This is the first heavy M14 barrel in 6.5 that Lothar Walther has made. They sent it to me for testing with a reduced size gas port instead of the standard gas port in 308. It's performed flawlessly with bullet weights from 120 grain to 156 grain ammo. This thread will document the accuracy and function with documented changes in the ammunition and setup until the best accuracy can be achieved.
On May 16th, I pulled apart my latest LRB build and installed the heavy 6.5 barrel onto it and set the headspace. This rifle had no NM modifications at all with the exception of the heavy barrel. The gas system isn't even shimmed. The spring guide is a GI spring guide, the piston is a standard piston. The stock is a Gi fiberglass stock that has not been reinforced in any way. I used my high Bassett and my SWFA scope with a Bradley cheek rest.
I only had 15 rounds to do a function check. All rounds functioned without any issue. Accuracy was superb for being un-bedded. After dialing in the scope, I shot a 3-shot group which measured 0.613" followed up by a 5-shot group which measured 1.3" at 100 yards.
While I was policing brass, I noticed three cases had split along the body. After a quick internet search, I found that others have had this issue with S&B 6.5 ammo, so I'm chalking it up to a bad lot of brass. I'll be loading more ammo in the 130 and 140 grain range and testing this barrel more in the future. I might throw it in my spare JAE and do some more testing in it.
On June 3rd, I had installed the action into a JAE-100 chassis for further testing. I loaded up some 6.5 rounds with StaBall 6.5 and Hornady 130 grain ELD's with the intention of testing this heavy 6.5 barrel. I also had a few rounds left over of S&B 140 grain FMJ (this is not the same stuff that had ruptured cases last time). I also had a box of Winchester Long Range Big Game 142 Nosler AccuBond ammo.
I intended on doing a ladder test with 130 grain ELD's starting with 41.5 grains of StaBall 6.5. and ending with 44.5 grains. Unfortunately, I forgot the power cable to my Labradar and I postponed the testing of those loads until another date.
I did, however run a few preliminary rounds of the factory ammo I had on-hand to at least see if there's any issue with those.
I'm happy to say that with the 5 rounds of 140 grain FMJ and the 142 grain long range hunter, I experienced no cycling or feeding issues. I did get a group with the 142 grain stuff and it measured right at 1.25
after a scope zeroing adjustment.
The rifle is a LRB M14NM receiver and the gas cylinder is shimmed. It's in a JAE-100 G3 chassis and I'm using a SWFA 10-X scope with a Bassett high mount. I did not adjust the barrel tensioner yet.
On June 4th, I took it out again and got some data to validate the gas port size. I was using 130 grain Hornady ELD’s with StaBall 6.5 powder, Hornady cases, and CCI-200 powders.
All the loads cycled the action without any issues from the lowest charge to the highest charge. Also note that the rifle has a standard trigger and a standard gas piston.
Here are the velocities:
41.5 grains: 2581 FPS 2620 high, 2520 low, ES 99, SD 36.6
42.0 grains: 2637 FPS. 2644 high, 2629 low, ES, 15, SD: 10.5 (Errored on 3 shots before I noticed, only 2 shots in this data set)
42.5 grains: 2658 FPS. 2679 high, 2631 low, ES: 48, SD: 19.7
43.0 grains: 2692 FPS. 2726 high, 2667 low, ES: 59, SD: 24.8
43.5 grains: 2708 FPS. 2742 high, 2688 low, ES: 54, SD: 21.6 (note that on the third round of this group, I broke the red tip off the bullet when loading it into the magazine. I expected the flyer in this group.
44.0 grains: 2774 FPS. 2797 high, 2736 low, ES: 60, SD: 23.4
44.5 grains: 2799 FPS. 2818 high, 2764 low, ES: 53.9, SD: 20.6
All the loads cycled the action without any issue. I started off with zero tension at the front end and adjusted the tensioner throughout the test ending with 1/4 turn past contact at max load. I had no case failures or ruptures like I did with the S&B ammo in another thread. My numbers aren't the best, but that's probably because I have very few pieces of brass and I didn't have enough to sort by weight.
I didn't see any obvious pressure signs and I didn't get any flattened primers like I usually do with my 308 win 175 grain loads.
I have 8 pounds of StaBall 6.5 inbound and will load with some Nosler CC's at a later date. I also have various boxes of match ammo inbound as well for testing.
On June 15th, I went out again to get some velocities and to test for function.
First up was American Eagle 120 grain OTM. No feeding or cycling issues.
Average velocity: 2871 FPS
High: 2881
Low: 2862
ES: 18.54
SD: 7.25
Next up was Hornady 147 grain ELD Match.
Average velocity: 2649 FPS
High: 2682
Low2616
ES: 66.52
SD: 24
Last was Federal Gold Medal Match Berger 130 grain
Average velocity: 2776
High: 2803
Low: 2758
ES: 44.84
SD: 16.81
I still have more tweaking to do with the chassis. I also noticed I needed to clear my handguard as it's touching the stock, which is not good for accuracy.
I made it out again on June 17th and made the following adjustments:
-Trimmed the handguard so it doesn't contact the JAE chassis
-Added 3/4 turn of draw pressure to the draw pressure screw
-Switched from ear muffs to ear plugs for better and more consistent cheek weld
I fired three shot groups, adding tension until I hit 3/4ths of a turn. All but two groups were under 1 inch. Ammo was American Eagle 120 grain OTM and Hornady Match 147 grain ELD-M. The Hornady produced a nice 0.68" 5-shot group with a final 4-shot group of 0.978".
I still have a box of Federal Gold Medal 130 grain Berger to test on my next trip.
So since starting the testing and tweaking, my groups have gone from the 2 inch range to sub-MOA with the right tuning. I still need to develop a load and add a match trigger as well as a better scope.
Tony.
On May 16th, I pulled apart my latest LRB build and installed the heavy 6.5 barrel onto it and set the headspace. This rifle had no NM modifications at all with the exception of the heavy barrel. The gas system isn't even shimmed. The spring guide is a GI spring guide, the piston is a standard piston. The stock is a Gi fiberglass stock that has not been reinforced in any way. I used my high Bassett and my SWFA scope with a Bradley cheek rest.
I only had 15 rounds to do a function check. All rounds functioned without any issue. Accuracy was superb for being un-bedded. After dialing in the scope, I shot a 3-shot group which measured 0.613" followed up by a 5-shot group which measured 1.3" at 100 yards.
While I was policing brass, I noticed three cases had split along the body. After a quick internet search, I found that others have had this issue with S&B 6.5 ammo, so I'm chalking it up to a bad lot of brass. I'll be loading more ammo in the 130 and 140 grain range and testing this barrel more in the future. I might throw it in my spare JAE and do some more testing in it.
On June 3rd, I had installed the action into a JAE-100 chassis for further testing. I loaded up some 6.5 rounds with StaBall 6.5 and Hornady 130 grain ELD's with the intention of testing this heavy 6.5 barrel. I also had a few rounds left over of S&B 140 grain FMJ (this is not the same stuff that had ruptured cases last time). I also had a box of Winchester Long Range Big Game 142 Nosler AccuBond ammo.
I intended on doing a ladder test with 130 grain ELD's starting with 41.5 grains of StaBall 6.5. and ending with 44.5 grains. Unfortunately, I forgot the power cable to my Labradar and I postponed the testing of those loads until another date.
I did, however run a few preliminary rounds of the factory ammo I had on-hand to at least see if there's any issue with those.
I'm happy to say that with the 5 rounds of 140 grain FMJ and the 142 grain long range hunter, I experienced no cycling or feeding issues. I did get a group with the 142 grain stuff and it measured right at 1.25
after a scope zeroing adjustment.
The rifle is a LRB M14NM receiver and the gas cylinder is shimmed. It's in a JAE-100 G3 chassis and I'm using a SWFA 10-X scope with a Bassett high mount. I did not adjust the barrel tensioner yet.
On June 4th, I took it out again and got some data to validate the gas port size. I was using 130 grain Hornady ELD’s with StaBall 6.5 powder, Hornady cases, and CCI-200 powders.
All the loads cycled the action without any issues from the lowest charge to the highest charge. Also note that the rifle has a standard trigger and a standard gas piston.
Here are the velocities:
41.5 grains: 2581 FPS 2620 high, 2520 low, ES 99, SD 36.6
42.0 grains: 2637 FPS. 2644 high, 2629 low, ES, 15, SD: 10.5 (Errored on 3 shots before I noticed, only 2 shots in this data set)
42.5 grains: 2658 FPS. 2679 high, 2631 low, ES: 48, SD: 19.7
43.0 grains: 2692 FPS. 2726 high, 2667 low, ES: 59, SD: 24.8
43.5 grains: 2708 FPS. 2742 high, 2688 low, ES: 54, SD: 21.6 (note that on the third round of this group, I broke the red tip off the bullet when loading it into the magazine. I expected the flyer in this group.
44.0 grains: 2774 FPS. 2797 high, 2736 low, ES: 60, SD: 23.4
44.5 grains: 2799 FPS. 2818 high, 2764 low, ES: 53.9, SD: 20.6
All the loads cycled the action without any issue. I started off with zero tension at the front end and adjusted the tensioner throughout the test ending with 1/4 turn past contact at max load. I had no case failures or ruptures like I did with the S&B ammo in another thread. My numbers aren't the best, but that's probably because I have very few pieces of brass and I didn't have enough to sort by weight.
I didn't see any obvious pressure signs and I didn't get any flattened primers like I usually do with my 308 win 175 grain loads.
I have 8 pounds of StaBall 6.5 inbound and will load with some Nosler CC's at a later date. I also have various boxes of match ammo inbound as well for testing.
On June 15th, I went out again to get some velocities and to test for function.
First up was American Eagle 120 grain OTM. No feeding or cycling issues.
Average velocity: 2871 FPS
High: 2881
Low: 2862
ES: 18.54
SD: 7.25
Next up was Hornady 147 grain ELD Match.
Average velocity: 2649 FPS
High: 2682
Low2616
ES: 66.52
SD: 24
Last was Federal Gold Medal Match Berger 130 grain
Average velocity: 2776
High: 2803
Low: 2758
ES: 44.84
SD: 16.81
I still have more tweaking to do with the chassis. I also noticed I needed to clear my handguard as it's touching the stock, which is not good for accuracy.
I made it out again on June 17th and made the following adjustments:
-Trimmed the handguard so it doesn't contact the JAE chassis
-Added 3/4 turn of draw pressure to the draw pressure screw
-Switched from ear muffs to ear plugs for better and more consistent cheek weld
I fired three shot groups, adding tension until I hit 3/4ths of a turn. All but two groups were under 1 inch. Ammo was American Eagle 120 grain OTM and Hornady Match 147 grain ELD-M. The Hornady produced a nice 0.68" 5-shot group with a final 4-shot group of 0.978".
I still have a box of Federal Gold Medal 130 grain Berger to test on my next trip.
So since starting the testing and tweaking, my groups have gone from the 2 inch range to sub-MOA with the right tuning. I still need to develop a load and add a match trigger as well as a better scope.
Tony.
