Ok, I am going to try very hard to keep this organized and to the point. I recently got a 243 win barrel for my remington 700. Its a factory 20" threaded 243 win barrel with a 1-in-9.125" twist. I am running it suppressed with a silencerco specwar 762 suppressor. I wanted a lighter profile barrel and lower recoil for my hunting rifle vs my heavy 308 win barrel I was using. Once I got the barrel I went down and got some IMR Enduron 4451 to try with 105gr hunting VLDS, at the same time I bought some HSM factory ammo loaded with 95gr berger hunting VLDs. The brass I am using is Lapua 308 Small primer brass reformed to 243. I initially tried 105gr hunting vlds hoping that they would stabilize (I have heard that some folks can get them stabilized in a 1-9 twist) but they did not, they were all over the paper. I also shot a few rounds of the HSM 95gr VLD ammo and it shot great! .75" group of 5. The HSM ammo is loaded with 41.8 gr of this short cut extruded powder (anyone recognize it) and bullets are seated to 2.128 CBTO (0.127 jump!).
Lucky for me I shoot 95gr VLDs in my 6mmAR. So I went home and loaded some 95gr VLDs in a charge test starting at 41gr and working up to 43gr of IMR 4451 in half grain increments. For seating depth I set them all to what the HSM ammo was seated to: 2.128 CBTO (0.217 jump). When I shot these loads I was pretty unimpressed with accuracy (average was about 2" per group), but I thought that since I am certainly using a different powder than the HSM factory ammo, It might effect seating depth tune. Also, no charge showed signs of excess pressure. So, I went home and loaded up several more loads. This time all were loaded at 42.5gr if IMR 4451 and seating depth test was done according the the Berger VLD Jump test recommendations. .010 off, .050 off, .090 off, and .130 off. I also shot one group at maximum magazine length, and 10 rounds and max jam. When I shot these I was really unimpressed with accuracy. 2-3" groups were really the best I could get. I also noticed that I was getting a lot of blowback gas on the cases, down one side and all the way back to the extractor groove. This was really surprising to me since the velocity on all seating depths was in the 2940 fps range. That should be plenty enough pressure to seal the chamber.
So, I need some help on where to go from here. Id love to shoot the 95gr VLD since I already have a load for it in another rifle and because it will obviously shoot based on the HSM factory ammo group. I have some theories that may explain the poor accuracy with these handloads and . Would you folks please let me know what you think?
Theory 1. Small primer brass, slow burning powder, cooler temperature (40ish degrees) is causing poor ignition. Id like to try some CCI 450 primers instead of the 400s that I have been using thus far.
Theory 2. rifle just doesn't like IMR 4451 powder. I may try varget, IMR 4064 (I have these on hand) or H4831 or H4350 (ill have to buy these).
Theory 3. Brass needs to be annealed. I have shot this brass twice now since reforming it to 243. It has an unknown past to me, so it may need to be annealed to help with chamber seal.
Theory 4. Need to work higher in charge and further back in seating depth to find the right node.
Here are some photos so that you can see exactly what I am working with.
HSM Factory 95gr VLD group:
Powder in HSM factory ammo (anyone know what it is?) 41.8gr
Charge weight test:
Seating depth test:
Thanks for any and all help. Let me know what you think!
Mason
Lucky for me I shoot 95gr VLDs in my 6mmAR. So I went home and loaded some 95gr VLDs in a charge test starting at 41gr and working up to 43gr of IMR 4451 in half grain increments. For seating depth I set them all to what the HSM ammo was seated to: 2.128 CBTO (0.217 jump). When I shot these loads I was pretty unimpressed with accuracy (average was about 2" per group), but I thought that since I am certainly using a different powder than the HSM factory ammo, It might effect seating depth tune. Also, no charge showed signs of excess pressure. So, I went home and loaded up several more loads. This time all were loaded at 42.5gr if IMR 4451 and seating depth test was done according the the Berger VLD Jump test recommendations. .010 off, .050 off, .090 off, and .130 off. I also shot one group at maximum magazine length, and 10 rounds and max jam. When I shot these I was really unimpressed with accuracy. 2-3" groups were really the best I could get. I also noticed that I was getting a lot of blowback gas on the cases, down one side and all the way back to the extractor groove. This was really surprising to me since the velocity on all seating depths was in the 2940 fps range. That should be plenty enough pressure to seal the chamber.
So, I need some help on where to go from here. Id love to shoot the 95gr VLD since I already have a load for it in another rifle and because it will obviously shoot based on the HSM factory ammo group. I have some theories that may explain the poor accuracy with these handloads and . Would you folks please let me know what you think?
Theory 1. Small primer brass, slow burning powder, cooler temperature (40ish degrees) is causing poor ignition. Id like to try some CCI 450 primers instead of the 400s that I have been using thus far.
Theory 2. rifle just doesn't like IMR 4451 powder. I may try varget, IMR 4064 (I have these on hand) or H4831 or H4350 (ill have to buy these).
Theory 3. Brass needs to be annealed. I have shot this brass twice now since reforming it to 243. It has an unknown past to me, so it may need to be annealed to help with chamber seal.
Theory 4. Need to work higher in charge and further back in seating depth to find the right node.
Here are some photos so that you can see exactly what I am working with.
HSM Factory 95gr VLD group:
Powder in HSM factory ammo (anyone know what it is?) 41.8gr
Charge weight test:
Seating depth test:
Thanks for any and all help. Let me know what you think!
Mason
