270 Win Load for Caribou

[Army SGM Retired]

Scotty, I will add to the two loads that I have started with till I’m at Max load. When should I start changing the OAL? I’m sitting just under magazine max length now. I also have some CCI primers o/h but can’t find Remington primers local, will send off soon. I ordered the case lube stuff you and DrMike suggested also, should be in by end of week. I see pictures that others post on the forum, how is that done. Would like to post pics of the cases I fired today, seem that they are very black at neck. Not sure if that’s from sizing issues or normal. Where is pressure data located at? Are there books that list max pressure loads or formulas for calculating? I was hoping too the 2900 fps’ish just for bullet drop corrections. Will add another topic asking for help on loads that others might have figured out already. Thanks.

 

[DrMike]

Nosler states that a maximum charge of H4831SC with a 140 grain AB yielded 3000 fps in a 24 inch tube. You likely have a 22 inch tube, so the maximum you would expect would be in the vicinity of 2950 fps. Allowing for differences in barrel diameter, atmospheric conditions, the price of cotton in Alabama, etc., 2900 fps would not be out of the realm of reason. What charge were you shooting that yielded 2697 fps? Following the Nosler Guide, a maximum charge of H4831SC is 58.0 grains.

I am assuming these are three-shot groups. For precision, the more shots, the more precise your data will be. However, as a quick and dirty review, three-shot groups are sufficient to give an idea. Ultimately, you will want to shoot three, three-shot groups to give you a good idea of the capability of your rifle. It may knock the bragging groups in the head, but it is more realistic and you won't be embarrassed by over-estimating the capability of your rifle.

The vital numbers at this point are Average Velocity and the Standard Deviation. The average velocity tells you what you can anticipate from your load in terms of velocity, in addition to permitting you to calculate minimum point blank range. The standard deviation will tell you a lot about the consistency of your load, which can be a predictor of accuracy. I look for a SD of no more than 1% on a good load. The less the SD, the easier it is to find an accurate load by adjusting seating depth or making incremental adjustments to powder charge.

 

[Army SGM Retired]

The 2697 fps came from 56.0 gr of H4831sc and 57.5 only produced 2796 average velocity and they both came in at 26 deviation. The 2796 fps load gave me a 1.60 shot group. All my loads were better than the factory load which came in at 2893 fps and group of 1.99 inches. My tube is 22 inches with BOSS and they were 3 shot groups with semi cool down between shots. Could not cool down to much due to the heat wave we are having. I bought some Remington primers both magnum and regular today so will change up some different loads the next go around.

 

[SJB358]

You are right on track. You may require changing powder to get your speed. Either way, I would load up to the max, keep monitoring your chrono and I think you will find what you are looking for. Scotty

 

[Army SGM Retired]

Thanks Scotty.. Posted the other topic but no replies yet. I did look through the hunting forum and found some good info on different loads to try. Like you said go for the max loads and watch your lane, ready on the left, green, ready on the right, green, the firing line is no longer clear. Commence firing!!!! Use to like those words.

 

[SJB358]

As long as you are going about it safely, keep driving on. The 270Win is a 60K PSI round I believe, so it is supposed to perform towards the upper end of the speed range. You will get what you are looking for. Scotty

 

[DrMike]

The 270 Win is standardized at 52,000 CUP (roughly 65,000 psi). It was a good move on Winchester's part to standardize it at a higher pressure rating than the 30-06.

 

[Army SGM Retired]

Thanks Doc, Can CUP pressure be calculated using load data or only measured with special device? I’m going to find some RL22 and load after the next go around of IMR 4831 and H4831sc. Question, If the max load per Nosler #6 book is XX.X and the velocity should be XXXX then if I load max and fall below said velocity could I not ramp up the grains till I hit the velocity the book states? What is the max velocity that would/could produce 60K psi?? I do not want to push the envelope but would like to know if I’m getting close. Thanks.

 

[DrMike]

CUP can only be assessed through use of laboratory equipment. There is no strict correlation between CUP and psi, though there is a general correspondence. Moreover, there is no strict correlation between pressure and velocity as there are other variables that must be taken into account. When you see a max velocity, it is generally a good idea to be cautious about generating higher velocities. You must assume responsibility for your load. A load producing higher velocity may be safe, but you must read the signs yourself and make that determination in light of all the criteria available to you. Unless you are comfortable with tickling the dragon's tail, it is a good idea to stop at maximum powder charge as listed by pressure tested data. Ultimately, the gain of a couple of hundred fps likely will not make a significant difference in either energy delivered on target or POI at normal hunting ranges.

These are not weasel words; they are cautionary statements advising the unwary to stay alert. When you pass maximum charges, you are on patrol in enemy territory. You can be safe, but you are responsible as there will be no one to bail you out when the balloon rises.

 

[SJB358]

Gary, there is no way to measure pressure, other than with pressure measuring equipment. You can look for signs of high pressure on your cases, and monitor your speeds with your chrono. If you are getting above book speeds, you are likely over pressure. Sometimes the data is low, but the speeds are the max, simply because they measured them, but may have gotten higher speeds due to different cases, pressure test barrels and other reasons. I would look at a few different sources of data and see what they are getting then work from there. Also, check out H1000/RL22, I think it would be another great powder, and you will likely gain another 100FPS overall in your loads. Scotty

Mike, I think we answered at the same time.

 

[Army SGM Retired]

Doc, I did go over by.5 using H4831sc, that’s where I left off from max load they other day. I changed to CCI-BR2 primers using the 2nd time fired brass but started from the bottom again with powder. I have loaded all the 140 accu bonds I had so I loaded some 130 ballistic Silvertips today in prep for the range at first light tomorrow. The next area for me will be the brass story telling if loads are getting to hot. How do I load pictures for review by the forum? Should I go to admin forum and ask the question? Do you just inert into the reply? Will give feedback after range day tomorrow.

 

[Army SGM Retired]

I’m back from the range, kind of full of mixed reviews. I shot 11 groups of 3 shots and the best had an average velocity of 2818, Deviation 10, and a group size of .88 inch. Could have been me, two shots almost in one hole and pushed 1 shot out to right.

140 Gr AccuBond 58.5 gr H4831sc

The issue I have is even over max powder load by .5 I still can not get to the book velocity of 3000 fps. Even using IMR 4831 with 54.0 gr (.5 over max load) I’m still only coming in at 2769 velocity with the book stating it should be 2910 + fps. Even changing to 130 gr Ballistic Silvertip loading with H4831sc at 59.0 gr my velocity was 2795 fps, the book states 3124. With that said I did not get a shot group on that 3 rounds due to they were off the paper. Two of the 3 rounds were 5 inches apart and I never found the 3rd shot. I have checked my powder each time I drop and even checked Load Master 750 against my regular scale, all good. Not sure if my chrono is calibrated, not sure how to even do that, it’s brand new. I’m open for discussion on why I can reach that 3000 window. Would bullet seating deeper help achieve my goal of a flatter shooting round? Is my chrono off so much that I’m pushing bullets off the scale. Brass looks good, no marks that I can see. Help.

 

[DrMike]

Nosler used a 24 inch barrel; yours is likely a 22 inch barrel. There is at least 50 fps difference in velocity. It is possible, due to normal variation in barrel production that you can account for another 50 fps or more. 2800 fps will produce only 200 ft-lbs of energy less at 200 yards than a bullet launched at 3000 fps, and less than four inches of drop at 400 yards compared to the drop from a bullet with 3000 fps muzzle velocity. You are there for caribou; if you do your part, it means caribou in the freezer this fall. Enjoy!

 

[CAhunter]

Army I would say that .88" group will work for a caribou. I wouldnt worry about the speed as much as the accuracy. Also many things can contribute to slower FPS than published such as shorter barrel, loose chamber, rough barrel, different powder lots. etc... Just load some more 140gr accubonds over 58.5 and play with seating depth a little to see if the group tightens any. If not .88 is a good group for hunting.. Good luck and have FUN!

 

[Army SGM Retired]

Sounds good to me hearing it from some seasoned vet’s. I was wanting that flat as can be but can just adjust sights for impact. I’m sure I can hit a target at 400+ yards but hope for one of those 20 yard shots all day long. I do have a 22 inch barrel so that might be the issue. I hope to find someone in the area that has a chrono to verify mine to make sure all is tracking. Now, seating depth, is there a minimum that I should stop at? What increments do you suggest I adjust in? I’m at 3.37 OAL which is my magazine max length.

 

[DrMike]

You are in line with anticipated velocities for the load you are shooting. I would be greatly surprised if your chronograph was giving aberrant data. Ensure that it is fully unfolded so that the distance between the electronic eyes is the calibrated distance. You can try seating your bullet deeper into the case in 0.005 increments, but it likely won't make a great difference. Having said that, there are always surprises.

 

[OldMan]

Army SGM, I have a 22 inch barreled 270 that wasn't showing much until I tried IMR-7828ssc powder and the 140 AB. It does 2940+ with all bullets touching when I do my part. I use 60 gr of 7828 in my rifle with no pressure signs, but work yours up slowly.

WW brass
7828ssc powder
CCI-250 primers
140 gr AB bullets
Good Luck on your hunt!

 

[Army SGM Retired]

Thanks Doc, not sure of those eyes your are talking about but will call the chronoy people and ask if there could be an issue.

OldMan, I have not heard of IMR-7828ssc powder, what book did that come from? Question being where/what is the limit for mix and matching of powder/bullet/ and brass? Why haven’t the powder makers fired all possible options with their bullets? Being new to this I have a lot of questions that probably can’t be answered by us but maybe someone has the answer.

 

[DrMike]

I would suppose that every possible combination has been fired, or at least considered. However, what is published are selected loads. Some loads can work, but they are potentially dangerous. Hence, they don't get published. Others simply don't give the performance desired. Consequently, they are not published. There is limited space in the reloading guides/manuals. Thus, the guides restrict themselves to optimal loads under their test conditions. For a 270 calibre, there are many more 200 bullets available for loading, and there are that many or more powders and at least ten primers and several brass manufacturers available. The number of potential load combinations is massive (at least 4 million potential loads). Few people want to wade through that particular book. However, most of us can handle the top ten or so loads for a given bullet and/or powder.

 

[Army SGM Retired]

Thanks Doc for bringing me back down to earth. I need to stay focused on my current requirements and go to Labrador and shot 2 Bou’s. I can’t wait, but have more shooting to do. Scotty suggested that I try RL22 so I got some today from Gander Mt. Will load this weekend and give feedback soon. Thanks again for your knowledge and wisdom, just wished you lived down the road from me, we could have some good long talks. :lol: