Reloading for OBR -Pressure Question

[mkollman74]

Hi All -

This AM I went to the range with my first batch of loads in trying to develop a load for my OBR. I am loading 175 SMKs into LC brass with FED 210M primers and Varget. I started with 42.0 grains and worked my way up to 44.0 in 0.5 grain increments. Accuracy ranged from 0.6MOA to MOA, and top velocity was ~2520 from my 18" barrel. My goal is to get to around 2600 fps. I am figuring I will get there somewhere around 45.0 grains.

If I like the accuracy I am getting there, I will call that my load. Anyone with more experience reloading for a semi- have any concerns about pressure or otherwise with my plans? I have been relaoding for awhile now, but never for a gasser.

 

[poison123]

Re: Reloading for OBR -Pressure Question

45gr's with a 175 is getting hot for a Bolt......I'd say that would be pretty hot for a gasser.

Try 44.2gr, should be a decent velocity with a good accuracy node.

 

[mkollman74]

Re: Reloading for OBR -Pressure Question

Thanks for the feedback. I'll work up in 0.2 grain increments checking for the normal pressure signs. I don't want to run it particularly hot.

 

[Strong972]

Re: Reloading for OBR -Pressure Question

You have me worried about my game plan. I have a 16” OBR and was planning on using an FDAC card for the 175 SMKs. The problem is that the card with the lowest velocity is 2500 fps. Based on your results, I am not sure if I’m going to get there. I believe the 16” barrel is about 50 fps slower than the 18”.

If you get the chance, please update us with your results at higher velocities.

 

[CST]

Re: Reloading for OBR -Pressure Question

You wont know whats hot for YOUR gun until you shoot it and look for the signs. LC brass is tight so 45grs. will be on the hotter side. I use 45grs. in winchester brass which put out 2550fps out of my 18" and puts out 2720 out of my bolt with little or no pressure(dpends on temp) you need to shoot for groups at 100 and 300 and check the chrono for numbers to figure out your load. Alot of the guys like the ladder or other methods all over the internet to choosing the load..

Dont sweat the number too much..in the long range shots your only going to be off a few 1\10s of a mil. Just concentrate on the accuracy..and mid 2500s seem to be ok for the 18" without too much pressure.

 

[mkollman74]

Re: Reloading for OBR -Pressure Question

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: CST</div><div class="ubbcode-body">You wont know whats hot for YOUR gun until you shoot it and look for the signs. LC brass is tight so 45grs. will be on the hotter side. I use 45grs. in winchester brass which put out 2550fps out of my 18" and puts out 2720 out of my bolt with little or no pressure(dpends on temp) you need to shoot for groups at 100 and 300 and check the chrono for numbers to figure out your load. Alot of the guys like the ladder or other methods all over the internet to choosing the load..

Dont sweat the number too much..in the long range shots your only going to be off a few 1\10s of a mil. Just concentrate on the accuracy..and mid 2500s seem to be ok for the 18" without too much pressure. </div></div>

Thanks for sharing your experience. I know I need to shoot the load in my gun to decide. My question was really whether others had found excessive pressure in theirs using the same components and charge weight. A buddy of mine is getting about 2524fps from M118LR from his 18" OBR. I am hoping I can duplicate that or do a smidge better with 0.75MOA or better accuracy.

 

[rowrd]

Re: Reloading for OBR -Pressure Question

I've been reloading for my 18" OBR for the last few months, but have been staying at the lower end of the pressure and velocity side.

What I've noticed in my particular rifle..others may be different....

VV140 (42 grs) and Sierra 175's (Winchester brass/Fed 210m) will average between 0.5 and 0.75 moa at 100.

Varget (42gr) and sierra 175's are about the same, but my shooting buddy did manage one great group of 0.3 at 100.

XBR 8208 (41.5grs) and Nosler Custom Competitions 168s' are promising..usually around or under 0.5....a little more consistant than 168 MatchKings.

XBR 8208 and Sierra 155's ..ejector swipes with at 43grs, groups similar to the Varget/175 combo

Of course, my shooting is not the best. It is true what everyone here has said about a 308 AR style rifle having to be "driven". Still learning....

 

[mkollman74]

Re: Reloading for OBR -Pressure Question

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: rowrd</div><div class="ubbcode-body">I've been reloading for my 18" OBR for the last few months, but have been staying at the lower end of the pressure and velocity side.

What I've noticed in my particular rifle..others may be different....

VV140 (42 grs) and Sierra 175's (Winchester brass/Fed 210m) will average between 0.5 and 0.75 moa at 100.

Varget (42gr) and sierra 175's are about the same, but my shooting buddy did manage one great group of 0.3 at 100.

XBR 8208 (41.5grs) and Nosler Custom Competitions 168s' are promising..usually around or under 0.5....a little more consistant than 168 MatchKings.

XBR 8208 and Sierra 155's ..ejector swipes with at 43grs, groups similar to the Varget/175 combo

Of course, my shooting is not the best. It is true what everyone here has said about a 308 AR style rifle having to be "driven". Still learning.... </div></div>

I am with you on the still learning bit. Learning this OBR has been humbling. It's a good challenge and it makes me think of technique and fundamentals with every shot...

 

[BCP]

Re: Reloading for OBR -Pressure Question

If 44 is giving you the velocity you want more or less maybe play around with seating depth? I have found 175SMK like to be 2.81-2.82 in my semis.

Also I don't see another grain of varget gettng you 80fps. Maybe 20-30 and 45 will be overmax in LC brass. If you want more velocity try a high energy powder like 2000MR. 50-100FPS gain at same pressures.

 

[mkollman74]

Re: Reloading for OBR -Pressure Question

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: BCP</div><div class="ubbcode-body">If 44 is giving you the velocity you want more or less maybe play around with seating depth? I have found 175SMK like to be 2.81-2.82 in my semis.

Also I don't see another grain of varget gettng you 80fps. Maybe 20-30 and 45 will be overmax in LC brass. If you want more velocity try a high energy powder like 2000MR. 50-100FPS gain at same pressures. </div></div>

Thanks for the knowledge. You may be right about the seating depth. I also haven't done a thing with brass prep - just took 'em from the box (once fired)cleaned and FL sized.

 

[mkollman74]

Re: Reloading for OBR -Pressure Question

Just a quick update: Back at the range today I got the following:

44.4 Varget = 2527fps; 0.579" 5 shot group
44.6 Varget = 2570fps; 0.458" 5 shot group(not including 1st round flyer. 1.27" with flyer)
44.8 Varget = 2607fps; 1.021" 5 shot group
45.0 Varget - 2615fps; 0.621 5 shot group

No visible pressure signs. Primers looked fine. No extraction issues.

 

[m1ajunkie]

Re: Reloading for OBR -Pressure Question

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: mkollman74</div><div class="ubbcode-body">Just a quick update: Back at the range today I got the following:

44.4 Varget = 2527fps; 0.579" 5 shot group
44.6 Varget = 2570fps; 0.458" 5 shot group(not including 1st round flyer. 1.27" with flyer)
44.8 Varget = 2607fps; 1.021" 5 shot group
45.0 Varget - 2615fps; 0.621 5 shot group

No visible pressure signs. Primers looked fine. No extraction issues. </div></div>

I am loading for a 16" LMT MWS and my load is using 44gr varget and lc lr brass with the 175smk. Velocity is right at 2500fps, I am very happy with this load. I would like more velocity, but I don't want to beat up my equipment to chase a couple fps.

 

[colt933]

Re: Reloading for OBR -Pressure Question

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: rowrd</div><div class="ubbcode-body">
Of course, my shooting is not the best. It is true what everyone here has said about a 308 AR style rifle having to be "driven". Still learning.... </div></div>

No doubt! I get 3-4 touching with a flyer making it 1.25MOA about half the time. The gas guns are much more demanding in NPA and follow through than bolt guns - even with a good brake.

 

[mkollman74]

Re: Reloading for OBR -Pressure Question

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: m1ajunkie</div><div class="ubbcode-body">
I am loading for a 16" LMT MWS and my load is using 44gr varget and lc lr brass with the 175smk. Velocity is right at 2500fps, I am very happy with this load. I would like more velocity, but I don't want to beat up my equipment to chase a couple fps. </div></div>

I hear you on not wanting to beat up your stuff just so you can squeeze every last fps out of it. Sounds like you are doing pretty well though. 2,500fps from a 16" with 44 grains of Varget seems pretty respectable to me.