300 grn 338 Berger test @ 3000+fps

[RDM416]

Got in a little trigger time today.

Rifle: 338 Kubla Khan, built by Kirby at APS. Nesika action, 30"Lilja, PK brake, A5 stock, NF NXS 5.5-22X56. Rifle has about 100 rounds down the new barrel just intalled by Kirby.

I set out to test changes (if any) from changing the seating depth of the 300 grain Bergers. I loaded 3 sets of 3 rounds using 105 grains of Retumbo, Fed 215M.

I have shot the Bergers in my other Khan, but this is first Bergers I have shot from this rifle. Load was based on development done on a different rifle at lower velocity of 2875fps using 102 grains of Retumbo.

The average speed as checked on an Oehler model 35 with 3 sky screens = 3024fps.

The test range was 300 yards with a 5 to 8 mph variable wind from left to right.

Group 1: 3022fps / 3017fps / 3024fps
Bullets seated .009 off the lands.
Group size in in MOA = a little under 1/2 moa

Group 2: 3024fps / 3022fps / 3018fps
Bullets seated .006 off the lands
Group size in MOA = Just over 1/4 moa

Group 3: 3032fps / 3027fps / 3032fps
Bullets seated .003 off the lands
Group size in MOA = 3/4 moa

Shot #3 on group 3 could have been me, the shot did not "feel" good, but I did not have another round loaded to try again.

Other than shot 3 group 3 the groups were shrinking in size as the seating depth got closer to the lands.

Velocity took a noticable jump on group 3 which would indicate pressures are going up as the bullet has less room to "jump".

Conclusion........ More testing needed, guess I'll just have to shoot some more.

Maybe conclusions: IF, big IF..... shot 3 group 3 was me, the Bergers look like they will handle 3000+fps with this rifle and load.

Now that I know this rifle likes the Bergers seated close to the lands, I will do the same type test with powder charges and probably try some other powders... H1000, 50BMG, and RL25 are the usual suspects. With the powder fine tuned I think it is very possible to get her to shooting 1/4 moa with the bergers.

Comments, and suggestions welcome. Just thought the 338 guys out there would like to know the result of a test of the 300 grain Bergers at over 3000fps.

 

[trebark]

Your third group is my typical experience with Bergers...two shots go in one hole and the third opens the group to .75 MOA. Have not found the formula that will stop the "flier". Would be interested to hear if and how you manage to remedy the issue.

 

[groper]

what barrel twist and rifling was used in this test? also throat lead/freebore and angle would be nice too...?

 

[RDM416]

Your third group is my typical experience with Bergers...two shots go in one hole and the third opens the group to .75 MOA. Have not found the formula that will stop the "flier".

Yeah, that is why I'm hoping further testing will show it was just me. If you notice both group 2 and 3 have the flier that dropped low and right from the group. Just was not as much in group 2. If you overlay group 2 and 3, and drop shot 3 from each, you pretty much have 4 out of 6 into the same ragged hole. I will load up a few more and try this again in a few days.

 

[RDM416]

what barrel twist and rifling was used in this test? also throat lead/freebore and angle would be nice too...?

I don't have the specs on the reamer, so I can only partially answer. The barrel is 1/10 RH twist. Kirby cut the throat long, specifically for a 300 grn SMK, although I do not have the actual spec. Hope that gives you some of what you were asking for.

 

[ICANHITHIMMAN]

Where is the gun porn?

 

[trebark]

Yeah, that is why I'm hoping further testing will show it was just me. If you notice both group 2 and 3 have the flier that dropped low and right from the group. Just was not as much in group 2. If you overlay group 2 and 3, and drop shot 3 from each, you pretty much have 4 out of 6 into the same ragged hole. I will load up a few more and try this again in a few days.

I assure you that this phenomenon is not you. I have this same thing happen in two rifles - a 260 and a 280.

 

[jmden]

Very interesting, RDM416. Thanks for sharing that and please keep us informed as you develop more data and experience.

BTW, how did Kirby throat your rifle? Did he use the 'hybrid' or 'modified hybrid' or a more traditional steeper angle throat?

Jon

 

[Camshaft]

I also have had issues with a flier in my groups in my 300rum and Retumbo. Running 210vlds at 3180fps. But when using the same bullets in my 300wsm at 2850fps I can shoot one ragged hole at 100yards using H4831.

 

[RDM416]

Icanhithimman, I'll get a pic of the rifle posted tomorrow..... it's too late tonight to go back down to the basement, take a pic.......

jmden, I think he used a traditional steeper angle throat, but I am really not sure. With both my Khan's he used a throat reamer to make the throat longer than the standard Kubla Khan reamer. The principal reason he and I talked about was so I could seat the long 300 SMK farther out to gain additional case capacity. Maybe Kirby will run across the thread and answer these more detailed questions on the throat lead and angle. I just have not gotten that far into the specifics with him. I give him the major requirements, send money....... wait...... he ships me a rifle and it shoots real good.

My older Khan built on a Wby MK V action was built with the same reamer and throated the same. I have been shooting the Bergers through it at 2875fps using 102 grains of Retumbo. It will shoot 1/4 moa with only a VERY occasional round dropping out of the group.

I may try loading some down to the same velocity for this rifle and see it that is it. I may just be seeing the same thing most everyone else is with the Bergers at higher velocities.

I'm still not sure it was not just me, I have been hunting for the last few months rather than shooting so I have not had a lot of trigger time lately. As I said before, if you take away the two fliers out of the last two groups and overlay them, it would be a sub 1/4 moa 4 shot group, maybe I just blew it with those two shots. I'll keep testing, the averages will start to stack up one way or the other after a few more rounds.

 

[trebark]

My older Khan built on a Wby MK V action was built with the same reamer and throated the same. I have been shooting the Bergers through it at 2875fps using 102 grains of Retumbo. It will shoot 1/4 moa with only a VERY occasional round dropping out of the group.

I may try loading some down to the same velocity for this rifle and see it that is it. I may just be seeing the same thing most everyone else is with the Bergers at higher velocities.

I'm still not sure it was not just me, I have been hunting for the last few months rather than shooting so I have not had a lot of trigger time lately. As I said before, if you take away the two fliers out of the last two groups and overlay them, it would be a sub 1/4 moa 4 shot group, maybe I just blew it with those two shots. I'll keep testing, the averages will start to stack up one way or the other after a few more rounds.

I would tend to agree that velocity might be the culprit here. I use VLDs pretty much just for hunting. So I push them about as fast as the cartridge will allow (140VLD in 260 going 3000fps and 168VLD in 280 going 2800fps). I've never tried to back the velocity down.

 

[jmden]

BTW, RDM416, what is your load/mv for the 300SMK, out of curiousity? I haven't shot any of the Bergers out of my 30" modified hybrid throated .338 AX yet, but was kind expecting the similar velocities out of it as you are getting. My current load is 102.0g Retumbo under the 300 SMK for 2980 ave. MV, but I think I'm going to back off of that a 1/2g or so next time I load.

 

[davewilson]

first off, thanks for your post/information. it's the kind of stuff we all "dig" i don't want to sound like Mr. negative, but assuming you have a group and flyers with 3 of the 9 shots, 33%, being called flyers is a pretty strong number. i'm not going to advocate shooting at least 15 shot groups like Bart B did, but i think you're making some assumptions without nearly enough information. i also don't agree with your assumption that they like to be close to the lands. certainly they might, but testing at 3 6 and 9 thousands off is way too fine of adjustments for starting loads. i had a fellow with a lot of competition and long range hunting experience tell me to experiment loading the 338 bullets .05 off for better accuracy. it held true for both of my 338's. i guess the point i'm trying to make is you're making conclusions based on way too little data.

 

[RDM416]

Icanhithimman, Here is your "gun porn"

jmden, With the first barrel (I just had replaced afer 1500 rounds) I was mainly shooting 250 SMKs. My load for them was 107grn RL25 / Fed 215M, 3350fps. I did work up a load for the 300 SMKs, 103 grn RL25, 3120fps.

With the new barrel I have wanted to focus on 300 grain bullets and had high hopes for the Bergers. Also, I want to get away from RL25 which gives me good velocity numbers, but is too temperature sensitive. Since getting the rifle back from Kirby I did a little testing with the 300 SMK working up to 106 grains of Retumbo which gave me 3050fps. I was having trouble with my scope/rings/base (my fault not Kirby's) so switched back to a known load with the 250s until I got the problem(s) worked out. Now I am back to trying to work up a load using either 300 grain Bergers or SMKs along with a different powder...... Retumbo is where I have started since I have quite a lot on hand.

Good luck with your 338AX, that is probably what I would have gone with when I had this rifle first built if Kirby had had it developed yet. Just ordered a 338AM from Kirby a few months ago, can't wait for it to come in!!! But, I guess I will have to.gun)