Thin sporter barrel load development

[K22]

Since I'm a hunter, the cold barrel shot is the most important for me so I focus my load development on groups fired from a barrel allowed to cool between shots.

I use a five shot group as an initial indicator of a load's potentially. Conducting load development on cool days or early in the morning in the spring / summer months can be helpful.

When I get something that appears promising I verify with a couple of follow up five shot groups.

During practical range practice, I keep a precise record of "cold barrel" shots and allow the barrel to cool between subsequent shots. On occasion, I'll take a quick second shot from a warm barrel to simulate a followup shot for further evaluation. In my hunting experience, very seldom do I get more that one follow up shot, if that, which can be precisely executed.

Most of my rifles prefer the barrel free floated, even the thin ones but I'm not suggesting that this is absolute. Interesting, Tikka free floats their thin barrel T3X Lite models. All of mine shoot terrific, out of the box with tailored reloads. Browning X Bolts are also free floated and all of mine possess excellent accuracy even with the less that optimum factirt triggers. However the Weatherby Vanguard's and thin barrel Rem 700's and 7's have pressure points on the barrel. With regards to the Rem's, all of mine shot better free floated. With the Vanguard, I experience no improvement free floating the barrel - go figure?

 

[RegionRat]

With light sporter bbls for hunting/walking, I will chime in with the others and admit it is a challenge to be gentle with the load development tests.

I punt sooner, like 2 rounds in some instances, then when the sweep shows promise with 3, I may test 5 to 7 from a cold bbl just to be confident.

Then, the cold bore testing and bbl fouling/cleaning tolerance testing begins.

 

[msinc]

I have two "mountain rifles" one has a pressure point the other is floated. The floater is a Kimber Mountain Ascent, the pressure point is a Remington Model 7. Both have pencil thin #1 contour barrels. I had a lot of trouble with accuracy when I first started out. Like you I always had heavy barrel target type rifles and no problems testing. Here is what I learned: at first I was trying to test like the other rifles. Different loads and keep on getting it. Bad idea...I thought I had a bad scope then a bad barrel, I was chasing accuracy and had no success and about to abandon the concept of a mountain rifle. To clarify, both rifles shot about a 2-3 inch group with the impact shifting around at random just like the scope was bad.
One thing I did notice was my first shot yesterday was identical to my first shot today on the target. I figured out that I didn't have to wait an entire day between shots, but I had to completely let the barrel cool off totally. That usually involved a half hour or so if it was warm outside.
As soon as I allowed the barrel plenty of time I realized the rifles were not that bad. Shoot one shot and wait, shoot again at the same spot. It does take a long time to test this way, but I found it to be the only way I could assess light weight barrels. In the end, both rifles shot 1/2"-3/4" at 100 yards with the same ammo that was "bouncing" all over the target. Turns out my reloads weren't bad after all.
Several of my shooting/hunting friends commented at the time that they would have given up based on what we saw initially. Hang in there and try it this way...what do you have to loose??? Absolutely do not waste your time shooting multiple shot groups one right after the other, it was very misleading and did not tell me anything. Best of luck sir!!!!

 

[PD Gohil]

Thank you everyone! There's some great nuggets of information in the replies I have received. As soon as I can harness the magnum primers and decide a powder I'll be set. Again, thank you.

PGohil
WV

 

[46and2]

Thank you everyone! There's some great nuggets of information in the replies I have received. As soon as I can harness the magnum primers and decide a powder I'll be set. Again, thank you.

PGohil
WV

I've had several 7RM barrels. All were loaded with GM210M primers except one that Preferred CCI250.

Do not be afraid of standard rifle primers. Also,
Imr7828 and RL23 are great powders for 7RM.

 

[hogpatrol]

Been covered in previous posts but my method is shoot like it's a hunt, i.e. make the first shot count. Develop the loads in the temperatures expected. I shoot one, set the rifle in the rack, bolt removed to get the stovepipe effect. Let the barrel go back to ambient temperature. Repeat until I get five shots. This can take a lot of time so I take other rifles. I found it works for the fire breathers.

 

[308 5R]

Once again, I’m not exactly a wealth of info on the subject, but I would be curious what others have to say on this. I have witnessed some of the troubles with light rifles like Kimbers that are free floated and accuracy potential that at times stops in the 1.25-1.5” range. I have seen Tikka’s that hammer for what they are. I have Remingtons with the pressure point still in place, and one that was removed and bedded. Both with .5/.75” accuracy ceiling. Finally I now have a NULA M20 with a #1 Douglas that is full length bedded from the receiver tang to forend tip. I can say for certain that Mr.Forbes is on to something here. While I do see some barrel warm up drift it’s the difference in an avg of .3” if allowed to cool, to .7-.9” if you just hammer five rounds out. I don’t think I have ever fired a group out of that rifle that went over 1” regardless of the method, or whether the load was optimized. While I understand that his stocks have everything to do with this being possible, my point is I wonder if you were to full length bed any of these light rifles, so long as they have a decent stock on them, if they would all benefit from this practice.

S/F
Ryan

 

[Ackman]

Getting ready to start load development for my Remington 700 7mm Magnum. I'm concerned because the barrel heats up rather quickly. Three shots and it's pretty warm. Five and it's almost hot.

What is the best way to approach this? The other load development I've done has always been with a heavier target barrel and could soak up more rounds before heating up changing velocities and POI. Would it be worth getting a barrel cooling fan? Also thought about using a temperature gun to check the barrel temperature and keep it within a certain range. Thoughts?
Thanks

PGohil
WV

I haven't read all the other replies, maybe it's already been said. But - that's not a high volume shooter. In the field you won't be firing it 5 times in a row anyway. Do your load workup with 3 shot groups, that'll tell you everything you need to know.

 

[TrapperBR549]

While testing loads this summer I rigged up a barrel cooler with some stuff I happened to have laying around.
I used an aquarium air pump and stuck the tube in the barrel. It draws the air from the bottom of the pump so I just stick it in a soft sided cooler with an icepack.
It reduced cooling time by about 2/3'rds.

 

[searcher]

I have several pencil barreled rifles (one is a 7-mag). I'd shoot 3-shot groups and allow it to cool (takes forever to get through 50 rounds). Most pencil barrel magnums start to wander a bit after two or three - some quite a bit. I'd not worry about changing conditions between volleys - the idea is grouping - not hitting a target in this phase. If I were you - if you find a load that shoots 1/2" to 3/4" and you have run your ladder at least 1 1/2 grains below AND above the powder setting you are happy with, I'd STOP. You can easily take a third of your barrel life off that 7 Mag trying to get significantly smaller groups and the fact is - most pencil barrel rifles won't shoot much better than 1/2" and it wouldn't be needed anyway unless you were shooting at 1,000 yards - to which I'd say you have the wrong barrel anyway - and even the mighty 7 lacks killing power at that range. At that point, I'd go back to the range early in the morning on a calm day and fire one shot at your target from a cleaned barrel. Make your scope adjustment, then fire again, make adjustment, etc. until done. Clean barrel, allow to cool. Fire a confirmation shot. From then on when practicing- pay more attention to where that first shot hits with that clean barrel - because that is not the "fouler" as used in target shooting - that is the kill shot. Also- If your barrel is properly bedded, I'd absolutely not add the "hump" under your barrel to stabilize it. For that "first shot" accuracy, it will cause you more grief than good as any movement in your stock whatsoever will change your point of impact on the first shot. This is more a concern with wood - but even glass moves the tiniest bit. Good luck!

 

[WEL]

Test a hunting rifle like you are going to shoot it. I figure 99% of the I’m shooting a cold bore shot then possibly a follow up shot. If I have to shoot a third time it’s a bad day. So I’ll shoot 2 shots then let the barrel cool completely. Then 2 more shots. I try and do my shooting in feb-April before it gets too hot. If it is hot out I will wait a bit before taking the second shot. Have realistic goals. I killed a ton of deer with a 1 1/2 moa savage 30/06. Fyi my model 7 will not shoot without the pad either. I had a kimber 7mm wsm. It would put two touching but that third one was always an inch out. Let it cool. 2 more right on top the others.

 

[Kevin Crain]

I have a sporter magnum 26" rem 700 in 7mag. I do the 2 rapid shot method at 100yds, simulated hunting
Scenario, I guess. First one is cold bore and a follow up 15-20 seconds later, they better be touching or one hole.

 

[Alex Wheeler]

I use 3 shot groups. If a barrel will not put the cold bore shot in the group with the other 2 it's coming off.

 

[INTJ]

I work up loads for sporter barrels like most here and I don't expect a hunting rifle to come close to my LR BR rifles in terms of accuracy and consistency. So for load development I shoot three shot groups--three in a row without waiting in between shots--then I let the barrel cool. When sighting in I use two shot groups and then let the barrel cool. If I have time I like to let the barrel get cold to the touch, but with the majority of my hunting rifles a little warm is okay.

The rifle I just finished yesterday is a 33-28 Nosler on a FN M-70 action in a B&C stock. It has a Benchmark #4 barrel, and the rifle with Leu 4.5x15 scope weighs 8.5 lbs. I realize some don't think that is a skinny barrel, but 225 grain TTSXs at 3160 fps heat it up qucikly even on cool days. That barrel is completely free-floated, and it's POI doesn't drift when its heated up--at least for three shot groups. I must also say that a 338 at nearly 50 ft lbs of recoil has a lot of wallop. It much rather shoot a 375 or 416 at that recoil level.

I had found a load a few months ago, so I went to the range with 30 rounds loaded up. I fired a couple of foulers then sighted it in for 200 yds. I wound up with two shots under a half inch apart, with a "group" center of 3/8" right and 5/8" high at 200. That is good enough for a walking rifle. Also, while I trust a Leupold VX-3i to hold zero very well, I do not trust the clicks to be precise.

I then went back to 100 yds and shot each of the aiming points on the B&C reticle. These were two shot groups, with letting the barrel cool to just a tad more than lukewarm between groups. These groups measured: 1/2", 1/4", 9/16", 7/16", and 7/8"--the last aiming point on the B&C reticle isn't as easy to align vertically as the others.

After inputting all the variables, the B&C aiming points correspond to: 220 yds, 330 yds, 440 yds, 510 yds, and 580 yds. I would be comfortable to 440 yds, IF I can get steady. If I expected to be shooting this rifle past 440 yds I would check the 510 and 580 yd aiming points at those distances. Under 440 yds, the error accumulation isn't really that much and 2 MOA accuracy in field conditions will result in a clean kill.

I have made a clean 435 yd shot using the B&C reticle with another rifle but using this same methodology of shooting in the aiming points and chronographing each shot. I think that's a reasonable limit for a carry rifle, and if I was expecting to shoot farther I'd get out the 338 Edge in a much heavier rifle.

 

[Webster]

Getting ready to start load development for my Remington 700 7mm Magnum. I'm concerned because the barrel heats up rather quickly. Three shots and it's pretty warm. Five and it's almost hot.

What is the best way to approach this? The other load development I've done has always been with a heavier target barrel and could soak up more rounds before heating up changing velocities and POI. Would it be worth getting a barrel cooling fan? Also thought about using a temperature gun to check the barrel temperature and keep it within a certain range. Thoughts?
Thanks

PGohil
WV

Many years ago I had a rem 700 BDL liight SS barrel. I shot Hornady 154 gr. Round Nose bullets. 4350 or 4831 powder. The rifle was completely stock. It shot groups around 1/2”. I didn’t pay attention to barrel temp. Probably had a minute or more between shots. Still have my 10 shot wallet target you could cover with a quarter.

 

[1/4 bore]

I use 3 shot groups. If a barrel will not put the cold bore shot in the group with the other 2 it's coming off.

@Alex Wheeler I’ve been playing with a 30-28 nosler with a proof barrel for a couple years now. Different bullet/ powder/primers/velocities/ hbn coating . I sight in for cold/fouled bore and ~ 98% of the time shot # 2 on will group 0.2 mil high at all distances. I have yet to determine how long it needs to sit/cool to go back to cold bore poi, I’ve had it return after 10 min and on other occasions not return after an hour. Do you think there’s stress in the barrel that’s uncurable? I wonder if the issue is in the metal/carbon/epoxy relationship that could be fixed by heating to soften the epoxy…maybe I’ll try, once I give up and rebarrel!!

 

[seymour fish]

I've had several 7RM barrels. All were loaded with GM210M primers except one that Preferred CCI250.

Do not be afraid of standard rifle primers. Also,
Imr7828 and RL23 are great powders for 7RM.

And N165 will work in a 7 mag while keeping the bbl cooler

 

[Webster]

Getting ready to start load development for my Remington 700 7mm Magnum. I'm concerned because the barrel heats up rather quickly. Three shots and it's pretty warm. Five and it's almost hot.

What is the best way to approach this? The other load development I've done has always been with a heavier target barrel and could soak up more rounds before heating up changing velocities and POI. Would it be worth getting a barrel cooling fan? Also thought about using a temperature gun to check the barrel temperature and keep it within a certain range. Thoughts?
Thanks

PGohil
WV

Years ago I had a Rem 700 7mm mag. SS barrel. Completley stock never modified in any way. It shot wallet size groups with Hornady 154 gr RN bullets. Cannot remember it was 4831 or 4350 powder. It's difficult to sit any length of time but try to space the shots a minute apart.