-bore prior to the first groove.

I've decided to test out longer than mag-length COALs to see what the differences and benefits might be. So far I’ve done the 110gr TSX (COAL 2.380”), 120gr SST (COAL 2.340”), and 130gr Nosler BT (COAL 2.425). I’ve really just started but I am seeing an improvement in accuracy so I started to modify my 6.8s to feed multiple rounds. I did this by cutting out the front of the magazine which allows COALs up to about 2.380”. I’m not concerned about reloading magazines when I hunt so the magazine mod is not an issue for me because I can insert it in controlled conditions. The cut-out doesn’t go below the lower receiver’s magazine well and the mag’s side-walls still remain stiff.

Update: January 2016 - CavityBackBullets now stocks 10-round PRI magazines modified to load longer than mag-length COAL. They are professionally done and available in 6.8mm as well as .223. I use them only for hunting and have kept my original modified mags just for testing at the range.

I also had the center groove in the front of the mag well expanded by a machine shop to be wide enough to accommodate double stacked rounds plus added grooves to the upper receiver feed ramps to match. These modification to the upper and lower receivers allow for COALs of 2.425” which would be sufficient for 130gr ballistic-tipped bullets. I’ve seen modified single-stacked magazines for wildcat cartridges like the WSSMs configured to use the lower receiver’s center groove in the mag well so thought I’d give this a try for a double-stacked arrangement.

As said before, I just started this project. I thought others might be interested. Also, maybe some shooters have already done some of these modifications and can provide some tips on how to be successful or things to avoid. Thanks for your interest.

Link to Testing of Power Temperature Sensitivity
https://68forums.com/forums/showthread.php?53653-Powder-Temperature-Sensitivity&highlight=temperature


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My freebore is .010" longer than yours.
About time somebody else starts doing something different, It will turn your rifle into a different animal for sure!
 

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My freebore is .010" longer than yours.
Yup, mine is also. H has done several improvements to his chamber over the years, so each batch of barrels could be different.

Sent from my DROID RAZR using Tapatalk
 

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Discussion Starter #4
About time somebody else starts doing something different, It will turn your rifle into a different animal for sure!

JW, I'm just following your lead. I'll be testing 110gr TSX this weekend with CFE223 looking for velocity and accuracy improvements. I did get groupings last trip to the range at 1 MOA with the longer COAL and 110 TSX over AA2200. The SDs on CFE223 are small with the SSTs along with the 1/4 MOA groups. Maybe I'll get lucky and find a go-to load with CFE & 110 TSX also.
 

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JW, I'm just following your lead. I'll be testing 110gr TSX this weekend with CFE223 looking for velocity and accuracy improvements. I did get groupings last trip to the range at 1 MOA with the longer COAL and 110 TSX over AA2200. The SDs on CFE223 are small with the SSTs along with the 1/4 MOA groups. Maybe I'll get lucky and find a go-to load with CFE & 110 TSX also.
You wouldn't happen to have any TAC, or PP-Varmint, BLC2, 335, I think these might work better with the 110's, I would like to see how the CFE does with them as well. I have not played with any barnes bullets in a while. Good luck, I hope the weather improves, its crappy down here.

Edit: If you try the 115CC's, I found the sweet spot at 2.30", its around .005" off the lands in my barrel.
 

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I've loaded the 110 TSX and TTSX to 2.385" and got the TTSX up to 2770 FPS with AA2200, but these were fired in the bolt gun. The 110 TTSX at that speed is wicked for sure.

I also loaded the 120 SST to 2.333"

The 135 SMK to 2.385"

The 105 GS Custom to 2.42"

Typically, I have been able to get about 100 FPS more in the bolt gun at these OAL's but pressures were just on the ragged edge in the AR. It may not be so much about increased speed with each bullet...this mod shows that longer, much higher BC bullets like the 135 SMK, 110 TTSX and 105 GS custom can now be loaded into the 6.8 X 43 case, whereas excessive compression prevented practical use of these in said case, before.
 

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Discussion Starter #7
You wouldn't happen to have any TAC, or PP-Varmint, BLC2, 335, I think these might work better with the 110's,
I have TAC and H335. I was going to focus on using those powders with the 130gr bullets. I'll use your lead to try those powders also. Even if I don't get higher velocities with the CFE, its standard deviations have been very small. I'll take accuracy over velocity. But, if this was a Ford commercial, I'd prefer to have both.

Thanks for the info, HTR. I may have to try some of the SMKs and GSCs later next year.
 

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Really great info on the measured lengths. Like HTR, I have played with longer COL for the 95 TTSX and 100 gr Accubond for my 700 bolt. I have tried them in my ARP 20" and seem OK. Although I did a slight mod on a CPD 10 round to hold couple cartridges for deer hunting purpose, I find using unmodified PRIs for my longer lengths. The PRI already has a rectangular slot that will allow 2 longer cartridges thus allowing a 2+1 (one in chamber). I try to use the longer recipes for deer and find 2.295" loads fine for pigs. Cannot imagine many times where I'll need more than 2+1 for deer situation (stuff a few 2.295" loads under the longer in event I need extra shots in a pig situation.
 

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X-man, We will take whatever information you can give, my pet load for the 115CC and TAC gives velocity of 2640, ES in the teens, SD of 9 at 2.33" in federal brass that was fired the second time in this barrel, I thought that was pretty good. Also this load is very gentle on the Fed. brass I didn't have any case webs expanded past .421" and I still have not had to trim them. I'm going to keep shooting them with this load and see how long they will last.

Here is a 5 round "shorty" mag I just did for a buddy next to a 130VLD loaded to 2.40"

View attachment 10579
 

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Discussion Starter #10
Here is a 5 round "shorty" mag I just did for a buddy next to a 130VLD loaded to 2.40"

The rounds in your shorty mag would be the 120gr Fusion MSRs?
 

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It was interesting that the 110 TSX measurement was 2.428" which seemed rather long compared to the 95 TTSX which was 2.375". This measurement checked the same in 16" and 18" ARP barrels, as it should. Further investigation showed that the 110gr TSX ogive, unlike the 95 TTSX, doesn't reach 0.278" before the first band. The 110gr TSX ogive measures 0.272" at the widest point before the first band. The 110 TSX is touching the lands after the first groove. The 85gr TSX is like this too but all the other .277 Barnes bullets I have reach full-bore prior to the first groove.
That is interesting because the first small batch of 95TTSX bullets HTR sent me were made with the ogive under diameter. I called Barnes and ask them if they could move the front band back .050 or something so the band would not be in the middle of the ogive and would be more accurate. They told me no, already in production and could not move it. I've never purchased a box of 95s because the first thing to hit the lands was the front of the first band...or it was then.
 

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Discussion Starter #13
H, looks like your request eventual was acted upon for the 95TTSx.
 

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There was a small production run of 120 grain fusions as components a while ago. Then they stopped when LWRC approached them for their little project. Now we got the 115 grain Fusions, still they ain't nothing to sneeze at.
 

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There was a small production run of 120 grain fusions as components a while ago. Then they stopped when LWRC approached them for their little project. Now we got the 115 grain Fusions, still they ain't nothing to sneeze at.
The 120's were never meant to be loaded into a 6.8 case, the ogive is too long to be loaded at mag length, they have to be loaded out close to 2.34" in order to keep the ogive outside the neck. I have loaded some @ 2.30" , they weren't very accurate.
 

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Discussion Starter #16
I'm learning to use the Syrac adjustable gas block that Aspp recommended. When closed down to the minimum to allow the bolt to function, it has added at least 50 fps to the muzzle velocity.

Here is a closer look at the modified 15-round magazine sitting next to an unmodified 10-round magazine. As modified, the magazine holds 11 rounds withing the lower receiver's magazine well. You can clearly see the mag well marks on the 10-rounder. The sides of the modified magazine flex just a little but have not interfered with operation.

 

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Tested 120 SST's loaded to 2.34" 27.5 gr of AA2200 less than .4" 3 shot group. I flinched on the 4th shot so the 4 shot group was .75". Very good load, probably the best I've ever shot. 28.0 grains opened up the group to 1.5". There may be a node above this that shows better accuracy, and I know this is not a very hot load. I need to test more loads with higher charges, but this is such an accurate load

110 TSX's loaded to 2.38" 29.5 gr of AA2200 slight swipes, small signs of pressure but manageable. Group was .6".

95 TTSX's were a disappointment loaded long. Pressure signs at 29.0 grains of AA2200 bullets seated at 2.35". Could be bullet is hitting lands at that length, I don't have the 6.8 shell for the bullet comparator. None of the groups less than 2"

Barrel is a Wilson Combat SPC II 18". Non-adjustable gas block.

Start below the loads I listed and work up.

Again, the Hornady 120 SST seated at 2.34" with 27.5 grains of AA2200 is without a doubt a great load for single loads or open mags.

The Barnes 110 TSX loaded to 29.5 gr of AA2200 seated at 2.38" is another great choice. Sorry, I don't have a chrony, hopefully someone can add some info on what velocities these may be.

EDIT: just looked over my notes. The 95 TTSX's were seated at 2.35". This must be on the lands and should probably be loaded at 2.32" or less.
 

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Soonlobo, just looking at your data here. I can`t believe that the 95 ttsx`s on sitting on the lands seated out to 2.35 but they very well could be. You should check your barrel and see what kind of oal that you can load. It is pretty simple-egt a 1/4 inch rod of some type and then get a couple of collars that will slip on the rod-make sure collars have a set screw where you can tighten it down on the rod. Now slide your bcg into the loaded position-slide rod in from muzzle end-rod should be contacting bolt face-slide one of the collars up to the end of muzzle-tighten set screw-now take bcg out and place a bullet in the throat and while putting a little pressure on the back of the bullet slide your rod into the muzzle again and when it touches the end of the bullet take your other collar and push it up against the barrel and tighten that set screw.
Now you can measure outside to outside of the collars and subtract one collars width and you should have the oal of that paticular bullet. You have to measure again when changing to different bullet.
Hope that this makes sense.
 

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Soonlobo, just looking at your data here. I can`t believe that the 95 ttsx`s on sitting on the lands seated out to 2.35 but they very well could be. You should check your barrel and see what kind of oal that you can load. It is pretty simple-egt a 1/4 inch rod of some type and then get a couple of collars that will slip on the rod-make sure collars have a set screw where you can tighten it down on the rod. Now slide your bcg into the loaded position-slide rod in from muzzle end-rod should be contacting bolt face-slide one of the collars up to the end of muzzle-tighten set screw-now take bcg out and place a bullet in the throat and while putting a little pressure on the back of the bullet slide your rod into the muzzle again and when it touches the end of the bullet take your other collar and push it up against the barrel and tighten that set screw.
Now you can measure outside to outside of the collars and subtract one collars width and you should have the oal of that paticular bullet. You have to measure again when changing to different bullet.
Hope that this makes sense.
I was surprised also but Xman sent me a PM and mentioned the 95 TTSX hit the lands on his barrel before the 110 TSX. If you compare the two you can see it, the ogives are different, and the 95 TTSX is wider towards the tip of the bullet. The other reason I believe it was loaded out too far is when this bullet is loaded at 2.295 for my regular magazine it is VERY accurate from my rifle with similar loads of the lower end of what I tried today. The only difference was how far out the bullet was seated and the lack of accuracy today. I tested both the long and regular seated loads at the same range with about ten degrees difference in temperature and no wind. The spread was at least one MOA worse accuracy today on the same powder and brass load.

The 110 TSX results are VERY encouraging. I don't know the velocity of this load but it must be at least 2750 fps out of my 18" barrel. The primer beginning to flatten a bit was the only sign of pressure I could find and a little over 1/2 MOA is awesome accuracy for my loadings. These were once-fired SSA brass cases.
 

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Just went back through the messages with Xman. He suggested seating the 95's at 2.325". I should have followed his advice. Pretty certain the 95's should be seated below 2.325" in my barrel, but each barrel is different.

The 2.38" for the 110 TSX 's and 2.34" for the 120 SST's I'm convinced are perfect for my barrel. The accuracy was just too good. I'll have to try a little warmer load for the SST to see if accuracy comes back and seat down the 95's to around 2.32".
 
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