Question about recoil in my .308

[pitsnipe]

I have been reloading .308 for about 12 years now. But not until recently did I get real "serious" about it. To the point of seperating brass by brand AND weight. I recently "discovered" (probably been happening all along but I didnt pay much attention to it) a difference in the way my model 88 Winchester recoils. Basicly two very distinct differences. With most of my loads a "sharp" snap or popping up off of the sandbag is present. In less of my loads a distintly different "punch" backward with no "bounce" of the barrel. Accuracy doesnt seem to vary much. As I have a few loads in 150, 165 and 180 grain that can consistantly punch MOA holes at 100yds. And the one load that had the smoothest "punch" recoil was a 180 grn load. Five shot group 1.125 MOA. Just curious if anyone can help me understand the reason why the gun would recoil so differently. And what that would mean.
Thanks, and a great site here on all things shooting long range.

 

[rscott5028]

Your explanation was somewhat vague about which load details produced a specific type of felt recoil.

But, in general terms...

Higher pressure with heavier projectiles will recoil different from lower pressure with lighter projectiles.

The amount of bearing surface for the different bullets will also have an effect on pressure and felt recoil.

And, different powder/primer combinations with varying burn rates under different case capacities due to seating depths of various bullets and various makes of brass will change the pressure curve and hence the characteristics of your felt recoil.

-- richard

 

[pitsnipe]

Richard,

Thank you for the reply. I was going to detail the bullet type, its weight , powder and amount but I thought theat would just drag on the question. In "general terms" was what I thought would make the answer easier. And you pointed that out for me very well. It was only that specific load (and it was with a 180 grn Nosler Partition) that the recoil was sooo much different. Almost more "pleasant" if you will. Just a nice punch vs the jump/snap with ALL of the other loads that ranged from 150, 165, and 180 grns. I will keep experimenting with the brass and powder charge to get the most accuracy. Just have too much fun with the challenge of shooting a MOA pattern at 300 plus yards. Working on the 400 yard mark. But I think I'm probably streching the limits of that ole .308.
Thanks again. Great site. And still learning a lot.

 

[baldhunter]

Powders and bullets do make a difference in felt recoil.In my 300 Win Mag,a 165gr bullet has a sharper felt recoil than in my 180gr loads.When I first started reloading for my 7mag,I tried some slow burning H-870.The recoil was fairly potent with the 160gr bullet I was shooting.I shot another round of test loads,this time with IMR-4350.The felt recoil was quite milder,but my chronograph told me I was 200fps faster!!!

 

[royinidaho]

Your experience gives the appearance of varying pressures with different loads.

I seem to remember that excessive pressure isn't a good thing with your rifle. With that as a caution, it may be well to chrono the two different 180gr loads.

You'll probably find that those that snap are more velocity/higher pressure than the pleasant push. If your partition load has performed well for you on game it could be the goto game load. If its just poking along you may wish to reconsider its use.

 

[pitsnipe]

Thank you for the input. I think you are correct that the loads that "snap" are likely higher pressure as they are loads at the top end of the bullet mfr's suggested range. I have a few loads made up that back off considerably from there to see if their is much difference in the "type" of recoil. I have been watching for excessive pressures closly. Examining each case after the shot for flattened primers and case stretching.
I dont have access to a chrono. So all I have been using as a gauge for what load I will settle for is accuracy. Taking the most accurate loads from the last time at the range and selecting a few for cold bore (the next time to the range) accuracy then with minor fouling, trying others.