308 Win 125 grs advice pls

[Roverguy]

I’m developing a 125 grs coyote load for my PTR 91. To answer the obvious question “why?” I have that rifle all set up for hog hunting, with a Sightmark Wraith night vision scope with an aftermarket IR Illuminator that’s good for 250 yards, at which distance the PTR is still sufficiently accurate for coyote.

Did an initial test yesterday with 3 powders: Benchmark, IMR 4895, and IMR 8208 XBR with two loads for each using 125 grs Hornady SST (all R-P brass and WLR primers). Start loads were just above Hodgdon published loads and Second loads were 1 - 2 grs below published max. Unfortunately, I kept the brass collector on for all tests and so when I looked at brass afterwards and saw some flattening of primers and some deeper than usual primer strikes, ie pressure signs, I don’t know which load they were from - yes, stupid. IMR 8208XBR seems the likely culprit given its published high pressure of 60,100 psi for max load of 49.2 grs.

In any event, my gut is saying “pursue Benchmark” and test again up to the second/higher charges, but wanted to see if anyone has experience of these powders with 125 grs and any advice?

All RP brass, WLR primers, 125 grs SST loaded to cannelure.

Benchmark 46.5 grs (1 grs below max)
SD 9.7
MV 2,947

IMR 4895 49 grs (2.8 below max)
SD 22.8
MV 2,945

IMR 8208XBR (1.2 grs below max)
SD 11.8
MV 3,009

Just wondering if anyone has prior experience with these powders and 125 grs bullets.

There was very little difference in accuracy between these groups, with the 4895 group opening up a bit. My plan would be to go back at Benchmark, starting at 44 grs and working up 45 grs, 45.5, 46 and back up to 46.5 looking for pressure signs. Any advice and counsel welcome but these are the powders and bullets I’m working with and this is the rifle it’s for, so “You should be using 223 and xyz components” may be true; but not relevant to this discussion, thanks.

 

[AJC1]

Your using exactly the powders I would recommend for good accuracy and good stability. With the velosity all being close, barring nothing else I would choose the one generating the lowest pressure. You didn't list the 8208 load but it appears benchmark is also the wowest charge weight, yeah fore effiency.

 

[TEXASJD]

I know it's not on your list but 748 is an awsome powder in 308 with 125s. I did have some accurate loads with benchmark and 125s in one of my ar10s and a M1A that I was testing. Of those powders you have if I could get 8208 too shoot that's what I would go with because it seems totally tempature stable in my testing.

 

[Charlie98]

It's my understanding IMR8208 gets a little flaky at max load, it's one of the reasons I've avoided it.

FWIW, you might consider something a wee bit faster. I use IMR3031 for my 110grn .308 loads, and if I was loading 125's, that's where I would go, too.

 

[IALoder]

I'd do your plan with Benchmark and then if you didn't find anything satisfactory, try the same with 8208XBR. Both are great powders for the bullets you're using!

 

[Barman54]

OK
I shoot a 125 TNT Speer in My M1A for 200 Stand & Sit In Highpower Competiton.
I Use 41.5/ IMR 489, 2.750 OAL
The load shoot Really Good

Barman54
Out

 

[41 Mag]

I've loaded the Hornady and the Barnes TTSX in 125gr. I used H4895 mainly because I had it and was working up reduced loads for my grandsons.

That said, I found that working up in small increments did effect the group sizes. The impact velocities need to be in the 2200'ish+/- range for full expansion.

I suggest starting at the point of reliable functioning and work up in around .2gr increments until something groups. Then, and I know that it's not much, but maybe check the seating depth. If you're using a crimp, start at the top edge and work to the bottom. If not, start at the max magazine length and work back a bit.

I didn't have much luck with 8208 with any weight in my semi, and I haven't tried Benchmark or the IMR version of 4895 but it's close enough to the Hodgdon with these weight bullets until you get on the top end and should work out well. I'm using the Hodgdon version with 150 and 165gr in mine.

 

[alsaqr]

FWIW, you might consider something a wee bit faster

Methinks so too.

Have not loaded 125 and 130 grain bullets in .308 for many years. My best loads with those bullets used IMR 3031. IMR 3031 is my got to powder for bullets of 150 grains and less.

Maybe i should do something with that box of .308 130 grain Barnes TSX bullets on the shelf.

 

[Nature Boy]

I made a bunch of 125gn VMAX loads for a Prairie Dog hunt and used Benchmark. Very accurate and light recoil for a .308

 

[cougar1717]

About 10 years ago, I tested 125gr Remington Accutip bullets in 308Win when the 30 RAR was flopping and manufacturers were liquidating components. I worked up loads for two semi-auto "battle" rifles with both TAC and IMR-3031. Both loads were able to attain just over 1 MOA performance (1.1" in one rifle and 1.25" in the other, with 5 shots at 100yds in a scoped rifle).
The problem was that these loads lived at or near max and the best groups came with flat primers and sometimes bent rims.

I get that attaining 1 MOA isn't the end all be all, but if the purpose is to varmint hunt with a rifle/load combination like this, it's tough sledding if the combination only attains 2.0-3.0 MOA. Small groups are needed to hunt small things.
I tested additional downloaded charge weights and found another accuracy node just over 1 MOA , but when I chrono'd that load, it only achieved 2650 fps. The BC's of the 125gr bullets aren't that great, so I really didn't want 30-30 performance out of my 308Win.

Semi-auto rifles are just machines and they need a certain bandwidth to cycle well and also have a reasonable lifespan without shedding parts.

So, I gave up on 125gr in 308Win and perfected loads in heavier bullet weights that don't show pressure signs. That was my experience with 125's in 308Win. This is an instance where a bolt rifle with this combination would work better since the cycling criteria is out of the equation.

 

[Roverguy]

About 10 years ago, I tested 125gr Remington Accutip bullets in 308Win when the 30 RAR was flopping and manufacturers were liquidating components. I worked up loads for two semi-auto "battle" rifles with both TAC and IMR-3031. Both loads were able to attain just over 1 MOA performance (1.1" in one rifle and 1.25" in the other, with 5 shots at 100yds in a scoped rifle).
The problem was that these loads lived at or near max and the best groups came with flat primers and sometimes bent rims.

I get that attaining 1 MOA isn't the end all be all, but if the purpose is to varmint hunt with a rifle/load combination like this, it's tough sledding if the combination only attains 2.0-3.0 MOA. Small groups are needed to hunt small things.
I tested additional downloaded charge weights and found another accuracy node just over 1 MOA , but when I chrono'd that load, it only achieved 2650 fps. The BC's of the 125gr bullets aren't that great, so I really didn't want 30-30 performance out of my 308Win.

Semi-auto rifles are just machines and they need a certain bandwidth to cycle well and also have a reasonable lifespan without shedding parts.

So, I gave up on 125gr in 308Win and perfected loads in heavier bullet weights that don't show pressure signs. That was my experience with 125's in 308Win. This is an instance where a bolt rifle with this combination would work better since the cycling criteria is out of the equation.

Thanks very much. That’s good insight. I’ve been away so haven’t had the chance to follow up at the range, but it may just be that forcing this rifle or 125s in 308 just aren’t a great idea. It’s not as if I don’t have good options in the 22 - 270 range; I’m just disguising lazy as exploratory

 

[TEXASJD]

When I get home I will look at some 125g loads I shot in gas guns. I had surgery today so may be a few days before I can, but I recall very good results with W748 and WC846. Bullets I remember where 125GK and 125MK

 

[Roverguy]

So, life happened, part of which was a very pleasant two weeks in Portugal so I do not complain, but I finally got back to this.

Went back and tested Benchmark from 45 grs up through 46.5 grs in 0.5 grs increments. No blown primers or even flattened or other pressure signs. I will measure case heads but the PTR does a number on brass, so that may be a fools errand. In any event, 46 grs came in at 2902 fps MV and an SD of 9.1, so I think that’s the likeliest candidate. Will shoot for fine accuracy next and see how it goes.

Doesn’t answer the question as to whether it was the 8208 XBR that gave me the blown primers. But I don’t feel the need to find out.