Is it safe to exceed the max load if one uses a chronograph?

[NYDAN]

I often read in this forum that shooters frequently don't achieve the velocities cited in reloading manuals due to a variety of factors such as chamber dimensions, barrel diameters, barrel lengths, etc. I also read that different manuals have different max loads due to differences in bullet construction and test barrels used. I believe that I understand all of this.

In reference to the .270 Winchester cartridge most manuals show velocities of about 3,000 fps for a 140 grain bullet at max loads of 58 - 60 grains of H4831 or H4831sc powder. The Nosler data shows a max load of 58 grains of H4831sc with a velocity of 3,000 fps for their 140 grain bullets.

If my .270 Winchester rifle (Remington 700 NA Custom with 24" barrel) exhibits a measured velocity of about 2,850 fps with a 140 gr AB with 58 grains H4831SC, (new Norma brass) can I safely (with the use of a chronograph) creep up my charge until I reach my goal of 2,900 fps which is still about 100 fps less than most manuals show as achievable velocity. I am thinking it would take about 59 grains of my batch of H4831SC to achieve 2,900 in my rifle. In this instance can I use the chronograph as a substitute pressure indicator?

 

[Sas874runner]

Yes and no. Mostly no. I have charged cases well over max book values before working up in .5gr increments checking for cratered primers and ease of bolt lift. Not typically recommended. Book values can change due to variance in powder lots. I had a 7mm rm that had an extremely loose chamber and was able to load 7 gr over max before I ran into cratered primers and a slightly sticky bolt.at that point I backed down 2.5 gr. Once again not recommended. There are a number of factors you can change without being unsafe. Try a mag primer. Seat bullets further out. Or it could just be a slow barrel. Sorry to say but your best bet may be to try a different powder/ primer combination to reach your goal.

 

[JD338]

NYDAN,
Welcome to the forum.
I will not tell you that it is safe to exceed published MAX load data but every rifle is different.

You might try bumping up in .5 gr increments and watch for excessive pressure signs. Once you reach your goal velocity, you may have to fine tune the charge weight and the COL to get the desired level of accuracy you are looking for.

Keep in mind that if you get a new lot of powder, you will need to drop down the charge weight and work up the load again. This is when a 8 lb jug is nice.
Also note that running at higher pressures you may exceed the safe limits of your rifle when shooting in the hot summer months and you will also have shorter case life.

Although the manuals typically show higher velocities, these are done in a lab environment. Gaining 125-150 fps really isn't going to result in any real noticeable difference in the field.
Remember to go slow.

You might also want to consider trying a different powder. RL 22 would be a good one to look at.

JD338

 

[DrMike]

I often read in this forum that shooters frequently don't achieve the velocities cited in reloading manuals due to a variety of factors such as chamber dimensions, barrel diameters, barrel lengths, etc. I also read that different manuals have different max loads due to differences in bullet construction and test barrels used. I believe that I understand all of this.

In reference to the .270 Winchester cartridge most manuals show velocities of about 3,000 fps for a 140 grain bullet at max loads of 58 - 60 grains of H4831 or H4831sc powder. The Nosler data shows a max load of 58 grains of H4831sc with a velocity of 3,000 fps for their 140 grain bullets.

If my .270 Winchester rifle (Remington 700 NA Custom with 24" barrel) exhibits a measured velocity of about 2,850 fps with a 140 gr AB with 58 grains H4831SC, (new Norma brass) can I safely (with the use of a chronograph) creep up my charge until I reach my goal of 2,900 fps which is still about 100 fps less than most manuals show as achievable velocity. I am thinking it would take about 59 grains of my batch of H4831SC to achieve 2,900 in my rifle. In this instance can I use the chronograph as a substitute pressure indicator?

First off, welcome to the forum. We're pleased to welcome new members to the friendliest shooting forum on the Internet.

The data printed in manuals produced by reputable manufacturers of powders and/or bullets are pressure tested and safe under the conditions stated in the manual. Since the factors you noted can (and do) differ, there are differences in velocities. Essentially all manuals have a section on signs of excessive pressure. As the hand loader, you are responsible to learn those signs and pay attention to them when they are present. The chronograph cannot be used as a means of assessing pressure, but it can give you an indication when something is wildly out of whack with a load.

You can work up carefully to achieve a maximum velocity if you pay attention to what your rifle is telling you by watching for the signs of excessive pressure. The laws of physics still hold, however, and ultimately, you will reach a pressure maximum.

If you are already producing 2850 fps, the change in point of impact, especially under field conditions, will be negligible when compared to 2900 fps. If this is important to you, then increase your charge by 0.5 grain increments, watching for pressure signs. It is likely that you can do this safely. Again, you are the one responsible to read the signs. Note the following projections, however, generated for a 24 inch barrel as used in the Nosler tests.

Cartridge : .270 Win. (SAAMI)
Bullet : .277, 140, Nosler AccuBond 54765
Useable Case Capaci: 59.393 grain H2O = 3.856 cm³
Cartridge O.A.L. L6: 3.340 inch = 84.84 mm
Barrel Length : 24.0 inch = 609.6 mm
Powder : Hodgdon H4831 SC

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 84 46.40 2379 1759 31114 8793 85.1 1.521
-18.0 86 47.56 2441 1852 33294 9105 86.5 1.481
-16.0 88 48.72 2504 1948 35632 9412 87.9 1.442
-14.0 90 49.88 2567 2048 38144 9712 89.3 1.397
-12.0 92 51.04 2630 2151 40845 10003 90.6 1.354
-10.0 94 52.20 2694 2257 43754 10284 91.8 1.310
-08.0 96 53.36 2759 2366 46888 10554 92.9 1.269
-06.0 99 54.52 2823 2478 50268 10811 94.0 1.228
-04.0 101 55.68 2888 2593 53919 11054 95.0 1.189
-02.0 103 56.84 2953 2711 57870 11282 95.9 1.152 ! Near Maximum !
+00.0 105 58.00 3019 2832 62150 11494 96.8 1.116 ! Near Maximum !
+02.0 107 59.16 3084 2957 66795 11687 97.5 1.081 !DANGEROUS LOAD-DO NOT USE!
+04.0 109 60.32 3150 3084 71840 11862 98.1 1.047 !DANGEROUS LOAD-DO NOT USE!
+06.0 111 61.48 3215 3214 77347 12015 98.7 1.014 !DANGEROUS LOAD-DO NOT USE!
+08.0 113 62.64 3281 3347 83320 12146 99.2 0.982 !DANGEROUS LOAD-DO NOT USE!
+10.0 115 63.80 3347 3483 89839 12254 99.5 0.951 !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 105 58.00 3170 3123 74608 11457 99.8 1.034 !DANGEROUS LOAD-DO NOT USE!
Data for burning rate decreased by 10% relative to nominal value:
-Ba 105 58.00 2821 2474 50734 10959 89.7 1.221

Cartridge : .270 Win. (SAAMI)
Bullet : .277, 140, Nosler AccuBond 54765
Useable Case Capaci: 59.393 grain H2O = 3.856 cm³
Cartridge O.A.L. L6: 3.340 inch = 84.84 mm
Barrel Length : 24.0 inch = 609.6 mm
Powder : Hodgdon H4831 SC

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 85 47.20 2421 1823 32602 9009 86.1 1.494
-18.0 87 48.38 2485 1920 34930 9323 87.5 1.453
-16.0 90 49.56 2549 2020 37433 9630 88.9 1.410
-14.0 92 50.74 2614 2124 40129 9928 90.2 1.365
-12.0 94 51.92 2679 2231 43032 10217 91.5 1.321
-10.0 96 53.10 2744 2341 46161 10494 92.7 1.278
-08.0 98 54.28 2810 2454 49546 10759 93.8 1.237
-06.0 100 55.46 2876 2571 53200 11009 94.8 1.197
-04.0 102 56.64 2942 2691 57151 11244 95.8 1.158 ! Near Maximum !
-02.0 104 57.82 3008 2813 61462 11462 96.6 1.121 ! Near Maximum !
+00.0 107 59.00 3075 2939 66130 11662 97.4 1.085 !DANGEROUS LOAD-DO NOT USE!
+02.0 109 60.18 3142 3068 71204 11841 98.1 1.051 !DANGEROUS LOAD-DO NOT USE!
+04.0 111 61.36 3209 3200 76757 12000 98.6 1.017 !DANGEROUS LOAD-DO NOT USE!
+06.0 113 62.54 3276 3336 82785 12136 99.1 0.985 !DANGEROUS LOAD-DO NOT USE!
+08.0 115 63.72 3343 3474 89371 12247 99.5 0.953 !DANGEROUS LOAD-DO NOT USE!
+10.0 117 64.90 3410 3615 96592 12333 99.8 0.922 !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 107 59.00 3223 3230 79359 11541 99.9 1.007 !DANGEROUS LOAD-DO NOT USE!
Data for burning rate decreased by 10% relative to nominal value:
-Ba 107 59.00 2878 2576 53908 11194 90.8 1.187

Cartridge : .270 Win. (SAAMI)
Bullet : .277, 140, Nosler AccuBond 54765
Useable Case Capaci: 59.393 grain H2O = 3.856 cm³
Cartridge O.A.L. L6: 3.340 inch = 84.84 mm
Barrel Length : 24.0 inch = 609.6 mm
Powder : Hodgdon H4831 SC

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 87 48.00 2465 1888 34161 9223 87.1 1.466
-18.0 89 49.20 2530 1989 36650 9537 88.5 1.426
-16.0 91 50.40 2595 2094 39329 9843 89.9 1.378
-14.0 93 51.60 2661 2202 42223 10140 91.2 1.333
-12.0 95 52.80 2728 2313 45346 10425 92.4 1.289
-10.0 98 54.00 2794 2427 48720 10697 93.5 1.246
-08.0 100 55.20 2861 2545 52373 10955 94.6 1.205
-06.0 102 56.40 2928 2666 56335 11198 95.6 1.166 ! Near Maximum !
-04.0 104 57.60 2996 2790 60635 11423 96.5 1.128 ! Near Maximum !
-02.0 106 58.80 3064 2918 65313 11629 97.3 1.091 !DANGEROUS LOAD-DO NOT USE!
+00.0 108 60.00 3132 3048 70409 11816 98.0 1.056 !DANGEROUS LOAD-DO NOT USE!
+02.0 111 61.20 3200 3182 75978 11980 98.6 1.021 !DANGEROUS LOAD-DO NOT USE!
+04.0 113 62.40 3268 3319 82043 12121 99.1 0.988 !DANGEROUS LOAD-DO NOT USE!
+06.0 115 63.60 3336 3460 88673 12237 99.5 0.956 !DANGEROUS LOAD-DO NOT USE!
+08.0 117 64.80 3404 3603 95954 12326 99.8 0.925 !DANGEROUS LOAD-DO NOT USE!
+10.0 119 66.00 3473 3749 103973 12388 99.9 0.895 !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 108 60.00 3277 3338 84450 11607 100.0 0.980 !DANGEROUS LOAD-DO NOT USE!
Data for burning rate decreased by 10% relative to nominal value:
-Ba 108 60.00 2936 2680 57329 11420 91.8 1.154 ! Near Maximum !

The difference in velocity between 58 grains of H4831SC and 60 grains of the same powder with a 140 grain AB is not as great as one would expect, despite pressure increasing significantly. Still, the projection indicates in a 24 inch barrel that the velocity should be at least 3000 fps. It will be ~50 fps less in a 22 inch barrel. For a 22 inch barrel (likely the length of your barrel) the velocities range between 2954 fps and 3068 fps for the same data set with chamber pressure remaining identical to the projections listed.

 

[Guest]

I think you're quibbling over something you will not be able to consistently measure or use, NYDAN. 100fps will change your point of impact around 3.5" at 500yds. If you're not shooting beyond 300yds (most hunters aren't) you're looking at roughly half an inch of difference, if you zero at 200yds. Zero at 250 and the difference disappears entirely at 300yds. The trajectory difference never gets more than 3" above point of aim for either velocity zeroed at 250, either. You won't miss much set up like that, even without the 100fps extra velocity.

If you just have to have the velocity, I'd suggest moving to Accurate MagPro or some other slower powder. If the 2850fps load is giving you good groups, I wouldn't bother.

 

[Sas874runner]

These guys all give sound advice. The test were I loaded way over max was to see if there would be a significant differance in powder lots and to see how quickly cases degrade at higher pressures.

 

[ScreaminEagle]

For me, a max load is when I first see pressure signs. It may be 5 grains above suggested load or 2 below. At any rate, as soon as the signs are found, I drop charge by one grain and that is my max.

 

[hubcap]

NYDAN, I had the same dileema with H-4831 sc and the 140 AB. I went all the way to 60.0 grains and still did not crack 2900. I switched to IMR-4831 and bam. 2900 and more was easy. The faster burning IMR worked out well in both of my .270,s. 2850 for the 140 is not really .270 velocity as far as I,m concerned. Just thought I would share a little since I had the same results as you with H-4831

 

[Dr. Vette]

I've recently tried H-4831SC and the 140 AB too. My 60.0 grains in FC brass will consistently break 3000 fps in my Weatherby Vanguard. Unfortunately I can't repeat the 0.78 inch group I got the first time with this combination so I'm a bit frustrated. I'll be posting pics of my results soon.

Patrick

 

[Sas874runner]

I am running ramshot magnum. With the 140 ab and a 24" barrel I'm pushing 3100 +- 10 fps. 64.5 gr. Also using fed 215 primers. Accuracy is at moa. For the time. Seating depth adjustment is in the work to tighten the group.but has been put on the back burner since the ablrs have arrived

 

[hubcap]

With IMR-4831 I use 57.0 for 3000 fps with PT,s and AB,s. Thats with a 22 inch barrel. Thats a max hunting load only. I reduce the charge for targets to 56 to 56.5. I will reshoot with a different lot of H-4831. I may have had a cold lot number. It is interesting that one guy gets 3000 with 60 gr, of H4831 and another gets 100 or more less. Thats reloading for sure. The variables are always an issue to say the least.

 

[NYDAN]

Thanks to all of you for your comments, suggestions, and questions. In my daily and weekly routines I don't get to speak with other rifle reloaders. Perhaps I should offer more of an explanation for why I am interested in this.

I am not new at reloading. Just have a chronograph now and that is a real eye opener. I have discovered that book velocities for reloads and velocity specifications for factory ammo have nothing to do with reality (except nosler factory loads - they do meet stated velocity specifications). I have reloaded shot shells since the 1970's, and rifle and pistol cartridges since the 1980's. I have developed sub moa accuracy loads for .264 mag., .260 rem, .308 win, 7mm-08 rem, and now the .270 win. (Most with nosler bullets) The only reason that I am undertaking another project is because I lost some of the vision in my right eye. I can't see clear enough to shoot accurately with my right eye anymore. After losing a shot at a very large buck two years because I was fumbling with a right handed rifle I decided to switch to a left handed rifle.

The choice of the .270 win, the 140 gr AB, and the target velocity of 2905 fps is no accident. I have a very unique hunting property here in NY with some very large fields surrounded by woods, creeks, and ponds. The end of the field behind my house is about 650 yards away. I reserve hunting from the back porch for sick days, pouring down rain days, and shooting cull deer. More than one deer has been shot by a coffee sipping, bath robe wearing, bleary eyed "sicky". The two primary hunting blinds/stands offer shots up to 250 yards. The next two secondary hunting blinds/stands offer shots exceeding 300 yards. My AVERAGE shot is 200 yards. Shots at 100 yards or less are rare for me.

I like to make use of a Leopold scope with the B&C reticule. As with my last right-handed rifle I am trying to custom taylor a load for my new left-handed rifle to precisely match the trajectory repesented by the Boone and Crocket Reticule. I believe a 140 gr AB at 2905 will do that for me. Also a 140 BT at 2940 fps or a 150 gr ABLR at 2930 fps should work. The nolser factory load of 130 gr AB (which shoots MOA) is actually too fast for the reticule.

The B&C reticule works very well for me. I have the yardages marked along the edge of the field and I can quickly place the correct cross hair on the aim point make a shot. No guess work, no holding over, no fiddling with dials.

I have worked with my friends' more powerful cartridges and I don't enjoy making repeated shots with the higher recoil of those cartridges.

 

[Guy Miner]

NYDAN, it seems that you have a very nice hunting setup. I like the idea of hanging out on the back porch, sipping coffee and waiting for a deer to amble into range!

I'm thinking that you and your .270 are in for much success.

Regards, Guy

 

[DrMike]

For sure, that is a great hunting setup. I'm sipping a cuppa' right now; it would surely make my morning joe that much more exciting to drop a fat deer while sipping the coffee. Best of luck to you in your hunts this fall.

 

[Dr. Vette]

FYI, if you get the program for your phone called Strelok (or iStrelok for an iPhone) you can input your data and it matches the reticle to your load. Much easier than fiddling with your load.

 

[OU812]

For me, a max load is when I first see pressure signs. It may be 5 grains above suggested load or 2 below. At any rate, as soon as the signs are found, I drop charge by one grain and that is my max.

I agree with Fotis on how to locate max as each individual rifle is different. If your need seeing pressure signs increase the charge .5 at a time till you see signs of pressure or hit your desired 2905.

On the other hand I also agree with Dubyam. 2850 to 2905 is not going to make a darn bit of difference. Try setting your scope power at the 2905 setting knowing your velocity is 2850 and shoot at 200, 300, 400 yards, ect. I'm willing to bet you will be surprised on how little difference in the drop there is. Other option is to fudge your scope setting to match the 2850 speed.

 

[NYDAN]

I truly appreciate all the comments and suggestions. I would like to correct a typo. In my previous post I indicated that the 150 gr ABLR at 2930 fps should also yield the results I am looking for. The correct velocity is 2830 fps. I have already achieved that velocity with IMR 7828, but not the accuracy I am looking for yet.

However, all of my previous work is probably for nought. After I started shooting the rifle I discovered that one bolt lugs was not showing any wear at all whereas the other one was showing wear. One of the specifications of that rifle is that it is supposed to be blueprinted with even contact on the bolt lugs. I contacted Remington and they had me return the rifle. They ended up replacing the receiver since the original couldn't be correctly aligned with the barrel. I just picked it up this week and haven't shot it yet. I have high hopes for it since the test groups they provided me with averaged .51 inches. Their test load was a 135 gr. Sierra Matchking with 53.3 gr. of IMR 4350 at a COAL of 3.340 inches. I have to say, that so far I am favorably impressed with Remington's response to this situation.

I am hoping to shot tomorrow (with the bench set up just inside the garage). I plan to run through the factory loads I have to check the velocities against what I measured with the original receiver. If time permits I will try the 58 grains of H4831 with the 140 gr AB and see what I get now.

I do have some H4350 on hand and am thinking about trying that just for kicks. That worked very well for me in the 7MM-08. I also have some IMR7828 I picked to use with the 150 gr ABLR.

I am not deciding what to do with reloads until after I see what results I get tomorrow. I am rapidly running out of time and may just stick with the Nosler factory loads for this hunting season. Would you like me to post my results?

 

[OU812]

Would you like me to post my results?

Absolutely!!!!!!!!!!!!

 

[Oldtrader3]

NYDAN, welcome to the forum. I will load with my chrono to the point where the velocity curve drops away at the next increment. Then I usually will back away from that to the best combination of velocity and accuracy. I also will stop at pressure signs in the rifle such as ejector marks on case or change in lift of bolt handle force to open.

 

[CatskillCrawler]

Little late to this party but I have some experience with the 140AB and H4831SC. My Rem in .270Win shoots great with 58.0gr @ 2850fps. Sound familiar? I've tried to hit 2900+fps for a few years now and haven't been able to find an accurate load whenever I do reach that plateau. With the H4831, I've increased my charge to 58.5 and found ejector marks and increased bolt lift force but not extreme. Shot one round with 59.0gr and had a very stiff bolt and ejector extrusion marks I could feel. It didn't take much to reach the edge of the envelope for my rifle.

I'm still happily shooting the 140AB at a very mundane 2850fps with boring accuracy and killing everything I shoot at.