Messing with OAL

[NiteQwill]

After the fiasco of Hornady's latest news, I decided to shoot off the rest of my AMAX's and break open some Berger 140 gr VLD bullets I've had laying around

Using 42.0 gr of H4350 inside Hornady brass trimmed to 1.915, I loaded 8x4 (32) pills at various lengths, starting with a 0.010 jump all the way to 0.120. Length was measured using Hornady's OAL & bullet comparator. Necks are NOT turned.

Weather was great today to go shooting but my trigger finger may have been a little chilly by SoCal weather standards...

Top row were 3 round groups shot with a Magnetospeed chrono.
Bottom row were 5 round groups shot without a chrono.

(Cold bore using 41.9 gr 140 AMAX on the top left dot. Regarding the groups, my rifle is zero'd for 200 yards. Barrel was shot straight, with the greatest rest period being ~5 minutes between groups. Measurements were done using a digital caliper minus bullet diameter [ignore the blackouts and bottom number {smallest group}, not so great at math ])

Now, I'm stuck. I don't know if I should go with 2.196 or 2.226 OAL, or somewhere inbetween. Thoughts?

[LeadFarmer74]

Interesting read. Well you now has a min 2.196 and a max of 2.226. The only thing I could suggest is load up maybe 10 of each and see how they group or break those max and mins into 5 new loads and test from there.

[slamfire1]

You really need to shoot more rounds per group to show that you have a trend.

[BigJ]

+1 on more per group. 5 shots minimum in my experience.

Also what made you settle on that powder charge?

[micro911]

I used to shoot 10 shot groups. It gives me better idea.

[NiteQwill]

You really need to shoot more rounds per group to show that you have a trend.

+1 on more per group. 5 shots minimum in my experience.

Also what made you settle on that powder charge?

5 shot groups were on the bottom row. But yes, I usually shoot 10 - time limited today.

Looking for ~2750 fps for long range. 42.0 gets me there, with a small ES.

I used to shoot 10 shot groups. It gives me better idea.

Next day at the range will be 10 round groups around the smallest OAL's.

[NiMiK]

Have you tried .015 off the lands and playing with the powder charge? I've had great success playing with different charges before fine tuning on the seating depth.

[RandyD]

There is a difference in using COAL and measuring how far the ogive is from the lands. All bullets, even those from the same lot tend to have a variance in length, so in using the COAL method, you have an unknown variable with each bullet. I would suggest changing over to the measurement relative to the lands. Next, I would suggest using at least a 300 yard range to test the accuracy.

[NiteQwill]

Have you tried .015 off the lands and playing with the powder charge? I've had great success playing with different charges before fine tuning on the seating depth.

Basically, I've been using this method for awhile now. It's worked well for me without having to chase charges.

There is a difference in using COAL and measuring how far the ogive is from the lands. All bullets, even those from the same lot tend to have a variance in length, so in using the COAL method, you have an unknown variable with each bullet. I would suggest changing over to the measurement relative to the lands. Next, I would suggest using at least a 300 yard range to test the accuracy.

I use a comparator, so yes, I measure at the ogive. Not the bullet tip. I basically take 3 bullets (Bergers have been consistent in my past experience) and take 5 measurements off the lands, then take the average among all measurements, and go from there when determining jump.

I'll take it out to 300 once I settle on a load get and to Pala (goes out to 897 yards). The rifle itself has seen its legs stretched to 1300 yards with my old load during a course of fire in Nevada.

[Metal God]

That bottom row shows a pretty consistent flyer up and right . Did you call those or is it something in your shooting ? Were they any specific shot number . Meaning all flyers were the first or last shots in the string ?

If that bottom row is really 5 shots each . That first and third targets are crazy good . No way I'd believe those were 5 shots unless I watched you shoot them.

[BigJ]

Looking for ~2750 fps for long range. 42.0 gets me there, with a small ES.

Understood and appreciated, but nothing says your system likes that exact FPS.

FWIW, I've heard more than once "charge, then jump" from some of the best LR and BR shooters in the country. These same guys say you can even sometimes skip the jump part; the results youll get from finding the right charge are dramatic, and often changing the jump has a relatively minimal affect. Depends on your goals and level of your build.

Or to put it another way, changing jump changes the volume inside the case available for powder to burn... what did the chrono show between your shortest and longest OAL? Are you dealing with two variables; a changing jump and a changing FPS? How do you know which is accounting for your results? Maybe it's a combo of both? By knowing what charge your gun likes first you can plunk yourself in the middle of that FPS "node" and minimize the affect the change in FPS is having on your jump test (or eliminate it by using a program like Quickload to tweak the charge for the new COAL for each test so FPS stays the same)

You might want to consider a series of "optimal charge weight" or "ladder" tests to find your system's sweet spot. Then move on to jump if you think the additional wear on the barrel is worth it.

PS: that Berger article you linked is good, but it's generally considered a marketing peice. It was written in response to the bad press VLDs started getting; turns out the VLD design specifically is unusually sensitive to jump. Most I've talked to consider it overkill for projectiles of pretty much any other design, and all think its only helpful to follow as a test procedure after you've determined what charge your system like best. FWIW.

[NiteQwill]

That bottom row shows a pretty consistent flyer up and right . Did you call those or is it something in your shooting ? Were they any specific shot number . Meaning all flyers were the first or last shots in the string ?

If that bottom row is really 5 shots each . That first and third targets are crazy good . No way I'd believe those were 5 shots unless I watched you shoot them.

All first shots. Honestly, probably just me. Due to time constraints, I was itching to get the first round off for each group. Thanks.

Understood and appreciated, but nothing says your system likes that exact FPS.

FWIW, I've heard more than once "charge, then jump" from some of the best LR and BR shooters in the country. These same guys say you can even sometimes skip the jump part; the results youll get from finding the right charge are dramatic, and often changing the jump has a relatively minimal affect. Depends on your goals and level of your build.

Or to put it another way, changing jump changes the volume inside the case available for powder to burn... what did the chrono show between your shortest and longest OAL? Are you dealing with two variables; a changing jump and a changing FPS? How do you know which is accounting for your results? Maybe it's a combo of both? By knowing what charge your gun likes first you can plunk yourself in the middle of that FPS "node" and minimize the affect the change in FPS is having on your jump test (or eliminate it by using a program like Quickload to tweak the charge for the new COAL for each test so FPS stays the same)

You might want to consider a series of "optimal charge weight" or "ladder" tests to find your system's sweet spot. Then move on to jump if you think the additional wear on the barrel is worth it.

PS: that Berger article you linked is good, but it's generally considered a marketing peice. It was written in response to the bad press VLDs started getting; turns out the VLD design specifically is unusually sensitive to jump. Most I've talked to consider it overkill for projectiles of pretty much any other design, and all think its only helpful to follow as a test procedure after you've determined what charge your system like best. FWIW.

I'll play with the charges next.

My last load development with AMAX's had me going as high for 43.8 gr H4350 with good groups. I honestly went with a lower charge simply because I didn't want to beat up my barrel. During that time, I noticed how sensitive my barrel was to jump (Brux barrel cut from 140 AMAX's).

[BigJ]

During that time, I noticed how sensitive my barrel was to jump (Brux barrel cut from 140 AMAX's).

It is? If I understand you correctly, you've got four in the same hole for those first three jumps. Relatively speaking .080 between the three is a HUGE number, and yet you're still putting 4 AMax's in the same hole (a middle of the road bullet by all accounts) with the 5th flier probably being your fault and not the ammo/gun. I dunno if I'd call that sensitive to jump

[RandyD]

I use a comparator, so yes, I measure at the ogive. Not the bullet tip. I basically take 3 bullets (Bergers have been consistent in my past experience) and take 5 measurements off the lands, then take the average among all measurements, and go from there when determining jump.

I'll take it out to 300 once I settle on a load get and to Pala (goes out to 897 yards). The rifle itself has seen its legs stretched to 1300 yards with my old load during a course of fire in Nevada.

I see you provided a link to Berger Bullets, I would follow their procedures. I like your procedure.

We may encounter each other at Pala. I have a walking varmiter rifle that I had built, and now I need to work up some loads. I need to begin by breaking in and cleaning the barrel after each shot. I recently joint Pala and will be doing my load testing and working up using the Pala range. I was planning on going on Mondays and was going to start in a couple of weeks.

[NiteQwill]

It is? If I understand you correctly, you've got four in the same hole for those first three jumps. Relatively speaking .080 between the three is a HUGE number, and yet you're still putting 4 AMax's in the same hole (a middle of the road bullet by all accounts) with the 5th flier probably being your fault and not the ammo/gun. I dunno if I'd call that sensitive to jump

Sorry. To clarify, the above picture was with Bergers. Yes, 4 shots in one hole + flier.

With my previous AMAX load (probably around 750 rounds), they were so sensitive to length that even a 0.020 change changed my POI 3/4 MOA and opened my groups considerably. I don't have my data in front of me right now but my OAL was somewhere a tad bit longer than magazine length.

Maybe the Bergers are the right bullet for my gun, then. I will probably use my 3rd group and I'll take your suggestion and work up some charges on the next run. Thanks

I see you provided a link to Berger Bullets, I would follow their procedures. I like your procedure.

We may encounter each other at Pala. I have a walking varmiter rifle that I had built, and now I need to work up some loads. I need to begin by breaking in and cleaning the barrel after each shot. I recently joint Pala and will be doing my load testing and working up using the Pala range. I was planning on going on Mondays and was going to start in a couple of weeks.

Perfect. Yup, I've been a member there for a few years now. While their fees are expensive, I find the facility (and the steel) more enjoyable to shoot at versus other ranges. My work schedule allows me to shoot on Monday and Friday. You will also find me shooting in the LDF matches once in awhile.

See you there maybe!