diff --git a/src/JBrowse/Store/SeqFeature/BAM.js b/src/JBrowse/Store/SeqFeature/BAM.js
index 00c476f19e..5ab5d42bba 100644
--- a/src/JBrowse/Store/SeqFeature/BAM.js
+++ b/src/JBrowse/Store/SeqFeature/BAM.js
@@ -146,8 +146,8 @@ return declare( [ SeqFeatureStore, DeferredStatsMixin, DeferredFeaturesMixin, In
                 baiFilehandle: baiBlob,
                 csiFilehandle: csiBlob,
                 renameRefSeqs: n => this.browser.regularizeReferenceName(n),
-                fetchSizeLimit: 100000000 || args.fetchSizeLimit,
-                chunkSizeLimit: 10000000 || args.chunkSizeLimit
+                fetchSizeLimit: args.fetchSizeLimit || 100000000,
+                chunkSizeLimit: args.chunkSizeLimit || 20000000
             })
 
             bamIndexedFilesCache.set(cacheKey, this.bam)
diff --git a/src/JBrowse/View/Track/Alignments2.js b/src/JBrowse/View/Track/Alignments2.js
index 3de15d695d..bc4cc904cb 100644
--- a/src/JBrowse/View/Track/Alignments2.js
+++ b/src/JBrowse/View/Track/Alignments2.js
@@ -157,8 +157,8 @@ return declare( [ CanvasFeatureTrack, AlignmentsMixin ], {
                 region.end = region.end
 
                 this.store.getPairedRanges(region, range => {
-                    region.start = Math.max(0, Math.max(range.min, reg.start - len*4))
-                    region.end = Math.min(range.max, reg.end + len*4)
+                    region.start = Math.max(0, range.min - len)
+                    region.end = range.max + len
                     this.store.getFeatures(region, function() {}, resolve, reject)
                 }, reject)
             }).then(() => {