Bullseye-L Forum
Would you like to react to this message? Create an account in a few clicks or log in to continue.

Velocity spread?

Go down

Velocity spread? Empty Velocity spread?

Post by JimTMich on Mon Jul 27, 2020 11:26 pm

I have been using 3.7 - 4.0 grains of Bullseye and 200 LSWC for 25+ years.

I finally had a opportunity to put a magazine full across a chronograph tonight and was shocked to see a spread from 690's to 740's with 4.0gr Bullseye.  Loading was done with an old Hornady Projector(old version of their current progressive press).

Is this normal, acceptable, common for progressives, fine for 25 yards but better hand weigh for 50 yard?  Or do I need to polish my powder measurer/weigh some loads and see what the powder spread is?

JimTMich

Posts : 135
Join date : 2019-04-01
Location : Kalamazoo, Michigan

Back to top Go down

Velocity spread? Empty Re: Velocity spread?

Post by Wobbley on Mon Jul 27, 2020 11:45 pm

I chronographed your range.  My results were:

3.8 gr   700 SD 8.0
4.0 Gr.  740 SD 5.8

SD is about 1/3 of the extreme spread so a SD of 8 would be an ES of 24... that means 95% of all rounds would be between 676 and 724.  

I load on a LNL but what powder measure are you using?
Wobbley
Wobbley

Posts : 2664
Join date : 2015-02-13

Back to top Go down

Velocity spread? Empty Re: Velocity spread?

Post by STEVE SAMELAK on Tue Jul 28, 2020 6:53 am

My question would be how are they grouping?  If you shot them well, why be concerned?
Yes consistency is key but I think consistency between the ears is the downfall of most of us.
STEVE SAMELAK
STEVE SAMELAK

Posts : 765
Join date : 2011-06-10

Al, BE Mike and lakemurrayman like this post

Back to top Go down

Velocity spread? Empty Re: Velocity spread?

Post by james r chapman on Tue Jul 28, 2020 7:35 am

I once shot trap with a world champion.
He neither patterned nor chronographed his loads.

He said he didn’t want his mind distracted by that information,
Was satisfied with breaking 200 birds consistently.
james r chapman
james r chapman
Admin

Posts : 4216
Join date : 2012-01-31
Age : 71
Location : HELL, Michigan

Al and lakemurrayman like this post

Back to top Go down

Velocity spread? Empty Re: Velocity spread?

Post by SteveT on Tue Jul 28, 2020 8:41 am

STEVE SAMELAK wrote:My question would be how are they grouping?  If you shot them well, why be concerned?
+1 There is low correlation between chrono and target performance with pistol loads.

Your results are higher than I would consider typical, but not completely ridiculous. I suspect powder position is a factor, especially if one or both of the extreme values is the first value after reloading. Most of our loads don't fill the case. If the powder is closer to the primer the pressure / velocity will be higher, if it is closer to the bullet the pressure will be lower. Tipping the pistol up or down before shooting can easily result in 30-50 fps difference. With dense powder like Titegroup it can be 100 fps.

A cold pistol/ammo that warms as you shoot can also result in increased velocity spread.
SteveT
SteveT

Posts : 581
Join date : 2011-06-10
Location : Illinois

https://sites.google.com/site/sdturner/shooting

Back to top Go down

Velocity spread? Empty Re: Velocity spread?

Post by Al on Tue Jul 28, 2020 10:52 am

Yeah, your spread is a bit. But remember, we're only shooting 50 yards with a pistol held with one hand. When I first started shooting BE, I would Ransom test my loads over my chronograph. The best load I was able to come up with, on that pistol, had 30-40 fps ES. Some of the best loads for ES were horrible on paper. Let the paper be your guide, not the chronograph.

I've been into shooting long range (500-1200 yds) prairie dogs for decades. On those rifles, you better believe I pay very close attention to my SD and ES.

Al

Posts : 493
Join date : 2011-06-10
Age : 65
Location : Bismarck, ND

Back to top Go down

Velocity spread? Empty Re: Velocity spread?

Post by PhotoEscape on Tue Jul 28, 2020 10:59 am

JimTMich wrote:I have been using 3.7 - 4.0 grains of Bullseye and 200 LSWC for 25+ years.

I finally had a opportunity to put a magazine full across a chronograph tonight and was shocked to see a spread from 690's to 740's with 4.0gr Bullseye.  Loading was done with an old Hornady Projector(old version of their current progressive press).

Is this normal, acceptable, common for progressives, fine for 25 yards but better hand weigh for 50 yard?  Or do I need to polish my powder measurer/weigh some loads and see what the powder spread is?
50 fps spread is not something to worry about even at 50Y, - please see target below as an example.  However information you provided isn't sufficient to judge either.  I.e. how many rounds tested, how you shot them, have you had barrel fouled prior to starting test, etc.Velocity spread? Img_4714
AP
PhotoEscape
PhotoEscape

Posts : 749
Join date : 2018-05-15
Location : Northern Illinois, USA

Back to top Go down

Velocity spread? Empty Re: Velocity spread?

Post by dronning on Tue Jul 28, 2020 11:25 am

At 50yards a bullet going 650fps verses 850fps will impact the target something less than 0.5" lower.  So if your groups are good don't worry about it.
dronning
dronning

Posts : 2572
Join date : 2013-03-20
Age : 66
Location : Lakeville, MN

Al likes this post

Back to top Go down

Velocity spread? Empty Re: Velocity spread?

Post by S148 on Tue Jul 28, 2020 2:34 pm

I agree that extreme spread is not a measure of accuracy.  Your target will tell you how accurate the ammo shoots, not the chronograph. 

You might find this article of interest:

https://americanhandgunner.com/handguns/exclusive-consistent-velocity-accuracy/

S148

Posts : 170
Join date : 2017-07-04

Back to top Go down

Velocity spread? Empty Re: Velocity spread?

Post by farmboy on Wed Jul 29, 2020 7:51 am

I have found that older cases, reloaded many, many time over, will do this..  You indicate 25+ years of shooting.  If brass is cleaned in cob or walnut media only for many years it can develop a thin film inside the case. This film can flake off and mix with powder and give funky readings. My experience was more deviation than you indicate though but no ill effect on accuracy.  .45 is a very forgiving round in a quality gun.
farmboy
farmboy

Posts : 240
Join date : 2012-10-04
Location : Wichita, KS

Back to top Go down

Velocity spread? Empty Re: Velocity spread?

Post by James Hensler on Wed Jul 29, 2020 10:09 am

I have some experience with this because I have tested for it.
Winchester large primer case the have been reloaded many many times normally have 30-50 FPS spread on my reloads. Repeating it over and over several 1000 cases. Brand new Winchester cases the spread is under 10 FPS using the same press loaded on the same day and fired on the same day. Targets looks exactly alike with no increase in group size.
James Hensler
James Hensler

Posts : 769
Join date : 2018-01-15
Age : 51
Location : Southwest Florida

Back to top Go down

Velocity spread? Empty Re: Velocity spread?

Post by JimTMich on Wed Jul 29, 2020 1:42 pm

Thanks for the insights!
It was 8 shots in a freshly cleaned, tight range officer.  I had just gotten a little leading out.  These were the first shots of the day.  Barrel would have started dry, gun very lubed up.
It was mixed brass, I do have a lot of 25+ year old WCC and R&P brass that I have been cleaning with corncob and a little polish, but not much, they are a little dull.  
This was using a new radar based velocity device, not the typical light based chronograph.

As far as accuracy goes, This Range Officer is OK.  The loads work a lot better in the purpose built wad gun with Kart barrel.  I should quantify that statement.

This all stems from a friends new toy, not accuracy troubles... So I won't stew about it, I'll focus on accuracy.
Thanks!

JimTMich

Posts : 135
Join date : 2019-04-01
Location : Kalamazoo, Michigan

Back to top Go down

Velocity spread? Empty Re: Velocity spread?

Post by rkittine on Wed Jul 29, 2020 2:28 pm

How were you measuring the powder charges? Exactly 4 grains each? For 1,000 yard bench rest 50 FPS can mean a lot of vertical spread 3/5s of a mile away, cutting kernals to get exact load weight to the .02 grains is normal. If you are using a bushing or other powder measurer and not hand weighing each exact load, you could be getting speed variation very easily. For my 1,000 yard bench rest loads I load match rounds all at the same time so that the powder has been in the same atmospheric conditions. 4 grains of power in high humidity may give different pressures (hence speeds) as compared to some loaded at a different time or with a different lot of powder.
rkittine
rkittine

Posts : 124
Join date : 2020-06-06
Age : 71
Location : Sag Harbor & Manhattan , New York

Back to top Go down

Velocity spread? Empty Re: Velocity spread?

Post by sharkdoctor on Wed Jul 29, 2020 2:37 pm

Perhaps I should start another thread for this, but what tools do you all use to cut a Bullseye powder grain in half? Smile

sharkdoctor

Posts : 98
Join date : 2014-10-16

Back to top Go down

Velocity spread? Empty Re: Velocity spread?

Post by rkittine on Wed Jul 29, 2020 2:42 pm

I don't cut any pistol powders, just wondering how exact the 4 grain charges are. For rifle powders I use a scalpel and tiny tweezers as well as a lab level scale. 1000 yard bench rest guys are anal.
rkittine
rkittine

Posts : 124
Join date : 2020-06-06
Age : 71
Location : Sag Harbor & Manhattan , New York

Back to top Go down

Velocity spread? Empty Re: Velocity spread?

Post by sharkdoctor on Wed Jul 29, 2020 3:49 pm

For some guidance, a Lyman reloading manual notes that for a 185 JHP and 200gr SWC, and Bullseye powder, velocity varies as 146 and 143fps/grain, respectively.  So +/- 0.1gr should yield about +/-15fps.  With little mods to my Dillon (there are threads here on this) my measure easily yields less than 1% variance (0.04gr) on a 4.0gr load.  That should yield about +/-6 fps.  Many factors affect velocity.  There is a point of diminishing returns when we shoot pistols for score and try to fine-tune reloading. Eventually one finds it is best to set it and forget it. The bottom line is, how do they print repetitively on paper at 50yds?

An anecdote:

An AMU shooter at Perry Nationals gave me some left-over Atlanta Arms ammo that he said "wouldn't shoot...".  To test it I chrono'ed some rounds at 772, 772, 770 and 772 fps.  It doesn't seem that velocity variation was the problem.  With 22LR even a relatively large velocity variation will still put them all in the X-ring at 50yds.

Well, it is 5 O'Clock somewhere and my HC siete anos is waiting.

Good luck with your reloading.

sharkdoctor

Posts : 98
Join date : 2014-10-16

Back to top Go down

Velocity spread? Empty Re: Velocity spread?

Post by Wobbley on Wed Jul 29, 2020 5:36 pm

A little example.  The below targets were shot with a S&W 745 which is not an “all-up bullseye Gun” but seems accurate.  The two targets were shot with leftover chronographing loads I mentioned in my earlier post.  So there are 3.8 grain, 4.0 grain. and 4.2 grain loads in east of these targets.  The gun was rested for this.  The wide ones were called by me.  So for 25 yards, I wouldn’t worry about powder charge variances and spend the time shooting.  BTW, weighing pistol charges on a RCBS Chargemaster Light is tedious.Velocity spread? Fe757110
Wobbley
Wobbley

Posts : 2664
Join date : 2015-02-13

Back to top Go down

Velocity spread? Empty Re: Velocity spread?

Post by James Hensler on Wed Jul 29, 2020 6:43 pm

Wobbley wrote:A little example.  The below targets were shot with a S&W 745 which is not an “all-up bullseye Gun” but seems accurate.  The two targets were shot with leftover chronographing loads I mentioned in my earlier post.  So there are 3.8 grain, 4.0 grain. and 4.2 grain loads in east of these targets.  The gun was rested for this.  The wide ones were called by me.  So for 25 yards, I wouldn’t worry about powder charge variances and spend the time shooting.  BTW, weighing pistol charges on a RCBS Chargemaster Light is tedious.Velocity spread? Fe757110

I do however use the damn RCBS for my 45 load line match only loads! Lol yeah it is tedious
James Hensler
James Hensler

Posts : 769
Join date : 2018-01-15
Age : 51
Location : Southwest Florida

Back to top Go down

Velocity spread? Empty Re: Velocity spread?

Post by Sponsored content


Sponsored content


Back to top Go down

Back to top


 
Permissions in this forum:
You cannot reply to topics in this forum