CAVEAT: Don't try this on your .308, this entire gun will be set up and optimized for one bullet and load combo......
ANYWAY:
I hate the recoil impulse of the big AR10/LR-series rifles, it makes the rifles very difficult to shoot accurately and quickly compared to their lighter brothers, the AR15 series. I have an OLY based 243 WSSM (AR15) and it recoils and stays on target UNBELIEVABLY well compared to an LR I have of the same weight. The heavy BCG really moves the bigger guns around a lot.
The common wisdom is to ADD weight to smooth things out, and this has merit in certain cases, mainly to cure problems that cannot be easily fixed on a stock gun.
I'm building another DPMS LR in 6mm Super LR (basically a .243 Win with longer neck and sharp shoulder) with a 7.5" twist Krieger bbl, throated for DTAC's at mag length.
There are only 3 basic things that will be different in the recoil equation in these 2 rifles (AR vs. LR), as both have the same cartridge case capacity, velocity, and can shoot the same bullets.
1. Recoiling mass
2. Strength of recoil spring
3. Length of this masses movement.
I believe the biggest difference is #1, the amount of recoiling mass, as luck would have it this is also about the only one I can modify.
I took some weights with an accurate scale.
DPMS LR –– Bolt and carrier ass'y weighs 18.8 ozs, Buffer, 5.4 ozs, total 24.2 ozs.
AR15 WSSM –– Bolt and carrier ass'y, 12.0 ozs, Buffer, 5.1 ozs, total 17.1 ozs
LR is 7.1 ounces heavier than AR, over 40% heavier!! It also moves .7 inches further rearward.
I called JP Enterprises and inquired about purchasing one of their Low Mass Carriers, which supposedly weigh 11.5 ozs compared to the stock carrier @ 15.3 Ozs.
They said they are not in production yet and would give no estimate on production date.
OK............ I'll just do it myself...........
After the mods and coating it with teflon/moly, it weighs 12.0 ozs, I cut off 3.3 ozs. of weight here.
Then I pulled 4 weights out of the buffer and added 2 of the aluminum spacers to reduce buffer weight to 3.4 ozs. This still leaves 2 steel weights and some "buffing" rattle to stop bolt bounce (if I need to lose more weight, I have some other options with the buffer)
I reduced the total reciprocating weight by a total of 5.2 ozs, about 25% lighter, a total mass of 19.0 ozs., compared to 24.2 stock.
I'm still 1.9 ozs heavier than the AR15, but believe this will make a HUGE difference in the recoil feel and gun movement.
The gas port is being drilled undersized so I can ream it out as needed and I will also have an adjustable gas block. I can also make TUBB style weights to add carrier weight back in if needed.
I'm also using a 2" extended gas system, to allow the use of the slower burning powders the 6mm's need with the DTAC's.
My chambered barrel should be here in the next week or two, I'll keep you posted.
ANYWAY:
I hate the recoil impulse of the big AR10/LR-series rifles, it makes the rifles very difficult to shoot accurately and quickly compared to their lighter brothers, the AR15 series. I have an OLY based 243 WSSM (AR15) and it recoils and stays on target UNBELIEVABLY well compared to an LR I have of the same weight. The heavy BCG really moves the bigger guns around a lot.
The common wisdom is to ADD weight to smooth things out, and this has merit in certain cases, mainly to cure problems that cannot be easily fixed on a stock gun.
I'm building another DPMS LR in 6mm Super LR (basically a .243 Win with longer neck and sharp shoulder) with a 7.5" twist Krieger bbl, throated for DTAC's at mag length.
There are only 3 basic things that will be different in the recoil equation in these 2 rifles (AR vs. LR), as both have the same cartridge case capacity, velocity, and can shoot the same bullets.
1. Recoiling mass
2. Strength of recoil spring
3. Length of this masses movement.
I believe the biggest difference is #1, the amount of recoiling mass, as luck would have it this is also about the only one I can modify.
I took some weights with an accurate scale.
DPMS LR –– Bolt and carrier ass'y weighs 18.8 ozs, Buffer, 5.4 ozs, total 24.2 ozs.
AR15 WSSM –– Bolt and carrier ass'y, 12.0 ozs, Buffer, 5.1 ozs, total 17.1 ozs
LR is 7.1 ounces heavier than AR, over 40% heavier!! It also moves .7 inches further rearward.
I called JP Enterprises and inquired about purchasing one of their Low Mass Carriers, which supposedly weigh 11.5 ozs compared to the stock carrier @ 15.3 Ozs.
They said they are not in production yet and would give no estimate on production date.
OK............ I'll just do it myself...........
After the mods and coating it with teflon/moly, it weighs 12.0 ozs, I cut off 3.3 ozs. of weight here.
Then I pulled 4 weights out of the buffer and added 2 of the aluminum spacers to reduce buffer weight to 3.4 ozs. This still leaves 2 steel weights and some "buffing" rattle to stop bolt bounce (if I need to lose more weight, I have some other options with the buffer)
I reduced the total reciprocating weight by a total of 5.2 ozs, about 25% lighter, a total mass of 19.0 ozs., compared to 24.2 stock.
I'm still 1.9 ozs heavier than the AR15, but believe this will make a HUGE difference in the recoil feel and gun movement.
The gas port is being drilled undersized so I can ream it out as needed and I will also have an adjustable gas block. I can also make TUBB style weights to add carrier weight back in if needed.
I'm also using a 2" extended gas system, to allow the use of the slower burning powders the 6mm's need with the DTAC's.
My chambered barrel should be here in the next week or two, I'll keep you posted.
