Exceed published data or not? 308 benchmark 168gr

[rweaver00geo]

Working up a load for a savage 10pc 20" barrel with benchmark powder 168gr hornady hpbt
Ive reached the max charge 42.0 grains 49,300 CUP (for a sierra 168gr hpbt) My groups have improved as the charge increased even from 41.5 grains but are not quite as tight as Im wanting. At 42 the primers are kinda flat, no cratering, no sticky extraction. Should I go up a little? If so how much? Why is 49,300 CUP max when 51,200 CUP is the max for H335 & a 150gr bullet?

 

[BCP]

Re: Exceed published data or not? 308 benchmark 168gr

I guess you could try going higher but honestly benchmark isn't the powder for what you are doing...varget, 4895, 4064, try one of those...

 

[DHDeal]

Re: Exceed published data or not? 308 benchmark 168gr

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: rweaver</div><div class="ubbcode-body">Working up a load for a savage 10pc 20" barrel with benchmark powder 168gr hornady hpbt
Ive reached the max charge 42.0 grains 49,300 CUP (for a sierra 168gr hpbt) My groups have improved as the charge increased even from 41.5 grains but are not quite as tight as Im wanting. At 42 the primers are kinda flat, no cratering, no sticky extraction. Should I go up a little? If so how much? Why is 49,300 CUP max when 51,200 CUP is the max for H335 & a 150gr bullet? </div></div>

When I see "kinda flat" I will usually stop there and reconsider what I am doing. Usually will try another powder but maybe a different primer.

I agree that Benchmark might not be the best powder for the 308, as there are many others that will get the velocity and accuracy you are looking for. My prefered powder for the 308 is H4895, but I have used many others.

Don't know why there is a different pressure reading listed between the different powders, but, not trying to tell you something you may already know, the manuals are a guide only. I am quite a bit above max with my son's 6.5 Creedmoor with H4350 and 140 grain bullets. And yes, accuracy improved the higher I got. I just had to decide if I wanted to sacrifice brass/safety chasing after more speed. I do not.

 

[insight3b]

Re: Exceed published data or not? 308 benchmark 168gr

I load over published max quite often. The best way to tell if you are getting into dangerous territory with pressure is to take a shell holder to the range with you. If the fired cases will still slip easily into and out of the shell holder I'm ok

 

[MtnCreek]

Re: Exceed published data or not? 308 benchmark 168gr

<div class="ubbcode-block"><div class="ubbcode-header">Quote:</div><div class="ubbcode-body">Why is 49,300 CUP max when 51,200 CUP is the max for H335 & a 150gr bullet?</div></div>
It’s probably because they saw something beyond their listed max, like a pressure spike.

 

[rweaver00geo]

Re: Exceed published data or not? 308 benchmark 168gr

Thanks good info so far. Im doing a ladder test with 2520 and then will start on varget. I noticed in the 223 with benchmark I achieved the best accuracy at the max charge gave(1/2 inch groups) I never felt the need to do better. In the 308 I went from a 1.1 inch group using 41.5 grain to .8 group 42 grain and wonder going to 42.2 or 42.5 would shrink the group further?

 

[DHDeal]

Re: Exceed published data or not? 308 benchmark 168gr

It's quite possible that accuracy will improve, then fall off at a certain pressure level. Many people will have different experiences, but with tried and true loads (Varget with 175 SMK, H4895 with 175 SMK, etc) most will have similar results. There are just too many variables between yours and mine to give a straight up answer. That being said, I would be surprised if 43 gr H4895, 210M, 175 SMK, @ 2.815"ish won't shoot well in most 308's. Same for 44.5 Varget, etc.

Just watch it close. I usually go up 1/2 grain at a time. YMMV some.

Have a good one.

 

[jdgray]

Re: Exceed published data or not? 308 benchmark 168gr

A listed max load is for the exact componets listed in the data. Chances are your not using all the same componets, so let your rifle be the guide. If the bolt lifts easily, you can carefully go higher. Using the instructions for Newberrys OCW method, you can safely run the next step higher charge, if the previous one has no pressure signs. He recommends 1% increases at the topend of the data.

 

[Grumulkin]

Re: Exceed published data or not? 308 benchmark 168gr

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: jdgray</div><div class="ubbcode-body">A listed max load is for the exact componets listed in the data. Chances are your not using all the same componets, so let your rifle be the guide. If the bolt lifts easily, you can carefully go higher.</div></div>

Exactly.

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: rweaver</div><div class="ubbcode-body">Why is 49,300 CUP max when 51,200 CUP is the max for H335 & a 150gr bullet?</div></div>

Good observation. They probably found the best accuracy at the 49,300 CUP load. Best accuracy among other things means best powder burning consistency.

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: insight3b</div><div class="ubbcode-body">I load over published max quite often. The best way to tell if you are getting into dangerous territory with pressure is to take a shell holder to the range with you. If the fired cases will still slip easily into and out of the shell holder I'm ok</div></div>

I can see no way that this method is safe. By the time a fired case won't slip easily in and out of a shell holder you will be WAY over pressure.

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: DHD</div><div class="ubbcode-body">It's quite possible that accuracy will improve, then fall off at a certain pressure level.</div></div>

In a strong and accurate firearm, I've found this to be true the great majority of the time. In addition, many times there will be a very noticeable change in the point of impact of bullets on the target. In some firearms, you will reach the maximum pressure the firearm can take before you reach optimal accuracy.

 

[Fuzzball]

Re: Exceed published data or not? 308 benchmark 168gr

"A listed max load is for the exact componets listed in the
data."

No change in the exact listed components can equal the possible effect of using a different rifle.

 

[MitchAlsup]

Re: Exceed published data or not? 308 benchmark 168gr

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: rweaver</div><div class="ubbcode-body"> At 42 the primers are kinda flat, no cratering, no sticky extraction. Should I go up a little? If so how much? Why is 49,300 CUP max when 51,200 CUP is the max for H335 & a 150gr bullet? </div></div>

Start walking up in 0.2 gr increments. That is load up 5 cases at 42.2, 42.4, 42.6, 42.8, 43.0 (carefully measured.) Fire from low CW towards higher CW, then examine each case for pressure signs before moving on to the next case. If anything changes, stop!

Primers are not all that good of a pressure sign, look, instead, for ejector marks, sticky bolt, change in sound of the balst wave; sometimes even the powder will smell differently. Use all your senses here.

 

[BCP]

Re: Exceed published data or not? 308 benchmark 168gr

What brass are you using? I have a rem 700 20" and 44 varget, LC brass, 168nosler was around 3/4" when I did my part. That is a good dupe for 168 TAP ammo. 168 FGMM is more like 41.5 Varget or maybe 42.

 

[insight3b]

Re: Exceed published data or not? 308 benchmark 168gr

Take a shell holder to the range with you...if the case slips easily in and out you are still ok.
In my experience this is the ONLY method that truly indicates whether or not a load is safe. Flattened primers and sticky bolts occur quite often with FGMM especially in .223 with 77gr SMK. I've experienced flattened primers and a stcky bolt with FGGM 168gr SMK in .308 also. That is factory loaded ammo with a reputation of being safe. They both still slip easily in and out of a shellholder though.
I try to limit my load development for the summer months though. A load worked up at 30 degrees will most likely be unsafe at 90 degrees

 

[Joop]

Re: Exceed published data or not? 308 benchmark 168gr

Sorry, but this shell holder method is just asking for trouble. There's no way this can be considered safe. I've blown heads clean off of cases before, on many occasions. Guess what. They still fit in the shell holder with no problem.

I've had good luck with 40.0 grains of Benchmark under the Hornady 168 BTHP with Winchester brass and Win. primer. This is out of my 10FP. Not a high velocity load, but very light recoil and extremely accurate for me out to about 600 yards. From there on, it drops off dramatically.

 

[insight3b]

Re: Exceed published data or not? 308 benchmark 168gr

Incipient seperation is a completely different subject and would never happen if proper case inspection steps are followed. Therefore, suspect cases would never receive any powder charge.

 

[Joop]

Re: Exceed published data or not? 308 benchmark 168gr

I'm wondering if you are aware of how cartridge cases are designed and constructed. Please, do us all a favor and where an orange flag on your hat at the range, so we know who not to be around when you you pull the trigger.

 

[insight3b]

Re: Exceed published data or not? 308 benchmark 168gr

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Joop</div><div class="ubbcode-body">I'm wondering if you are aware of how cartridge cases are designed and constructed. Please, do us all a favor and where an orange flag on your hat at the range, so we know who not to be around when you you pull the trigger.</div></div>

I know I've never had an incepient seperation, damaged any weapon, or hurt myself or anyone else when using my handloads. Most of them have been over max published charge too.
Good record keeping, sound sizing techniques, and knowing how to inspect brass has saved me from incepient seperations though

 

[rweaver00geo]

Re: Exceed published data or not? 308 benchmark 168gr

Im using rem case and fed 210 primer, book data shows win case and fed 210m. One more thing I have not noticed any extractor marks on the brass at 42 grains.

 

[victorz]

Re: Exceed published data or not? 308 benchmark 168gr

Somehow, Sierra's load data is kind of different (low) from other sources. If your data is not from sierra you may want to be caution, because temperature also effects MV or pressure (It's winnter now). I don't know much about your powder, if its temperature sensitive, you may want to be careful shooting it in summer with the same load you use now.

I use 44.1 varget("high tech" temperature stable powder) FC case, cci br-2, 175smk, and still can notice the temperature shift(I'm not sure if it's temperature or clean bore). it's excellent with my 1:12 26" bbl CZ550 and ssg69.

 

[2Shots]

Re: Exceed published data or not? 308 benchmark 168gr

Like most guys here I would start with varget, load in the 42.5 grain range and work up. Watch for pressure signs as you go up, flat or flowing primers, sticky bolt, ejector swipe etc. Don't increase over .2 gr at a time and stay off the lands. You'll see where it wants to be. With that short barrel you will be a little over book.

 

[rweaver00geo]

Re: Exceed published data or not? 308 benchmark 168gr

42.2 grains benchmark test results = Im still alive. Heres what I observed after shooting a 3round test group. No sticky bolt, no marks on the case from bolt face, primers kinda flat, firing pin strikes were deeper, no point of impact shift. .2 grains of benchmark is about 28 pieces thats all.
Pic states 3mils up when it was 3/10 up, that was scope setting adjusted not actual shift up. Holes were measured outside to outside. I guess accuracy technically increased however its not really worth it and ideally a 5 round group would have been better. The 3 round 42grain test was used for a comparison and that was accurate for past 42 grain tests.