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Posted: 7/16/2012 8:10:53 AM EDT
| Is there an optimum distance to set for the amount of travel from bullet to barrel lands in this rifle? I'm having spotty accuracy in my rifle and measure this distance to be 0.045", which I'm sure is too far. |
| what kind of rifle? SA NM, standard, loaded model, norinco, gi bbl, etc? what kind of ammo are you loading. Most everybody loads to 2.800 because of mag length. You can load them a tad longer but thats it, unless you wanted to single load them. What kind of bullets are you loading? |
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Smith Enterprise Crazy Horse barrel with an M118LR chamber on an SAI receiver. Right now I am loading 147gr Privi Partisan bullets, but will be moving to heavier bullets later.
Keep in mind that I am not attempting to control overall length, other than staying within the max overall, but am attempting to control the bullet jump from case to barrel lands. I'm using the Hornady tool that measures length on the portion of the ogive that would touch the lands. |
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Smith Enterprise Crazy Horse barrel with an M118LR chamber on an SAI receiver. Right now I am loading 147gr Privi Partisan bullets, but will be moving to heavier bullets later. Keep in mind that I am not attempting to control overall length, other than staying within the max overall, but am attempting to control the bullet jump from case to barrel lands. I'm using the Hornady tool that measures length on the portion of the ogive that would touch the lands. Prvi Partisan might be part of your problem. I have never gotten that stuff to shoot well in my 10T or my SuperSASS, but they both love 175gr SMK or even the Georgia Arms G308J which uses a 175gr BTHP as well. M118LR is a 175gr BTHP round and your rifle is set up for it. Try some 175gr stuff. I just have my M14S set up as a service/battle rifle. |
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You need a headspace gauge to find what your individual rifle needs. I'm using the Hornady case length gauge to measure that, although I suspect they are measuring slightly different things. What would be the optimum relationship once I have established a measurement? 0.010" off the lands? 0.020"? I suspect 0.045" is too much. |
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Prvi Partisan might be part of your problem. I have never gotten that stuff to shoot well in my 10T or my SuperSASS, but they both love 175gr SMK or even the Georgia Arms G308J which uses a 175gr BTHP as well. M118LR is a 175gr BTHP round and your rifle is set up for it. Try some 175gr stuff. I'll order a box or two of that ammo next time I'm at Midway to see how much of a difference it makes. I forgot to bring my 168gr GMM with me the last time out. I'm not trying for gnat's ass accuracy at the moment. I'd be happy with a 1.5"-2" grouping as I presently can't shoot that well slung prone. Right now I'm off a SAGE stocked bipod with a bean bag, and the 147gr gives weird groupings. A 10 shot group gives me an overall 4MOA group, but there are sub-groups within overall group approaching 1MOA each. On one hand it seems as if the accuracy might be there due to the clustering, so I'm checking out my loads. |
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Prvi Partisan might be part of your problem. I have never gotten that stuff to shoot well in my 10T or my SuperSASS, but they both love 175gr SMK or even the Georgia Arms G308J which uses a 175gr BTHP as well. M118LR is a 175gr BTHP round and your rifle is set up for it. Try some 175gr stuff. I'll order a box or two of that ammo next time I'm at Midway to see how much of a difference it makes. I forgot to bring my 168gr GMM with me the last time out. I'm not trying for gnat's ass accuracy at the moment. I'd be happy with a 1.5"-2" grouping as I presently can't shoot that well slung prone. Right now I'm off a SAGE stocked bipod with a bean bag, and the 147gr gives weird groupings. A 10 shot group gives me an overall 4MOA group, but there are sub-groups within overall group approaching 1MOA each. On one hand it seems as if the accuracy might be there due to the clustering, so I'm checking out my loads. Is that 147gr just plain ol' FMJ? |
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Is that 147gr just plain ol' FMJ? Yup I have shot 147-150gr FMJ, both new and surplus, in several precision 7.62x51/.308 rifles and got about what I expected. You can't expect more more than 3-4 MOA and groups all over the place. Get you some 168-175gr BTHP ammo, either roll your own or buy some. I really like the Federal 175gr SMK and the Georgia Arms G308J is some good stuff. I kinda stuck with 175 since I like to reach out to 1000 sometimes and I see no need to keep 168 AND 175 ammo on hand and the 175 will still do the job in closer. 
The only surplus or FMJ of just about any kind that I personally have ever shot that was even reasonably accurate was the old Greek and LC .30-06. I can shoot 1 MOA at 100 with both in my 110FP. I have a ton of it and it really saves me money buying precision .30-06 ammo because I think that is plenty good enough for my liking with that rifle.
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I have shot 147-150gr FMJ, both new and surplus, in several precision 7.62x51/.308 rifles and got about what I expected. You can't expect more more than 3-4 MOA and groups all over the place. I guess expectations are the problem. I shoot bulk Hornady 55gr ball bullets in my reloads and easily attain 2MOA at 100yds all day long, slung prone, from my AR15s. I don't shoot better groups with GMM, so I figure I'm the weak link. I know it's a different platform, but I didn't figure the 308/M1A to be like this. Get you some 168-175gr BTHP ammo, either roll your own or buy some.
I really like the Federal 175gr SMK and the Georgia Arms G308J is some good stuff. I kinda stuck with 175 since I like to reach out to 1000 sometimes and I see no need to keep 168 AND 175 ammo on hand and the 175 will still do the job in closer. .I will do that on my next shopping trip, thanks! |
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Don't expect every FMJ to be as accurate as the 55 FMJ Hornadys. They're a better bullet than their 55 FMJ peers, far better in fact (especially including Winchester which I think are junk quality). The Hornady 55 FMJ is a value for what you're getting.
If you want to know what a cartridge will do in your M1a/M14, shoot a 5 or even a 10 shot group off sandbags on a bench, loading rounds singly (consistent and avoids the bench double tap that M1's and M14s are prone too). As long as your rest and bench technique is good that's likely the best the combo will do. Then do the same slung prone. Unless your rifle is messed up you will see a difference between a good 168 BTHP and a standard 147/150 plinker grade milspec type bullet. For my money PRVI doesn't make match quality anything. Their match is little better than military fodder. (That includes their component bullets which I think Wideners sells as their own) Try some Black hills or Fed GMM. Shoot it off the bench, sandbagged, single loaded like I said. That'll give you a much better picture. Once you find what your gun likes and what it's capable of, get off the bench! Work on your positions again, knowing that anything bigger than your bench group is you. 
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