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Kenny Jarrett's Pet Calibers

With years of experience, you learn that certain things work better than others. This is certainly true for our cartridge choices. We chamber for over 90 different cartridges and those mentioned here are some of our favorites.

Available Pet Calibers

.223 Remington

40 gr. Nosler bullet ......... 3700 f.p.s.
50 gr. Sierra ................... 3300 f.p.s.
55 gr. Nosler bullet ......... 3190 f.p.s.

Developed in 1964 by the Government and Robert Hulton, I can honestly say I’ve had more fun shooting prairie dogs with a .223 than I can begin to describe in a paragraph. It’s a wonderful little cartridge and very close to being perfect for this work, especially with 40 grain bullets. Cull does with the 55 gr. bullet, a round accurate enough for headshots and very inexpensive to shoot.


70 gr. Nosler bullet ......... 3650 f.p.s.
85 gr. Sierra Spitzer ......... 3450 f.p.s.

I believe the second reamer that I ever bought was a .243 Improved. I’ve had over 30 years experience with this dual-purpose varmint and deer cartridge, and it’s one of my top 5 favorites. The trick is to chamber it in a one twelve twist barrel. You can have a super varmint bullet in 65-70 gr. and shoot 85 gr. bullets for deer. I’ve killed more than 250 hogs and deer with this one cartridge. I shot the old screw machine Nosler Partitions at 3440 f.p.s. out of a 20" barrel. Recoil is mild, but believe me when I tell you velocity kills! The cases are easily fire formed and loaded and normally last 30% longer than standard brass. This cartridge, in a heavy barrel varmint rig with a 26" barrel, is a real performer if you are a 6mm fan. In thinking about it, I have never culled a .243 Improved in the tuning room. The .243 Improved is not finicky in any way, so I highly recommend it. This cartridge does best with a 20" barrel.


68-70 gr. bullet ................... 4100 f.p.s.
85 gr. bullet ........................ 3800 f.p.s.

95 gr. Nosler Partition ......... 3500 f.p.s.The .243 Catbird was conceived to be an ultra-long range 6mm varmint round, but also works quite well for a deer cartridge. It is a .270 Winchester case necked down to .243 and blown out with a 35 degree shoulder. This case is delivering some impressive velocities. Our original goal was to get 4000 f.p.s. with a 68-70 gr. bullet. However, we surpassed this goal with 4100 f.p.s. We were able to achieve 3800 f.p.s. with an 85 grain bullet and 3500 f.p.s. with a 95 grain Nosler Partition. This cartridge packs plenty of punch for long range varmint hunting or medium range deer hunting.

Cases for this chambering are quite easy to form. You simply run a .270 Win. case through a Catbird full length sizing die, load it with a reduced load and fire-form it by simply shooting it through your gun. There are two versions of this cartridge. One of them has a tight neck and the other has a standard neck. The cases for the tight necked version must be neck turned before they can be loaded and fired. Once cases have been fire-formed for either version they can be reloaded as any other cartridge. While this cartridge may not be for everybody, many people will love the high velocity and the accompanying flat trajectories that can be achieved. This round may be the fastest 6mm. cartridge ever developed. Of course, you have to give something to get something. She is a “barrel eater” -- expect about 1500 rounds of good accuracy.


140 gr. Nosler bullet ......... 3050 f.p.s.
120 gr. Nosler bullet ......... 3150 f.p.s.

The 7mm-08 Ackley Improved has been very popular with us for many years. Most importantly, it provides high end .280 Remington performance in a short action receiver. Most of our 7mm-08 Imp. rifles have a fairly short barrel, usually no longer than 20”, yet we get an honest 3050 f.p.s. with a 140 gr. bullet, and 3150 feet per second with a 120 gr. The original .308 case has been transformed into many kinds of nice cartridges. I believe that the 7mm-08 Ackley Improved is at the top of the heap. We have tuned several for 160 gr. Nosler Partitions for African hunts and hear nothing but praise for their performance. Bullets striking animals at 100 to 200 yards at 7mm-08 velocities will show perfect performance every time. Perfect for whitetail, it is one wildcat that deserved to be born! I like its performance, which is best with a 20" barrel.

.280 Remington

120 gr. bullet .......... 3150 f.p.s.
140 gr. bullet .......... 3000 f.p.s.
150 gr. bullet ......... 2925 f.p.s. 
160 gr. bullet .......... 2800 f.p.s.

The .280 Remington is one of the greatest cartridges to ever come down the pipe. The .280 will generate impressive velocities while maintaining excellent accuracy in a good rifle. The .280 got a slow start at its inception because it wasn’t loaded up to its potential. It also suffered through a name change in 1979 from .280 Remington to 7mm Express Remington. Often referred to as the “Ultimate Deer Cartridge,” its great appeal stems from the tremendous assortment of bullets available.


120 gr. Nosler bullet ......... 3340 f.p.s.
140 gr. Nosler bullet ......... 3150 f.p.s. 
160 gr. Nosler bullet ......... 2950 f.p.s.

If I had to lay my finger on one thing that really brought Jarrett Rifles to the dance, it would be the .280 Improved. We have made over 1100 rifles in this caliber and probably rebarrelled at least that many. For me to say I’ve had more experience with this cartridge than anyone else is a safe bet. After several long discussions with P.O. Ackley, I decided I wanted to work with this cartridge. Even though P.O. Ackley would not take credit for its creation, it bears all the markings of Ackley’s work. (Ackley also made a 7mm-06 version, which is slightly shorter and has a little less capacity than the .280 version.) Mr. Ackley was very enthusiastic about the .280 Improved and told me that he felt its capacity was the maximum useable powder for 7mm. Mr. Ackley had a lot of influence on me in the earlier days and out of respect for his help, most of my .280 Imp. rifles still bear his name. Several aspects make the .280 Imp. a wonderful cartridge: first, factory ammo can be used in the Improved chamber, second, its brass life is good, and third, its versatility created by the high degree of accuracy with bullet weights ranging from 120gr. to 160gr. One can see there is very little difference, if any, between the magnum 7mm’s and the .280 Improved. Mr. Ackley felt strongly that a belted case was not needed in 7mm. Listed are average velocities for the .280 Improved and I say “average” because rifles are individuals. In fact, the tight bore barrels, dimensionally speaking, produce the best accuracy but not the best velocity.

On the light bullet end, you have a set up that will beat a .25-06 all to pieces. Conversely, the heavy end bullets will out perform a .30-06, velocity wise. The higher ballistic co-efficient of 160 gr. 7mm bullets allow them to retain their down range velocity better compared to 160 gr. .30 caliber bullets..

If you only want one custom rifle, then versatility should be your prime consideration. The .280 Improved is totally adequate on small African game or antelope with the 120's. It’s perfect for larger deer with the 140's, and a real elk and moose buster with the 160's. The .280 Improved has been one of our best sellers because they work extremely well. Unless you are really recoil shy, a muzzle brake is not necessary on a .280 Improved. Thousands upon thousands of animals have been taken worldwide with the Jarrett Rifle in .280 Imp. That many dead animals couldn’t be wrong! For more information on the .280 Imp., refer to the Nosler No.4 reloading manual.

Remington Mag

140 gr. Nosler bullet .......... 3175 f.p.s.
150 gr. Nosler bullet ......... 3000 f.p.s.
160 gr. Nosler bullet ......... 2980 f.p.s.

The 7mm Remington Magnum is one of the most popular cartridges in America today. Its popularity is similar to the .280 because the 7mm bullet selection is so great. Due to its performance with 160 and 175 gr. bullets, the 7mm Mag. has been accepted as a big game cartridge. If you compare the ballistics to the .280 Improved, you will find they are almost identical. We can make a 7mm Remington Magnum shoot extremely well, so it helps us in a unique way. Example: A customer wants a very accurate 7mm round with a lot of wallop, but he wants to be able to shoot factory ammo in his rifle. The 7mm Remington Magnum fits the bill.


We were amazed that the .300 Winchester Magnum had never been reduced to 7mm successfully. The wheels really began to turn wondering exactly what the volume of the case would be. We designed a different case taper, then used our traditional 35 degree shoulder along with a lead angle in the throat to accommodate 140 and 160 gr. bullets. We had a reamer made and proceeded to build the .284 Jarrett! After the case fire forming was completed, we did comparisons with the other big sevens to see where ours fit. We checked all of the cases by water volume and this is what we came up with: (volume to base of neck)

7mm Remington Magnum ......... 73.5 gr.
7mm Weatherby Magnum ......... 78.0 gr.
.284 Jarrett ............................... 85.5 gr.
7mm STW ................................ 98.3 gr.

It’s interesting to note where we are volume wise: 12 gr. greater than the Remington Magnum and 13 gr. less than the 7mm STW.

The next step was to shoot this thing! Of foremost importance to us was its accuracy. If it’s not accurate, the velocity doesn’t matter. The cartridge responded well to a variety of powders and without effort we were under our half minute accuracy with velocities appropriate for this case capacity. Our testing produced the following results:

140 gr. Nosler bullet .......... 3450 to 3500 f.p.s.
150 gr. Nosler bullet ......... 3350 to 3375 f.p.s.
160 gr. Nosler bullet ......... 3250 to 3300 f.p.s.

These velocities are identical to a 7mm STW with a lot less powder. Even though all of the 7mm cartridges listed are overbore cartridges, the question is how much overbore can you stand and still have a dependable cartridge? I do know the velocities shown are the absolute maximums for 7mm bullets, regardless of how much powder you use. The Mexican standoff: the bigger case won’t give you any more, and a smaller case won’t give you as much. This is the reason, for all the 7mm fans, we have to max out the 7mm bullet. It rounds out our performance cartridge line and gives us a big 7 that meets our accuracy criteria while producing predictable velocities. In an emergency, a Weatherby cartridge can be used in the .284 Jarrett, but I don’t recommend reloading them because the neck will be too short. Put a .284 Jarrett in your battery soon!

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150 gr. Nosler bullet ......... 2900 f.p.s.
165 gr. Nosler bullet ......... 2800 f.p.s.
180 gr. Nosler bullet .......... 2727 f.p.s.

The .30-06 still lives today because it was good from the beginning, thus gaining the reputation as an ‘all around’ performer on game throughout the world. This veteran cartridge has held its own in the velocity and accuracy department. Just like the 7mm’s, part of the magic in the .30-06 is its bullet selection. We have made a lot of .30-06's through the years for customers who did not want anything else. The ’06 has proven itself in target competition, further increasing its popularity.

Winchester Magnum

150 gr. Nosler bullet ......... 3275 f.p.s.
165 gr. Nosler bullet ......... 3160 f.p.s.
180 gr. Nosler bullet ......... 3065 f.p.s.

Before I developed the .300 Jarrett, I did most of my big game hunting with a .300 Win. Mag. The .300 Win. Mag. has accuracy with power, two things I like. It’s America’s most popular magnum in .30 caliber today. High power shooters, military snipers, and police sharpshooters all place great faith in the .300 Win. Mag. With a premium 180 gr. bullet, it’s impressive on big animals too. The .300 Win. Mag. is easy to load for, and is fuel efficient.

the .280 Imp., refer to the Nosler No.4 reloading manual.


150 gr. Nosler bullet ......... 3550 to 3600 f.p.s.
165 gr. Nosler bullet ......... 3400 to 3450 f.p.s.
180 gr. Nosler bullet ......... 3200 to 3250 f.p.s.
200 gr. Nosler bullet ......... 3000 to 3050 f.p.s.

Since the inception of the .300 H&H Magnum, hunters and target shooters alike have realized the potential of thirty caliber bullets at high velocities. The .300 Winchester Magnum and the .300 Weatherby further validated just how good they really were for long range shooting. Having produced a lot of Jarrett Rifles in the .300 Win. Mag. caliber, we knew we could consistently derive extremely good accuracy and performance from this cartridge. With the .300 Weatherbys we could get the velocity, but the accuracy was erratic due to the free-bore design. Because of the powder selections Mr. Weatherby had to work with at the time, free-boring (clearance in front of the bullet before the rifling) was necessary when he created the cartridge. Our goal was to achieve the Weatherby ballistics, or better them if possible, combined with the inherent accuracy of the .300 Win. Mag.

We chose the 8mm Remington Magnum case, because in a blown out improved configuration it would give us the case capacity we need. The brass is very tough and inexpensive compared to Weatherby brass. A 35 degree shoulder angle was chosen for the new cartridge. We arrived at a lead angle in the throat area of the chamber (classified information). I’m sure similar cartridges have been developed and used, but our advantage was the availability of new slow burning powders and a greater variety of bullets and primers.

Our results with these rifles proved to be good representative examples of the .300 Jarrett’s potential. With the 165 gr. Nosler Ballistic Tip bullet, the velocities ran from 3350 fps to 3450 f.p.s., with ½ minute of angle, three shot accuracy at 100 yards from an 8 pound rifle. The 180 gr. Partitions went from 3150 to 3250 f.p.s. With identical powder charges used in the .300 Weatherby, we gained increased velocities in the .300 Jarrett of 100 to 150 f.p.s., proving it to be a more efficient case. It will consistently deliver a 200 gr. Nosler Partition at 3000 f.p.s. average. At that point, I knew I had a winner with the cartridge that would be the ultimate long range deer rifle with 165 gr. bullets. To add icing on the cake, at 250 yards, the .300 Jarrett with a 200 gr. bullet (muzzle velocity 3000 f.p.s.) has more energy than a .338 Win. Mag. with a 250 gr. bullet (muzzle velocity 2700 f.p.s.). This flatter trajectory and higher energy levels beyond 250 yards also made the .300 Jarrett a better long range elk rifle. For the one rifle advocate, this combo will outperform anything I know of at the present time, especially with the unbelievable consistency in accuracy using different bullet weights.

To make the .300 Jarrett, we run the 8mm Rem. Mag. brass through a Redding .300 Jarrett full length die. We then load 79 gr. of H1000 powder with any 180 gr. .30 caliber bullet and fire it in the rifle. That’s all there is to it. As an emergency alternative, the .300 Weatherby Mag ammo can be safely fired in the .300 Jarrett, but the fired case cannot be reloaded because the neck area is too short after firing. We now have our special .300 Jarrett brass, so fire-forming is no longer necessary. The .300 Jarrett is here to stay because it gets the job done with authority on targets, deer, elk and most of the African animals. It’s my own personal favorite, has become our flagship cartridge, and is our number one seller!


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

The .300 was such a success, we tried necking up to .338 and leaving the case as it was. We also left the 35 degree shoulder angle. Once again we were pleased with the results. Of course, the great .338 bullet selection was very helpful, too. There was a special happiness when we knew we could make the .338 shoot well! This was really a sore spot because the .338 Win. Mag. was so popular. The great news is that the .338 Jarrett has as much energy at 200 yards as the .338 Win. Mag. has a foot in front of the muzzle. We’ve had good reports from our successful clients on .338 Jarrett kills. With Swift A-frame bullets and Bear-Claw bullets, numerous Cape Buffalo and big bears have been victims of the big boom of the .338 Jarrett. The ballistics listed above will bear out my point.

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284 jarrett calibers.png

Holland & Holland

260 gr. bullet ......... 2780 f.p.s.
300 gr. bullet ......... 2545 f.p.s.

The .375 H&H was born in 1912 and destined to achieve greatness. It has been said many times that it is the finest all around cartridge the world has ever seen. That’s just an opinion, but a very popular one. Many have also stated that the .375 H&H is one of the only cartridges ever designed that can be taken anywhere in the world and used on any game. In fact, few hunters anywhere would call it unsuitable. Many people still take one rifle to Africa, and invariably it will be the trusty .375 H&H.


300 gr. bullet ......... 2820 f.p.s.
350 gr. bullet ......... 2610 f.p.s.
400 gr. bullet ......... 2429 f.p.s.

In the early fifties there was a void in the cartridge line up. A big cartridge was needed that shot as flat as the .375 H&H, but had the punch of the .458 Mag. That void wasn’t filled until 1988. I’m not sure, but I may have played a little part in its development. In early 1987, Layne Simpson and I were doing a lot of shooting and experimenting. We talked about doing a .416, and the next thing I knew, a reamer came from Clymer but was billed to Remington Arms Co. Next, two stainless .416 barrels materialized. We made a complete rifle with one, and rebarrelled an existing rifle with the other one. Layne shot them a lot, and carried both of them with him. I suspect one went to Ilion, New York, but I am not sure. A year later I read about the “breaking news” of the new .416 Remington in Shooting Times. It has proven to be a very good cartridge that basically gives .416 Rigby performance in a .375 H&H package. It has gained respect for taking the largest game in Africa and North America.


465 gr. bullet ......... 2442 f.p.s.
500 gr. bullet ......... 2370 f.p.s.

Because of a trip to Africa in 1994, I thought about doing a good .45 caliber cartridge. I also felt the .458 was slow, never really liked it, and wanted something with a little more zip. On our way to Africa, my hunting partner wanted to stop in London and pick up a used Rigby double rifle in .470 Nitro he’d purchased. I mentioned the possibility of necking up the .416 Rigby to .45 caliber to Mr. Roberts, the owner of the rifle at the time. Mr. Roberts said he had been doing some work along those lines. While he didn’t have any performance data because he hadn’t made one yet, he produced a reamer print, along with his blessings to make the .450 Rigby.

I changed the lead angle on the front and had a reamer made. The .450 Rigby has gone beyond our expectations in every category. The greatest surprise was the accuracy of such a massive cartridge. The field reports from everyone who has used one in Africa have been stellar! These folks so impressed me with their comments that I used one on my next trip to Africa! In 2007, I took two elephants in the Kilwa region of Tanzania with a .450 Rigby and using a solid, actually produced an exit wound on the off side of one of them! In our Professional Hunter, this cartridge is the ultimate we could offer anyone. It’s a dandy, no question about it!


CALL 803.471.3616

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