FOGGER Report post Posted November 20, 2015 I built a .260 Rem and I've been building a load. I've gotten great groups, sub 1/2moa but my velocities are all over the board +/- 150fps. I double checked my chronograph with another rifle and it's working correctly. Any ideas how to get more consistent velocity? I'm using Lapua brass and 4831sc Share this post Link to post Share on other sites
FOGGER Report post Posted November 20, 2015 With WLR primers and Berger 140vld Share this post Link to post Share on other sites
STOMP442 Report post Posted November 20, 2015 Shoot it at longer ranges, if it holds half moa I wouldn't worry about what the chrony says. Share this post Link to post Share on other sites
Tac Report post Posted November 20, 2015 changes due to barrel temp? Share this post Link to post Share on other sites
308Nut Report post Posted November 20, 2015 Try the Rem 9-1/2 large rifle primer with 4831SC. Check neck tension consistency. Try another chrony. Make sure the sun shades are on properly and make double sure all or part of one or the other isn't shaded. Also agree with C. Test it at longer ranges. If it groups well, forget the chrony. M 1 Share this post Link to post Share on other sites
oz31p Report post Posted November 20, 2015 Just so I understand the question your getting a sd of 150fps(velocity spread of 300fps) and your groups shooting less than 1/2 inch at 100yards? Share this post Link to post Share on other sites
GreyGhost85 Report post Posted November 20, 2015 Shoot it out further and see how it groups. If it holds half MOA to 500, who cares. If there is that much deviation, i would think you would have a hard time shooting that well at 100 even. Chronos get you close, but best to true your velocity by shooting different ranges. Just 10-20 fps can make a lot of difference downtown 2 Share this post Link to post Share on other sites
rcdinaz Report post Posted November 21, 2015 Try different primers. 308 pointed out neck tension and I have had that happen as well, actually to loose so the bullets ended up being able to move a little. The result was them moving further from the lands on some of the cartridges. This was in my phase of constantly screwing with everything, trimming, chamfering, deburring, neck tension adjustment, meplat uniforming... too much of a good thing! Share this post Link to post Share on other sites
FOGGER Report post Posted November 21, 2015 My jump is .040 off the lands. I'm measuring of the ogive. I'm using the RCBS chargeMaster and backing up ever charge with a Dillion manual scale. As far as neck tension I'm using a Redding competition bushing die. I had the guy at Bruno's measure my lot of cases and he picked out the bushing I needed. This is the first time using this type of die. I have always just used a standard RCBS die. Most of my other rifles are within 10fps of each other. Should I change my neck tension? Share this post Link to post Share on other sites
Mike S Report post Posted November 21, 2015 I'd be really suspicious of either the chrono itself or the lighting conditions when you took the readings. If you can get out mid day on an overcast day you may see different readings. Share this post Link to post Share on other sites
cactusjack Report post Posted November 22, 2015 do you know anyone with a Magneto-speed? Share this post Link to post Share on other sites
FOGGER Report post Posted November 22, 2015 I'm shooting a 140VLD Berger hunting 150ES Cheap pro chrono (it's dead on with my other rifles) 2726-2889 No I don't know anyone with a magneto-speed. Are those good? I'll have to just shoot it out to 500 and see Share this post Link to post Share on other sites
firstcoueswas80 Report post Posted November 22, 2015 Did this happen one time, or is it a common occurrence? Share this post Link to post Share on other sites
FOGGER Report post Posted November 22, 2015 Happens every time I've tested it. 45.5 of 4831SC WLR primers My COAL is 2.950 (My chamber and throat were machined to the specs of a loaded round to allow for the long 140grn bullets to be seated long) I have some H4350 but my groups were so good I didn't experiment with it much. Remington 700LA. Completely gone through and blueprinted by Bob Brackney. Bartlein 1-8twist 25" All work done by Bob Brackney. 1 Share this post Link to post Share on other sites
cactusjack Report post Posted November 22, 2015 I have a Chrono-speed. When and where do you shoot? I love an excuse to go shooting. I have a scope to change out on a 308. Share this post Link to post Share on other sites
