Anyone have experience/luck reloading for ar10/15 accuracy by adjusting bullet jump?

[Morndorff95]

Jump can have an effect on accuracy as has been stated. I do not however fool with it in gas guns I load the bullets mag length and forget seating depth after that. Just adjust powder charge for best accuracy if that fails to give the accuracy you find acceptable change powders. There are some bullets that simply don't shoot well out of some guns also. In AR-15 with light bullets 50-55gr try Benchmark powder for heavies 75-77gr try IMR 8208 XBR powder. If you can achieve MOA with a gasser your doing well. Also a trigger upgrade from Mil spec will help achieve MOA accuracy.

I've been trying out a couple different different powders and bullets without adjusting seating depth. Last trip to the range and just got to a 1.1" group @ 100 yards with 23.5gr CFE 223 and 75gr Hornady match HPBT. Tried 68gr match HPBT with no luck at all. And a 1.2" @ 100 with 42gr IMR 4064 and 168 gr Hornady match HPBT in the 308. Making fine adjustments in powder for this weekend to test. Also have had Rise Armament RA434 triggers in both guns.

 

[Old Rooster]

I've been trying out a couple different different powders and bullets without adjusting seating depth. Last trip to the range and just got to a 1.1" group @ 100 yards with 23.5gr CFE 223 and 75gr Hornady match HPBT. Tried 68gr match HPBT with no luck at all. And a 1.2" @ 100 with 42gr IMR 4064 and 168 gr Hornady match HPBT in the 308. Making fine adjustments in powder for this weekend to test. Also have had Rise Armament RA434 triggers in both guns.

let me know how it works out.I use 24.7 gr Tac and 55 gr Hornady spire point and get 1 inch groups most of the time.
Looking to see if maybe I could do a little better.

 

[mongo4567]

Put intended quote below

 

[mongo4567]

I've been trying out a couple different different powders and bullets without adjusting seating depth. Last trip to the range and just got to a 1.1" group @ 100 yards with 23.5gr CFE 223 and 75gr Hornady match HPBT. Tried 68gr match HPBT with no luck at all. And a 1.2" @ 100 with 42gr IMR 4064 and 168 gr Hornady match HPBT in the 308. Making fine adjustments in powder for this weekend to test. Also have had Rise Armament RA434 triggers in both guns.

I found what I believe to be an issue with temperature sensitivity with CFE223 and one slow twist rifle. I had a very small node that kept moving based on temperature in the summer. It would be .5" to 1.5" depending on what the temp was....found the issue when I went back to confirm.

 

[Kansaswoodguy]

I've used maybe 10lbs of CFE 223 not my favorite powder for accuracy but meters great so I do use it for Prairie Dogs. Tomorrow if I get over to the other house I'll look up my dog load and post it.

 

[NW NM hunter]

So I'll start off by saying I'm new to this but have read certain bullets do better with a jump. So for my PSA ar10 6.5 creedmoor I ran 140 eld-m bullets with good success. My understanding the eld-m line seems to like a jump. I'm loaded just .01 over the hornady COAL listing to fit my mag length. I'm a little under 1 moa with 3 shots but still tweaking the powder volume.

 

[ElkSurgeon]

I just got into reloading and have an AR10 (308) and AR15 (5.56) and was wondering if anyone has had any luck in regards to accuracy by adjusting bullet jump, or if the magazine is enough of a limiting factor to where length of the bullet seating depth to the leads would make it not be worth it to mess with jump at all. Ex. Not being able to seat the bullet further up and there by not fitting in the mag. And if I should just focus on the powder load for the best reasonable accuracy.

I know every chamber is different and jump is more of a term/applicable for bolt rifles, but if there are people who have had success or even failure with adjusting jump for ARs then I would like to hear about your experience with it before I invest in the tools to pursue it instead of just using measurements from factory match loads. I would definitely pursue that after developing a reliable powder load if people have had luck with it.

My ARs are stock Diamondback DB10BGB and DB15BGB if it matters. I also various bullets for my twist rates and powders based off of several relaoding sources to test so im good there. I know I'll never achieve BR rifle accuracy or probably even bolt rifle accuracy with them but I'm looking to make loads for them as accurate as possible so when I hunt with them I know I will be as accurate as possible at ranges 300-500 yards max so shots will be as clean as possible.

I would start off by upgrading your triggers in both rifles. Helped me a lot with groups when I replaced my 7lb triggers & my AR platforms significantly improved on groups. I'm playing around with my 5.56 currently working on groups & loads. I've got Hogdon Benchmark & a Lee Factory Crimp die, found these items to help with consistency on an AR-15 platform & bulk production. As far as AR10…..mine absolutely loves RL15 & the 168gr Amax in .308. I just load to standard COAL in both calibers, never played with seating depth as I have with my bolt guns

 

[Morndorff95]

UPDATE!
For the 223, I annealed the brass* (now that is was all once fired), used 23.5gr CFE 223, seated the 75gr Hornady Match HPBT to max COL 2.250", and used a lee factor crimp adjusted to 3/4 of a turn after touching the shell holder*, to achieve the grouping below @100 yards. The one flier was because I flinched on last shot really trying to put it in the group.
*Did not anneal the brass for prior loads because it was factory new, and did not crimp before. Will be doing both for now on.
More work to do with the 308, going to try some 155gr and 178gr ELD bullets.

 

[bamban]

UPDATE!
For the 223, I annealed the brass* (now that is was all once fired), used 23.5gr CFE 233, seated the 75gr Hornady Match HPBT to max COL 2.250", and used a lee factor crimp adjusted to 3/4 of a turn after touching the shell holder*, to achieve the grouping below @100 yards. The one flier was because I flinched on last shot really trying to put it in the group.
*Did not anneal the brass for prior loads because it was factory new, and did not crimp before. Will be doing both for now on.
More work to do with the 308, probably going to try some 150/155 gr bullets.

A few guys on the NM Forum found that 75 HDY BTHP Match shot better with COL of around 2.230, + 0.005.

In case you want to play with the rifle set up, here's a good read.

Maximizing The AR-15: A former military armorer reveals his secrets for cutting AR-15 group sizes in half. - Free Online Library

Free Online Library: Maximizing The AR-15: A former military armorer reveals his secrets for cutting AR-15 group sizes in half.(TECH TOPICS) by "American Gunsmith"; Sports, sporting goods and toys industry Sport, sporting goods and toys industry

www.thefreelibrary.com

 

[budlight]

I determined that 223's are limited to 75-77gr because of the neck length. If you have delusions of shooting 80 - 90's you should have bought something else like the Valkyrie. My main powders are AR-Comp, CFE 223, TAC, power Pro Varmint for 55- 62 grain and 2000 - MR for up to the 77 gr BTHP.

Years ago I bought 10,000 of these highest BC 62 grain BTHP made and they have been my cheap shooting favorite paper and critter getters! My best AR's are match grade SS are all 20 - 24 inch piston guns with drop in triggers down to 2.5 pounds.

Quality Ar's are tight with 7075-T6 forged aluminum uppers and lowers using free float handguard that comes with a 6061-T6 aluminum barrel nut and anti-rotation tabs for an extremely strong lock up that will hold tight on any Mil-Spec receiver.

STAY AWAY from all cheap M-16 look alike rifles which require an Accu-Wedge to even get close to MOA

 

[Koda_]

I determined that 223's are limited to 75-77gr because of the neck length. If you have delusions of shooting 80 - 90's you should have bought something else like the Valkyrie.

For semi autos only, or does that include bolt guns?

 

[milo-2]

A few guys on the NM Forum found that 75 HDY BTHP Match shot better with COL of around 2.230, + 0.005.

In case you want to play with the rifle set up, here's a good read.

Maximizing The AR-15: A former military armorer reveals his secrets for cutting AR-15 group sizes in half. - Free Online Library

Free Online Library: Maximizing The AR-15: A former military armorer reveals his secrets for cutting AR-15 group sizes in half.(TECH TOPICS) by "American Gunsmith"; Sports, sporting goods and toys industry Sport, sporting goods and toys industry

www.thefreelibrary.com

Same bullet here seems to work best at 2.245", been quite some time, but I think 55gr species did best around 2.252".
I may try your suggestion, I stopped at 2.245", thanks

 

[budlight]

For semi autos only, or does that include bolt guns?

single shot and bolt guns are not limited by mag length just the free bore to the lands. If you really look into ballistic charts and use real world chronograph data of your rounds out of your gun and max accuracy is usually achieved at something less than max loaded short case life rounds. Then you plug in all the BC and data and I came to the conclusion that the heaviest bullets per caliber were not always the best because a small volume case just can't push them fast enough. The starting velocity is so low that they become more like artillery with the bullet drop. The heavies with higher BC only have a foot pound advantage way out there.

The case volume of a 223 is tiny compared to my 26 inch 22-250 where a 90 gr actually makes sense

 

[jbs2014]

Thank you all, I greatly appreciate the replies and information

We're you able to try seating them deeper? If so how did it work?