338 Jarrett reload information.

[salmonchaser]

I need a little help with my 338 Jarrett. I had the rifle built by a former employee of Jarrett rifles and to that end I have no complaints. However; the only information I was able to get was start with 340 weatherby info and work your way from there. I've been loading for about 40 years, shooting Nosler bullets since Bend had one stop light, and never deviated from the book. I have never been comfortable looking for pressure signs so I'm probably not getting everything out of the rifle it is capable of.

The rifle does shoot. Hell, when I was fireforming my first batch of cases I had a coniption fit because only the first two rounds hit the target, or so I thought. After I took a deep breath, checked everything else, I realized I had stumbled into a very accurate rifle. The rifle put 10 rounds in one ragged hole I easily covered with a dime.

Thanks in advance
Don

 

[Guy Miner]

Welcome aboard, and wow, that must be quite a rifle! Not to mention that someone is one heck of a shot.

Cool.

Where do you chase salmon? I love catching salmon & steelhead here in Washington State!

Don't know a thing about loading for your rifle, but WELCOME!

Guy

 

[sask boy]

Welcome Don, that sound like a heck of a rifle and shooting like that means the guy pulling the trigger is no slouch either.
Someone on the forum will have some info for you that I am sure of. I think you will find that the people here are lots of fun & very knowledgeable with 40 years of loading experience I am sure you will have a lot of input to our conversations .

PS. Do you shoot from the left side 8).

Blessings,
Dan

 

[IdahoCTD]

I have 2 338 Baer's which are almost the same thing (blown out 338-8mm Rem Mag.) as the Jarrett. My loads are 84grs of R-22, 85grs of 7828, and 80grs of H-1000 behind a 250gr Sierra boattail. I have some loads for the 215gr Sierra's and 200gr Ballistic tips as well but I'd have to dig them up.

 

[OU812]

What bullet weight are you running and at what speeds? Jarrett rifles won't give you any load data?

The 338-8mm in all intent and purpose is a 340 Weatherby without the shoulder radius and cheaper brass. Other names for the 338-8mm are 338 Arnold, 338 Gaillard and .338 SDM (Swamp Donkey Magnum).

This is just my thoughts. The Jarrett may have a different shoulder angle and blown out case than the above listed 338-8mm rounds but I would feel just fine using 340 Weatherby data.

Bill

 

[salmonchaser]

Bill, the jarrett does have a different shoulder angle than the Arnold, you are correct. I don't know the other two you mentioned. I called Jarrett when I got the rifle, I've heard good things about them; however, they didn't want to share any information. Perhaps I caught them on a bad day.
I have pushed the envelope a little loading 84 gr. rl 19 behind a 250 grain AccuBond. 10 shots gave me an average of 2950 fps. Accuracy fell off a little but still minute of mule deer so to speak.
Jarrett gets 2950 out of their rifles with partitions. I would like to do that but I get a little nervous when I start exceeding 340 load data. Every time I pull the trigger on the damn thing snot comes out my nose; I may as well get every ounce of energy out of it if I'm going to use it.
The good news is it kills elk, thankfully I've never needed to take a second shot so I had plenty of time to clean the snot off my scope.

 

[salmonchaser]

Bill
I've been told imitation is the sincerest form of flatery; I'd never use it here but your footer regarding the speed of light is perfect. I must admit I've already adapted it to my day to day conversations. Hope you don't mind, it simply fits so many people I meet.

Don;
Keep your head down and your powder dry.

 

[OU812]

Bill, the jarrett does have a different shoulder angle than the Arnold, you are correct. I don't know the other two you mentioned. I called Jarrett when I got the rifle, I've heard good things about them; however, they didn't want to share any information. Perhaps I caught them on a bad day.
I have pushed the envelope a little loading 84 gr. rl 19 behind a 250 grain AccuBond. 10 shots gave me an average of 2950 fps. Accuracy fell off a little but still minute of mule deer so to speak.
Jarrett gets 2950 out of their rifles with partitions. I would like to do that but I get a little nervous when I start exceeding 340 load data. Every time I pull the trigger on the damn thing snot comes out my nose; I may as well get every ounce of energy out of it if I'm going to use it.
The good news is it kills elk, thankfully I've never needed to take a second shot so I had plenty of time to clean the snot off my scope.

You could try 7828, RL25 or RL22 to increase speed but if your already getting 2950 with a 250 AccuBond I'm not sure you could ask for more. If my memory is correct the 8mm case when blown out as with your chambering will have slightly more case capacity than a 340.

Bill

 

[OU812]

Bill
I've been told imitation is the sincerest form of flatery; I'd never use it here but your footer regarding the speed of light is perfect. I must admit I've already adapted it to my day to day conversations. Hope you don't mind, it simply fits so many people I meet.

Don;
Keep your head down and your powder dry.

Enjoy and use away Don. As sad as it is I too find it to fit all to well as I go about my day.

Bill

 

[longrangehunter]

Welcome to the forum Don.

I've been a customer and old friend of Kenny Jarrett for well over a decade, his rifles are all tack drivers and I own two of them, a 280 AI and a 300 Jarrett. Who put together your gun?

Kenny has a file drawer in his reloading room with well over 10,000 load data cards for each and every customers rifle he ever built. Even though he didn't build your rifle, call up Jarrett Rifles and ask to speak to Kathy, she usually answers the phone now. She has put all of his load data on a data base, and can look up and/or tell you what has worked in the past. Please understand Kenny has built hundreds of his 338 Jarrett and she or Jay is not going to give you every load that worked! But as you can see the gun was not picky to load for when you were forming cases, his guns usually aren't. If that doesn't workout or you don't care to ask them for the load data the 340 Wby. data will get you close enough without over pressure concerns even +1-1.5 grains more then what's listed. This is what you should expect velocity wise taken directly from his website for the 338 Jarrett.

200 gr. bullet ......... 3250 f.p.s.
225 gr. bullet ......... 3150 f.p.s.
250 gr. bullet ......... 2950 f.p.s.

Good luck

 

[salmonchaser]

Cole
Thanks for the information, I'll give Kathy a call. If I could simply get a max load for three or four powders I'd be real happy. I "lucked" into the load with Rl19 and it gets me to their published load, velocity but I'm a little worried I might be a little hot given the rifle is more accurate when I drop the load a few grains.

The rifle was built by Carolina Precision rifles. I sent him my old 8mm remington he sent it back piller and glass bedded with a Pac Nor BBl. He really wanted to put it in a composite stock but I wanted the original stock. I bought the 8mm at the Corvallis Oregon Payless store when they still sold guns back in 1979 or 80. I wanted the rifle to feel familiar.

Like your jarretts it is a tack driver, shoots better than I do.

Don

 

[SJB358]

Welcome aboard, if you give me the H20 capacity, of a fired case, I could run data using 340 WBY data and change the H20 capacity to match your 338.

Sounds like an awesome rifle though..

 

[sask boy]

I knew the information would start to stream :mrgreen:. The guys here never let a mate down!!!!

Blessings,
Dan

 

[salmonchaser]

sjb 358
I've only played with the h20 capacity a couple of times. with each effort I come up with 98.5 to 100 grains. I must admit I was not very sceintific with my efforts. I attribute part of the difference may be due to some of my brass is getting a little long in the tooth. I know it must be at least 98.5 as I have found the 8mm mag has a case capacity of 98 gr. H20. Given the shoulder of the 338 Jarrett is blown forward it would be logical to assume there is at least a little more room.

 

[SJB358]

sjb 358
I've only played with the h20 capacity a couple of times. with each effort I come up with 98.5 to 100 grains. I must admit I was not very sceintific with my efforts. I attribute part of the difference may be due to some of my brass is getting a little long in the tooth. I know it must be at least 98.5 as I have found the 8mm mag has a case capacity of 98 gr. H20. Given the shoulder of the 338 Jarrett is blown forward it would be logical to assume there is at least a little more room.

SC, fill an empty, fired case from your rifle with water all the way to the top. I usually use 3 cases and take an average of the three. Weigh the empty, weigh it filled all the way to the top of the neck. Send me the difference and I will run the data..

Another thing I thought of it the Weatherby data is probably designed for a freebored rifle, where as I am not sure if your 338 has as much as a freebored rifle. Scotty

 

[JD338]

Don

Welcome to the forum.
The 338 Jarrett sounds interesting. Pretty similar to the 338 RUM performance wise.

JD338

 

[salmonchaser]

Still coming up with 98.5 to 100 grains h20. I happened to locate 10 brand new 8mms mag cases I'll fire form them next week and try again.
Not certain on the freebore, Nosler Partition touch the lands at 3.7 , accuabonds at a whopping 3.895. The longest OAL I can use given the magazine is 3.67.

 

[rick smith]

Since John Lewis built the rifle, call him. He still has a shop. Rick.

 

[salmonchaser]

81 grains rl 19/ 250 gr Nosler Pt / 3 shots .7cc. /2850 fps. Certainly accurate enough but shy by 100 fps of the rifles potential.
I still need to come up with good h20 capacity.

 

[SJB358]

I used 340 WBY stat's to run this, but QL is showing 100.00 grains H20 capacity. I do not know how to alter QL's output in order to account for freebore, if you have any in your Jarrett. But it looks like your case capacity is very close to the WBY, at least with the brass you are using right now.

Let me know what else you'd like us to run. Some slower powder may scoot your FPS up as well. Something in the 7828, MRP, RL22 would probably be pretty good as well.

No matter what comes out of it, 2900 with a 250 PT is a smashing load! I am not sure a guy could ask for anything more, far reaching and ton's of energy on target. Good luck with your load work. Keep us in the loop, pretty interesting.


Cartridge : .340 Weath. Mag.
Bullet : .338, 250, Nosler PART SP 35644
Useable Case Capaci: 88.084 grain H2O = 5.719 cm³
Cartridge O.A.L. L6: 3.675 inch = 93.35 mm
Barrel Length : 26.0 inch = 660.4 mm
Powder : Alliant Reloder-19

Predicted data by increasing and decreasing the given charge,
incremented in steps of 2.0% of nominal charge.
CAUTION: Figures exceed maximum and minimum recommended loads !

Step Fill. Charge Vel. Energy Pmax Pmuz Prop.Burnt B_Time
% % Grains fps ft.lbs psi psi % ms

-20.0 81 65.60 2352 3072 34684 8896 94.5 1.648
-18.0 83 67.24 2408 3219 37009 9143 95.4 1.604
-16.0 85 68.88 2463 3369 39486 9379 96.3 1.556
-14.0 87 70.52 2519 3522 42128 9602 97.1 1.509
-12.0 89 72.16 2574 3677 44940 9813 97.8 1.465
-10.0 91 73.80 2629 3836 47911 10010 98.4 1.422
-08.0 93 75.44 2683 3997 51061 10192 98.9 1.381
-06.0 95 77.08 2738 4160 54415 10358 99.3 1.342 ! Near Maximum !
-04.0 97 78.72 2792 4326 57988 10508 99.6 1.304 ! Near Maximum !
-02.0 99 80.36 2845 4494 61796 10641 99.8 1.267 ! Near Maximum !
+00.0 101 82.00 2898 4663 65858 10755 100.0 1.232 !DANGEROUS LOAD-DO NOT USE!
+02.0 103 83.64 2951 4835 70194 10852 100.0 1.198 !DANGEROUS LOAD-DO NOT USE!
+04.0 105 85.28 3004 5008 74826 10939 100.0 1.165 !DANGEROUS LOAD-DO NOT USE!
+06.0 107 86.92 3055 5183 79781 11024 100.0 1.133 !DANGEROUS LOAD-DO NOT USE!
+08.0 109 88.56 3107 5359 85087 11105 100.0 1.103 !DANGEROUS LOAD-DO NOT USE!
+10.0 111 90.20 3158 5538 90775 11182 100.0 1.073 !DANGEROUS LOAD-DO NOT USE!

Results caused by ± 10% powder lot-to-lot burning rate variation using nominal charge
Data for burning rate increased by 10% relative to nominal value:
+Ba 101 82.00 3000 4995 77961 10352 100.0 1.151 !DANGEROUS LOAD-DO NOT USE!
Data for burning rate decreased by 10% relative to nominal value:
-Ba 101 82.00 2749 4194 53907 10849 97.0 1.340


RL22

Cartridge : .340 Weath. Mag.
Bullet : .338, 250, Nosler PART SP 35644
Useable Case Capaci: 88.084 grain H2O = 5.719 cm³
Cartridge O.A.L. L6: 3.675 inch = 93.35 mm
Barrel Length : 26.0 inch = 660.4 mm
Powder : Alliant Reloder-22

Predicted data by increasing and decreasing the given charge,
incremented in steps of 2.0% of nominal charge.
CAUTION: Figures exceed maximum and minimum recommended loads !

Step Fill. Charge Vel. Energy Pmax Pmuz Prop.Burnt B_Time
% % Grains fps ft.lbs psi psi % ms

-20.0 83 68.00 2346 3055 32703 9276 93.7 1.686
-18.0 85 69.70 2405 3211 34998 9546 94.8 1.640
-16.0 87 71.40 2464 3370 37460 9803 95.8 1.595
-14.0 89 73.10 2523 3532 40101 10045 96.7 1.545
-12.0 91 74.80 2581 3699 42937 10272 97.5 1.496
-10.0 93 76.50 2640 3868 45986 10482 98.2 1.450
-08.0 95 78.20 2698 4041 49251 10674 98.8 1.405
-06.0 97 79.90 2756 4216 52724 10846 99.2 1.362
-04.0 99 81.60 2814 4395 56442 10999 99.6 1.320 ! Near Maximum !
-02.0 101 83.30 2871 4576 60430 11131 99.8 1.281 ! Near Maximum !
+00.0 104 85.00 2928 4759 64711 11240 100.0 1.242 !DANGEROUS LOAD-DO NOT USE!
+02.0 106 86.70 2985 4945 69311 11328 100.0 1.205 !DANGEROUS LOAD-DO NOT USE!
+04.0 108 88.40 3041 5133 74260 11408 100.0 1.170 !DANGEROUS LOAD-DO NOT USE!
+06.0 110 90.10 3096 5322 79592 11483 100.0 1.135 !DANGEROUS LOAD-DO NOT USE!
+08.0 112 91.80 3152 5515 85345 11555 100.0 1.102 !DANGEROUS LOAD-DO NOT USE!
+10.0 114 93.50 3207 5709 91561 11621 100.0 1.070 !DANGEROUS LOAD-DO NOT USE!

Results caused by ± 10% powder lot-to-lot burning rate variation using nominal charge
Data for burning rate increased by 10% relative to nominal value:
+Ba 104 85.00 3042 5138 78305 10777 100.0 1.151 !DANGEROUS LOAD-DO NOT USE!
Data for burning rate decreased by 10% relative to nominal value:
-Ba 104 85.00 2758 4222 51581 11345 96.7 1.364

IMR7828SSC

Cartridge : .340 Weath. Mag.
Bullet : .338, 250, Nosler PART SP 35644
Useable Case Capaci: 88.084 grain H2O = 5.719 cm³
Cartridge O.A.L. L6: 3.675 inch = 93.35 mm
Barrel Length : 26.0 inch = 660.4 mm
Powder : IMR 7828 SSC

Predicted data by increasing and decreasing the given charge,
incremented in steps of 2.0% of nominal charge.
CAUTION: Figures exceed maximum and minimum recommended loads !

Step Fill. Charge Vel. Energy Pmax Pmuz Prop.Burnt B_Time
% % Grains fps ft.lbs psi psi % ms

-20.0 82 68.00 2334 3024 32413 9191 91.3 1.676
-18.0 84 69.70 2394 3182 34679 9480 92.6 1.630
-16.0 86 71.40 2455 3346 37109 9758 93.8 1.585
-14.0 88 73.10 2516 3513 39716 10021 94.9 1.534
-12.0 90 74.80 2576 3685 42518 10268 95.9 1.485
-10.0 92 76.50 2637 3861 45530 10499 96.8 1.438
-08.0 94 78.20 2698 4041 48773 10712 97.6 1.393
-06.0 96 79.90 2759 4224 52264 10904 98.3 1.349
-04.0 98 81.60 2819 4412 56030 11076 98.9 1.307 ! Near Maximum !
-02.0 100 83.30 2879 4602 60098 11226 99.3 1.267 ! Near Maximum !
+00.0 102 85.00 2939 4796 64498 11353 99.7 1.228 !DANGEROUS LOAD-DO NOT USE!
+02.0 104 86.70 2999 4993 69263 11455 99.9 1.190 !DANGEROUS LOAD-DO NOT USE!
+04.0 106 88.40 3058 5193 74432 11532 100.0 1.153 !DANGEROUS LOAD-DO NOT USE!
+06.0 108 90.10 3117 5395 80051 11587 100.0 1.118 !DANGEROUS LOAD-DO NOT USE!
+08.0 110 91.80 3176 5600 86171 11635 100.0 1.084 !DANGEROUS LOAD-DO NOT USE!
+10.0 112 93.50 3234 5807 92850 11678 100.0 1.051 !DANGEROUS LOAD-DO NOT USE!

Results caused by ± 10% powder lot-to-lot burning rate variation using nominal charge
Data for burning rate increased by 10% relative to nominal value:
+Ba 102 85.00 3065 5214 78637 10855 100.0 1.136 !DANGEROUS LOAD-DO NOT USE!
Data for burning rate decreased by 10% relative to nominal value:
-Ba 102 85.00 2756 4217 52085 11297 95.0 1.347


Norma MRP (getting pretty available in my area)

Cartridge : .340 Weath. Mag.
Bullet : .338, 250, Nosler PART SP 35644
Useable Case Capaci: 88.084 grain H2O = 5.719 cm³
Cartridge O.A.L. L6: 3.675 inch = 93.35 mm
Barrel Length : 26.0 inch = 660.4 mm
Powder : Norma MRP

Predicted data by increasing and decreasing the given charge,
incremented in steps of 2.0% of nominal charge.
CAUTION: Figures exceed maximum and minimum recommended loads !

Step Fill. Charge Vel. Energy Pmax Pmuz Prop.Burnt B_Time
% % Grains fps ft.lbs psi psi % ms

-20.0 81 68.80 2364 3102 32189 9567 95.2 1.693
-18.0 83 70.52 2424 3262 34482 9833 96.3 1.646
-16.0 85 72.24 2484 3426 36946 10081 97.2 1.601
-14.0 87 73.96 2544 3593 39596 10312 98.0 1.550
-12.0 89 75.68 2604 3764 42447 10522 98.6 1.500
-10.0 91 77.40 2663 3938 45519 10712 99.2 1.453
-08.0 93 79.12 2723 4115 48831 10879 99.6 1.407
-06.0 95 80.84 2781 4294 52404 11023 99.8 1.363
-04.0 97 82.56 2840 4476 56246 11143 100.0 1.320 ! Near Maximum !
-02.0 99 84.28 2897 4660 60354 11239 100.0 1.279 ! Near Maximum !
+00.0 102 86.00 2955 4846 64773 11328 100.0 1.240 !DANGEROUS LOAD-DO NOT USE!
+02.0 104 87.72 3011 5034 69533 11413 100.0 1.202 !DANGEROUS LOAD-DO NOT USE!
+04.0 106 89.44 3068 5225 74665 11493 100.0 1.166 !DANGEROUS LOAD-DO NOT USE!
+06.0 108 91.16 3124 5417 80207 11570 100.0 1.131 !DANGEROUS LOAD-DO NOT USE!
+08.0 110 92.88 3180 5613 86201 11642 100.0 1.097 !DANGEROUS LOAD-DO NOT USE!
+10.0 112 94.60 3235 5811 92695 11709 100.0 1.064 !DANGEROUS LOAD-DO NOT USE!

Results caused by ± 10% powder lot-to-lot burning rate variation using nominal charge
Data for burning rate increased by 10% relative to nominal value:
+Ba 102 86.00 3067 5222 79384 10868 100.0 1.146 !DANGEROUS LOAD-DO NOT USE!
Data for burning rate decreased by 10% relative to nominal value:
-Ba 102 86.00 2782 4298 50984 11649 98.0 1.367