ax338 OCW test DILEMMA

[timelinex]

So after my initial pressure test, /i thought this was going to be easy..... HA... far from it.
Im using 300gr bergers (that were once pulled from my last brass), 215m primers, lapua brass and lastly retumbo. All bullets were seating about .01 into the lands. Weather has been relatively consistent at 80-90 degrees.

Keep in mind, while I'm new to this rifle, I have been shooting a 110ba in 338, so im not new to magnums. I could shoot that rifle relatively well and even when I did have a 'pulled' round, it would never be more than a quarter inch here or there.

Here is a a picture of a part of my pressure testing...

Judging off this small sample, I thought it was going to be easy, the entire 91-92.5gr range fell into like a half inch group! There was a stark difference in POI in the range before and after this, so it definitely seemed like a node.

Here is a picture of my first round of OCW

As you can see, groups are pretty bad overall, but its still showing that there should be a node in the same range.

Here is round 3:

This time around, everything seemed EXCELLENT, with what looked like 2 misplaced shots. I did call that I pulled that one in 92.0gr, but not the 92.5 one. Also, I didn't think I pulled it that pad.. So a bit inconclusive.

Here is my last round that I just did:

I decided to stick with 91.4gr. So I loaded 90.9gr, 91.4gr, 91.9gr (groups 2-4), and expected them all to have the same POI ,each be a nice small group and between all 9 shots make a less than moa group. Well that was definitely wrong. while 90.4 and 91.4 had similar POI, 91.9 was almost a whole inch higher. .The rest of the groups is me doing 91.4gr with different variations of using a chrono(magnetospeed) to get the speed and suppressor. Check out that round on group 5 though. Its WAAAAAAAY up there.Makes no sense. I did not pull it. The only thing I can think of, is mysteriously, on my piece a paper was a very small pen tip size hole. I'm thinking its possible that the jacket somehow started falling apart on that bullet, and that what created the hole and diverted shot? Here's a close up of that hole below the group.

Anyways. I'm looking for some advice here. Something funny is going on. I've been using a chargemaster, that has done well for me in the past. When I got home today, I even double checked it with a beam scale and the charges were always within .1gr of target(usually right on)

Lastly, chrono numbers aren't looking too good either.. I'm getting SD's of around 16 with 3 shot groups.. When on my 110ba I would get ES's of <5 over 5 shot groups. Lastly, when I did pressure testing, my chrono showed velocities
91:2736
91.5:2759
92gr:2777

while right now my 91.4gr velocities avg'd around 2790. The magnetospeed has always been very consistent from range trip to rangetrip with my other rifles, so I doubt its that....

I dont know what to do. I can start from scratch, but 338 components aren't exactly cheap!

Any advice?

 

[timelinex]

The one thing I wanted to add is that the only 'trouble" I had in this last range trip was that after I fired all my rounds, I moved the elevation turret on my vortex RAZOR and after a few clicks it stopped clicking. It looks like the 3 zero stop screws weren't tight enough and came loose. However the 'outer' turret was still in tact very well. So I don't think this could have done anything to negatively effect results, since the turrets stayed at '0' the entire time throughout testing.

 

[ChrisGarrett]

No offense buddy, but you seem to be over analyzing this to the Nth degree.

2790 fps for a 300gr bullet out of at 27" tube is an excellent velocity and getting into the 'hot' or 'very hot' category. I think that the original mil spec was 2800 fps with the 300s and 2950 fps with the 250s.

I don't know about you, but I'm good for about 40-60 rounds of 338LM per session, taking my time like you're doing and so that's two, or three, boxes of 20 rounds. Take two, or three loads with varying powder charge weights and load up twenty rounds of each, keeping everything else the same. That's four 5 shot groups for each charge weight and see what you see.

On the next session, if you're not happy with the initial batches, switch it up and see.

Chris

 

[timelinex]

No offense buddy, but you seem to be over analyzing this to the Nth degree.

2790 fps for a 300gr bullet out of at 27" tube is an excellent velocity and getting into the 'hot' or 'very hot' category. I think that the original mil spec was 2800 fps with the 300s and 2950 fps with the 250s.

I don't know about you, but I'm good for about 40-60 rounds of 338LM per session, taking my time like you're doing and so that's two, or three, boxes of 20 rounds. Take two, or three loads with varying powder charge weights and load up twenty rounds of each, keeping everything else the same. That's four 5 shot groups for each charge weight and see what you see.

On the next session, if you're not happy with the initial batches, switch it up and see.

Chris

Chris,

Thank you for chiming in.

My disappointment isn't with the velocity, but rather the inconsistency of my results.

I've done OCW on a couple rifles now and I am sitting happy with the results. I've changed brakes, added suppressors and shot in all kinds of temperature, and they always continue shoot great with the same load. Which is supposedly the point of doing an OCW.

This time however, with this rifle, it seems like results are bit sporadic.

So weights what are you recommending then? The ones I've already been working with, or just something like 90, 91.5 and 93gr and see what ends up better.

The only other idea ive have had is load up 20 of the 91.5 and just take it out to 1500+ to see the results.... Understand that if this was 223 or even 308,i wouldnt mind loading up however many it takes until I get it down right... But with 338 every shot is alot more expensive and is wearing the barrel...

 

[ChrisGarrett]

I didn't see where you stated the distance of your OCW shots?

OCW presumes that you're a rock solid foundation when you're shooting each and every shot. Especially at 300, 400, or 500 yards, it doesn't take much of a pulled shot to skew the results.

I mean really, did you just get lucky on 91.5grs, or is it really that much better than 91.0grs? Maybe a little of each, but both of those are worth pursuing if you ask me? Now...if those shots are at 100 yds and from a Ransome rest, maybe you just stick with 91.5grs ?

Personally, I'd load up two boxes, one at 91.0grs and the other at 91.5grs and go from there. It's 40 rounds of practice, if anything.

Chris

 

[timelinex]

I didn't see where you stated the distance of your OCW shots?

OCW presumes that you're a rock solid foundation when you're shooting each and every shot. Especially at 300, 400, or 500 yards, it doesn't take much of a pulled shot to skew the results.

I mean really, did you just get lucky on 91.5grs, or is it really that much better than 91.0grs? Maybe a little of each, but both of those are worth pursuing if you ask me? Now...if those shots are at 100 yds and from a Ransome rest, maybe you just stick with 91.5grs ?

Personally, I'd load up two boxes, one at 91.0grs and the other at 91.5grs and go from there. It's 40 rounds of practice, if anything.

Chris

OCW is at 100 yards. If it was at 200+ I would not be complaining about the results!

This was all done at a range with a good prone platform... Or at least, the same exact platform each time.

This is with pulled bullets, so I wouldn't be disappointed if the groups werent too good the entire time. However some of the times out it was great grouping and other times it was not consistent with that.

I think I will load 20 of the 91.4 and just try that out at the range next time. See if i can find some consistency with atleast the same load.

 

[timelinex]

Well I tried again yesterday with a couple different variations and nothing worked. It grouped at around 1 inch, like every other Damn charge I put through it.



That's a 3 round and 6 round group. As seen from the 6 round group, no vertical or horizontal stringing that would signify a problem. Just plain old 1 moa random variation.

I'm thinking it might be that this rifle just does not like this particular combo of parts. I bought some factory Hornady match ammo to try and some 285gr Hornady bullets. Loaded up an OCW window new bullets and will be running it today.

 

[Dogtown]

I'm thinking it might be that this rifle just does not like this particular combo of parts. I bought some factory Hornady match ammo to try and some 285gr Hornady bullets. Loaded up an OCW window new bullets and will be running it today.

Dude, I went through the same exact head-scratching frustration trying to get 285s working with my 26" barrel. After a few months and about 150 bullets, I just gave up thinking that I'd somehow lost the ability to properly work up a load. After a week of sulking I decided to give 300 Scenars a try (I'd dismissed them six years earlier) just as 500gm of N570 showed up. I found a good load on my first outing, refined it a bit on the second outing, then shot it in a couple of matches, all of which made me happy.

 

[timelinex]

Dude, I went through the same exact head-scratching frustration trying to get 285s working with my 26" barrel. After a few months and about 150 bullets, I just gave up thinking that I'd somehow lost the ability to properly work up a load. After a week of sulking I decided to give 300 Scenars a try (I'd dismissed them six years earlier) just as 500gm of N570 showed up. I found a good load on my first outing, refined it a bit on the second outing, then shot it in a couple of matches, all of which made me happy.

I'm glad I'm not the only one!

Well I went to try out the 285's today and what a relief, success! I did a ladder from 91gr to 93.5gr and here are the results.

To be honest, they all have about the same POI, so thats great news. It does seem like 92.5 is a scatter node though because the group really opened up, and the group right before it is one of the tightest (generally signs of a scatter node)

The group 7 text is superimposing groups 2 and 3 together and group 8 is superimposing groups 5 and 6 together. Less than 3/4 a moa over the entire grain with 6 shots and thats before even playing with seating. I would call that not bad!

So now I have to decide whether to go with 92.0gr or 93.5gr. Any suggestions? There didn't seem to be any kind of major pressure issues anywhere within the OCW range. 92gr was about 2870fps and 93.5 was about 2915fps. This particular chrono reads them a little faster than others though (generally knock off 20-30fps).The 93.5 had better velocity spreads though.

decisions decisions.

 

[Dogtown]

If the accuracy is similar and there are no pressure signs, I'd take the higher velocity of the two.

 

[ChrisGarrett]

Dude, I went through the same exact head-scratching frustration trying to get 285s working with my 26" barrel. After a few months and about 150 bullets, I just gave up thinking that I'd somehow lost the ability to properly work up a load. After a week of sulking I decided to give 300 Scenars a try (I'd dismissed them six years earlier) just as 500gm of N570 showed up. I found a good load on my first outing, refined it a bit on the second outing, then shot it in a couple of matches, all of which made me happy.

I remember back in '05 and '06, when I was first got my Savage 10FP LE2b and was getting decent 5 round groupings, but groupings that were 1", 1.5" and 2"--all there, but rarely sub MOA as a whole.

I got on here and lamented about it and was all set to just sell the rifle off after 700 rounds of blasse' shooting until one day when I went shooting with a buddy and it just started shooting MOA and better. All the same loads, nothing really changing except rounds down the pipe. Great groups and I still have pictures of the targets to prove it.

I remember the day vividly and thought that this couldn't be happening, but it's been nuts on with 150s up through 190s, for about 3000 rounds. Most of us think that ~200 rounds is sufficient, but not always.

Keep shooting it and see. A 500 round break-in on a 338LM might be painful, but if your rifle does what mine ended up doing, you'll be quite happy.

Chris

 

[timelinex]

If the accuracy is similar and there are no pressure signs, I'd take the higher velocity of the two.

Well generally I would agree with you. However, compared to most other peoples loads with these, it seems like 93's is a high charge... And I know I have read that many times 338lm doesn't show classic signs of pressure. Keep in mind, I'm not looking for a light load to maximize case life. I think that defeats the purpose of using 338lm. However, I also don't want to use such a high pressure load that it causes case head separations after only 3-4 loadings or less.

Here is a picture of all the case heads, on the left is 91gr, on the right is 93.5gr

Here is a picture of 91gr closeup, next to a new cartridge

Here is the same thing but next to 93.5gr

Keep in mind the shiny swipe on the inside is from uniforming the pockets, not from the bolt. So I don't really see any pressure sign differences between the two charges.

The main difference I see is when I measure the area where casehead separations occur. A new piece of brass has a measurement of 0.577, the 91gr has a measurement of 0.580 and the 93.5 has a measurement of 0.582 . How much growth is considered "OK"?

 

[ChrisGarrett]

You almost need a more precise and accurate caliper to measure case head expansion and while your numbers seem to be off quite a bit in that regard, your cases are going to go through an initial expansion to fit your chamber, so numbers will increase, in the beginning.

You can always do the 'paper clip test' and know for sure, if incipient case head separation is occurring.

Your cases look fine to me, BTW.

I'm on 13+ cycles with some of my Lapua brand brass, so you've got a ways to go I'd imagine?

Chris

 

[timelinex]

You almost need a more precise and accurate caliper to measure case head expansion and while your numbers seem to be off quite a bit in that regard, your cases are going to go through an initial expansion to fit your chamber, so numbers will increase, in the beginning.

You can always do the 'paper clip test' and know for sure, if incipient case head separation is occurring.

Your cases look fine to me, BTW.

I'm on 13+ cycles with some of my Lapua brand brass, so you've got a ways to go I'd imagine?

Chris

Good to hear your view on the matter. I will go with 93.5 then.

Time to move on to the last stages.

I think I will try to do 9 rounds total of charges between 93-94 to make sure it's a good tolerant node.

Then 5 rounds each of the current depth(supposedly .01 into lands) , .01 deeper, and .02 jump.

 

[Glockin' Bob]

You might try letting those 300 gr. Bergers jump a bit more. Try some loads .040" from the lands and see what happens...

 

[BULL]

watching....

 

[nso123]

Try giving it a little jump like mentioned above. I have also found that 89.9gr of Retumbo is the sweet spot in my rifle.

 

[timelinex]

Try giving it a little jump like mentioned above. I have also found that 89.9gr of Retumbo is the sweet spot in my rifle.

It's not even worth going back to the bergers. I tried playing with seating depth and it didn't help. It's odd, but I guess the rifle just really doesn't like bergers with retumbo.

<90gr would definitely be too low of a charge for my purposes. I never take out the rifle unless I'm shooting over a mile. At 2000+ yards, I need all the velocity I can accurately get!

 

[timelinex]

Just finalized my load and zeroed everything at the 100 yard line.

I was getting pretty good results with my 285gr Hornady (between .4 and .7 moa depending on the group). Then I started using a new lot of Retumbo (almost ran out of the last) which tightened things up even a little more to my surprise. I had to add .5gr to match my last loads velocity. I was surprised that this lot was so much slower than my last one. But now that I got these results, I'm leaving the remaining 1lb of the old lot and using strictly my new one!

So here is my final load is

285gr Hornady .012" into the lands
Lapua brass
215m primers
93.9gr Retumbo

Velocity ~2890 with suppressor.

I'm glad I tried the hornady's and it all finally worked out. I was SO frustrated with the amount of lead I sent down range, just to see disappointing results. Now the results are FANTASTIC.

Yes, they are only 3 round groups... But good enough for me. Group number 4 I couldn't believe how small it turned out. Literally all in one hole, just barely enlarged it. I wouldn't believe it myself at first.

So to anyone reading my thread and having similar difficulties.. don't waste any more of your time, try to change your components.


I will be confirming these results at 1500 and 1950 yards within a week hopefully.

 

[Tristian19]

Timelinex,

Just came across this thread and very interested in seeing your results. I am in load development right now for my new .338 Lapua rig who is less than 2 months old.

If I read your components correctly I am running same in my initial test load.

285 Hornady over Retumbo inside of Lapua with 215M.
* Nodes areas for me appeared to 89.8, 92.0 and 93.7.
I have not narrowed down nodes using .1 grain as of yet followed by seating depth.

Chrony results:
91.8 ~ 2755 (2760, 2760, 2743, 2754)
94.0 ~ 2855 (2855, 2855, missed)
94.3 ~ 2874 (2892, 2873, 2873)

05.02.14
Temp: 64F
DALT: 1016-1119
Alt: 515'
Pressure: 29.19
HUM: 38.4
DPOIN: 40.0-40.2
WETB: 52.0
MOST CLOUDY

I am hoping it is decent weather so I can hit range this weekend to continue Load Development. Rained hard last two scheduled range days.

Other two loads:
300 SMK and 300 OTM
Retumbo
215M
Lapua Brass

 

[Lowlight]

You're welcome,

no one listens and just wants to argue with me because they heard from guy shooting rocks a mile away how great the other bullets are...

I get it, it's vogue to disagree with me, but lucky for many I am not deterred and will continue to make my point, as demonstrated here by, not me. That e tra 120fps will come in handy, and with extra accuracy= winning.