Finding maximum load in YOUR rifle

[selmerfan]

Reading the post about best way to find a load got me to thinking (based on some of the comments) of "How do I find the maximum load in my particular rifle?" Over a decade ago I found an excellent deer hunting load for both my .260 Remington in a Ruger 77 MkII and, incidentally, my 18" MGM .260 Rem Encore barrel I used for pistol hunting deer in Minnesota shotgun zone. The load is a 129 gr. Hornady Interlock with 44 gr. IMR 4350 behind it. It's not a barn burner of a load - 2825 fps from the Ruger and 2650 from MGM barrel. Looking at current load data from IMR, I'm waaayyyy over their maximum load. Like, by 4 grains over. But I was within published specs when I developed the load for both guns. I want to return to some load development with the MGM barrel after I have Holland put a brake on the barrel and the loads I'm seeing are comparably anemic. So I'm wondering what your method is to determine what the max charge with a given powder and bullet combo is in your rifle. I'm imagining basically a ladder test by .5 gr. increments to see when over-pressure signs show up. What other methods are out there without having a chamber pressure gauge on hand?

 

[Jud96]

I load up a pressure test and shoot the shots over a chronograph to know where I'm at with velocity. When I see shiny marks from the ejector/and or heavy bolt lift, I back off 0.5-1.0gr and then call that my safe max.

 

[comfisherman]

On established cartridges I use pressure data from establishes similar bullets and powder companies. Then shoot over a chrony, if my velocity is within explainable (barrel length, elevation, natural variation in barrels) that's the max I go with. I've had re barreled guns with the same length barrels deviate on speed by as much as 50 fps, but not more than that.

Take a tight custom action in a chamber cut by a reamer that's not mass assembly used with adg brass.... primed with cci primers... you ain't seeing grandaddys pressure signs.

 

[Huntnful]

I go off bolt lift only now. I've seen ejector marks show way below max pressure. I still use them as an indication, but a bolt click at the top is definitely what I consider max pressure.

 

[waveslayer]

That's why you always do your own work up! Use data as reference, start low and work up. I've done it for some calibers and powder that there is 0 load data for. Start load and let the fun begin.

Also, check primers they tell a lot and brass

 

[memtb]

My method may not meet the criteria used and accepted by many.

I'll just use my hunting rifle as my example. I can't rely on chronograph numbers as my cartridge is an AI and there's not a lot of data available…..so, the chrono is out.

I only do load development (if max loads will be the goal) on hot days, generally in the 90's. As my rifle may be used at any time of the year…..I don't want any pressure surprises!

I do use existing load data, if available though some may be old data, to get a realistic starting point. I load 3 rounds with the cases being marked with a felt tip marker, then incrementally increase the charges marking the cases with Roman Numeral indicating the increase in charge. This is continued until I see the pressure signs that indicate "to me" pressure issues.

I ignore flattened primers, even "slightly" cratered, as primer cups of different manufacture are different in hardness and possibly thickness!
I also don't get to excited about shinny marks on the case (extractor, ect.) for similar reasons as above…..some brass is harder than others!

It does get my attention when I see serious primer cratering or extreme flattening…..usually these occurs simultaneously. I also know that I've "crossed over" the line when I begin to get heavy bolt lift. It is at these points, I back off a bit and look for low shot to shot velocity deviation and group potential. I continue to incrementally reduce the charge looking for the best groups!

It may not be approved by the majority, but has worked for me! It's probably "not" the most efficient use of components, but once I develop a satisfactory load I never deviate…..unless I feel the need to change components!

That said, after using one load for the past 7 1/2 years, this summer I will be working-up a new load for my hunting rifle. If successful, this load should carry me beyond my big game hunting and to the grave! memtb

 

[selmerfan]

That's why you always do your own work up! Use data as reference, start low and work up. I've done it for some calibers and powder that there is 0 load data for. Start load and let the fun begin.

Also, check primers they tell a lot and brass

Calibers and powders with 0 load data - that's the other reason I'm asking. The .350 Rem Mag doesn't have ZERO load data, but it's definitely limited, especially for newer powders. Stuff like 8208XBR and Varget SHOULD work well, based on their relative burn rate, but there is almost no data for them in the .350 RM. I SWAG'd it with 8208 XBR with 180 gr. Speer FNSP and found a load that groups very well, but it's only running at 2400 fps from y 16" XP100 barrel. Zero pressure signs and I doubt that I've found the maximum for my gun at 57 gr. 8208 XBR with this bullet. But it was good enough and that's what I needed this year with limited time to put a load together for deer hunting. And it did the job. I just want to find out where my maximum is at. What I'm hearing here is just go for the classic signs and then back off a grain and consider that the functioning maximum for that powder/bullet/primer combo in that gun. Which is pretty much what I've always done. I just wanted to know if there was a better mousetrap

 

[waveslayer]

My method may not meet the criteria used and accepted by many.

I'll just use my hunting rifle as my example. I can't rely on chronograph numbers as my cartridge is an AI and there's not a lot of data available…..so, the chrono is out.

I only do load development (if max loads will be the goal) on hot days, generally in the 90's. As my rifle may be used at any time of the year…..I don't want any pressure surprises!

I do use existing load data, if available though some may be old data, to get a realistic starting point. I load 3 rounds with the cases being marked with a felt tip marker, then incrementally increase the charges marking the cases with Roman Numeral indicating the increase in charge. This is continued until I see the pressure signs that indicate "to me" pressure issues.

I ignore flattened primers, even "slightly" cratered, as primer cups of different manufacture are different in hardness and possibly thickness!
I also don't get to excited about shinny marks on the case (extractor, ect.) for similar reasons as above…..some brass is harder than others!

It does get my attention when I see serious primer cratering or extreme flattening…..usually these occurs simultaneously. I also know that I've "crossed over" the line when I begin to get heavy bolt lift. It is at these points, I back off a bit and look for low shot to shot velocity deviation and group potential. I continue to incrementally reduce the charge looking for the best groups!

It may not be approved by the majority, but has worked for me! It's probably "not" the most efficient use of components, but once I develop a satisfactory load I never deviate…..unless I feel the need to change components!

That said, after using one load for the past 7 1/2 years, this summer I will be working-up a new load for my hunting rifle. If successful, this load should carry me beyond my big game hunting and to the grave! memtb

Saying a Chrono is out of the question because of the AI version is missing the mark and why Chrono... you're wasting and missing a lot of vital data. How are you finding good nodes, how are you tracking SD's of your loads?, how are you finding changes in velocity with load work ups? Sometimes velocity will degrade as you increase powder charges, how are you tracking velocity in relation to ambient air temp?
You might do better to rethink your thoughts on a chrono, AI or not. AI versions are nothing special or new. What AI version are you running, I bet there are a lot of data unless it's a true wildcat you have that was custom ordered reamer etc... which I doubt

 

[Reelamin]

These might provide some information to cover your situation. Hope you find what your wanting as lots of great help on the site.

https://www.longrangehunting.com/threads/pressure-signs-way-below-max-load.224944/

https://www.longrangehunting.com/threads/pressure-question-on-max-charge.22184/

https://www.longrangehunting.com/threads/pressure-signs-well-above-max-load.284203/

https://www.longrangehunting.com/threads/pressure-signs-not-sh

owing-at-max-load.224732/

 

[memtb]

Saying a Chrono is out of the question because of the AI version is missing the mark and why Chrono... you're wasting and missing a lot of vital data. How are you finding good nodes, how are you tracking SD's of your loads?, how are you finding changes in velocity with load work ups? Sometimes velocity will degrade as you increase powder charges, how are you tracking velocity in relation to ambient air temp?
You might do better to rethink your thoughts on a chrono, AI or not. AI versions are nothing special or new. What AI version are you running, I bet there are a lot of data unless it's a true wildcat you have that was custom ordered reamer etc... which I doubt

I guess that I'm pretty old school…..hell, never even heard of "nodes" until a few years ago. Don't do enough shooting/reloading for this "old dog" to learn new tricks.

I mentioned that my methods are not as efficient as others…..but, served me well for 50+ years!

As for the AI! It's a .375, and years ago had difficulty finding any decent load data and virtually none with the newer powders. I used some older .375 Weatherby data, extrapolating that old data with newer powders, and found what worked pretty good.

All of my bench shooting is done across the chrono when doing development.…..and again at ambient temps similar to expected hunting condition! Tracking with air ambient temps…..I'm not attempting to shoot the distances with my hunting rifle that you guys shoot! I'll do some shooting at the expected ambient conditions and adjust/compensate for the differences! Certainly not as scientific as you guys…..but again, shorter distances!

This summer, I'll start again, working with a 270 grain LRX! I may try to learn about "ladders", "nodes" and such…..but, may continue with what I'm comfortable with! I have over 6 months to think it over before it gets warm enough for testing! memtb

 

[nksmfamjp]

1. Establish a max pressure based on brass quality and action strength….there should be a rating for both…action - max bolt thrust; case - max pressure of parent, siblings, etc. All based on SAAMI ratings for cartridges in the action and case.
2. Use Quickload to help find ~5 powders that give good velocity; >95% burn; 90-103% case fill at max. Pick one….best balance, availability. When these parameters cannot be met, just keep going down the list looking for available and good enough.
3. Determine charge for that pressure in Quickload…best possible untuned max load.
4. Size your cases to the correct size bolt close -0.002" std size.
5. Start there. Load that as max and -25% as MIN. Load 10 pressure increments. Use a good scale. Variation is both dangerous and ruins the quality of results.
6. Shoot from MIN to MAX. At first bolt lift, ejector mark, solid click(clicks hard to feel consistently), blown primer, flat primer, etc. STOP!
7. Reduce 1-2 increments. I usually reduce 2 increments. This charge weight is over pressure. I want to be under MAX.

This works for cartridges with and without data. Helps you get around anomalies in data related to weak guns, odd history, etc.

 

[QuietTexan]

I'm imagining basically a ladder test by .5 gr. increments to see when over-pressure signs show up.

Yup. Go really crazy and use a single case for the test, keep resizing it and you'll know the top for pressure and how long your cases will last. Then shoot the "max safe" load you find that many times from a second case to make sure your brass lasts that long. Only two cases trashed this way - if a case clicks or gets hammered by the ejector, it's out of the standard rotation for me.

 

[selmerfan]

Yup. Go really crazy and use a single case for the test, keep resizing it and you'll know the top for pressure and how long your cases will last. Then shoot the "max safe" load you find that many times from a second case to make sure your brass lasts that long. Only two cases trashed this way - if a case clicks or gets hammered by the ejector, it's out of the standard rotation for me.

I never would have thought of using (and trashing) just two cases. Great idea - thank you!